Muter's Analytical Chemistry The Standard Chemical Text-books. 
RICHTER’S INDRGANIC AND ORGANIC CHEMISTRY. 
Inorganic Chemistry, a Text-book for Students. By Prof. Victor 
von Richter, University of Breslau. Third American from 
Fifth German Edition. Authorized Translation. By Edgar 
F, Smith, m.a., ph.d., Prof, of Chemistry, Wittenberg College, 
formerly in the Laboratories of the University of Pennsylvania, 
Member Chem. Societies Berlin and Paris, etc. With 89 Ulus, and 
a Colored Plate of Spectra. 12mo. Cloth, $2.00 
OCr” This Edition has been thoroughly revised, and many parts rewritten, 
and is handsomely printed. 
From F. A. Genth, Prof, of Chemistry, and F. A. Genth, Jr., Ass't Prof, of Chemistry, University of Penn- 
sylvania. 
“We have examined with much care the ‘lnorganic Chemistry’of Pi'of. Victor von Richter, re- 
cently translated by Dr. E. E. Smith. Botli theoretical and general chemistry are treated in such a 
clear and comprehensive manner that it has become one of the leading text-books for a University 
course in Germany. We are indebted to I)r. Smith for his translation of this excellent work, which 
may help to facilitate the study of chemistry in this country.” 
From Prof. B. Silliman, Yale College, New Haven, Conn.—“It is decidedly a good book, and in some 
respects the best manual we have.” 
From Prof. Sam'l S. Green, Swarlhmore College, Penn'a.—“ lam of the opinion that it is the best text- 
book of the kind I have seen. I shall recommend it to my classes.” 
From Prof. A. A. Bennett, Chicago University.—-“I am satisfied this work is the best that I have yet 
seen, and that it will in a high degree fill the want.” 
Prom E. H. S. Bailey, University of Kansas, Lawrence.—“ Dr. Smith has, by his excellent translation, 
brought into prominence one of the best and most recent books upon the science of chemistry.” 
From the Science Record, Boston.—“ Notwithstanding the multitude of text-books on chemistry, 
there is always room for a good one, and the present work will undoubtedly fall under this head. 
Prof, von Richter’s work met with great success abroad, owing to its unusual merit. In presenting 
the subject to the student, the author makes a point to bring out prominently the relations existing 
between fact and theory, too commonly considered apart. * * * The rapid sale, in Germany, ot 
three editions of this work seems to show the common verdict is greatly in favor of its inductive 
methods. * * * The periodic system is so treated as to prove a really valuable aid to the student, 
and especially in the relations of the metals. * * * Von Richter’s text-book deserves a hearty 
welcome at the hands of teachers of chemistry desirous of instructing in modern theories and on a 
rational basis. This translation is neatly printed on paper of light weight, making a very convenient 
handbook.” 
From Prof. T. H. Norton, University of Cincinnati.—“Few modern authors of chemical text-books 
have succeeded as happily as von Richter in presenting to the student, in an attractive, comprehensible 
manner, the leading features of theoretical chemistry. * * * Von Richter’s clear, lucid presenta- 
tion of fact and theory has, if anything, gained by Dr. Smith’s admirable translation.” 
BY THE SAME AUTHOR AND TRANSLATOR, 
CHEMISTR Y OF THE CARBOH COMPOUNDS, or, 
O/ganic Chemistry ; a complete Text-hook and Laboratory Guide 
for Students. Authorized Translation from the Fourth German 
Edition. Illustrated. Cloth, $3.00 
In those schools where not sufficient time is given to allow of using 
a complete Text-book, this work will be found of incalculable use 
for a reference. It is the most compendious and the latest Organic 
Chemistry. 
From W. 11. Seaman, Prof, of Chemistry, Howard University, Washington, D. G.—“ It is undoubtedly 
the best text-book of its class.” 
From T. J. Wrampelmeier, Asst. Prof, of Organic Chemistry and Pharmacy, University of Michigan, Ann 
Arbor.—“ I shall recommend it to my classes as the best text-book on organic chemistry. ■' 
Prom J. S. Schanclc, Princeton College, N. J.—“I consider it one of the choicest works on organic 
chemistry.” 
From Prof. F. P. Venable, University of North Carolina, Chapel Hill, N. O.—“ The methods of dividing 
and grouping is a great aid to the memory and to an intelligent conception of the subject.” 
From Sam'l T. Sadtler, Prof, of General and Organic Chemistry, University of Pennsylvania, and Prof, 
of Chemistry, Philadelphia College of Pharmacy.—“ It presents in a concise form the most modern views 
of the theory, and gives, moreover, many very practical methods. * * * The freshness of its 
information may he noted. * * * I consider it compares favorably with any book upon this 
subject in the English language.” 
OCU Richter’s Chemistries are recommended at Yale College, Uni- 
versity of Pennsylvania, Johns Hopkins and Rutgers Colleges, 
Rennsselaer Polytechnic Institute, Troy, N". Y., Wisconsin State 
University, Trinity College, Hartford, Conn., and many other 
prominent Schools. Descriptive Circular upon Application. 
P. BLAKISTON, SON & CO., 1012 WALNUT STREET, PHILADELPHIA. A MANUAL 
OF 
ANALYTICAL CHEMISTRY, 
QUALITATIVE AND QUANTITATIVE— 
INORGANIC AND ORGANIC. 
ARRANGED ON 
THE PRINCIPLE OF THE COURSE OF INSTRUCTION GIVEN AT 
THE 
SOUTH LONDON CENTRAL PUBLIC LABORATORY, 
AND THE 
SOUTH LONDON SCHOOL OF PHARMACY. 
BY 
JOHN MUTER, M.A., Ph.D., F.R.S.E., F.I.C., F.C.S., 
DIRECTOR OF THE LABORATORY; ANALYST TO THE METROPOLITAN ASYLUMS BOARD; PUBLIC ANALYST 
FOR LAMBETH, WANDSWORTH, SOUTHWARK, NEWINGTON, BERMONDSEY, ROTHERHITHE, AND 
TENTERDEN ; PAST PRESIDENT OF THE SOCIETY OF PUBLIC ANALYSTS ; AUTHOR OF ’ 
c£ PHARMACEUTICAL AND MEDICAL CHEMISTRY” (THEORETICAL AND 
DESCRIPTIVE), “A KEY TO ORGANIC MATERIA MEDICA 
EDITOR OF “THE ANALYST,” ETC., ETC. 
THIRD EDITION, ENLARGED, WITH 
ILLUSTRATIONS. 
PHILADELPHIA: 
P. BLAKISTON, SON & CO., 
1012 Walnut Street, 
1887. PREFACE. 
In the present edition of this book a condensation in bulk has been 
attained, but, by help of a change in the style of printing, a greatly 
increased amount of special matter has at the same time been introduced. 
In writing such a book it is always difficult to draw the line as to the 
exact extent to which it should go, but I trust that I have fairly 
succeeded in adopting a wise limit. 
The object of the work has been to produce a manual at once short 
and easily understood, but yet taking the student from the simplest to 
the most complex matters of qualitative analysis, and also dealing with 
quantitative work sufficiently to give him a fair insight into all branches 
of this department. Students preparing for special examinations will find in 
the book information suitable for every Pharmaceutical or Medical and most 
general University Examinations in Practical Chemistry now in existence ; 
while the student who works through it will become a sufficiently expert 
general analyst to enable him to decide to what speciality, and consequently 
to which of the large standard works, he will devote his future attention. 
Teachers will also, I hope, find the present edition specially worthy of 
attention, as it is divested of those minute details which can really only 
be supplied by personal supervision. Every process given is the result 
of twenty years’ experience in the teaching of practical chemistry, and 
all have been carefully tested by actual work in the hands of students, 
except where official processes of the Pharmacopoeia are necessarily intro- 
duced. The acid course is, so far as I know, the only one published that 
goes on like the ordinary metal course, and certainly and successively 
detects all the acids in one direct line of experiments. 
In conclusion, I trust that an equal amount of favor will be shown to 
present edition as has been extended to the past ones, both in Great 
Bntain and in America. 
J. M. 
"Winchester House, Kennington, London, S.E., 
September 1887. TABLE OF CONTENTS. 
PART /.—QUALITATIVE ANALYSIS. 
CHAPTER I. 
The Processes Employed by Practical Chemists. 
PAGE , 
1. Solution ..... i 
2. Lixiviation and Extraction . . 2 | 
3. Precipitation .... 2 j 
4. Decantation . . . . 3 
5- Filtration ..... 3 
6. Distillation 4 
7- Sublimation . . . . 4 
PAGE 
8. Fusion ..... 4 
9. Evaporation .... 5 
10. Crystallisation and Dialysis . 5 
11. Electrolysis .... 6 
12. Pyrology ..... 7 
13. Preparation of sulphuretted hy- 
drogen ..... 9 
CHAPTER 11. 
Detection and Separation of the Metals. 
Group Reagents .... io-ii 
Group I. . , . ( j j 
1. Silver . . . . . u 
2. Mercurosum . . . . 12 
3- Lead . . . . . X 2 
Group 11. 13-18 
Division A. . . . t .13-15 
1. Mercuricum . . . _ I-. 
2. Bismuth .... 14 
3. Copper • . . . ! 14 
4. Cadmium . _ _ _ 
Division B. . . . .15-18 
1. Arsenic ..... 15 
2. Antimony .... 16 
3- Tin ..... 17 
4- Gold ..... 17 
5- Platinum .... 18 
Group 111 18-24 
Division A. . . . . . 18-21 
1. Iron . . . . . 18 
2. Cerium ..... 20 
3. Aluminium .... 20 
4. Chromium . . . . 21 
Division B. . . . . 21-24 
1. Manganese . . . . 21 
2. Zinc ..... 22 
3. Nickel ..... 23 
4. Cobalt ..... 23 
Group IV. 24-26 
1. Barium ..... 24 
2. Strontium .... 25 
3. Calcium . . . . 25 
Group V. ..... 26-28 
1. Magnesium .... 26 
2. Lithium .... 26 
3. Potassium .... 27 
4. Sodium .... 27 
5. Ammonium .... 27 viii 
TABLE OF CONTENTS. 
CHAPTER 111. 
Detection and Separation of Acidulous Radicals. 
PAGE 
1. Hydrofluoric Acid and Fluorides 29 
2. Chlorine, Hydrochloric Acid, and 
Chlorides .... 29 
3. Hypochlorites .... 30 
4. Chlorates ..... 30 
5. Separation of Chlorates and 
Chlorides .... 30 
6. Perchlorates .... 30 
7. Bromine, Hydrobromic Acid, and 
Bromides .... 30 
8. Detection of Chlorides in the 
presence of Bromides . . 31 
9. Hypobromites . . . . 31 
10. Bromates ..... 31 
11. lodine, Hydriodic Acid, and lo- 
dides ..... 32 
12. Detection of Bromides in the 
presence of lodides . . 32 
13. Detection of Chlorides in the 
presence of lodides . . 32 
14. Separation of an lodide from a 
Bromide and Chloride . . 33 
15. lodates 33 
15a. Detection of an lodate in an 
lodide 33 
16. Periodates . . i . . 33 
17. Water and Plydrates ... 33 
18. Oxides ..... 34 
19. Sulphur, Hydrosulphuric Acid, 
and Sulphides ... 34 
20. Detection of a Soluble Sulphide 
in presence of a Sulphite and 
a Sulphate .... 36 
21. Thiosulphates (Hyposulphates) . 36 
22. Separation of Thiosulphates from 
Sulphides .... 36 
23. Sulphurous Acid and Sulphites . 36 
24. Sulphuric Acid and Sulphates . 37 
25. Separation of Sulphides, Sul- 
phites, and Sulphates . . 38 
26. Carbon, Carbonic Acid, and Car- 
bonates .... 3^ 
27. Boric Acid and Borates .. . 39 
28. Silicic Acid and Silicates . . 39 
29. Separation of Silicic Anhydride 
(Silica) from all other Acids. 40 
30. Hydrofluosilicic Acid . . . 40 
31. Nitrous Acid and Nitrites . . 40 
32. Detection of a Nitrite in the 
presence of a Nitrate . . 41 
33. Nitric Acid and Nitrates . . 41 
34. Detection of free Nitric Acid in 
the presence of a Nitrate . 42 
35. Detection of a Nitrate in the 
presence of an lodide . . 42 
36. Separation of Chlorides, lodides, 
and Bromides from Nitrates 42 
37. Cyanogen, Hydrocyanic Acid, 
and Cyanides ... 43 
38. Separation of Cyanides from 
Chlorides .... 44 
PAGE 
39. Cyanic Acid and Cyanates, 
Cyanuric Acid, and Fulminic 
Acid 44 
40. Thiocyanates (Sulphocyanates) . 44 
41. Ferrocyanides .... 44 
42. Ferricyanides .... 45 
43. Separation of Ferro- from Ferri- 
cyanides .... 45 
44. Detection of Cyanides in the 
presence of Ferro- and Ferri- 
cyanides .... 45 
45. Hypophosphites.... 46 
46. Phosphorous Acid and Phos- 
phites ..... 46 
47. Meta- and Pyro-Phosphoric Acids 
and their Salts . . . 46 
48. Orthophosphonc Acid (8.P.) and 
Orthophosphates ... 47 
49. Detection of a Phosphate in the 
presence of Calcium, Barium, 
Strontium, Manganese, and 
Magnesium .... 48 
50. Detection of a Phosphate in the 
presence of Iron ... 48 
51. Arsenious Acid and Arsenites . 48 
52. Arsenic Acid and Arseniates . 48 
53. Separation of an Arseniate from 
a Phosphate .... 49 
54. Manganates .... 49 
55. Permanganates .... 49 
56. Chromic Acid and Chromates . 49 
57. Stannic Acid and Stannates 
(Stannites ?) . . . 50 
58. Antimonic Acid .... 50 
59. Formic Acid and Formates . 50 
60. Detection of a Formate in pre- 
sence of Fixed Organic Acids 
which reduce Silver Salts . 50 
61. Acetic Acid and Acetates . . 51 
62. Valerianic Acid and Valerian- 
ates . . . . . 51 
63. Sulphovinates (Ethysulphates) . 51 
64. Stearic Acid and Stearates . 52 
65. Oleic Acid and Oleates . . 52 
66. Lactic Acid and Lactates . . 52 
67. Oxalic Acid and Oxalates . . 52 
68. Succinic Acid and Succinates . 53 
69. Malic Acid and Malates . . 53 
70. Tartaric Acid and Tartrates , 53 
71. Citric Acid and Citrates. . . 54 
72. Separation of Oxalates, Tartrates, 
Citrates, and Malates . . 55 
73. Meconic Acid and Meconates . 55 
74. Carbolic Acid (or Phenol) and 
Carbolates (Phenates) . . 55 
75. Benzoic Acid and Benzoates . 56 
76. Salicylic Acid .... 56 
77. Detection of Carbolic Acid in 
presence of Salicylic Acid . 57 
78. Tannic, Gallic, and Pyrogallic 
Acid ..... 57 TABLE OF CONTENTS. 
Qualitative Analysis, as applied to the Detection of Unknown Salts. 
CHAPTER IV. 
TABLES. 
PAGE 
Full table for the Detection of the 
Metal in a Solution containing one 
Base only ..... 62 
Table for the Detection of the Metal 
in a Simple Salt, the Metal present 
being limited to the Salts used and 
included in the British Pharma- 
copseia . . ... 64 
Table for the Separation of Metals 
into Groups ..... 66 
Table A. Separation of Metals 
of Group I. .... 67 
Table B. Separation of Metals 
of Group 11., Div. (a) . . 68 
Table C. Separation of Metals 
of Group 11., Div. (6) . . 69 
Table D. Separation of Metals 
of Group 111., Div. (o) . . 7° 
Table E. Separation of Metals 
of Group 111., Div. (a). in pre- 
sence of Phosphoric Acid . 71 
Table F. Separation of Metals 
of Group 111., Div. (6) . . 72 
Table G. Separation of Metals 
of Group IV. . . . . 73 
Table H. Separation of Metals 
of Group V. .... 74 
PAGE 
§ I. General Preliminary Exami- 
nation . . . • 58 
§ 11. Detection of the Metal 
present in any Simple 
Salt (with tables for 
same) .... 61-64 
§ 111. Detection of the Metals in 
Complex Mixtures of two 
or more Salts (with Tables 
for same) ... 65 
§ IV. Detection of the Acidulous 
Radical .... 75_^° 
Div. A. Preliminary Examina- 
tion . . • 75 
„ B. Preparation of Solution 77 
„ C. Course for Inorganic 
Acids ... 78 
„ D. Course for Organic 
Acids ... 80 
Solubility Tables . 82, 83 
§ V. Special Processes for proving 
the Identity of certain 
readily recognisable Sub- 
stances .... 84-88 
CHAPTER V. 
Qualitative Analysis of Alkaloids and of the so-called "Scale” Medicinal 
Preparations containing them, with a General Sketch of 
Toxicological Analysis. 
Division A. Course for the Detection of the Alkaloids and Alkaloid Salts used in 
Medicine ........ 89-91 
, B. Qualitative Analysis of Scale Preparations . . . . 91-92 
~ C. General Sketch of the Method of Testing for Poisons in Mixtures . 92-93 
„ D. General Resume of the Tests for all the chief Alkaloids (as under) . 94 
Aconitine. 
Atropine. 
Beberine. 
Berberine. 
Brucine. 
Caffeine. 
Calabarine. 
Chelidonine. 
Cinchonine. 
Cinchonidine. 
Codeine. 
Colchicine. 
Colchicei'ne. 
Coniine. 
Curarine. 
Delphinine. 
Delphinoidine. 
Emetine. 
Gelsemine. 
Hyoscyamine. 
Jervine. 
Morphine. 
Narceine. 
Narcotine. 
Nepaline. 
Nicotine. 
Papaverine. 
Physostigmine. 
Pilocarpine. 
Piperine. 
Quinamine. 
Quinidine. 
Quinine. 
Sabadilline. 
Sabatrine. 
Solanine. 
Staphysagrine. 
Strychnine. 
Taxine. 
Thalictrine. 
Theobromine. 
Thebaine. 
Veratrine. 
Veratroidine. TABLE OF CONTENTS. 
PART lI.—QUANTITATIVE ANALYSIS. 
CHAPTER VI. 
Weighing, Measuring, and Specific Gravity. 
PAGE 
1. Weighing and Measuring. . 95-96 
2. Specific Gravity 
(a) Of Fluids .... 97~99 
(b) Of Solids .... 99-100 
PAGE 
(c) Practical Applications of 
Specific Gravity . . ioi 
(d) Of Gases .... ioi 
(■e) Vapor Density . . . 102-104 
Volumetric Quantitative Analysis and Use of the “Nitrometer.” 
CHAPTER VII. 
I. Introductory Remarks . . 105 
A. Standard solutions . .105 
B. Indicators . . . 105 
C. General Modus Operandi . 105 
D. Apparatus employed . 106 
E. Weighing operations . 107 
11. Standard Solution of Oxalic 
Acid . . . . .108 
A. Preparation and Check . 108 
B. Estimation of Alkaline 
Hydrates . . .108 
C. Estimation of Alkaline 
Carbonates . . . 109 
D. Estimation of Lead . . no 
E. Estimation of the Organic 
Salts of the Alkalies . 110 
F. Official Standards of 
Strength . . .11l 
111. Standard Solution of Sodium 
Hydrate . . . .112 
A. Preparation and Check . 112 
B. Acidimetry . . .112 
C. Official Standards of 
Strength . . .112 
IV. Standard Solution of Argentic 
Nitrate . . . 113 
A. Preparation and Check . Xl 3 
B. Estimation of Soluble Ha- 
loid Salts . . . 113 
C. Volhard’s Method . .H3 
D. Estimation of Hydrocyanic 
Acid . . . .114 
E. Official Standards of 
Strength . . .114 
V. Standard Solution of lodine . 114 
A. Preparation and Check . 114 
B. Estimation of Arsenious 
Acid . . . 115 
C. Estimation of Sulphurous 
Acid . . . .115 
D. Estimation of Thiosul- 
phates . . . .115 
VI. Standard Solution of Sodium 
Thiosulphate . . 115 
A. Preparation and Check . 115 
B. Estimation of Free lodine 115 
C. Estimation of Free Chlorine 
and Bromine. . . 116 
D. Estimation of Available 
Chlorine . . .116 
E. Official Standards of 
Strength . . .117 
j VII. Standard Solution of Potassium 
Bichromate . . .117 
A. Preparation and Check . 117 
B. Estimation of Ferrous 
Salts . . . . 117 
C. Estimation of Ferric 
Salts . . . .118 
D. Official Standards of 
Strength . . .118 
VIII. Fehling’s Standard Solution of 
Copper . . . .119 
A. Manufacture and Check . Xl 9 
B. Estimation of Sugar. . 120 
C. Estimation of Starch . 120 
IX. Estimation of Phosphoric Acid . 120 
X. Estimation of Sulphates by 
Standard Barium Chloride 121 
XL Standard Mayer’s Solution for 
Estimation of Alkaloids . 121 
XII. Analysis by the Nitrometer . 122 
A. General Remarks . . 122 
B. Estimation of Nitrous 
Ether . . . .123 
C. Estimation of Nitrates . 123 
D. Estimation of Soluble Car- 
bonates . . . .123 
E. Estimation of Hydrogen 
Peroxide .. . .124 
F. Estimation of Urea . . 124 
XIII. Colorimetric Analysis . . 124 
(а) Estimation of Ammonia by 
“Nesslerising” . . 125 
(б) Estimation of Salicylic 
Acid .... 126 
XIV. Table of Coefficients for Volu- 
metric Analysis . .127 TABLE OF CONTENTS. 
CHAPTER VIII. 
Gravimetric Quantitative Analysis of Metals and Acids. 
. PAGE 
Div. I. Preliminary Remarks . .128 
A. Preparation of Filters . . 128 
B. Estimation of Ash Filters . 129 
C. Collection and Washing of 
Precipitates . . .129 
D. Drying of Precipitates . . 129 
E. Igniting and Weighing of 
Precipitates . . .130 
F. Estimation of Moisture . 131 
G. ~ of Ash in Organic 
Bodies . . . .131 
H. Use of Analytical Factors . 131 
Div. 11. Gravimetric Estimation of 
the Metals . . .132 
1. Estimation of Silver : 
A. As Chloride. . . .132 
B. As Metal . . . .132 
2. Estimation of Lead : 
A. As Oxide .... 132 
B. As Chromate . . . 133 
3. Estimation of Mercury : 
A. As Metal .... 133 
B. As Sulphide. . . . 133" 
4- Estimation of Cadmium . 134 
5- „ of Copper ; 
A. As Oxide . . . 134 
B. As Metal .... 134 
6. Estimation of Bismuth : 
A. As Oxide . . . .134 
B. As Sulphide . . .135 
7. Estimation of Gold . . . 135 
8. „ of Platinum . I^3 
9- „ °f Tin : 
A. As Oxide . . . . 135 
B. As Metal .... 135 
10. Estimation of Antimony . .136 
11. „ of Arsenic: 
A. As Sulphide. . . .136 
B. As Magnesium-Ammonium- 
Arseniate . . . .136 
12. Estimation of Cobalt . .136 
I - ~ „ Nickel . . 137 
r4- „ „ Manganese. . 137 
*5- ~ „ Zinc . . . 137 
” » Iron . . .137 
„ ~ Aluminium . . 138 
I°- » „ Chromium . . 138 
*9- )> „ Barium . .138 
2°- » „ Calcium . . 138 
PAGE 
21. Estimation of Magnesium . 139 
22. „ „ Potassium . . 139 
23. „ „ Sodium . . 139 
24. „ „ Potassium and 
Sodium in presence of Metals 
of the Fourth Group . . 140 
25. Estimation of Ammonium . 140 
Div. 111. Gravimetric Estimation of 
Acidulous Radicals . 141 
1. Chlorides ..... 141 
2. lodides ..... 141 
3. Bromides ..... 141 
4. Cyanides ..... 141 
5. Estimation of an lodide in the 
presence of a Chloride and 
Bromide .... 141 
6. Mutual Estimation of Chloride, 
Bromide, and lodide in the 
presence of each other . , 141 
7. Sulphides ..... 141 
8. Sulphates . . . . .142 
9. Nitrates ..... 
A. In Alkaline Nitrates . . 142 
B. As Nitric Oxide . . . 142 
C. As Ammonia . . .143 
10. Estimation of Phosphates 
A. Estimation of the strength 
of Free Phosphoric Acid . 143 
B. Alkaline Phosphates . . 143 
C. In presence of Calcium and 
Magnesium . . . 143 
D. In presence of Iron and 
Aluminium . . . 144 
E. Estimation as Phospho- 
molybdate.... 144 
11. Estimation of the “Total” and 
“ Soluble ” Phosphates in a 
Manure or Soil . . . 144 
12. Estimation of Arseniates . . 145 
r3- » „ Carbonates. . 145 
14- „ 1, Oxalic Acid . 146 
15- » Tartaric Acid . 146 
16. „ ~ Silicic Acid. . 146 
A. Insoluble Silicates . . 146 
B. Soluble Silicates . . .146 
Div. IV. Quantitative Separations: 
Full Mineral Analysis of 
Water .... 147 
Ultimate Organic Analysis. 
CHAPTER IX. 
1- Apparatus required . . .150 
2- Estimation of Carbon and Hy- 
drogen . . . . .151 
3- Estimation of Nitrogen . . . 
(«) Method of Varrentrapp and 
Will 153 
(b) Process of Dumas . . 154 
(5) Kjeldahl’s Process . .154 
4. Estimation of Chlorine . . .154 
5. Estimation of Sulphur and Phos- 
phorus and Arsenic . . 15^ TABLE OF CONTENTS. 
Special Processes for the Analysis of Water, Air, and Food. 
CHAPTER X. 
PAGE 
Div. I. The Sanitary Analysis of 
Water . . .156 
1. Collection of Sample . -156 
2. Color . ■ . . .156 
3. Odor . . . . -156 
4. Total Solids . . . .156 
5. Chlorine . . . . . 157 
6. Phosphoric Acid . . 157 
7. Nitrogen and Nitrates . . 157 
8. Ammonia and Albuminoid Am- 
monia . . . . .158 
9. Oxygen Consumed . . .160 
10. Hardness ..... x6l 
11. Judging the Results . . . 162 
Div. 11. The Sanitary Analysis of Air 163 
1. Estimation of Carbon Dioxide . 163 
PAGE 
2. Estimation of Organic Matter . 163 
3. Testing for Gaseous Impuri- 
ties . . . .163 
Div. 111. Food Analysis . . . 164 
1. Milk 164 
Table Degrees of Thermometer 165 
2. Butter . . . . .166 
3. Bread . . . . . 167 
4. Alcohol (Estimation of) . .167 
Table Percentages of Alcohol . 168 
5. Mustard . . . . . 169 
6. Pepper 169 
7. Colored Sweets . . .169 
8. Direct Estimation of Starch 
(new process) . . .169 
9. Vinegar . . . . . 171 
CHAPTER XL 
Special Processes for the Analysis of Drugs, Urine, and Urinary Calculi. 
Div. I. Analysis of Drugs . .172 
1. General Scheme of Dragen- 
dorff . . . . .172 
2. Cinchona Bark . . . .174 
3. Opium . . . • .176 
4. Alkaloidal Strength of Extracts 177 
5. Methylated Spirit in Tinctures 177 
6. Strength of Resinous Drugs . 178 
7. Testing the Purity of Quinine 
Sulphate . . . .178 
8. Alkaloidal Strength of Scale 
Preparations . . 179 
9. Estimation of Phenol . 179 
10. Estimation of Fatty Acids in 
Soap . . . . .180 
11. Estimation of Oleic Acid . .180 
12. „ of Glycerine . . 180 
Dxv. 11. Micro-chemical Analysis of 
Drugs (illustrated) . . 181 
Div. 111. Analysis of Urine . . 184 
1. Specific Gravity . . .184 
2. Reaction . . . . .184 
3. Deposit . . . . .184 
4. Albumin (and estimation) . 184 
5. Sugar (and estimation) . . 185 
6. Bile 186 
7. Urea (and estimation) . . 186 
8. Uric Acid „ . . 186 
9. Phosphates . . . .187 
10. Sulphates . . . , .187 
11. Chlorides . . . . .187 
12. Blood . . . . .187 
Analysis of Urinary Calculi ; 
(а) Organic 188 
(б) Inorganic 188 
CHAPTER XII. 
Analysis of Gases, Polarisation, and Spectrum Analysis. 
Div. I. Analysis of Gases by Reiser’s Apparatus 189 
„ 11. Analysis by the Polariscope .......... 192 
„ 111. Spectrum Analysis . . . . . . . . . . .194 
„ IV. Melting Points . ........... 195 PART I. 
QUALITATIVE ANALYSIS. 
CHAPTER I. 
THE PROCESSES EMPLOYED BY PRACTICAL CHEMISTS. 
It is advisable that the student should understand the raison d'etre, of the 
chief processes he will be called upon to employ, before commencing in detail 
the study of Analysis. 
I. SOLUTION. 
This process consists in stirring a solid body in contact with a fluid until 
it dissolves, heat being occasionally used. Bodies which refuse to dissolve 
in any particular fluid are said to be insoluble in it; the liquid used is called 
the solvent, and sometimes the menstruum; a liquid having taken up all the 
solid matter possible is said to be saturated. A knowledge of the solubility 
of various substances in the chief menstrua, such as water, acids, alkalies, 
alcohol, ether, chloroform, and glycerine, is of the utmost importance. By 
this we are enabled to separate one body from another; and by attention to 
minute details it is even possible to divorce bodies which are soluble in the 
same menstruum, but in different degrees. As an example we shall suppose 
three substances—one readily soluble, one partially so, and one but slightly 
soluble, in ether. By a careful use of three successive quantities of the 
liquid at different temperatures, we can obtain separate solutions of each. 
This process is named fractional solution. In order to ascertain if any 
substance be soluble in any particular liquid, it is simply requisite to stir it 
into the fluid, applying heat if necessary. A portion of the liquid is then 
poured off, and heated until it has passed away in vapour, when, if any of the 
solid was held in solution, it will remain as a visible residue. As a general 
rule, the higher the temperature to which a liquid is raised, the greater 
becomes its capacity for saturation. Thus, one part of common nitre will 
require for solution about four parts of cold water; but the same weight of 
the solid will dissolve in less than half a part of boiling water. There are 
many exceptions to this rule—notably that of calcium oxide, which is less 
soluble in boiling water than in cold. Many bodies, during solution, absorb 
so much heat that any substance placed in the liquid has its temperature 
remarkably reduced. Potassium nitrate and ammonium chloride, dissolved 
together in water, form in this manner a very efficient refrigerant when snow 
or ice is not obtainable. 2 
CHEMICAL PROCESSES. 
11. LIXIYIATION AND EXTRACTION. 
These processes include the digestion of a mixture of solids in a fluid, so 
as to dissolve the soluble portion. The solids, in the form of powder, are 
introduced into a vessel, and the water or other liquid having been added, 
the whole is well stirred. Remaining at rest until all the insoluble matter has 
subsided, the clear fluid, charged with all that was soluble in the mixture, is 
decanted, or poured off. On the large scale, in chemical works, the clear 
liquor is usually drawn off by means of a siphon. 
When a substance is to be extracted by means of a readily volatile solvent, 
such as ether or chloroform, the arrangement now commonly 
used is that known as Soxhlet’s apparatus. This is illustrated 
in fig. i. A flask (a) is charged with the solvent. The sub- 
stance (e) is put into a cartridge of filtering paper, and intro- 
duced into the Soxhlet tube (d) ; the latter is in turn connected 
with the upright condenser (c), through the jacket of which a 
stream of cold water is made to pass. Heat is now applied to 
the flask by a water-bath, and the vapor of the ether rising 
through (b), condenses and drops on to the powder in the 
cartridge. When the instrument has become filled by the 
condensed solvent to the level of the top of (f), it runs 
back into the flask charged with the soluble matter that has 
been extracted. This process then repeats itself until the 
whole soluble portion has been extracted and transferred to 
the flask, which latter may then be attached to an ordinary 
condenser, and the solvent distilled off, leaving the soluble 
matters of the original powder in the flask. Resinous and 
sticky substances should be mixed with a little purified sand 
to prevent them clogging up the apparatus. 
Another method of extraction is that known as per- 
colation, a process much used in pharmacy. 
The apparatus employed is illustrated in 
fig. 2. The upper portion (a) is the per- 
colator, in which the powder to be extracted 
is tightly packed; and the solvent having 
been poured upon it, the whole is allowed to 
macerate for some time. The stopcock (c) being then opened, 
the fluid gradually filters into the receiver (b), and more solvent is 
then poured on until the soluble portion of the contents of the 
percolator has been entirely transferred to the receiver. 
Fig. 1. 
Is the mixing of two substances in solution so as to form a third 
substance, which, being insoluble in the fluids employed, sinks to 
the bottom, and is called the precipitate. The clear liquid 
which remains after the precipitate has settled down, is called 
the supernatant liquid. 
When precipitates are totally insoluble in water, such as barium sulphate 
or argentic chloride, the operation is best conducted at a boiling heat, as the 
high temperature causes the precipitate to aggregate and become more dense, 
so that it subsides rapidly, and is less liable to pass through the pores of the 
filter. 
111. PRECIPITATION 
Fig. 2. 
On the other hand, there are some precipitates which must never be 
heated, but be allowed to form slowly by standing in the cold for several 
hours. To this class belong ammonium-magnesium phosphate, and potassium PRECIPITA TION—DECANTA TION—FILTRA TION. 
3 
acid tartrate. When it is desirable to cause precipitates to form quickly, 
resort may be had to violent shaking, or stirring with a glass rod, so that it 
scrapes against the sides of the vessel. 
In qualitative analysis precipitation is usually conducted in test-tubes, 
shown in fig. 3. These are kept in a stand (fig. 4) having holes for the 
reception of tubes actually in use, and also a row of pegs upon which freshly 
Fig. 3. 
Fig. 4. 
Fig. 5. 
Fig. 6. 
washed tubes may be inverted to drain. Figure 5 illustrates the appliance 
used to hold tubes when their contents are to be boiled, and fig. 6 shows the 
brush used for cleansing them. 
In quantitative analysis precipitation is generally performed in beakers. 
These are very thin tumblers made of glass, free from lead, and 
annealed so as to permit their use with boiling liquids without 
risk of fracture. A nest of such beakers is illustrated in fig. 7. 
Precipitates are separated from the supernatant liquor by one 
of two methods. First:— 
IV. DECANTATION, 
which consists in allowing the precipitate to settle to the bottom 
°f the liquid; pouring off the clear liquor, then pouring on 
distilled water, and repeating the process until the precipitate is 
thoroughly washed. Second : 
Fig. 7. 
which consists in transferring the whole to a piece of folded filtering-paper 
or cloth placed in a funnel, so that the liquid passes through, while the pre- 
cipitate remains. This may be washed by the addition of distilled water. 
The liquor which has thus passed through the filter is called the filtrate. 
The process of precipitation is probably one of the most common with which 
the practical chemist meets. 
Specially prepared papers for filtration, cut into circles, are sold, and they 
have only to be folded to fit the funnel for which they are destined. The 
V. FILTRATION, 
Fig. 8. 
Fig. 9. 
illustrations show, fig. 8 (a), the circle of paper, and (b) the same as folded 
or use, while fig. 9 represents the whole arrangement ready for use. 4 
CHEMICAL PROCESSES. 
VI. DISTILLATION 
is the changing of a fluid into vapour by the aid of heat, and passing the 
vapour into a cooling apparatus, called the condenser, where, its latent heat 
being abstracted, it is again deposited as a liquid. This process is employed 
for the separation of volatile fluids from non-volatile substances. The fluid 
which passes over and is condensed in the receiver is called the distillate; 
while the non-volatile matter which remains 
in the retort is called the residue. Figure 10 
shows the arrangement most commonly 
used in laboratories for small distillations. 
a is the retort in which the fluid is boiled, 
and b is called a Liebig’s condenser, through 
the jacket of which a stream of water is 
caused to pass, and beneath the end of this 
is placed a vessel (c) for the reception of 
the distillate. By careful attention to their 
boiling points, various volatile fluids may 
Fig. 10. 
thus be separated from each other. Suppose, for example, that we have a 
mixture of three substances boiling respectively at iBo°, 220°, and 240°, and 
their separation is desired, we should introduce the mixture into a retort fitted 
with a thermometer, the bulb of which was placed just above the level of the 
fluid. The whole being then attached to the condenser, the heat would be 
gradually raised until the thermometer marked a little over 180°, when that 
temperature would be steadily maintained as long as anything continued to 
collect in the receiver. When the liquid ceased to accumulate, the receiver 
would be changed, and the temperature raised to a little over 220°, and the 
distillation continued until the second liquid had ceased to pass over. The 
receiver being once more changed, the heat would be again raised, and 
maintained until the last liquid had been obtained as a distillate. This 
process, which is exceedingly useful in practical chemistry, is called fractional 
distillation. 
VII. SUBLIMATION 
is the changing of a solid into a vapor by heat, and recondensing the vapor 
into a solid form in a cooled vessel. It is employed for the separation of 
volatile from non-volatile solids, and is thus conducted :—The substance to 
be sublimed is thinly spread over the bottom of a shallow' iron pan, and the 
vessel is covered with a sheet of bibulous paper perforated with numerous 
pin-holes, or with a piece of muslin. By means of a sand bath, the heat is 
slowly raised to the desired degree, when the vapor passes through the 
strainer, and condenses in a cap of wood or porcelain, lined with stout 
cartridge paper, and placed over the heating-pan and kept cool. Fractional 
sublimation is often useful, and may be employed in a similar manner to 
fractional distillation. 
VIII. FUSION 
is the heating of a solid until it melts. It is usually carried out in a vessel 
called a “crucible,” made of fire-clay. On the small scale, or for the purposes 
of analysis, fusion is generally conducted in porcelain crucibles; or, where the 
substances are such as would attack porcelain, in vessels of platinum or silver. 
Alkalies should be fused only in crucibles made of the latter metal. A 
peculiar kind of fusion, called cupellation, is resorted to in the assay of gold 
and silver. The alloy to be assayed is wrapped in a piece of lead foil, and 
the whole is then heated in a little cup made of bone earth, called a cupel, 
when the lead and all impurities fuse and sink into the substance of the E VAPORA TION—CR YSTALLISA TION AND DIAL VSIS. 
5 
porous vessel, leaving the pure metal as a metallic button, which may then 
be weighed. The illustration (fig. xi) shows a set of crucibles for fusion—a, 
being of fire-clay; b, a platinum crucible; c, one of porcelain; and d, what is 
called Rose's crucible, for heating substances in a current of hydrogen when 
Fig. 11. 
is desired to prevent access of air, or to produce rapid reduction to the 
metallic state. 
IX. EVAPORATION 
consists in heating a fluid until the whole, or as much of it as may be 
required, passes off in vapor. A solution thus treated until it has wholly 
passed into vapor is said to be evaporated to dryness, and the solid 
substance remaining is called the residue. 
Solutions which contain any organic or volatile matter ought always to be 
evaporated on a water bath ; that is, in a vessel exposed only to the heat of 
boiling water. With ordinary non-volatile or metallic substances in solution 
this precaution is unnecessary, and of no practical advantage. Evaporation 
may be conducted slowly, without raising the fluid to its boiling point, when 
it is called simple vaporisation; but when sufficient heat is applied, the 
evaporation takes place rapidly, and is accompanied by the disengagement of 
bubbles of vapour, and the fluid is then said to be in a state of ebullition. 
All liquids possess the continual desire, as it were, to pass into vapor; and 
the amount of elastic force which the vapor thus given off exerts is called 
ffs tension. The more the liquid is heated, the greater becomes its tendency 
to vaporise, and consequently the more powerful is the tension of its vapor; 
and when the latter is sufficiently marked to overcome the pressure exerted 
by the atmosphere and the cohesion of the liquid itself, ebullition takes place. 
The boiling point of a fluid is therefore the temperature at which the tension of 
lts vapor is equal to that of the superincumbent atmosphere. If the pressure of 
the atmosphere be increased artificially, the boiling point of the liquid will 
riSe in proportion. For example : boiling water in an open vessel under 
ordinary circumstances will have a temperature of 2120 ; but water in a steam 
boiler, under a pressure of 60 lb. per square inch, will be found to be heated 
nearly to 264°. As steam under pressure can thus be obtained at high 
temperatures, it is made use of for the rapid evaporation of liquids on a large 
scale, by causing it to pass into a jacket or through a coil of pipes surrounding 
the evaporating pan. The apparatus thus made use of is called a steam bath, 
the heat of which is usually understood to be about 230° Fahr. 
If water be boiled in a chemically clean glass vessel, and more particularly 
if a precipitate be suspended in the water, the boiling does not take place 
regularly, but the liquid becomes heated above its boiling point, and suddenly 
lushes into vapor in gusts. This is called by practical chemists “bumping,” 
and may be prevented by putting in a few fragments of platinum foil, which 
act as nuclei, to aid in the regular disengagement of the vapor. 
X. CRYSTALLISATION AND DIALYSIS. 
Many substances when dissolved in a boiling liquid separate out, as soon 
as the fluid cools, in masses having a well-defined and symmetrical shape, 6 
CHEMICAL PROCESSES. 
bounded by plain surfaces and regular angles. These bodies are named 
crystalline; the deposited masses, crystals ; and the remaining solution, the 
mother liquor. Substances which are not susceptible of crystallisation are 
called amorphous (i.e. formless) bodies; while solids, such as glue and gums, 
which are soluble in water and yet not crystallisable, are named colloids. 
Crystallisation may also occur during solidification after fusion, and by the 
spontaneous evaporation of liquids holding crystalline substances in solution. 
All crystalline bodies invariably assume the same form, and may thus be 
unmistakably recognised from each other. The process is also useful for 
purification, as at the moment of crystallisation all impurities are rejected, 
and may be poured off with the mother liquor. Many circumstances affect 
the size of the crystals produced in any solution ; as a rule, the more rapidly 
crystallisation takes place, the smaller are the crystals. An example of the 
extreme variation in the size of the crystals produced from the same solution 
may be seen in ferrous sulphate. When allowed to deposit slowly, we have 
the ordinary well-marked commercial crystals; but the same salt dissolved in 
boiling water, and the solution suddenly poured, with constant stirring, into 
spirit, gives granulated ferrous sulphate in crystals so minute that a lens is 
required to distinguish them. For the formation of large and well-defined 
crystals perfect rest is required, and it is often desirable to introduce pieces 
of wood or string so as to form nuclei on which the crystals collect. Good 
examples are seen in commercial crystallised sugar-of-milk and sugar-candy. 
Some bodies are capable of crystallising in two or more forms, and are called 
polymorphous. Instances of this property may be seen in mercuric iodide 
and in sulphur. 
When small quantities of crystalline substances exist in a solution together 
with a large quantity of uncrystallisable colloid bodies, their mutual separation 
is effected by dialysis. This process consists in introducing the mixture into 
a glass vessel having a bottom made of vegetable parchment. This, called 
the dialyser, is floated in a large quantity of distilled water in a basin. At 
the expiration of several hours the whole of the crystalline bodies will have 
, „ passed through the parchment, and will have become dis- 
solved in the water in the basin, while the colloids remain 
in the dialyser. A very good way of practising this process 
is to dialyse a solution of glue in which a few grains of salt 
have been dissolved, when the salt will be found to have 
passed into the water in the basin, while all the glue will 
remain behind. This process is sometimes employed for 
the separation of crystalline poison, like strychnine, from the 
contents of a stomach. The rapidity of the dialysis is greatly 
increased by causing a stream of water to pass through the 
outer basin, but of course this is only applicable where it is desired to retain 
the colloid body and not the crystalloid, as in the manufacture of the 
preparation known as dialysed iron. The apparatus used is shown in the 
illustration (fig. 12), in which a is the dialyser containing the mixture, while 
b contains the water into which the crystalline matter passes. 
Fig. 12. 
XI. ELECTROLYSIS. 
Electricity is one of the most powerful analytic forces with which the 
chemist has to deal. A current of electricity results from the action of 
chemical agents upon various metals, the apparatus in its simplest form being 
called a voltaic or galvanic cell or element, and a combination of several cells 
being termed a battery. Bunsen’s battery, which is very extensively used and 
of great power, consists of an outer cell or jar of glazed earthenware in which 
is placed a cylinder of zinc, an inner unglazed porous jar and a rod of carbon, PYROLOGY. 
7 
both furnished with binding-screws for attaching wires to them. The acids 
used are dilute sulphuric around the zinc, and strong nitric in contact with the 
carbon in the inner cell. The zinc constitutes the positive (or most attacked), 
the carbon the negative (or least attacked) element; but when wires are 
attached to these, the end of the wire connected with the zinc is termed the 
negative electrode or cathode, whilst that in union with the platinum in the 
battery is the positive electrode or anode. To explain this apparent contra- 
diction we must imagine that the current generated by the zinc passes through 
the fluid in the cell and then through the carbon, while at the same time an 
opposite current is generated from the carbon through the liquid to the zinc, 
and thus the effect of each current is felt at the ends of the wires from the 
opposite plate. These electrodes, when placed near one another in a compound 
liquid, occasion the phenomena of electrolysis, which is simply the splitting 
up of conductors of electricity into their elements or into simpler forms. For 
instance, a solution of HCI gives off Cl at the positive electrode and the H at 
the negative, as a result of the axiom that unlike electricities attract and like 
repel one another, Cl itself being electro-negative and H electro-positive. 
Dealing with H2S04, we get H2 at one electrode and S04 at the other; the 
latter, however, at once splitting up into O (given off) and S03, which re forms 
H.S04 with the water present. 
Further reference to applications of electrolysis will be found in Chapter X., 
when the student arrives at quantitative analysis. It is also applied in a 
modified form in qualitative analysis to the separation of tin and antimony. 
Under this name are included all processes of analysis depending for their 
action on the use of fire, or, in other words, what were formerly called 
“ reactions in the dry way.” The chief instruments used are the blowpipe and 
the Bunsen burner. The blowpipe is a tube with a narrow nozzle, by which 
a continuous current of air can be passed into an ordinary flame. The ordi- 
nary gas flame consists of three parts : (a) A non-luminous nucleus in the 
centre ; (h) A luminous cone surrounding this nucleus ; and {c) An outer 
and only slightly luminous cone surrounding the whole flame. The centre 
portion (a) contains unaltered gas, which cannot burn for want of oxygen, 
that necessary element being cut off by the outer zones. In the middle por- 
tion (b) the gas comes in contact with a certain amount of oxygen, but not 
enough to produce complete combustion; and therefore it is chiefly the 
hydrogen which burns here, the carbon separating and, by becoming intensely 
ignited, giving the light. In the outer zone [c) full combustion takes place, 
and the extreme of heat is arrived at, because chemical action is most intense. 
The outer flame therefore acts readily on oxidisable bodies, because of the 
high temperature and the unlimited supply of air, while the luminous zone 
tends to take away oxygen by reason of the excess of unburned carbon 
or hydrocarbons therein existing. For these reasons the former is called the 
oxidising flame, and the latter the reducing flame. The effect of blowing 
air across a flame is, first, to alter the shape of the flame, which is at once 
lengthened and narrowed; and, in the second place, to extend the sphere of 
combustion from the outer to the inner part. As the latter circumstance causes 
an increase of the heat of the flame, and the former a concentration of that heat 
within narrower limits, it is easy to understand the great heat of the blowpipe 
flame. The way of holding the blowpipe and the strength of the blast always 
depends upon whether the operator wants a reducing or an oxidising flame. 
The reducing flame is produced by keeping the jet of the blowpipe just on the 
border of a tolerably strong gas flame, and driving a moderate blast across it. 
ihe resulting mixture of the air with the gas is only imperfect, and there 
XII. PYROLOGY. 8 
CHEMICAL PROCESSES. 
remains,.between the inner bluish part of the flame and the outer barely visible 
part a luminous and reducing zone, of which the hottest point lies somewhat 
beyond the apex of the inner cone. To produce the oxidising flame, the gas 
is lowered, the jet of the blowpipe pushed a little farther into the flame, and 
the strength of the current somewhat increased. This serves to effect an inti- 
mate mixture of the air and gas, and an inner pointed, bluish cone, slightly 
luminous towards the apex, is formed, and surrounded by a thin, pointed, 
light-bluish, barely visible mantle. The hottest part of the flame is at the 
apex of the inner cone. Difficultly fusible bodies are exposed to this part to 
effect their fusion; but bodies to be oxidised are held a little beyond the 
apex, that there may be no want of air for their combustion. 
The current is produced by the cheek muscles alone, and not with the 
lungs. The way of doing this may be easily acquired by practising for some 
time to breathe quietly with puffed-up cheeks and with the blowpipe between 
the lips ; with practice and patience the student will soon be able to produce 
an even and uninterrupted current. 
The supports on which substances are exposed to the blowpipe flame are 
generally either wood charcoal, or platinum wire or foil. 
Charcoal supports are used principally in the reduction of metallic oxides, 
etc., or in trying the fusibility of bodies. The substances to be operated 
upon are put into small conical cavities scooped out with a penknife or with 
a little tin tube. Metals that are volatile at the heat of the reducing flame 
evaporate wholly or in part upon the reduction of their oxides ; in passing 
through the outer flame the metallic fumes are re-oxidised, and the oxide 
formed is deposited around the portion of matter upon the support. Such 
deposits are called incrustations. Many of these exhibit characteristic colors 
leading to the detection of the metals. Thoroughly burnt and smooth pieces 
of charcoal only should be selected for supports in blowpipe experiments, as 
imperfectly burnt and knotty pieces are apt to spirt and throw off the matter 
placed on them. 
The great use of charcoal lies (i) in its low degree of conductivity ; (2) its 
porosity, which causes it to absorb fusible bodies and leave infusible ones 
upon its surface; and (3) its power of aiding the effects of the reducing 
flame. 
Platinum wire and foil are used for supports in the oxidising flame, and 
the former is specially employed for trying the action of fluxes and the color 
communicable to the blowpipe or Bunsen flame. The platinum wire, when 
employed for making beads of borax or other fluxes, should be about 3 to 4 
inches long, with the end twisted into a small loop. The loop is then heated, 
and dipped while hot in the powdered borax, when it takes up a quantity 
which is then heated till it fuses to a clear bead formed within the loop. 
When cold, this is moistened and dipped in the powder to be tested, and 
again exposed to the flame, and the effect noted. For trying the color 
impartable to the flame by. certain metals, the wire is first cleaned by boiling in 
dilute nitric acid and then holding it in the flame until no color is obtained. 
The loop is then dipped in the solution to be tested, and held near the flame 
till the adhering drop has evaporated to dryness, and then heated in the mantle 
of the flame near the apex of the inner cone, and the effect observed. 
The Bunsen burner consists of a tube having at its base a series of holes 
to admit air, and also a small gas delivery tube. By means of this contrivance 
the gas is mixed with air before it burns, and more perfect oxidation, and 
consequently much greater heat, is secured. Looking attentively at the flame 
of a Bunsen burner, we distinguish in it an inner part and two mantles sur- 
rounding it. The inner part corresponds to the dark nucleus of the common 
gas flame, and contains the mixture of gas and air issuing from the burner. PREPARATION OF SULPHURETTED HYDROGEN. 
9 
The mantle immediately surrounding the inner part contains still some un- 
consumed carbide of hydrogen ; the outer mantle, which looks bluer and less 
luminous, consists of the last products of combustion. This hottest part—lying 
in the mantles surrounding the inner part of the flame, in a zone extending 
a few hundredths of an inch upwards and downwards from the transverse 
section of the flame across the apex of the inner part—has, according to 
Bunsen’s calculation, a temperature of 41720 F. This is termed the zone of 
fusion. The outer margin of this zone of fusion acts as oxidising flame, the 
inner part of it as reducing flame. The spot where the reducing action is 
the most powerful and energetic lies immediately above the apex of the inner 
part of the flame. The Bunsen flame brings out the coloration which many 
substances impart to flames, and by which the qualitative analyst can detect 
many bodies, even though present in such minute quantities that all other 
means of analysis except the spectroscope fail to discover them. The subject 
of the coloration of flames will be discussed fully under each metal. 
XIII. PREPARATION OF SULPHURETTED HYDROGEN. 
This is done by acting upon ferrous sulphide with dilute sulphuric acid. 
The illustration (fig. 13) shows the apparatus. The ferrous sulphide, broken 
into lumps the size of a nut, is placed in the generating bottle (a), and 
dilute sulphuric acid is poured in by the funnel (c) in small quantities as 
required, (b) is a bottle containing distilled water, through which the gas 
Fig. 13. 
Fig. 14. 
Fig. 15. 
passes to free it from any traces of acid mechanically carried over. Owing to 
the disagreeable odor, it is desirable to have special appliances, by means of 
which the evolution of the gas can be stopped as soon as it has done the work 
required. Such an apparatus for use in a large laboratory is that of Kipps 
(fig. 14); and one suitable for use by a single student is that of Van Babo 
(fig. 15). Both illustrations sufficiently explain themselves. CHAPTER II. 
DETECTION OF THE METALS. 
For the purposes of qualitative analysis we employ certain chemicals, either 
in the solid or liquid state, which by producing given effects enable us to 
detect the existence of the substance searched for. These substances are 
always kept ready for use, and are called reagents. They are of three classes ; 
i st, Group reagents, which, by yielding a precipitate under certain condi- 
tions, prove the substance to be a member of a certain group of bodies; 
2nd, Separatory reagents, by means of which the substance under examination 
is distinguished from the other members of the group; 3rd, Confirmatory 
reagents, by which the indications previously obtained are confirmed and 
rendered certain. 
The Metals are divided into five groups, each of which has its group 
reagent, as follows : 
Group i. Metals the chlorides of which, being insoluble in water, are precipi- 
tated from their solution by the addition of hydrochloric acid. They 
are silver, mercurous mercury and lead (the latter in cold strong 
solutions only). 
Group 2. Metals the sulphides of which, being insoluble in dilute hydro- 
chloric acid, are precipitated from their solutions by the addition of 
sulphuretted hydrogen in the presence of hydrochloric acid. This 
group includes mercury, lead, bismuth, copper, cadmium, antimony, 
tin, gold, platinum, and the metalloid arsenic, and is divided into two 
sub-groups, as follows : 
A. Metals the sulphides of which are insoluble in both dilute 
hydrochloric acid and ammonium sulphide. The precipitated sul- 
phides separated by sulphuretted hydrogen are therefore insoluble, 
after washing, in ammonium sulphide. They are mercury, lead, 
bismuth, copper and cadmium. 
B. Metals the sulphides of which, although insoluble in dilute 
acids, are dissolved by alkalies, and the precipitates from their solu- 
tions by sulphuretted hydrogen therefore dissolve in ammonium 
sulphide. They are gold, platinum, tin, antimony and arsenic. 
Group 3. Embraces those metals the sulphides of which are soluble in dilute 
acids, but are insoluble in alkalies, and which consequently, having 
escaped precipitation in Group 2, are now in turn precipitated by 
ammonium sulphide. They are iron, nickel, cobalt, manganese and 
zinc. In this group are likewise included aluminium, cerium and 
chromium, which are precipitated as hydrates by the alkalinity of the 
ammonium sulphide. Magnesium would also be precipitated as 
hydrate, but, as that would be inconvenient at this stage, its precipi- 
tation is prevented by the addition of ammonium chloride, in which 
its hydrate is soluble. S/L VER—MERCUROS UM. 
11 
Group 4. Comprises metals the chlorides and sulphides of which, being 
soluble, escape precipitation in the former groups, but the carbonates 
of which, being insoluble in water, are now precipitated by ammonium 
carbonate. They are barium, strontium, and calcium. Magnesium 
is not precipitated as carbonate, owing to the presence of the ammonium 
chloride already added with the sulphide in Group 3. 
Group 5. Includes metals the chlorides, sulphides and carbonates of which, 
being soluble in water or in ammonium chloride, are not precipitated 
by any of the reagents already mentioned. They consist of magne- 
sium, lithium, potassium, sodium and ammonium. 
As the analytical grouping of the metals is undoubtedly one which is most 
important to the student for practical purposes, we shall adhere to this 
arrangement in giving the methods for their detection. 
GROUP I. 
Metals precipitable as chlorides by the addition of hydrochloric acid to 
their solutions. 
I. SILVER (Ag). 
(a) WET REACTIONS. 
(To be practised upon a solution of argentic nitrate—AgNOs.) 
1. HCI {lst group reagent) or any soluble chloride gives a curdy white pre- 
cipitate of argentic chloride—AgCl—insoluble in boiling nitric acid 
but instantly soluble in ammonium hydrate. It is also soluble in KCy, 
Na2S203, and in strong solutions of soluble chlorides. 
2. KHO or HaHO both produce a brownish precipitate of argentic oxide, 
Ag20, insoluble in excess. A similar effect is produced by the hydrates 
of barium, strontium and calcium. 
3. K2Cr04 gives a red precipitate of argentic chromate—Ag2Cr04—soluble 
in large excess of both nitric acid and ammonium hydrate; and there- 
fore the solution should always be as neutral as possible. 
4. H2S and NH4HS, both produce black argentic sulphide—Ag2S—insoluble 
in excess, both soluble in strong boiling nitric acid. 
5. KI and KBr both produce curdy precipitates, the former yellow argentic 
iodide—Agl—insoluble in ammonium hydrate, and the latter argentic 
bromide—Agßr—dirty-white and slowly soluble in ammonium hydrate. 
6. KCy gives a curdy-white precipitate of argentic cyanide—AgCy—readily 
soluble in excess, and also in boiling strong nitric acid. 
7. Many organic salts, such as formates and tartrates, boiled with solutions of 
silver, precipitate the metal as a mirror on the tube. 
8. Fragments of copper, zinc, iron and tin, introduced into a solution of 
silver, all precipitate the metal. 
(b) DR V REACTION. 
(To be practised on argentic oxide—Ag20.) 
Mixed with sodium carbonate and heated on charcoal before the blowpipe, 
a bead of silver is formed, hard, glistening, and soluble in nitric acid, yielding 
solution of argentic nitrate to which the wet tests may be applied. 12 
DETECTION OF THE METALS. 
11. MERCUROSTIM (Hg,)". 
(a) WET EE ACTIONS. 
(To be practised on a solution of mercurous nitrate—(Hg2)" (NO3)2—prepared 
by acting upon a globule of mercury with cold and dilute nitric acid, so 
as not quite to entirely dissolve the metal.) 
1. HCI (i st group reagent) gives a white precipitate of mercurous chloride, 
(Hg2)//Cl2/ turned to black mercuros-ammonium chloride 
NH2(Hg2)" Cl/—by ammonium hydrate. It is also insoluble in boiling 
water, but soluble in strong nitric acid, being converted into a mixture 
of mercuric chloride—HgCl2—and mercuric nitrate—Hg(N03)2. 
2. KHO and HaHO both give black precipitates of mercurous oxide—Hg20— 
insoluble in excess. 
3. NH4HO produces a black precipitate of dimercuros-ammonium nitrate— 
NH2(Hg2)''N03H20—also insoluble in excess. 
4. SnCl2 boiled with the solution causes a grey precipitate of finely divided 
mercury, which, if allowed to settle, and then boiled with hydrochloric 
acid and some more stannous chloride, aggregates into a globule. 
{b) DRV REACTION. 
Mercurous compounds heated, break up into the corresponding mercuric 
salt, which sublimes, and metallic mercury, which also sublimes at a higher 
temperature. 
(To be tried upon mercurous iodide.) 
111. LEAD (Pb). 
(a) WET REACTIONS. 
(To be practised on a solution of plumbic acetate—Pb(C2H302)2.) 
1. HCI (Ist group reagent) forms in cold strong solutions a white precipitate 
of plumbic chloride—PbCl2—soluble in boiling water. 
2. H2S after acidnlation by HCI {2nd group reagent) gives a black precipitate 
of plumbic sulphide—PbS—insoluble in ammonium sulphide. By 
treatment with boiling strong nitric acid it is decomposed, partly into 
plumbic nitrate, but chiefly into insoluble plumbic sulphate. It is 
entirely dissolved by hot dilute nitric acid with separation of sulphur. 
3. H S04 gives a white precipitate of plumbic sulphate—PbS04—slightly 
soluble in water, but rendered entirely insoluble by the addition of a 
little alcohol. It is decomposed by boiling strong hydrochloric acid, 
and is also freely soluble in solutions of ammonium acetate or tartrate, 
containing an excess of ammonium hydrate. 
4. K,Cr04 gives a yellow precipitate of plumbic chromate—PbCr04—in- 
soluble in acetic and very dilute nitric acids, but soluble in strong 
boiling nitric acid. 
5. KI gives a yellow precipitate of plumbic iodide—Pbl2—soluble in boiling 
water, and crystallising out on cooling in golden scales. 
6. KHO and NaHO both cause white precipitates of plumbic hydrate— 
Pb(HO)2—soluble in excess, forming potassium or sodium plumbates 
K2Pb02 and NaOPb02. 
7. NH4HO causes a white precipitate of a white basic nitrate—Pb(N03HO) 
insoluble in excess. 
8. KCy produces a white precipitate of plumbic cyanide—PbCy2—insoluble 
in excess, but soluble in dilute nitric acid. MERCURICUM. 
13 
9. Alkaline Carbonates cause a precipitate of (PbCO3)2Pb(HO)2— 
“white lead ”—insoluble in excess, and also in potassium cyanide. 
10. Fragments of zinc or iron in the presence of a little acetic acid cause the 
separation of metallic lead in crystalline laminae. 
(To be practised on red lead—Pb304, or litharge—PbO.) 
(b) DRY REACTION. 
Heated on charcoal in the inner blowpipe flame, a bead of metallic lead is 
formed, which is soft and malleable and soluble in dilute nitric acid. The 
solution thus obtained gives the wet tests for lead. 
GROUP 11. 
Metals which are not affected by acidulation with hydrochloric acid, but are 
precipitated by passing sulphuretted hydrogen through the acidulated solution. 
DIVISION A. 
Metals which when precipitated by sulphuretted hydrogen as above, yield 
sulphide insoluble in ammonium sulphide. 
I. MERCURICUM (Hg). 
(a) WET REACTIONS. 
1. H2S after acidulation by HCI (2nd group reagent) gives a black pre- 
cipitate of mercuric sulphide—HgS—insoluble in ammonium sulphide 
and nitric acid, and only soluble in nitro-hydrochloric acid. Care 
must be taken that the sulphuretted hydrogen is passed really in excess, 
and that the whole is warmed gently, as unless this be done, the pre- 
cipitate is not the true sulphide, but a yellowish-brown dimercuric 
sulpho-dichloride—Hg2SCl2. Although insoluble in any single acid, 
mercuric sulphide may be caused to dissolve in hydrochloric acid by 
the addition of a crystal of potassium chlorate.* 
2. KHO or NaHO both give a yellow precipitate of mercuric oxide—HgO— 
insoluble in excess. 
(To be practised on a solution of mercuric chloride—HgCl2.) 
3. produces a white precipitate of an insoluble mercur-ammonium 
chloride—(NH2Hg)Cl—also insoluble in excess. 
4. KI yields a red precipitate of mercuric iodide, soluble in excess both of 
the precipitant and the mercuric salt. 
5. SnCl2, boiled with a mercuric solution, first precipitates mercurous chloride, 
and then forms metallic mercury, as in the case of mercurosum com- 
pounds. 
6. Alkaline Carbonates (except ammonium carbonate) produce an immediate 
reddish-brown precipitate of mercuric oxy-carbonate. 
7. Fragments of Cu, Zn, or Fe precipitate metallic mercury in the presence 
of dilute hydrochloric acid. 
(To be tried on mercuric oxide—HgO—and on “Ethiops mineral”—HgS.) 
{b) DRY REACTION. 
All compounds of mercury are volatile by heat; the oxide breaking up 
into oxygen and mercury, which sublimes, while the sulphide sublimes unaltered, 
unless previously mixed with sodium carbonate or some reducing agent. DETECTION OF THE METALS. 
11. BISMUTH (Bi). 
[a) WET REACTIONS. 
(To be practised upon bismuth subnitrate, dissolved in water by the aid of 
the smallest possible quantity of nitric acid, and any excess of the latter 
carefully boiled off.) 
1. H2S after acidulation by HCI (2nd group reagent) gives a black precipitate 
of bismuth sulphide—Bi2Sa—insoluble in ammonium sulphide, but 
soluble in boiling nitric acid. 
2. H.2SOt gives no precipitate (distinction from lead). 
3. NH4HO, KHO, and NaHO, all give precipitates of white bismathous hydrate 
—Bi2FL2O4 or BiO(OH)—insoluble in excess and becoming converted 
into the yellow oxide—Bi2G3—on boiling. 
4. H,O in excess to a solution in which the free acid has been as much as 
possible driven off by boiling, gives a white precipitate of a basic salt 
of bismuth. This reaction is more delicate in the presence of hydro- 
chloric than of nitric acid; and the precipitate, which is in this case 
bismuth oxy-chloride—BiOCl—is insoluble in tartaric acid (distinction 
from antimonious oxy-chloride). 
5. K2Cr04 yields a yellow precipitate of bismuth oxy-chromate—Bi202Cr04 
soluble in dilute nitric acid, but not in potassium hydrate (distinction 
from plumbic chromate). 
6. KI gives brown bismuthous iodide, soluble in excess. 
7. Alkaline Carbonates give white precipitates of bismuth oxy-carbonate, 
insoluble in excess. 
8. Fragments of zinc added to a solution of bismuth cause a deposit of the 
metal as a dark grey powder. 
(b) DRY REACTION. 
(To be practised upon bismuth subnitrate.) 
Mixed with sodium carbonate and heated on charcoal before the blowpipe, 
a hard bead of metallic bismuth is produced, and the surrounding charcoal is 
incrusted with a coating of oxide, deep orange-yellow while hot and pale yellow 
on cooling. 
(a) WET REACTIONS. 
111. COPPER (Cu). 
(To be practised with a solution of cupric sulphate—CuS04.) 
1. HVS after acidulation with HCI (2nd group reagent) forms a precipitate of 
brownish-black cupric sulphide—CuS—which is nearly insoluble in 
ammonium sulphide but soluble in nitric acid. Its precipitation is 
prevented by the presence of potassium cyanide (distinction from 
cadmium). When long exposed to the air in a moist state, it oxidises 
to cupric sulphate and dissolves spontaneouslv. 
2. nh4ho causes a pale blue precipitate instantly soluble in excess, forming a 
deep blue solution of tetrammonio-cupric sulphate—(NH3)4CuS04H20. 
3. K4FeCy6 yields a chocolate-brown precipitate of cupric ferrocyanide— 
Cu2FeCy6. This test is very delicate, and is not affected by the 
presence of a dilute acid, but does not take place in an alkaline liquid. 
4. KHO or NaHO precipitates light-blue cupric hydrate—Cu(HO)2—insoluble 
in excess, but turning to black cupric oxy-hydrate—(CuO)2Gu(HO)2 
on boiling. CADMIUM—A RSENIC. 
15 
5. KNaC4H406 and NaHO added successively, the latter in excess, produce 
a deep blue liquid (Fehling’s solution), which when boiled with a 
solution of glucose (grape sugar) deposits brick-red cuprous oxide— 
Cu20. 
6. The Alkaline Carbonates behave like their respective hydrates. 
7. Fragments of zinc or iron precipitate metallic copper from solutions acidu- 
lated with HCI. 
(b) DRY REACTIONS. 
(To be practised upon cupric oxide—CuO—or verdigris—Cu20(C2H302)2.) 
1. Heated with Na2C03 and KCy on charcoal, in the inner blowpipe flame, 
red scales of copper are formed. 
2. Heated in the borax bead before the outer blowpipe flame, colors it green 
while hot and blue on cooling. By carefully moistening the bead with 
SnCl2 and again heating, this time in the inner flame, a red color is 
produced. 
IV. CADMIUM (Cd). 
(a) WET REACTIONS. 
1. H.,S after acidulation with HCI ( 2nd group reagent) gives a yellow precipitate 
of cadmium sulphide—CdS—insoluble in ammonium sulphide, but 
soluble in boiling nitric acid. This precipitate does not form readily 
in presence of much acid; but its production is not hindered by the 
addition of potassium cyanide (distinction from copper). 
2. NH4HO produces a white precipitate of cadmium hydrate—Cd(HO)2 
soluble in excess. 
3. KHO or NaHO both give precipitates of cadmium hydrate—Cd(HO)2 
insoluble in excess (distinction from zinc). 
4. Alkaline Carbonates precipitate cadmium carbonate—CdCOd—insoluble in 
excess. 
(To be practised with a solution of cadmium iodide—Cdl2.) 
(£) DRY REACTION. 
(To be practised on cadmium carbonate—CdCO...) 
Heated on charcoal before the blowpipe, a brownish incrustation of oxide 
is produced, owing to reduction of the metal and its subsequent volatilisation 
and oxidation by the outer flame. 
DIVISION B. 
Metals which are precipitated by sulphuretted hydrogen in the presence of 
hydrochloric acid, but yield sulphides which are soluble in ammonium sulphide. 
I. AESENIC (As). 
{a) WET REACTIONS. 
(To be practised with a solution of arsenious anhydride in boiling water 
slightly acidulated by hydrochloric acid.) 
1. H2S, after acidulation with HCI, causes a yellow precipitate of arsenious 
sulphide—As2S3—soluble in ammonium sulphide, forming ammonium 
sulpharsenite—(NH4)3AsS3-—but insoluble in strong boiling hydro- 
chloric acid (distinction from the sulphides of Sb and Sn). This pre- i6 
DETECTION OF THE METALS. 
cipitate is also soluble in cold solution of commercial carbonate of 
ammonia (distinction from the sulphides of Sb, Sn, Au, and Pt). Dried 
and heated in a small tube with a mixture of Na2C03 and KCy, it 
yields a mirror of arsenic. 
2, Boiled with KHO and a fragment of Zinc, arseniuretted hydrogen—AsH3 
is evolved, which stains black a paper moistened with solution of 
argentic nitrate and held over the mouth of the tube during the ebul- 
lition {Fleitmanris test). 
3. Boiled with j of its bulk of HCI and a slip of Copper, a grey coating is 
deposited on the copper of cupric arsenide. On drying the copper 
carefully, cutting it into fragments, and heating in a wide tube, a 
crystalline sublimate of arsenious anhydride—As203 
is obtained, which, when dissolved in water, gives a 
yellow precipitate of argentic arsenite—Ag3As03—with 
solution of ammonio-nitrate of silver (Reinch's test). 
4. Placed in a gas bottle furnished with a jet (illustrated in 
the margin), together with dilute sulphuric or hydro- 
chloric acid and a few fragments of zinc, arseniuretted 
hydrogen—AsH3—is evolved, which may be lighted 
at the jet, and burns with a lambent flame, producing 
As203. If a piece of cold porcelain be held in the 
flame, dark spots of arsenic are obtained, readily volatile 
Fig. 16. 
by heat and soluble in solution of chlorinated lime (Marsh's Test). 
Note.—For reactions of arsenites and arseniates, see Acidulous Radicals. 
{b) DRY REACTION. 
(To be practised on arsenious anhydride—As203.) 
Heated in a small tube with Na2C03 and KCy, a mirror of arsenic is pro- 
duced, accompanied by a garlic-like odor. The same effect may be produced 
with black flux. 
11. ANTIMONY (Sb). 
{a) MET REACTIONS. 
1. H2S, after acididation by HCI, causes an orange precipitate of antimonious 
sulphide—Sb2S3—soluble in ammonium sulphide, forming ammonium 
sulphantimonite—(NH4)3SbS3—also soluble in strong boiling hydro- 
chloric acid, forming antimonious chloride—SbCl3—but insoluble in 
cold solution of commercial carbonate of ammonia. 
(To be practised with a solution of tartar emetic.) 
2. KHO and NaHO produce precipitates of antimonious oxide readily soluble 
in excess to form antimonites (K35803 or Na3Sb03). 
3. Acidulated with HCI and introduced into a platinum dish with a rod of 
zinc so held that it touches the platinum outside the liquid, a black 
stain of metallic antimony is produced closely adherent to the platinum. 
This stain is not dissolved by HCI (tin reduced in the same manner 
is granular and soluble in boiling HCI). 
4. Reinch’s test (see Arsenic) produces a black coating on the copper, which, 
when heated, forms an amorphous sublimate of Sb203 close to the copper, 
and insoluble in water, but dissolved by a solution of cream of tartar in 
which H2S then produces the characteristic orange sulphide. 
5. Marsh’s test (see Arsenic) yields stains of antimony on the porcelain, not TIN—GOLD. 
17 
nearly so readily volatile by heat as in the case of arsenic, and not 
discharged by solution of chlorinated lime. 
6. Fleitmann’s test will not act with antimony at all (distinction from 
arsenic). 
{b) DRY REACTION-. 
(To be practised on antimonious oxide—Sb2Cb.) 
Heated on charcoal with Na2C03 and KCy before the blowpipe, a bead 
ol metallic antimony is formed and copious white fumes of the oxide are 
produced. 
111. TIN (Snu or Sniv). 
(a) WET REACTIONS. 
(To be practised with a solution of stannous chloride—SnCl2—and one of 
stannic chloride—SnCl4—prepared by warming the stannous solution with 
a little nitric acid.) 
1. H,S, after acidulation with HCI, produces a brown or yellow precipitate 
of SnS or SnS2 respectively, both soluble in ammonium sulphide and 
in boiling hydrochloric acid. 
2. KHO or NaHO both produce white precipitates of Sn(HO)2 or Sn(HO)4, 
soluble in excess, the former to produce stannites and the latter stag- 
nates. The stannous solution is, however, reprecipitable on boiling, 
while the stannic is not. 
3. NH4HO produces similar precipitates, very difficultly soluble in excess. 
4. Acidulated by HCI, and introduced into a platinum dish with a rod of 
zinc, so held in the fluid that it touches the platinum outside the liquid, 
granules of metallic tin are deposited, soluble in boiling HCI, to form 
stannous chloride. 
5. HgCl2 boiled with stannous salts deposits a grey precipitate of metallic 
mercury. 
(b) DRY REACTION. 
(To be practised on putty powder—Sn02.) 
Heated on charcoal with Na2C03 before the blowpipe, a bead of metallic 
tin is produced, and a white incrustation of oxide is formed on the charcoal. 
IV. GOLD (An). 
(a) WET REACTIONS. 
(To be practised with a solution of auric chloride—AuC13.) 
1. H2S (group reagent) in the presence of HCI gives black auric sulphide 
—Au2S3. If the solution be hot, aurous sulphide—Au2S—falls. Both 
are only soluble in nitro-hydrochloric acid, but they are soluble in 
ammonium sulphide when it is yellow. 
2. NH4HO precipitates reddish ammonium aurate, or fulminating gold— 
Au2(NH3)202—but KHO gives no result. 
3- H2C204 (or_ FeS04) when boiled with an acid solution throws down Au. 
Reducing agents generally act thus. The liquid containing the metal 
may exhibit a blue, green, purple, or brown color. 
4- SnCl2 throws down a brownish or purplish precipitate, known as “ purple 
of Cassius,” consisting of the mixed oxides of gold and tin. 
5- Zn, Cu, Fe, Pt, or almost any metal, gives a precipitate of metallic Au in a 
finely divided state. i8 
DETECTION OF THE METALS. 
[b) DR Y RE ACTION. 
(To be practised on any gold salt.) 
Heated on charcoal with Na2C03, the metal is produced. 
V. PLATINUM (Pt). 
(a) WET REACTIONS. 
(To be tested with a solution of platinic chloride—PtCl4.) 
1. H2S (2nd.group reagent) in presence of HCI gives a brown precipitate 
of platinic sulphide—PtS2. This precipitate forms slowly, and is 
readily dissolved by yellow ammonium sulphide. 
2. KCI in presence of HCI, especially after addition of alcohol, produces 
a yellow crystalline precipitate of potassium platinic chloride— 
PtK2Clfi—soluble to a moderate extent in water, but not in alcohol. 
Decomposition takes place when this is strongly heated, metallic Pt 
and KCI remaining. 
3. NH4CI gives a precipitate of ammonium platinic chloride—Pt(NH4)2Cl6, 
which is almost identical in properties, but is more readily decom- 
posed by heat, pure platinum remaining. 
4. Zn, Fe, and several other metals decompose platinic salts with the pro- 
duction of the metal. 
(b) DRY REACTION. 
(To be practised upon potassium platinic chloride—PtK2ClG.) 
Heat on charcoal, with or without Na2C03, before the blowpipe. The 
metal is produced by reduction. 
GROUP 111. 
Metals which escape precipitation by sulphuretted hydrogen in presence 
of hydrochloric acid, but which are precipitated by ammonium sulphide in the 
presence of ammonium hydrate, ammonium chloride having been previously 
added to prevent the precipitation of magnesium. 
DIVISION A. 
Metals which, in the insured absence of organic matter, are precipitated as 
hydrates by the addition of the ammonium chloride and ammonium hydrate 
only. 
I. IRON [Ferrous, Fe ; and Ferric, Fe2). 
[a) WET REACTIONS. 
(To be practised successively on solutions of ferrous sulphate—FeS04—and 
ferric chloride—Fe2Cl6.) 
I. NH4HO in the presence of NH4CI [group reagent) yields either a dirty- 
green precipitate of ferrous hydrate—Fe(HO)2—or a reddish-brown 
precipitate of ferric hydrate—Fe2(HO)6. The former is slightly soluble 
in excess, but the latter is insoluble, and it is therefore preferable 
always to warm the solution with a little nitric acid, to insure the 
raising of the iron to the ferric state, before adding the ammonium 
hydrate. The presence of organic acids, such as tartaric or citric, IRON. 
i9 
prevents the occurrence of this reaction ; and therefore, if any such 
admixture be suspected, the solution should first be evaporated to dry- 
ness, the residue heated to redness, and then dissolved in a little 
hydrochloric acid, heated with a drop or two of nitric acid, diluted, and 
lastly, the NH4CI and NH4HO added and boiled. 
2. NH4HS, added to a neutral or alkaline solution, produces a precipitate 
of ferrous sulphide—FeS—which is black (distinction from Al, Ce, 
Cr, Mn, and Zn), and readily soluble in cold diluted hydrochloric 
acid (distinction from the black sulphides of Ni and Co). This re- 
action takes place even in the presence of organic matter, and the 
precipitated sulphide, if exposed to the air, gradually oxidises to 
ferrous sulphate—FeS04—and disappears. It is insoluble in acetic acid 
(distinction from MnS). 
3. K4FeCy0, in a neutral or slightly acid solution, gives, with ferrous salts, a 
white precipitate (rapidly changing to pale blue) of Everett’s salt—potas- 
sium ferrous ferrocyanide—K2Fe • FeCy6—and with ferric salts, a dark 
blue precipitate of Prussian blue—ferric ferrocyanide (Fe2)2(FeCy6)3. 
These precipitates are decomposed by alkalies, producing the hydrates 
of iron, and forming a ferrocyanide of the alkali in solution; but the 
addition of hydrochloric acid causes the re-formation of the original 
precipitate. 
4. KGFe2Cy12 gives, with ferrous salts, in neutral or slightly acid solutions, a dark 
blue precipitate of Turnbull’s blue—ferrous ferricyanide, Fe3Fe2Cy12— 
but with ferric salts it gives no precipitate, simply producing a brownish 
liquid. With alkalies, Turnbull’s blue is decomposed, yielding black 
ferroso-ferric hydrate, and a ferricyanide of the alkali; but the addition 
of hydrochloric acid reproduces the original blue. 
5. KCyS gives no precipitate with ferrous salts, but with ferric compounds 
it yields a deep blood-red solution. This color is not discharged by 
dilute hydrochloric acid (distinction from ferric acetate), but imme- 
diately bleached by solution of mercuric chloride (distinction from 
ferric meconate). 
or NaHO, produces effects similar to those of ammonium hydrate. 
HP04 in the presence of NaC2H302 or nh4c2h302 gives a whitish 
gelatinous precipitate of ferrous or ferric phosphates—Fe3(P04)2 or 
Fe2(PC>4)2—insoluble in acetic acid, but soluble in hydrochloric acid. 
The previous addition of citric or tartaric acids prevents this reaction. 
8. NaC2H302, added in excess to ferric salts, produces a deep red solution of 
ferric acetate—Fe2(C2H302)6—which on boiling deposits as a reddish- 
brown ferric oxyacetate—Fe20(C2H302)4. This precipitate dissolves 
slightly on cooling; but iron can be entirely precipitated in this form 
if the solution be instantly filtered while hot. 
9. Alkaline Carbonates, added to a ferrous salt, precipitate white ferrous 
carbonate—FeC03—but with ferric salts, throw down the reddish-brown 
ferric hydrate already described. 
(b) DRY REACTIONS. 
(To be practised on ferric oxide.) 
1. Heated on charcoal before the inner blowpipe flame, a black magnetic 
powder is obtained, which is not the metal, but is ferroso-ferric oxide 
—Fe3O4. 
2. Heated in the borax bead in the inner blowpipe flame, a bottle-green 
color is produced ; but in the outer flame the bead is deep red while 
hot, and very pale yellow when cold. 20 
DETECTION OF THE METALS. 
11. CERIUM (Ce). 
(a) WET REACTIONS. 
(To be practised on cerous chloride—CeCl2—prepared by boiling cerum 
oxalate with sodium hydrate, washing the insoluble cerous hydrate with 
boiling water, and dissolving it in the least possible excess of hydrochloric 
acid.) 
i. NH4HO in the presence of NH4CI (group reagent) gives a white precipitate 
of cerous hydrate— Ce(HO)2—insoluble in excess. 
2. KHO and NaHO give a similar precipitate, turning to yellow ceroso-ceric 
oxide—Ce304—on the addition of chlorine water. 
3. (NH4)2C204 gives a white precipitate of cerous oxalate—CeC204—insoluble 
in excess, and not readily dissolved even by hydrochloric acid. The 
presence of citric or tartaric acid does not interfere with this reaction. 
4. K2S04 in a saturated solution causes the formation of white crystalline 
potassium cerium sulphate—K2Ce(S04)2—soluble in hot water. 
(b) DR Y EE ACTIONS. 
Heated to redness in contact with the air, a deep red residue of ceric 
oxide—Ce203—is obtained, difficultly soluble even in strong hydro- 
chloric acid. 
(To be practised on cerium oxalate.) 
Heated in the borax bead, cerium behaves like iron in the outer flame, 
but the inner flame yields a colorless or opaque yellow bead. 
11l ALUMINIUM (Al). 
(a) WET REACTIONS. 
(To be practised on a solution of common alum.) 
NH4HO in presence <7/NH4CI (group reagent) gives a gelatinous white pre- 
cipitate of aluminic hydrate—Al2(HO)6. This precipitate is slightly 
soluble in a large excess of the precipitant, but separates completely on 
boiling. 
KHO and NaHO both give a similar precipitate, soluble in excess, but 
reprecipitated by boiling with an excess of ammonium chloride, or by 
neutralising with hydrochloric acid and boiling with a slight excess 
of ammonium hydrate. 
Na,,HP04 in the presence of NaC2H302 or NH4C2H302 gives a white 
"precipitate of aluminic phosphate—AlP03—insoluble in hot acetic 
acid, but soluble in hydrochloric acid. The presence of citric or 
tartaric acids prevents the occurrence of this reaction. 
(b) DRY REACTION. 
Heat strongly on charcoal before the blowpipe, when a strong incan- 
descence is observed, and a white residue is left. Moisten this residue 
with a drop of solution of cobaltous nitrate—Co(N03)2—and again heat 
strongly, when a blue mass is left. This test is not decisively characteristic, 
as other substances, such as zinc and earthy phosphates, show somewhat 
similar colours. 
(To be practised on dried alum.) CHROMIUM—MA NGANESE. 
21 
IV. CHROMIUM (Cr). 
(a) WET REACTIONS. 
(To be practised on a solution of potassium chromic chloride, prepared by 
dissolving potassium dichromate—K2Cr207—in water, acidulating with 
hydrochloric acid, heating and dropping in rectified spirit till the solution 
turns green.) 
1. NH4HO in the presence (group reagent) precipitates green chromic 
hydrate—Cr2(HO)6—slightly soluble in excess, but entirely reprecipi- 
tated on boiling. The presence of citric or tartaric acid interferes 
with the completeness of this reaction. 
2. KHO, or NaHO, gives similar precipitates, freely soluble in excess when 
cold, but entirely reprecipitable by continued boiling. 
3. NaOCl, or Pb02, boiled with an alkaline solution of a chromium salt, pro- 
duqes a yellow solution of sodium chromate —Na2CrO4. 
4. NaHP04 in the presence of NaC2H,{02 or NH4C2Hs02 throws down pale 
green chromic phosphate—CrP04—soluble when freshly precipitated 
in excess of hot acetic acid, and freely soluble in hydrochloric acid. 
The presence of organic acids prevents this reaction. 
if) DRY REACTIONS. 
1. Heated in the borax bead in the inner blowpipe flame, a fine green 
color is obtained. 
2. Fused on platinum foil, with a mixture of KNaC03 and KNOs, a yellow 
residue is obtained, consisting of chromates of the alkalies used. This 
mass is soluble in water, yielding a yellow solution turned deeper 
in color by the addition of hydrochloric acid, owing to the formation 
of dichromates, and becoming green on warming and dropping in 
rectified spirit. 
DIVISION B. 
Metals the hydrates of which, being soluble in excess of ammonium hydrate 
in the presence of ammonium chloride, escape precipitation by that reagent, 
but are separated as insoluble sulphides by the addition of ammonium sulphide 
to the same liquid. 
I. MANGANESE (Mn). 
{a) WET REACTIONS. 
(To be practised on a solution of potassium manganous chloride, prepared by 
heating a solution of potassium permanganate with hydrochloric acid, and 
dropping in rectified spirit until a colorless solution is obtained.) 
I. nh4hs in the presence of NH4CI and NH4HO {group reagent) precipitates 
a flesh-colored manganous sulphide—MnS—soluble in dilute and 
cold hydrochloric acid (distinction from the sulphides of Ni and 
Co). It is also soluble in acetic acid (distinction from zinc sulphide). 
This precipitate forms sometimes very slowly and only after gently 
warming. If a good excess of NH4CI has not been added, or if, after 
adding the excess of ammonium hydrate, the solution be exposed to 
the air, a portion of the manganese will sometimes precipitate sponta- 
neously, as manganic dioxyhydrate—Mn202(HO)2—and be found with 
the iron, etc., in the first division of the third group. In this case its DETECTION OF THE METALS. 
22 
presence will be easily made manifest during the fusion for chromium 
by the residue being green. It is therefore evident that small quantities 
of manganese cannot be perfectly separated from large quantities of 
iron by NH4CI and NH4HO only. 
2. KHO and KaHO both yield precipitates of manganous hydrate insoluble 
in excess, and converted by boiling into dark brown manganic dioxy- 
hydrate—Mn202(HO)2. 
3. NH4HO gives a similar precipitate, soluble in excess of ammonium chloride, 
but gradually depositing as Mn202(HO)2 by exposure to the air. For 
this reason, if the presence of manganese be suspected, the addition of 
NH4CI and NH4HO must be followed by instant filtration, and any 
cloudiness coming in the filtrate must be simply taken as indicating 
manganese, and disregarded. 
4. K4FeCy0 gives a precipitate of manganous ferrocyanide—Mn2FeCyc—very 
liable to be mistaken for the corresponding zinc compound. 
5. Boiled with plumbic peroxide and nitric acid a violet color is produced in 
the liquid, due to the formation of permanganic acid. (Crum's test.) 
(b) DRY REACTIONS. 
(To be practised upon manganese peroxide—Mn02.) 
1. Fused on platinum foil with KNaC03 and KN03, a green mass of 
manganates of the alkalies is formed. This residue is soluble in water, 
yielding a green solution, turning purple on boiling, owing to the 
formation of permanganates. The solution is rendered colorless by 
heating with hydrochloric acid and dropping in rectified spirit, the 
operation being accompanied by the odor of aldehyd. 
2. Heated in the borax bead in the outer blowpipe flame, a color is produced 
which is violet-red while hot and amethyst on cooling. The bead is 
rendered colorless by the reducing flame. 
(a) WET REACTIONS. 
11. ZINC (Zn). 
(To be practised on zinc sulphate—ZnS04.) 
1. NHdHS in the presence of NH4CI and NH4HO {group reagent) gives a white 
precipitate of zinc sulphide—ZnS—insoluble in acetic acid, but readily 
soluble in dilute hydrochloric acid. 
2. KHO, NaHO, and NH4HO, all give precipitates of gelatinous white zinc 
hydrate, soluble in excess to form zincates. The addition of sulphu- 
retted hydrogen or ammonium sulphide reprecipitates the zinc as zinc 
sulphide—ZnS. 
3. K4FeCyfi gives a gelatinous white precipitate of zinc ferrocyanide— 
Zn2FeCyG—insoluble in dilute acids. 
4. Alkaline Carbonates precipitate ZnC03(Zn2HO)2H20—zinc hydrato- 
carbonate—insoluble in excess of the carbonates of potassium and 
sodium, but soluble in that of ammonium. The latter solution, diluted 
and boiled, deposits the oxide. 
(To be practised on zinc carbonate.) 
(b) DRY REACTIONS. 
1, Salts of zinc heated leave the oxide, yellow while hot, and white on 
cooling. NICKEL—COBALT. 
23 
2. Heated on charcoal before the blowpipe an incrustation forms, yellow 
while hot, and white on cooling. Moisten with a drop of cobaltous 
nitrate—Co(N03)2—and again heat in the outer flame, when a fine 
green color is produced. 
111. NICKEL (Ni). 
{a) WET REACTIONS. 
1. NH4HS in the presence of NH4CI and NH4HO {group reagent) gives a black 
precipitate of nickelous sulphide—NiS—-slightly soluble in excess, but 
entirely precipitated on boiling. It is not soluble in cold dilute 
hydrochloric or in acetic acid, but requires boiling with strong 
hydrochloric acid, and sometimes even the addition of a drop or two 
of nitric acid. 
(To be practised on a solution of nickelous sulphate—NiS04.) 
2. KHO or NaHO both give a green precipitate of nickelous hydrate— 
Ni(HO)2—unaltered by boiling (distinction from cobalt). 
3. KN02 added to a neutral solution, followed by an excess of acetic acid, 
gives no precipitate (after standing some hours) on the addition of 
potassium acetate and rectified spirit (very useful separation from 
cobalt). 
4- KCy in excess produces a greenish-yellow precipitate of nickelous cyanide 
—NiCy2—which quickly redissolves. On adding a drop of hydro- 
chloric acid and boiling in a fume chamber, and repeating this till no 
more fumes of hydrocyanic acid come off", and then adding sodium 
hydrate, a precipitate of nickel hydrate is produced. It is better, 
although less convenient, to use a strong solution of chlorinated soda 
—NaCINaCIO—in the last stage, when nickelic hydrate—Ni(HO)e— 
is slowly precipitated (separation from Co, which gives no precipitate). 
5. Alkaline Carbonates behave, so far as color and solubility in excess are 
concerned, like their respective hydrates. 
{h) DRY REACTIONS. 
1. Heated on charcoal with Na2C03 in the inner blowpipe flame, a grey 
metallic and magnetic powder is produced. 
2. Heated in the borax bead in the outer blowpipe flame, red to violet-brown 
is produced while hot, and a yellowish to sherry-red when cold 
These colors might be mistaken for those of iron; but on fusing a 
small fragment of potassium nitrate with the bead, its color at once 
changes to blue or dark purple (distinction from Fe). 
IV. COBALT (Co). 
(a) WET REACTIONS. 
(To be practised on a solution of cobaltous nitrate—Co(N03)2.) 
1. NH4HS in the presence of NH4CI and NH4HO {group reagent) gives a black 
precipitate of cobaltous sulphide—CoS—insoluble in acetic and cold 
dilute hydrochloric acid, and requiring to be boiled with the strongest 
HCI, often with the addition of a drop or two of nitric acid before 
solution is effected. 
2. KHO, or NaHO, gives a blue precipitate of cobaltous hydrate—Co(HO)2 
rapidly changing to pink, on boiling (distinction from nickel). 
3- KCy gives a light brown precipitate of cobaltous cyanide, rapidly soluble 24 
DETECTION OF THE METALS. 
in excess but reprecipitated by excess of dilute hydrochloric acid. If, 
however, the HCI be added drop by drop just so long as it causes 
the evolution of hydrocyanic acid fumes on boiling,* soluble potassium 
cobalticyanide—K6Co2Cy12—results, which is not decomposed by 
hydrochloric acid ; nor is any precipitate produced on adding excess 
of sodium hydrate or chlorinated soda (separation from nickel). 
4. Alkaline Carbonates throw down basic carbonates, behaving like the 
respective hydrates. 
(b) DRY REACTIONS. 
1. Heated on charcoal with Na2C03 in the inner blowpipe flame, the cobalt 
separates as a grey magnetic powder. 
2. Heated in the borax bead, first in the outer and then in the inner flame, 
a fine blue color is produced. It is an important distinction of cobalt 
from copper, manganese, etc., that prolonged heating in the inner fia?ne 
does not affect this blue. 
GROUP IV. 
Metals the hydrates and sulphides of which, being soluble, are not precipi- 
tated by the addition of NH4HO and NH4HS in the presence of NH4CI, 
but separate as insoluble carbonates on the addition of ammonium carbonate 
to the same solution. 
I. BARIUM (Ba). 
(a) WET REACTIONS. 
(To be practised on a solution of barium chloride—BaCl2.) 
1. (NH4)2CO3 in the presence of NH4CI and NH4HO (group reagent) produces 
a white precipitate of barium carbonate, BaC03, soluble with 
effervescence in dilute acetic acid. 
2. H2S04 and all soluble Sulphates give a white precipitate of barium sul- 
phate—BaS04—insoluble in ammonium acetate or tartrate (distinction 
from PbS04) and also in boiling nitric abid. 
3. K2Cr04 gives a yellow precipitate of barium chromate—BaCr04—insoluble 
in water and in dilute acetic acid, but soluble in hydrochloric acid 
(distinction from Sr and Ca). 
4. (NH4)2C204 gives a white precipitate of barium oxalate—BaC204—not 
readily formed in the presence of much acetic acid. 
5. Na2HP04 gives a white precipitate of barium hydrogen phosphate— 
BaHP04—soluble in acetic acid, and to some extent in ammonium 
chloride. 
(To be also practised on barium chloride.) 
(f) DRY REACTION. 
If a platinum wire be dipped first in hydrochloric acid and then in the salt 
and held in the inner blowpipe or Bunsen flame, the outer flame is colored 
yellowish-green. 
* This must be done in a fume chamber, as it is a highly poisonous operation if the fumes 
should happen to escape into the room. STRONTIUM—CALCIUM. 
25 
11. STRONTIUM (Sr). 
{a) WET REACTIONS. 
(To be practised on strontium nitrate—Sr(N03)2.) 
I. (NH4)2CO3 ( group reagent) in the presence of NH4CI and NH4HO gives a 
white precipitate of strontium carbonate—SrC03—soluble in dilute 
acetic acid. 
2. H2S04, or a soluble sulphate (preferably calcium sulphate), yields a white 
precipitate of strontium sulphate—SrS04—which only separates com- 
pletely from dilute solutions on allowing them to stand in a warm 
place for some hours. It is insoluble in a boiling strong solution of 
ammonium sulphate rendered alkaline by ammonium hydrate (distinc- 
tion from calcium sulphate). 
3. The other reactions are similar to those of calcium. 
{b)DRY REACTION. 
(To be also practised on Sr(NO3)2.) 
A platinum wire moistened with hydrochloric acid, dipped in the substance 
and introduced into the inner blowpipe or Bunsen flame, colors the outer 
flame crimson. 
111. CALCIUM (Ca). 
(a) WET REACTIONS. 
(To be practised on a solution of calcium chloride—CaCL.) 
1. (NH4)2CO3 in presence of NH4CI and NH4HO {group reagent) produces a 
white precipitate of calcium carbonate—CaC03—soluble in acetic acid 
and settling best on warming. 
2. (NH4)2C204 precipitates white calcium oxalate—CaC204—insoluble in 
acetic or oxalic acids, but soluble in hydrochloric acid. 
3- H,SO4 in strong solutions produces a precipitate of calcium sulphate— 
CaS04. Being slightly soluble in water, it does not form in dilute 
solutions, nor is it precipitated by a saturated solution of calcium 
sulphate (distinction from Ba and Sr). It is soluble in a boiling 
saturated solution of ammonium sulphate containing excess of ammo- 
nium hydrate, but quite insoluble in a mixture of two parts alcohol 
and one part water. 
4. Na2HP04 produces a white precipitate of calcium phosphate soluble in 
acetic acid. 
(h) DRY REACTION 
A platinum wire moistened with hydrochloric acid, dipped in the substance 
and held in the inner blowpipe or Bunsen flame, colors the outer flame 
yellowish-red. This reaction is masked by the presence of barium or 
strontium. 
(To be practised on calcium carbonate—CaC03.) 26 
DETECTION OF THE METALS. 
GROUP V. 
Metals not precipitable either as sulphide, hydrate, or carbonate, including 
magnesium the precipitation of which as hydrate or carbonate has been 
prevented by the presence of ammonium chloride. 
I. MAGNESIUM (Mg). 
(a) WET REACTIONS. 
(To be practised on a solution of magnesium sulphate—MgS04.) 
1. Na,HP04 i7i the presence of NH4CI and NH4HO produces a white crystalline 
precipitate of ammonium magnesium phosphate—MgNH4P04. It 
is slightly soluble in water, and scarcely at all in water containing 
ammonium hydrate, but entirely soluble in all acids. In very dilute 
solutions it only forms on cooling and shaking violently, or on rubbing 
the inside of the tube with a glass rod. 
2. (NH4)sHAsO4 produces a similar precipitate of MgNH4As04, possessing 
like features. 
3. KHO, NaHO, and NH4HO give precipitates of magnesium hydrate— 
Mg(HO)2—insoluble in excess, but soluble in the presence of 
ammonium salts. The alkaline carbonates (except ammonium 
carbonate) precipitate magnesium carbonate, also soluble in ammonium 
salts. 
4. Ca(HO)2 and Ba(H0j2 produce a similar effect. Either of these reagents is 
useful for the separation of magnesium from all the alkalies except 
ammonium. The solution, which must contain no ammonium salts, is 
treated with excess of either lime or baryta water. The precipitated 
magnesium hydrate is then filtered out and excess of ammonium 
carbonate added, which precipitates in turn the excess of Ca or Ba 
employed, and leaves K, Na, or Li in solution. 
{b) DR Y REA CTION. 
(To be practised on magnesium oxide.) 
Heated on charcoal before the blowpipe, it becomes strongly incandescent, 
and leaves a white residue, which when moistened with a drop of solution of 
cobaltous nitrate—Co(N03)2—and again heated, becomes rose-colored. This 
test is not, however, infallible. 
11. LITHIUM (Li). 
(a) WET REACTIONS. 
(To be practised on a solution of lithium chloride, prepared by dissolving 
lithium carbonate in dilute hydrochloric acid.) 
1. Na2HP04 in strong solutions produces a white precipitate of lithium phos- 
phate—Li3P04—on boiling only (distinction from Mg). It is soluble 
in hydrochloric acid, and reprecipitated by boiling with ammonium 
hydrate. 
2. Na2C03 and even NaHO, in very strong solutions, yield the carbonate and 
hydrate respectively. 
3. PtCl4 gives no precipitate (distinction from potassium). POT A SSIUM—SODIUM—A MMONIUM. 
27 
{b) DRY REACTION. 
(To be practised with lithium carbonate.) 
A platinum wire, moistened with hydrochloric acid, dipped in the substance 
and held in the inner blowrpipe or Bunsen flame, colors the outer flame 
carmine red. The presence of sodium disguises this reaction. 
111. POTASSIUM (K). 
WET REACTIONS. 
(To be practised on solution of potassium carbonate treated with dilute HCI 
till effervescence ceases, forming potassium chloride—KCI.) 
1. PtCl4, in strong solutions, gives a yellow crystalline precipitate of potas- 
sium platino-chloride—K2PtCl6—soluble on great dilution, especially 
on warming, but insoluble in acids, alcohol and ether. 
2. H2C.H406 throws down, from strong solutions only, a white crystalline 
precipitate of potassium hydrogen tartrate—KHC4H406—soluble in 
much cold water, rather freely in hot water, readily in acids and in 
KHO or NaHO, and not formed unless the original solution be nearly 
neutral. Its separation is facilitated by stirring and shaking violently, 
in which case it settles quickly. 
3. H_SiFtJ (hydrofiuosilicic acid) yields white gelatinous potassium fluosilicate— 
K2SiF6—sparingly soluble in water. 
DRY REACTION. 
(To be practised on potassium carbonate—K2C03.) 
Dip a platinum wire, moistened with HCI, in the salt. Held in a Bunsen 
flame a violet color is imparted. The masking effect of Na {yellow) is 
obviated by viewing the flame through indigo glass. 
IV. SODIUM (Na). 
WE T REA C TIONS. 
(To be tested with solution of sodium chloride—Nad) 
1. KShO . {potassium metantimoniate) gives a white granular precipitate of 
sodium metantimoniate—-NaSb03—from strong solutions only, which 
must be neutral or alkaline. This precipitate is insoluble in alcohol. 
2. H2SiP6 gives a similar precipitate to that obtained with K salts in concen- 
trated solutions only. 
Sodium salts are, practically, all soluble in water, and there is no thoroughly 
trustworthy wet reaction which can be applied to detect small quantities. 
If we have a solution which gives no precipitate with any of the group 
reagents, but leaves, on evaporating, a fixed residue capable of imparting a 
strong yellow color to the Bunsen flame (dry reaction), we may infer with 
certainty the presence of sodium. 
V. AMMONIUM (NH4). 
WET REACTIONS. 
1. PtCl4 produces a heavy yellow precipitate of ammonium platino-chloride— 
(NH4)2PtCI6—which, being rather soluble in water, is not formed in 
(To be tested with solution of ammonium chloride—NH4C1.) 28 
DETECTION OF THE METALS. 
dilute solutions, unless alcohol, in which it is insoluble, be added in 
considerable quantity. When ignited, pure spongy platinum is left. 
This precipitate may be distinguished from that with K salts by adding, 
after ignition, a little water and AgNOs, when no white precipitate of 
AgCl is formed (the K salt leaves KCI on being strongly heated). 
2. H2C4H40g yields ammonium hydrogen tartrate—(NH4)HC4H406—almost 
identical with KHC4H406 in its properties. On ignition, however, the 
latter gives a black residue, which turns moistened red litmus paper 
blue (K2CO3 and C), the former leaving pure C without reaction. 
3. NaHO or Ca(HO)2 boiled with the solution causes the evolution of ammonia 
gas—NH3. A glass rod dipped in HCI or HC2H302 produces, when 
held over a mixture evolving NH3, white clouds (solid NH4 salts), and 
moist red litmus paper is turned blue. 
4. Nessler’s Solution (Hgl2 dissolved in KI and KHO added) gives ajyellow 
or brown color or a brown precipitate of N(Hg")2I with all NH4 salts. 
This reaction is extremely delicate, and the estimation of NH4 in 
water is founded upon it. 
Ammonium salts volatilise (1) with decomposition, leaving a fixed acid 
[e.g., phosphate); (2) with decomposition, leaving no residue whatever {eg., 
sulphate, nitrate); (3) without decomposition, when they are said to sublime 
{eg., chloride, bromide, etc.) 
DRY REACTIONS. 29 
CHAPTER III. 
DETECTION AND SEPARATION OF ACIDULOUS 
RADICALS. 
1. HYDROFLUORIC ACID and FLUORIDES. 
(The test for fluorides undernoted may be practised on fluor spar—CaF2.) 
Hydrofluoric Acid, or Fluoric Acid, is known,— 
x. By its strongly acid reaction and corrosive power. 
2. By its action upon glass, from which it dissolves out silicic acid— 
Si02—thus roughening the surface and rendering it semi-opaque 
or translucent, and white ; a colorless gas, silicic fluoride— 
SiF4—passing off. 
Fluorides are detected as follows : 
The mineral or salt is finely powdered, and introduced into a leaden dish 
with a little sulphuric acid. A piece of glass, previously prepared by coating 
its surface with wax, and etching a few letters on the waxed side with the 
point of a pin, is placed over the dish, waxed side down. A gentle heat is 
then applied, but not sufficient to melt the wax, and the operation continued 
for some time. The glass is then taken off, and the wax removed from it; 
when, if fluorine was present, the letters written on the waxed surface will be 
found engraved upon it by the action of the hydrofluoric acid. 
2. CHLORINE, HYDROCHLORIC ACID, and CHLORIDES. 
Free Chlorine—Cl2—may be detected,— 
1. By its odor. 
2. By turning paper dipped in solution of potassium iodide brown. 
3. By bleaching a solution of indigo or litmus. 
Hydrochloric Acid—HCl—may be recognised,— 
1. By its acidity and odor of its fumes. 
2. By producing dense white fumes when a rod dipped in ammonium 
hydrate is held over the mouth of the bottle. 
3. By giving a curdy white precipitate of argentic chloride with argentic 
nitrate, instantly soluble in ammonium hydrate. 
Chlorides give the following reactions (to be practised with any soluble 
chloride, say NaCl) : 
1. Heated with sulphuric acid they evolve white fumes of HCI. 
2. Heated with H2S04 and Mn02 they evolve chlorine. 
3. Ag-NOg in the presence of HN03 gives a white precipitate of argentic 
chloride—AgCl—insoluble in boiling nitric acid, but instantly 
soluble in dilute ammonium hydrate of a strength of x in 20. DETECTION, ETC., OF ACIDULOUS RADICALS. 
4. The solid substance mixed with K2Cr207 and distilled with H2S0+ 
yields chloro-chromic acid—CrCl202—in red fumes which, when 
passed into dilute ammonium hydrate, color it yellow, owing to 
the formation of ammonium chromate—(NH4)2Cr04. The 
yellow should change readily to green on the addition of a 
few drops of sulphurous acid. 
Insoluble Chlorides should be first boiled with strong sodium hydrate and 
the whole diluted and filtered. The chloride is then transferred to the 
sodium, and is to be searched for in the filtrate by acidulating with nitric acid 
and adding argentic nitrate, as above described. 
3. HYPOCHLORITES. 
(Practise on a solution of chlorinated lime.) 
Hypochlorites are all readily soluble in water, are contained in the so-called 
chlorinated compounds, and are recognised— 
1. By having an odor of chlorine. 
2. By giving a blue with potassium iodide, starch paste and acetic acid, 
due to liberation of chlorine. 
4. CHLORATES. 
(To be practised on potassium chlorate—KCI03.) 
1. Heated on charcoal, they deflagrate. 
2. Heated with strong sulphuric acid, they evolve chlorine peroxide— 
C1204—which is yellow and explosive. 
3. Their solutions yield no precipitate with argentic nitrate ; but if a 
little of the solid be heated to redness, and the residue dissolved 
in water, a precipitate of argentic chloride is obtained. The 
same reduction from chlorate to chloride may also be effected 
by adding zinc and dilute sulphuric acid to the solution. 
4. Mixed with KI and starch paste and acidulated with acetic acid 
they give no blue (distinction from hypochlorites), but on 
adding HCI, a blue is developed. 
5. SEPARATION OE CHLORATES AND CHLORIDES. 
(Practise on mixed solutions of KCI and KCI03.) 
Add excess of argentic nitrate, filter out the argentic chloride formed, and 
then acidulate with sulphuric acid, and drop in a fragment of zinc, when, if a 
chlorate be present, a second precipitate of argentic chloride will form. 
6. PERCHLORATES. 
These are distinguished from chlorates— 
1. By giving off perchloric acid, when heated with sulphuric acid, without explosion 
or evolution of chlorine peroxide. 
2. Like chlorates, they require reduction to chlorides before giving a precipitate with 
argentic nitrate. 
7. BROMINE, HYDROBROMIC ACID, and BROMIDES. 
Bromine is distinguished,— 
1. By its appearance—heavy, reddish-brown liquid, giving off reddish 
fumes of a very penetrating, unpleasant odor. BROMIDES—BROMA TES. 
3i 
2. By turning starch paste yellow or pink. 
3. When present in small quantity in solution, on adding a few drops 
of chloroform and shaking, an orange color is imparted to 
that liquid, which sinks to the bottom of the aqueous solution. 
Hydrobromic Acid is known,— 
By its acid reaction and the production of fumes of bromine when 
heated with strong sulphuric acid. 
Bromides are all soluble in water, except the silver, mercurous and lead salts ; 
they are detected by the following characters (to be practised 
on potassium bromide—Kßr) ; 
1. Heated with strong sulphuric acid, they evolve red vapors of 
bromine. 
2. A similar effect is produced by sulphuric acid and metallic 
dioxides, such as Pb02, Mn02. 
3. Mixed with starch paste, and a few drops of chlorine water 
carefully added, they give an orange color (starch bromide). 
4. Mixed in a long tube with chloroform, and a few drops of chlorine 
water added, the whole, when shaken well together, leaves a 
characteristic reddish-colored stratum at the bottom of the 
liquid in the tube, due to free bromine in the chloroform. 
5. With argentic nitrate they give a dirty-white precipitate of argentic 
bromide, insoluble in nitric acid, slowly soluble in ammonium 
hydrate, but insoluble in dilute NH4HO, of a strength of 1 in 20 
(argentic chloride dissolves). 
6. Distilled with potassium dichromate and sulphuric acid, red fumes 
are evolved, which give no color when passed into ammonium 
hydrate (distinction from chlorides). 
Insoluble Bromides should be first boiled with NaHO, as described under 
insoluble chlorides. 
8. DETECTION OF CHLORIDES IN THE PRESENCE OF BROMIDES. 
(To be practised on a mixture of KCI and KBr.) 
The solution is divided into two parts, in one of which the bromide is proved 
by the addition of chlorine water, and shaking up with chloroform. The 
second portion is either—(l) Evaporated to dryness, the residue placed in 
a tube retort with a little potassium dichromate and sulphuric acid, while into 
the receiver is placed a little dilute ammonium hydrate, and distillation is 
proceeded with, when, if a chloride be present, the liquid in the receiver will 
be colored yellow; or—(2) Precipitated with excess of AgN03, washed on a 
filter percolated with dilute NH4HO (1 in 20) and nitric acid added to the 
percolate, when a distinctly curdy white precipitate proves the presence of 
chlorides. This latter method is simple, and rarely fails if, on adding the acid, 
a mere cloud be disregarded. 
9. HYPOBROMITES. 
These are very similar to hypochlorites, and react as follows : 
1. They decompose by heat, leaving a bromide ; 
2, On boiling with an alkali, a mixture of bromide and bromate results. 
10. BROMATES. 
These are recognised— 
1. By deflagrating on charcoal, leaving the corresponding bromide. 
2. By liberating bromine on the addition of dilute sulphurous acid. 32 
DETECTION,, ETC., OF ACIDULOUS RADICALS. 
11. lODINE, HYDRIODIC ACID, and lODIDES. 
lodine is readily known by its glistening black scales, its odor, the violet 
vapor on heating, and the production of blue iodide of starch on adding a 
solution to starch paste. 
Hydriodic Acid, in the gaseous state, is known by the formation of a brown 
color on holding paper moistened with chlorine water (blue if also dipped in 
starch paste) over a tube in which it is being evolved. 
lodides are readily known by the following reactions (which may be prac- 
tised on a solution of potassium iodide, KI) : 
i. Heated with strong sulphuric acid they give a liberation of iodine 
with violet fumes. 
2. Mucilage of Starch and nitric acid or chlorine water (if not added 
too plentifully), produces blue iodide of starch, decomposed by 
heat but re-formed on cooling ; also destroyed by excess of Cl 
(iodine trichloride—lC13—being produced). 
3. The light yellow precipitate of argentic iodide—Agl—formed when 
a solution (containing alkaline metals only) is added to 
argentic nitrate dissolved in water. The precipitate, when 
freed from the supernatant liquid, does not dissolve in hot 
HNOs, and is practically insoluble in ammonium hydrate, 
being thus distinguished from a chloride. 
4. A neutral solution (produced, if alkaline in the first place, by the 
cautious addition of dilute HN03; if acid, by dropping in 
KHO solution until test-paper is unaffected) gives with one 
part of cnpric sulphate—CuS04—and three parts, or rather 
less, of ferrous sulphate—FeS04—-dissolved in a little water, 
a greyish precipitate of cuprous iodide—(Cu2)'T2. 
The same precipitate is produced if sulphurous acid—H2S03 
—be used with the cupric sulphate instead of ferrous sulphate. 
5. Palladious Chloride—PdCl2—or palladious nitrate—Pd(N03)2 
gives a black precipitate of palladious iodide—Pdl2—decom- 
posed somewhat below the temperature of boiling mercury, 
iodine being evolved, and the metal left. This is a very 
expensive but efficient separation. 
6. Mercuric chloride and plumbic nitrate give respectively red and 
yellow precipitates with soluble iodides. 
12. DETECTION OF BROMIDES IN THE PRESENCE OF lODIDES. 
Add to the solution a very small quantity of starch paste and then a drop 
or two of chlorine water, when a blue color will be produced, proving the 
iodide. Continue to add more chlorine water until this blue is entirely dis- 
charged, and then shake up with chloroform, when, if a bromide be present, the 
characteristic golden color will be communicated to the chloroform. 
(Practise on a mixture of KBr and KI.) 
13. DETECTION OF CHLORIDES IN THE PRESENCE OF lODIDES. 
Add excess of argentic nitrate, warm, pour off the supernatant liquid, wash 
with warm water, and shake up the precipitate in dilute solution of ammonium 
hydrate (x in 3). The argentic iodide will remain insoluble, while the chloride 
will dissolve and may be detected in the solution after filtration by reprecipita- 
(Practise on a mixture of KCI and KI.) lODIDES—WATER AND HYDRATES. 
33 
tion with excess of nitric acid. As argentic iodide is not absolutely insoluble 
in ammonium hydrate, a mere cloud on adding the nitric acid is to be dis- 
regarded. This test is only accurate in the insured absence of a bromide, 
proved as above directed (see 12). 
14. SEPARATION OF AN lODIDE FROM A BROMIDE AND CHLORIDE. 
1. Add to the solution a mixture of one part cupric sulphate and three parts 
ferrous sulphate, or mix the solution with excess of cupric sulphate and 
drop in sulphurous acid till precipitation ceases. The iodide will separate 
as cuprous iodide—Cu2I2—leaving the bromide and chloride in solution. 
Unless carefully done, this separation is not absolutely accurate, 
2. Add to the solution palladious nitrate until precipitation ceases. Filter out the 
palladious iodide which separates, and pass sulphuretted hydrogen through 
the liquid to remove excess of palladium, and again filter. Boil to expel the 
excess of H2S, and the bromide and chloride remain in solution. 
(Practise on a mixture of KCI, KBr, and KI.) 
15. lODATES. 
(Practise on solution of potassium iodate.) 
lodates are known,— 
1. By giving, when heated with strong sulphuric acid, effects likely to be mistaken 
for chlorates. 
2. By giving a blue with starch paste on the addition of sulphurous acid. 
3. By giving a blue with starch paste on the addition of potassium iodide and 
tartaric acid. 
4. By yielding a precipitate of ferric oxy-iodate on adding ferric chloride. 
15a. DETECTION OF AN lODATE IN AN lODIDE. 
(Practise on a solution of iodine in heated potassium hydrate—KI-f-KI03.) 
When excess of tartaric acid is added to potassium iodate, iodic acid is set 
free; and when the same acid is added to potassium iodide, hydriodic acid is 
set free, and potassium hydro-tartrate formed. Thus: 
SKI + KI03 + 6H2C4H4Oc= SHI5HI + HI03 + 6KHC4H406. 
If these acids be thus liberated together, they immediately decompose, 
forming water and free iodine ; 
SHI + HI03=3T2 + 3H20. 
If therefore starch paste and tartaric acid be added to pure potassium iodide 
no coloration takes place, because only hydriodic acid is liberated; but if the 
sample contains potassium iodate, an immediate production of free iodine 
ensues, which turns the starch blue. 
16. PERIODATES. 
Periodates are distinguished,— 
I. By precipitating with barium chloride—BaCl2—in a neutral solution and digest- 
ing in ammonium carbonate to which some NH4HO has been added. The 
periodate is not decomposed. lodates leave barium carbonate, which when 
washed dissolves in acid with effervescence. 
2. By adding Hg(NC>3)2 and treating the yellowish precipitate with SnCI2. It turns 
green, Hgl2 being produced. 
17. WATER and HYDRATES. 
Water is recognised,— 
1. By its absolute neutrality to test paper. 
2. By its evaporating without residue, fumes or odor of any kind. 34 
DETECTION., ETC., OF ACIDULOUS RADICALS. 
3. By its turning white anhydrous cupric sulphate blue. 
4. By its yielding pure hydrogen when boiled and the steam passed 
slowly over copper turnings heated to bright redness in an iron 
tube. 
5. By its undergoing electrolysis, and yielding hydrogen at the negative 
and oxygen at the positive electrode. 
The soluble Hydrates, viz., KHO, NaHO, Li HO, Ba(HO)2, Sr(HO)2, and 
Ca(HO)2 are known,— 
1. By being more or less soluble in cold water, yielding solutions 
which are strongly alkaline to test-paper. 
2. By dissolving in hydrochloric acid without effervescence and without 
smell. 
3. By giving a brownish-black precipitate of argentic oxide—Ag20— 
with argentic nitrate. 
The insoluble Hydrates are recognised,— 
By giving off steam when heated in a dry test-tube, and leaving a 
residue which behaves like the corresponding oxide. 
18. OXIDES. 
All oxides are insoluble in water. Those of K, Na, Li, Ba, Sr, and Ca, 
when placed in contact with that liquid, unite with it to form hydrates, which 
dissolve with a greater or less degree of readiness and give the characters of 
the soluble hydrates already mentioned. 
Normal Oxides can only be recognised by negative results, such as : 
1. Heated alone, they are not changed; except argentic oxide, which 
leaves the metal, and mercuric oxide, which volatilises and 
breaks up into the metal and oxygen. 
2. They are insoluble in water (exceptions K, Na, Li, Ca, Ba, and Sr, 
converted into soluble hydrates), but soluble in hydrochloric or 
nitric acid without effervescence and without smell. 
3. After dissolving and removing the metal by H2S or Na2C03 as most 
convenient, no acidulous radical is found, other than that of 
the acid used to dissolve. 
4. Boiled with strong NaHO and filtered, or fused with KNaCOs and 
digested with water, the solution gives, no reaction for any acid 
radical except the soluble hydrate or carbonate employed. 
Peroxides, on account of their containing an excess of oxygen, differ from 
normal oxides (practise on Mn02), 
1. By giving off oxygen when strongly heated. 
2. By evolving chlorine when heated with hydrochloric acid. 
19. SULPHUR, HYDROSULPHURIC ACID, and SULPHIDES. 
Ordinary Sulphur is recognised,— 
x. By its burning entirely away with a pale blue flame, and evolving 
sulphurous anhydride. 
2. By its insolubility in all ordinary menstrua, such as water, alcohol, 
and ether, but dissolving readily in carbon disulphide. 
3. When slowly heated in a tube, it first melts, then thickens, then 
melts again, and finally boils, the vapor taking fire and forming 
sulphurous anhydride. 
Precipitated Sulphur possesses the above characters, and is specially distin- SULPHUR, HYDROSULPHURIC ACID AND SULPHIDES. 
35 
guished from ordinary sulphur by being quite amorphous under 
the microscope, while the latter is crystalline. 
Hydrosulphuric Acid (sulphuretted hydrogen) is known,— 
1. By being a colorless gas with a disgusting odor of rotten eggs, and 
inflammable, burning in the air to produce sulphurous acid. 
2. By turning a piece of paper black, which has been moistened with 
solution of plumbic acetate and held over the mouth of the tube 
or jet from which it issues. 
Normal Sulphides are divisible into five classes : 
1. Soluble in water, including the sulphides of K, Na, NH4,°Ca, Sr, Ba 
and Mg. 
2. Insoluble in water, but readily soluble in dilute hydrochloric acid, 
including those of Fe, Mn, Zn. 
3. Insoluble in dilute, but soluble in strong boiling hydrochloric acid, 
including the sulphides of Ni, Co, Sb and Sn (PbS is also 
slightly affected, but separates on cooling, as chloride). 
4. Insoluble in hydrochloric acid, but attacked by strong heated nitric 
acid, being converted wholly or partially into sulphates. These 
include the sulphides of Pb, Ag, Bi, Cu (arsenious sulphide is 
slowly affected). 
5. Not dissolved by any single acid, but converted into a soluble 
sulphate by the action of nitro-hydrochloric acid, or hydro- 
chloric acid and potassium chlorate; including those of 
Hg, As, Au, and Pt. 
Sulphides soluble in water or in hydrochloric acid are recognised (practise 
on solution of Na2S),— 
1. By giving off sulphuretted hydrogen when heated with that acid, 
which gives the smell and reactions already noted. 
2. Soluble sulphides precipitate solutions of lead and cadmium, black 
and yellow respectively. 
3. Soluble sulphides give a purple color with sodium nitroprusside 
only after the addition of a soluble hydrate. 
Sulphides insoluble in hydrochloric acid are best detected (practise on 
vermilion),— 
1. By heating with strong nitric or nitro-hydrochloric acid, diluting 
the solution, and testing for a sulphate with barium chloride 
(see 24). 
2. By fusion with KNaC03 and KN03, digesting the residue in water, 
filtering and testing the solution for a sulphate formed by the 
oxidising action of the potassium nitrate. 
3. Mix a little with sodium carbonate and borax, and heat on charcoal 
before the blowpipe. Remove the mass thus obtained, place it 
on a clean silver coin, and moisten with a drop of distilled water ; 
when, owing to the formation during ignition of sodium sulphide 
—Na2S—a black stain of argentic sulphide—Ag2S—will be 
produced. 
Polysulphides as commonly met with are those of the alkalies, and are soluble 
in water. They are known (practise on sulphuretted potash),— 
1. By the deep yellow or orange color of their solutions. 
2. By evolving sulphuretted hydrogen accompanied by a deposit of 
sulphur when treated with hydrochloric or dilute sulphuric 
acids. 
The polysulphides which are insoluble in hydrochloric acid, such as iron 
pyrites, copper pyrites, etc., are best proved by fusion with potassium nitrate 36 
DETECTION, ETC., OF ACIDULOUS RADICALS. 
and carbonate and conversion into sulphate. They may, however, be recog- 
nised by heating with hydrochloric acid and zinc, when the excess of sulphur 
will pass off as H2S, leaving the normal sulphide. 
20. DETECTION OE A SOLUBLE SULPHIDE IN PRESENCE OE A 
SULPHITE AND A SULPHATE. 
Pour the solution on a little cadmium carbonate—CdC03—filter, and treat 
the insoluble matter with acetic acid to remove any unacted-upon cadmium 
carbonate. ‘ If a sulphide have been present, a yellow residue of cadmium 
sulphide will remain insoluble in the acetic acid, while cadmium sulphite and 
sulphate will be found in the first filtrate, if these two radicals were present 
(see Separation of Sulphites and Sulphates). 
(Practise on mixed solutions of-Na2S, Na2S03, and Na2S04.) 
21. THIOSULPHATES (Hyposulphites). 
(Practise on solution of commercial hyposulphite of soda.) 
These salts, commonly known as hyposulphites, are usually soluble in water, 
and exhibit the following characters ; 
1. With either dilute or strong HCI and H2S04, they yield S02 gas 
and a yellow deposit of S (distinction from sulphides, poly- 
sulphides, and sulphites). 
2. AgN03 gives no precipitate at first, owing to excess of a hypo- 
sulphite dissolving argentic hyposulphite—Ag2S903—but on 
continuing the addition, this Ag2S203 is precipitated of a white 
color. The salt splits up spontaneously, becoming yellow, 
brown, and lastly black, and being changed completely into 
argentic sulphide—Ag2S. The same decomposition of the 
precipitate occurs on substituting HgN03 or Pb(NO3)2 for 
AgN03; and in all three cases heat accelerates the action, 
and H2S04 is the by-product. 
3. Fe2Cl6, Na2OCl2, and Cl water convert hyposulphites into sulphates, 
even without applying heat. 
Na2S203 + H2O + 4Na2OCl2 = 2NaHSO4 + BNaCI. 
The first produces a reddish-violet color, and this gradually disappears 
as FeCl2 is formed. (This color is not produced hy sulphites.) 
(Practise on solution of commercial hyposulphite of soda to which a drop of 
NH4HS has been added. ) 
22. SEPARATION OE THIOSULPHATES FROM SULPHIDES. 
Having obtained a good preliminary idea by heating with H2S04, add to 
a portion of the original solution—ZnS04—in excess, and filter. 
(a) Precipitate white, and soluble in HCI, with smell of H9S 
= Sulphides. 
(b) A portion of filtrate heated with H2S04 deposits S and smells of 
S02; and another portion added to a drop or two of ammonio- 
cupric sulphate instantly causes decolorisation. 
Hyposulphites. 
23. SULPHUROUS ACID and SULPHITES. 
Sulphurous acid in solution is recognised,— 
1. By its pungent odor of burning sulphur. 
2. By adding barium chloride in excess, filtering out any precipitate SULPHITES AND SULPHATES. 
37 
of barium sulphate which may form (owing to the fact that all 
samples of the ordinary acid contain sulphuric acid), and 
then adding chlorine water and getting another copious white 
precipitate of barium sulphate, owing to the conversion of the 
sulphurous into sulphuric acid by the oxidising action of the 
chlorine water, thus ; 
H2S03 + BaCl2 + Cl2 + H2O = BaS04 + 4HCI. 
3. Treated with zinc and hydrochloric acid, it evolves sulphuretted 
hydrogen, thus : 
3Zn + 6HCI + H2S03 = 3ZnCI2 + H2S + 3H20. 
4 When a solution of iodide is dropped into the liquid, its color is 
discharged, owing to its conversion into hydriodic acid by the 
hydrogen of the water, the oxygen of which passes at the same 
time to the sulphurous acid, forming sulphuric acid. 
H2S03 +I2 + H2O = H2SOi + 2HI. 
Sulphites are known by the following characteristic (practise on solution 
of sodium sulphite):— 
1. All except the alkaline sulphites are sparingly soluble in water. 
2. When heated with sulphuric acid they evolve sulphurous anhydride, 
without deposit of sulphur. 
3. Acted on with zinc and hydrochloric acid, they evolve sulphuretted 
hydrogen, which blackens a piece of paper moistened with 
plumbic acetate and held over the mouth of the test-tube. 
4. A salt of silver, mercury, or lead, produces a precipitate which on 
heating turns dark, owing to the formation of a sulphide and 
free sulphuric acid. 
5. By boiling with barium chloride and chlorine water or nitric acid, 
barium sulphate is produced, and precipitates. 
6. The acid gas—S02—combines directly with peroxides to form 
gaseous sulphates. For instance : 
Pb02 + S02 = PbS04. 
This reaction is utilised in gas analysis, to separate S02 from a 
mixture. 
7. K2Cr207 and HCI give a beautiful green coloration of chromic 
sulphate or chloride. This test is very delicate, but by itself is 
not conclusive. 
24. SULPHURIC ACID and SULPHATES. 
The acid is detected,— 
1. By its appearance. A heavy, oily, odorless, and nearly colorless 
liquid, powerfully acid and corrosive. 
2. By its charring effect. This is made evident when the strong acid 
is dropped upon white paper, wood, etc., or when the dilute 
acid is evaporated in a basin containing a little white sugar. 
The carbonisation is due to the power the acid has of abstract- 
ing the elements of water from organic bodies. 
3. By liberating an explosive gas from KCI03 when heated with it. 
The test is not available with dilute acid. 
Sulphates are soluble in water, with the exception of basic sulphates (soluble 
in acids) and BaS04, SrS04, CaS04, and PbS04. (Ag2S04 is only slightly 
soluble.) When those insoluble in dilute acids are required to be analysed, 
they are decomposed either by boiling with potassium or sodium hydrates or 
by ignition with KNaC03, the latter being preferable. The sulphate radical, 
being brought into combination with K or Na to form a soluble sulphate, is to 38 
DETECTION, ETC., OF ACIDULOUS RADICALS. 
be tested for in the filtrate after boiling with water. Sulphates are recognised 
by the following characters (practise on solution of magnesium sulphate):— 
1. BaClo or 8a(N03)2 produces a white precipitate of barium sulphate 
—BaSO*—insoluble in boiling water and also (after washing to 
remove excess of BaCl2) in boiling nitric acid. This washing 
is necessary, as the addition of a strong acid to a solution of 
barium chloride often causes the reagent to crystallise out, and 
this is then mistaken by the student for a true precipitate of 
sulphate. 
2. The addition of a soluble salt of lead or strontium also causes the 
formation of insoluble sulphates ; but these reactions are never 
in practice used, the barium chloride being at once the most 
delicate and serviceable reagent. 
3. Heated with a little Na2C03 on charcoal in the inner blowpipe 
flame, sulphates are reduced to sulphides; and the residue placed 
on a clean silver coin and moistened with water, leaves a black 
stain. 
25. SEPARATION of SULPHIDES, SULPHITES, and SULPHATES. 
(Practise on mixed solutions of sodium sulphite and sulphate, to which a 
drop of NH4HS has been added.) 
Pour the solution on an excess of cadmium carbonate, digest at a gentle 
heat, filter, and examine the precipitate for a sulphide as already directed (19). 
The filtrate, which may contain the sulphite and sulphate, is precipitated by 
barium chloride, the insoluble precipitate filtered out and boiled with a little 
hydrochloric acid, which will dissolve the barium sulphite with evolution 
of sulphurous anhydride—S02—and leave the barium sulphate insoluble. 
26. CARBON, CARBONIC ACID, and CARBONATES. 
Carbon is known 
1. By its black color and the production of a gas when burnt which 
is odorless, so heavy that it can be poured from one vessel to 
another, and causes a white precipitate when passed into solu- 
tion of calcium hydrate. 
2. By its capability of removing many vegetable coloring matters 
from their solutions. 
Carbonic Acid is not known in the free state, splitting up into carbonic 
anhydride—C02—and water. C02 is recognised,— 
1. By being odorless and giving white insoluble CaC03 (or BaCOs) 
when passed into a solution of Ca(HO)2 or Ba(HO)2. 
2. By turning blue litmus purple or wine-red, the originaf tint being 
restored by heat, the C02 escaping. 
Carbonates are mostly insoluble in water, the alkaline carbonates alone 
dissolving. CaC03, SrC03, BaC03 and MgCOs (also MnC03 and FeCOs), 
dissolve in water containing C02 (especially under pressure), forming bicar- 
bonates or hydrogen carbonates, from which C02 passes off on boiling. All 
carbonates give off C02 on ignition, except K2C03 and Na2C03. A white 
heat is needed to decompose BaC03 and SrC03. Most carbonates on heating 
to redness leave the oxide. Their recognition depends upon (practise upon 
calcium carbonate) : 
1. Effervescing with a solution of almost any acid (H2S and HCy 
excepted), organic or inorganic, and giving off an odorless 
gas—C02. BORIC ACID, BORATES AND SILICATES. 
39 
2. When the gas given off is poured or passed into a solution of 
calcium hydrate, a white precipitate of CaC03 falls, which dis- 
solves on continuing to add C02. When the gas given oft' has 
the odor of H2S or S02, either of these may be removed by 
passing through K2Cr04 and HCI, which is rendered green, 
and the unacted-upon C02 is allowed to pass into calcium 
hydrate solution as before. 
27. BORIC ACID and BORATES. 
Boric {or Boracic) Acid—H3B03—is distinguished as under: 
1. It is a white crystalline solid, giving off water on being heated, and 
leaving the anhydride—B203. 
2. When warmed with alcohol, a green flame is produced on applying 
a light to the latter. 
3. When dissolved in hot water, and a piece of turmeric paper dipped 
in the solution, the yellow color is unaffected ; but upon drying 
the paper it becomes brownish-red. 
All borates dissolve in dilute acids, but few in water, and when 
decomposed by hot acids, let fall crystalline boric acid on 
cooling, which answers to the above characters. 
The presence of soluble borates is detected by the following tests (practise 
upon borax) : 
1. They give, on heating with calcium chloride, rendered slightly 
alkaline with ammonium hydrate, a white precipitate of calcium 
borate, soluble in acetic acid, and so distinguished from oxalate. 
2. On rendering the solution just acid with hydrochloric acid, and then 
dipping in a piece of turmeric paper, and drying the same after 
immersion at a gentle heat, it will be turned red. 
3. Besides these two tests, which are in themselves, taken together, quite 
conclusive, borates give a precipitate with argentic nitrate soluble 
in nitric acid. 
4. When a little of the solid borate is moistened, first with a drop of 
sulphuric acid with about a drachm of spirit of wine, the 
alcoholic solution of boric acid so obtained burns with a bright 
green flame. 
28. SILICIC ACID and SILICATES. 
The acid H4Si04 is scarcely ever met with, and we have practically to deal 
with the anhydride—Si02—which is totally insoluble in water and dilute acids, 
the acid dissolving slightly in both. Si02 is characterised,— 
1. By its infusibility when heated. 
2. By its insolubility in water and all acids except HF. 
3. By forming, when heated with H2S04 and CaF2 in a leaden vessel, 
, gaseous silicic fluoride—SiF4—which deposits the acid—H4Si04 
—and forms hydro-fluosilicic acid—H2SiF6 in contact with 
moisture. 
Silicates are not as a rule soluble in water, K4Si04 and Na4Si04 being the 
only ones thus affected, especially when much KHO or NaHO is present. 
Many of them do not dissolve in strong acids (a few are decomposed by hot 
H2S04, but by no other acid), but all are split up by the action of gaseous 
hydrofluoric acid or a mixture of CaF2 and H2S04. 
1. On adding HCI to a soluble silicate, H4Si04 falls as a gelatinous 40 
DETECTION,, ETC., OF ACIDULOUS RADICALS. 
—scarcely visible—precipitate, slightly soluble in water. On 
evaporating to dryness and heating to 280° or 300° F., the 
addition to the residue of a little HCI and water leaves the Si02 
as a white gritty powder. 
2. NH4CI precipitates H4Si04 from a soluble silicate. 
3. Silicic anhydride is separated from all acidulous and basylous 
radicals by fusing the finely powdered insoluble silicate with 
Na2C03 (or fusion mixture), in a platinum crucible ; boiling with 
water, filtering, evaporating nearly to dryness, adding dilute HCI 
until the whole is acid, re-evaporating, moistening with water, and 
when dry heating to 280° or 300° F. On adding a little HCI, 
Si02 alone remains insoluble. 
29. SEPARATION OF SILICIC ANHYDRIDE (SILICA) FROM ALL 
OTHER ACIDS. 
Fuse the substance with a large excess of KNaC03 in a platinum crucible, 
and when all action has ceased, cool, and boil the residue with water. The 
silica passes into solution with the other acid radicals, and the metals are left 
as oxides. Acidulate the solution with hydrochloric acid, evaporate to dryness, 
and heat the residue to 280° Fah., and maintain the heat for some time. 
Drench the residue with strong hydrochloric acid, then add water, and boil, 
when the silica will alone remain insoluble. 
(Practise upon powdered glass.) 
This acid is only known in solution. 
1. It is very acid, and dissolves metals with the evolution of hydrogen, forming 
• silico-fluorides which decompose by heat, leaving fluorides, and giving off 
silicon fluoride—SiF4. 
2. It gives off hydrofluoric acid when evaporated, and should not, therefore, be heated 
in glass vessels, as they would be etched. 
3. The majority of silico-fluorides are soluble, the exceptions being K2SiF6, 
BaSiF6, and Na2SiF6, which are insoluble, especially in presence of a little 
alcohol. 
30. HYDROFLTJOSILICIC ACID (H2SiF6). 
4. It does not precipitate strontium salts, even from strong solutions, but throws 
down BaSiF6 on adding BaCl2 and alcohol, as a white translucent crystalline 
precipitate. 
5. .Potassium salts throw down gelatinous K2SiF6. 
31. NITROUS ACID AND NITRITES. 
Nitrous Acid (so called commercially) is nitric acid containing nitrous 
anhydride. It is } ellowish in color, and evolves reddish fumes. 
Nitrites are all soluble in water, the least so being argentic nitrite. They are 
known as follows (practise upon potassium nitrate which has been heated 
to dull redness) : 
1. They give red fumes when treated with strong sulphuric acid. 
2. They give an instantaneous blue color with potassium iodide and 
starch paste on the addition of a few drops of dilute sulphuric 
acid. The sulphuric acid liberates hydriodic acid from the 
iodide, and nitrous acid from the nitrite; the hydriodic acid 
is decomposed by the nitrous acid into iodine, water, and nitric 
oxide : 
2HN02+2 HI =I2 + 2H20 + 2NO. 
[Nitrates, it must be remembered, would give frequently a similar reaction after 
standing, through the possible reduction of some portion of their nitric acid NITRITES AND NITRA TES. 
4i 
to nitrous acid ; so that unless the reaction appears instantly, and is confirmed 
by others, it is not safe to rely upon it as a test.] 
3, They give a dark brown color with ferrous sulphate without the 
previous addition of sulphuric acid, as required by nitrates. 
4. Potassium dichromate in solution is converted into a green liquid 
by the addition of a nitrite and an acid. These two latter 
substances also reduce an auric solution, forming a precipitate 
of the metal, possessing a dark color. 
32. DETECTION OF A NITRITE IN THE PRESENCE OF A NITRATE. 
(Practise upon potassium nitrate which has been slightly heated so as to 
partially decompose it.) 
Add a little potassium iodide and starch paste, then introduce a small pinch 
of powdered metallic zinc, and lastly acidulate with acetic acid, when, if a 
nitrite be present, a blue color will be produced, due to the liberation of 
iodine. This test is often a very necessary one when dealing with drinking 
water, the presence in which of nitrites, derived from the oxidation of com- 
paratively recent organic contamination, is a dangerous indication. 
33. NITRIC ACID and NITRATES. 
Nitric Acid is strongly acid and corrosive, fumes in the air, and readily dis- 
solves most metals. It may be at once recognised by the following 
characters ; 
1. When poured on a piece of copper foil, and a piece of white paper 
held behind the test-tube, it is observed to be filled with 
orange-red fumes of nitric peroxide—N204. 
2. When dropped on a piece of quill in a basin, or if the solution be 
weak when evaporated in contact with the quill, the latter is 
stained yellow. This stain is intensified to orange on adding 
an alkali, and is not discharged by warming, both of which 
decolorise the corresponding stains produced by iodine and 
bromine. 
3. Dropped on a few crystals of brucine, a deep red color is 
produced. 
Nitrates are characterised by the following properties (practise upon solution 
of potassium nitrate) : 
t. All nitrates are soluble in water, especially when slightly acidulated 
with nitric acid. The nitrates of the alkalies are only decom- 
posed by a very high temperature, but most of the nitrates 
of the heavy metals, such as copper, mercury, and lead, when 
heated are really decomposed, leaving a residue of oxide. 
Argentic nitrate, however, when heated leaves metallic silver. 
2. When heated with sulphuric acid they evolve pungent fumes of 
nitric acid. 
3. When heated with sulphuric acid and a piece of copper wire, they 
produce red fumes of nitric peroxide (caused by the union of 
the nitric oxide evolved with the oxygen of the air). 
4 When mixed with a solution of ferrous sulphate in the presence of 
sulphuric acid, a black coloration is produced, which is due to 
the production of nitric oxide, and its absorption by the ferrous 42 
DETECTION, AFC., OF ACIDULOUS RADICALS. 
salt. On heating, the color disappears, and the ferrous is 
changed to the ferric sulphate. 
Note.—There are two ways of applying this test : 
[a] Place a drop or two of the suspected solution on a white porcelain slab or crucible 
lid, and having added a drop of strong sulphuric acid, put a small and clean 
crystal of the ferrous sulphate in the liquid, when a black ring will gradually 
form round the crystal. 
(Ib) Place the suspected solution in a tube, and having added some strong solution 
of ferrous sulphate, cautiously pour some strong sulphuric acid down the 
side of the tube, so that it sinks to the bottom by reason of its great gravity 
without mixing with the fluid. If nitric acid be present, a dark line will be 
formed at the junction of the two liquids. 
5. Treated with sulphuric acid, and a few drops of indigo sulphate 
added, the blue color of the latter is destroyed, being changed 
to yellow (not characteristic). 
6. The most delicate test for nitrates is, however, phenyl-sulphuric 
acid. This reagent is prepared by dissolving one part of 
carbolic acid in four parts of strong sulphuric acid, and then 
diluting with two parts of water. A few drops of the solution 
to be tested are evaporated to dryness on a porcelain crucible 
lid over the water bath, and while still over the bath a drop of 
the reagent is added, when a reddish color is immediately 
produced, owing to the formation of nitro-phenol. 
34. DETECTION OF FREE NITRIC ACID IN THE PRESENCE OF A 
NITRATE. 
Digest with excess of barium carbonate ; filter, and add to the filtrate some dilute sulphuric 
aaid, when, if the free acid were present, a precipitate of barium sulphate will be produced. 
This test is only good in the insured absence of sulphates and of any other acid capable of 
dissolving barium carbonate. It will also serve for detecting free hydrochloric and acetic 
acids in presence of their salts. 
35. DETECTION OF A NITRATE IN THE PRESENCE OF AN lODIDE. 
(Practise upon mixed solutions of potassium nitrate and potassium iodide.) 
The fact that the addition of strong sulphuric acid liberates iodine renders 
the proof of a nitrate by the ordinary iron process doubtful in the presence 
of iodides and bromides. In this case proceed by one of the following 
methods : 
1. Boil with excess of potassium hydrate until any ammonium salts 
are decomposed, then add a fragment of zinc and again boil. 
Any nitrate present will be converted into ammonia, which 
may be recognised in the steam with moistened red litmus 
paper. 
2. Warm with a little zinc amalgam and add a little acetic acid and 
starch paste, when the nitrate, being reduced to nitrite, will 
cause the liberation of iodine, and color the starch paste blue. 
3. Boil with stannous chloride and a large excess of hydrochloric acid, 
which will produce ammonium chloride from a nitrate ; and by 
boiling the liquid with excess of potassium hydrate, the ammonia 
gas may be evolved. Of course the absence of ammonium 
salts must be first insured. 
36. SEPARATION OF CHLORIDES, lODIDES, AND BROMIDES FROM 
NITRATES. 
Digest with argentic sulphate, which will precipitate the halogens as silver 
salts and leave the nitrate in solution. CYANOGEN, HYDROCYANIC ACID AND CYANIDES. 
43 
Cyanogen is a colorless gas, which is recognised,— 
1. By its odor of bitter almonds. 
2. By its burning in the air with a peach-blossom-colored flame, pro- 
ducing carbonic anhydride and nitrogen. 
Hydrocyanic Acid is volatile, soluble in water, and possesses a characteristic 
faint sickly odor of almonds. Its reddening action on litmus paper is 
very transient. Its tests are four in number, as follows.;— 
1. The Silver Test.—Argentic nitrate added to a solution of prussic 
acid gives a curdy white precipitate of argentic cyanide. The 
precipitate is soluble in ammonium hydrate and in strong boil- 
ing nitric acid, but not in dilute nitric acid ; nor does it blacken 
on exposure to the light. 
2. Scheele’s Iron Test.—An excess of solution of potassium hydrate is 
mixed with the solution. To this a mixture of a ferrous and a 
37. CYANOGEN, HYDROCYANIC ACID and CYANIDES. 
ferric salt is added, and the whole acidulated with hydrochloric 
acid. If hydrocyanic acid be present, Prussian blue will be 
formed. 
The explanation of the test is as follows (according to Gerhardt’s view) ; 
(1) The hydrocyanic acid and the potassium hydrate form potassium cyanide. 
(2) The addition of the ferrous salt produces ferrous cyanide. 
(3) This reacting with the excess of alkali forms potassium ferrocyanide. 
(4) On the addition of the ferric salt, it is at first precipitated by the excess of alkali, 
as ferric hydrate, which on acidulation dissolves to ferric chloride, forming 
ferric ferrocyanide (Prussian blue). 
(i) 6HCy+6KHO = 6KCy + 6H,0. 
(ii) 6KCy+3FeCll=3FeCy,+6KCl. 
(iii) F3eCy2-f 4KH O=K4FeCy6+ 2Fe(FIO)2. 
(iv) 3K4FeCy6 + 2Fe2Cl6=(Fe2)2(FeCy6)3+i2 KCI. 
Or the whole may be shown in one equation, thus, which is quite sufficient 
iBKCy+3FeCl2+2Fe2Cl6=(Fe2)2(FeCy6)3+iB KCI. 
3. The Sulphur Test.—A few drops of yellow ammonium sulphydrate is 
added to a solution of hydrocyanic acid, and the whole evapo- 
rated to dryness at a very gentle heat, with the addition of a 
drop of ammonium hydrate. A residue is thus obtained which 
strikes a blood-red color with ferric chloride, not dischargeable 
by hydrochloric acid, but at once bleached by solution of 
mercuric chloride. 
This color is due to the formation of ammonium sulphocyanide (which takes 
place when an alkaline sulphide, containing excess of sulphur, is brought 
into contact with cyanogen)— 
and subsequent production of red ferric sulphocyanide. 
2HCy+(NH4),S+S>=2NH4CyS + H,SI 
4. Schbnbein's Tesi.~~lt has been stated that a very delicate means 
of detecting HCy is based upon its action on filtering paper, 
soaked, first in a 3 per cent, alcoholic solution of guaiacum 
resin, and then in a 2 per cent, solution of cupric sulphate, 
and exposed to the air. The presence of HCy causes the pro- 
duction of a blue color. The paper may be either moistened 
with the suspected solution or exposed to its vapor. 
Cyanides are known (practise upon solution of potassium cyanide),— 
1. By effervescing and giving off the odor of hydrocyanic acid when 
heated with sulphuric acid. 
2. By answering to all the tests for hydrocyanic acid above mentioned. 
Note.—In using the silver test to a soluble cyanide, the reagent must be added 
in excess, as argentic cyanide is soluble in alkaline cyanides to form double DETECTION, ETC., OF ACIDULOUS RADICALS. 
44 
cyanides of silver and the alkali used. Excess of argentic nitrate, however, 
decomposes these compounds, and forms insoluble argentic cyanide. The 
previous addition of a slight excess of dilute nitric acid ensures the immediate 
separation of the argentic cyanide, by preventing the reaction just referred to. 
3. Insoluble cyanides yield cyanogen when heated per se in a small 
dry test-tube, the open end of which has been drawn out into a 
jet after the introduction of the cyanide. The application of a 
light to the jet causes the characteristic flame of cyanogen. 
38. SEPARATION OF CYANIDES FROM CHLORIDES. 
(Practise on a mixed solution of KCN and KCI.) 
Acidulate slightly with nitric acid, add excess of argentic nitrate, wash the 
precipitate thoroughly with boiling water by decantation, allow it to settle 
completely, pour off all the water, and boil with strong nitric acid, when the 
argentic cyanide is decomposed, leaving the chloride insoluble. The solution 
in nitric acid is diluted and hydrochloric acid added, when any dissolved 
silver is detected by precipitation, as chloride, thus indicating the presence of 
argentic cyanide in the original mixture. 
39. CYANIC ACID and CYANATES, CYANURIC ACID, and FU L INIC 
ACID. 
Cyanic acid is characterised,— 
1. By being a colorless liquid, having a strong pungent odor, greatly resembling 
acetic acid, or sulphurous acid when in small quantity, and forming ammonium 
bicarbonate on adding water. 
2. By changing into a white solid isomer on keeping, heat being evolved, but no 
decomposition occurring. 
Cyanates are known,— 
1. By giving, when moistened, a bicarbonate. (The potassium salt—KCyO—for 
instance, forms potassium bicarbonate—KHCOa.) 
2. By producing urea when evaporated with an ammonium salt. 
Cyanuric acid is a polymeric modification of cyanic acid, which is recognised,— 
1. By being a crystalline solid, yielding cyanic acid on applying heat. 
2. By not being decomposed by strong hot HN03 or H2S04. 
Fulminic acid (intermediate between the two above acids) differs from both by the fearful 
explosibility of its salts. 
40. THIOCYANATES (Sulphocyanates). 
Sulphocyanates are recognised,— 
1. By being usually colorless and soluble, and evolving hydrocyanic 
acid and depositing sulphur on heating with sulphuric acid. 
2. By producing with a ferric salt, a blood-red solution of ferric 
sulphocyanate—Fe2(CyS)6—the color of which is notdestroyed 
by HCI, but disappears on adding mercuric chloride—HgCff. 
41. FERROCYANIDES. 
Ferrocyanides are mostly insoluble in water, except those of the metals of the 
first and second groups. They are characterised,— 
1. By giving off hydrocyanic acid and forming a deposit on heating 
with sulphuric acid. 
2. By giving with a ferrous salt a white precipitate of ferrous 
potassium ferrocyanide—K2Fe(FeCy6)— changing quickly to 
blue. 
(Practise upon solution of potassium ferrocyanide.) FERROCYANIDES AND FERRICYANIDES. 
45 
3. By yielding with a ferric salt a dark blue precipitate of ferric 
ferrocyanide—(Fe2)2(FeCy6)3. This precipitate and (1) are 
both insoluble in HCI, but KHO decomposes them, producing 
potassium ferrocyanide. When it is boiled with HgO and 
water, mercuric cyanide—FIgCy2—and Fe203 remain. 
4. Cupric salts produce a reddish-brown precipitate of cupric ferro- 
cyanide—Cu2FeCy6—insoluble in acids, dissolved by NH4HO, 
but left unaltered on evaporating off the ammonia. 
5. By precipitating a white ferrocyanide from a solution of a lead salt. 
6. By yielding a white mercuric ferrocyanide in a mercuric solution. 
7. By giving no effect with magnesium salts but a white gelatinous 
precipitate, soluble in NH4HO on the addition of a solution 
containing a zinc salt. 
8. By producing with argentic nitrate—AgNCb—white gelatinous silver 
ferrocyanide, dissolved by NH4HO. 
None of these precipitates can be produced in alkaline solutions ; and they form 
best in slightly acid solutions. 
42. FERRICYANIDES. 
(Practise upon solution of potassium ferricyanide.) 
Most ferricyanides are insoluble, those of the alkalies and of the barium group 
being exceptions. They are recognised,— 
1. By yielding an odor of hydrocyanic acid, and a deposit on heating 
with sulphuric acid. 
2. By producing with a ferrous salt dark-tinted Turnbull's blue— 
Fe3Fe2Cy12—insoluble in acids, but forming KGFe2Cy12 when 
boiled with KHO. 
3. By producing a brownish coloration when added to a ferric salt 
in solution, from which H2S03, Stannous Chloride—SnCl2—and 
other reducing agents throw down Turnbull's blue or Prussian- 
blue (distinction between H6Fe2Cy12 and FI4FeCy6). 
4. By giving no precipitate in a lead solution (another distinction of a 
ferricyanide from a ferrocyanide). 
5. By throwing down mercurous ferricyanide of a brownish-red color 
from a mercurous solution. 
6. By yielding with argentic nitrate solution an orange precipitate of 
argentic ferricyanide. 
7. Mercuric salts, giving no precipitate. 
8. Stannous salts, a white precipitate, soluble in HCI. 
9. Stannic salts, no visible alteration. 
43. SEPARATION OF FERRO- FROM FERRI CYANIDES. 
(Practise upon mixed solutions of potassium ferro- and ferricyanides.) 
Acidulate with hydrochloric acid, add excess of ferric chloride, warm 
gently; the ferrocyanide will be precipitated. Pour off some of the brownish 
liquid and heat with a little zinc amalgam, when a blue precipitate will form, 
owing to the reduction of the ferri- to ferro-cyanide. 
44. DETECTION OF CYANIDES IN THE PRESENCE OF FERRO- 
AND FERRI-CYANIDES. 
(Practise upon mixed solutions of potassium cyanide and ferrocyanide.) 
Acidulate slightly with nitric acid and add an excess of a mixture of ferrous 
and ferric sulphates; warm gently, and allow the precipitate to subside. Pour 46 
DETECTION, ETC., OF ACIDULOUS RADICALS. 
off a little of the supernatant liquid, add to it excess of potassium hydrate, 
and then acidulate with hydrochloric acid, when the production of another 
blue precipitate will prove the cyanide. 
(Practise upon solution of calcium hypophosphite.) 
45. HYPOPHOSPHITES. 
The silver salt alone is insoluble in water, and few are insoluble in alcohol. 
The following reactions serve for their detection : 
i. When heated in a solid state, they take fire, evolving phosphuretted 
hydrogen, and leaving a residue of pyrophosphate. 
Note.—This must be done on porcelain, as they destroy platinum foil. 
2. With argentic nitrate they give a white precipitate, which turns 
brown owing to its reduction to metallic silver. 
3. With mercuric chloride they yield, when slightly acidulated with 
HCI, a precipitate of calomel, which, on heating, turns dark, 
owing to a reduction to the metallic state. 
4. After removal of the base, the free hypophosphorous acid, when 
boiled with solution of cupric sulphate, will give a deposit of 
metallic copper. 
5. Treated with ammonium molybdate they give a fine blue precipitate. 
As afterwards mentioned, phosphates give a yellow, and con- 
sequently when the solution contains both classes of salts the 
precipitate is green. This forms an excellent and rapid method 
of checking any commercial sample of hypophosphites. 
They are distinguished from phosphites by not giving precipitates with 
neutral barium, or calcium, chlorides, or with plumbic acetate. In performing 
the 4th reaction, the base, if calcium, is removed by oxalic acid, if barium, by 
sulphuric acid, and if a heavy metal, by sulphuretted hydrogen. 
46. PHOSPHOROUS ACID and PHOSPHITES 
are distinguished as follows : 
1. Heated on platinum foil, they bum. They are powerful reducing agents. 
2. The only phosphites soluble in water are those of K, Na, and NH4, but acetic 
acid dissolves all, except plumbic phosphite. 
3. With zinc and sulphuric acid (nascent hydrogen) they yield phosphuretted hydro- 
gen, burning with an emerald-green color, and throwing down Ag3P, as well 
as Ag from AgNOa in solution. 
4. They give precipitates with neutral barium, and calcium chlorides, and also with 
plumbic acetate, which hypophosphites do not. 
5. Heated with mercuric chloride or argentic nitrate, they yield a precipitate of 
metallic mercury or silver. 
2HgCl2+2H3P03+2H20=2H3P04+Hg2+4HCl. 
47. META- AND PYRO-PHOSPHORIC ACIDS AND THEIR SALTS. 
Metaphosphoric Acid is a glassy solid, not volatile by heat. It is freely soluble in cold water, 
and is converted by boiling into orthophosphoric acid. It is known by giving a white pre- 
cipitate with argent-ammonium nitrate, and by its power of coagulating albumen. 
Metaphosphates are known by,— 
1. Giving no precipitate with ammonium chloride, ammonium hydrate, and mag- 
nesium sulphate, added successively. 
2. By giving a white precipitate of argentic metaphosphate—AgP03—with argentic 
nitrate only in neutral solutions, and soluble both in nitric acid and ammonium 
hydrate. 
Pyrophosphoric Acid is also soluble in water and convertible by boiling into orthophosphoric 
acid. It gives a white precipitate with argent-ammonium nitrate, but does not coagulate PHOSPHORIC ACID AND PHOSPHATES. 
47 
albumen. Pyrophosphates are insoluble in water, except those of the alkalies. Their tests 
are not very well defined, but they give,— 
1. A white precipitate of argentic pyrophosphate—Ag4P207—with argentic nitrate in 
a neutral solution only and soluble both in nitric acid and ammonium hydrate. 
2. (NHj)2Mo04 does not produce an immediate precipitate. 
48. ORTHOPHOSPHORIC ACID and ORTHOPHOSPHATES. 
Orthophosphoric acid is a liquid with a strongly acid reaction, converted by 
heat first into pyro- and finally into meta-phosphoric acid, which remains 
as a glassy residue. It is,— 
1. Not volatile by a red heat. 
2. It gives a yellow precipitate of argentic phosphate—Ag3P04—when 
treated with argent-ammonium nitrate, soluble both in nitric 
acid and ammonium hydrate. 
Phosphates are as a rule insoluble in water, except the alkaline ones. They 
are readily soluble in dilute acids, and entirely reprecipitated on neutral- 
ising by an alkali or alkaline carbonate. Calcium, strontium, and barium 
phosphates are only partly soluble in dilute sulphuric acid, being converted 
into a soluble phosphate and an insoluble sulphate of the metal. If the 
insoluble phosphate be filtered out, the addition of an alkali causes only a 
slight precipitate of a dimetallic phosphate, and a phosphate of the alkali 
used is left in solution; but it is only after the use of sulphuric acid that 
any phosphate thus remains dissolved. 
Phosphates are detected as follows (practise on solution of sodium phos- 
phate) : 
i. With barium or calcium chloride white precipitates are produced, 
soluble in acetic acid (distinction from oxalates) and all stronger 
acids. 
2. With argentic nitrate a lemon-yellow precipitate of argentic 
phosphate forms, soluble both in nitric acid and ammonium 
hydrate. 
3. With ferric chloride in the presence of ammonium acetate a white 
precipitate of ferric phosphate appears, insoluble in acetic acid. 
4. With magnesia mixture phosphates yield a white crystalline pre- 
cipitate, forming slowly in dilute solutions, consisting of ammo- 
nium-magnesium phosphate—Mg(NH4)P04-I-6H^O—soluble 
in acetic and all acids. 
5. With solution of ammonium molybdate in nitric acid a yellow 
precipitate is produced, insoluble in nitric acid, but soluble in 
ammonium hydrate. 
6. With uranic nitrate phosphates yield a yellow precipitate of 
uranic phosphate, also insoluble in acetic acid. 
7. With mercurous and bismuthous nitrates white precipitates are 
formed, the former soluble and the latter insoluble in nitric 
acid. 
8, With any soluble salt of lead a white precipitate of plumbic 
phosphate is produced, soluble in nitric acid, but insoluble in 
acetic acid or ammonium hydrate. 
It is important to note that all these reactions may be caused by arsenic 
acid, except that with argentic nitrate, argentic arseniate differing from 
argentic phosphate in being brick-red instead of yellow. 48 
DETECTION, ETC., OF ACIDULOUS RADICALS. 
49. DETECTION OF A PHOSPHATE IN THE PRESENCE OF CALCIUM, 
BARIUM, STRONTIUM, MANGANESE, AND MAGNESIUM. 
(Practise on ordinary “ phosphate of lime.”) 
Dissolve in water by the aid of the smallest quantity of nitric acid, then add 
excess of ammonium acetate, which will remove the excess of nitric acid with- 
out rendering the solution alkaline. In this solution the phosphate may be 
proved by adding a drop or two of ferric chloride and warming, when a white 
precipitate of ferric phosphate—Fe2(P04)2—will form, insoluble in the acetic 
acid liberated. 
50. DETECTION OF A PHOSPHATE IN THE PRESENCE OF IRON. 
(Practise on ordinary “ phosphate of iron.”) 
Dissolve in the smallest possible quantity of hydrochloric acid, add some 
citric acid, and then excess of ammonium hydrate. By this means an alkaline 
liquid is obtained, owing to the power of the organic acid to prevent the pre- 
cipitation of the metal by the ammonium hydrate ; and in this liquid, when 
cold, magnesia mixture (ammonio-sulphate of magnesia) causes the precipitation 
of white crystalline magnesium-ammonium phosphate. 
Arsenious Acid—H3As03—is not known in the free state; but its anhydride 
—As2O3—is common. The latter has the following qualities : 
i. Dropped upon red-hot charcoal or coal, or heated in a dry tube 
with black flux, or a mixture of dry sodium carbonate and 
potassium cyanide, the metalloid As4 is set free, and volatilises 
with a garlic odor, producing a steel-grey mirror on the sides 
of the tube. 
51. ARSENIOUS ACID and ARSENITES. 
2. Dissolved in water only, and argent-ammonium nitrate added, a 
canary-yellow precipitate of argentic arsenite—Ag3As03—is 
produced, soluble in excess of either NH4HO or HN03. 
3. A pure aqueous solution, mixed with cupr-ammonium sulphate, 
gives a bright-green cupric arsenite—Scheelds green—also soluble 
in NH4HO or in HNOs. 
4. Any solution yields all the tests for arsenic (see page 15). 
Arsenites behave peculiarly in many respects. Ammonium arsenite leaves 
arsenious acid on evaporating a solution, while potassium and sodium 
arsenites possess a degree of alkalinity which no excess of arsenious acid 
will disturb. Ba, Sr, and Ca form soluble hydrogen salts. All other arsenites 
are insoluble. 
Neutral solutions of arsenites are possessed of the undermentioned distinctive 
peculiarities:— 
1. CuSO4 throws down greenish cupric arsenite. 
2. AgN03 is transformed into yellow insoluble argentic arsenite. 
3. H2S in the presence of hydrochloric acid, gives a yellow precipitate 
of arsenious sulphide. f 
4. The solution gives the usual tests for arsenic (see page 15). 
52. ARSENIC ACID and ARSENIATES. 
Arsenic Acid—H3As04—is known by the following characters : 
1. The crystals are deliquescent, white, and strongly acid. Heated, 
they leave a residue, which, on moistening with water, is also 
acid. MANGANA TES—PERMANGANA TES— CHROMA TES. 
49 
2. It is strongly corrosive and blisters the skin. It gives brick-red 
Ag3As04 on adding argent-ammonium nitrate. 
Arseniates are characterised by behaving in every respect exactly like phos- 
phates, except that they give a brick-red precipitate with argentic nitrate, 
instead of a yellow. Insoluble arseniates are best treated by boiling with 
NaHO, filtering, exactly neutralising the filtrate with dilute HNOs, and 
then getting the brick-red precipitate with AgN03. 
53. SEPARATION OF AN ARSENIATE FROM A PHOSPHATE. 
This can only be done by acidulating with hydrochloric acid, and passing a 
slow stream of sulphuretted hydrogen through the solution for several hours, 
until the whole of the arsenic is removed. 
Manganates are unstable compounds, and only the alkaline salts dissolve in water, forming 
green solutions. 
I. Soluble manganates decompose spontaneously, depositing Mn02, the green color 
changing to purple or reddish violet, owing to the formation of a perman- 
ganate. 
54. MANGANATES. 
2. Dilute acids effect this change more rapidly, and the reaction is very delicate. The 
free hydrate is then replaced by a chloride, nitrate, or sulphate. 
3. Strong, heated H2S04 acts as represented in this equation : 
3K2MnO4 + 2H20 = 2KMn04 + 4KHO + Mn02. 
4. Strong HCI causes the evolution of Cl2. The other actions are similar to those of 
permanganates, but less energetic. 
K2Mn04+ 2H2S04=K2S04 + MnS04 + 2H20 + 02. 
55. PERMANGANATES. 
(Practise on solution of potassium permanganate.) 
Permanganates are known,— 
1. By the violet color of their solutions, which is entirely bleached by 
oxalic acid or by heating with hydrochloric acid and dropping 
in rectified spirit. 
2. By giving off oxygen on heating. 
3. By giving off oxygen when heated with sulphuric acid, often with 
explosive violence. 
4. By evolving chlorine when simply mixed with hydrochloric acid. 
56. CHROMIC ACID and CHROMATES. 
Chromic Acid—H2Cr04—not being definitely proved to exist, is represented 
by its anhydride—Cr03. This is a dark red crystalline solid, and when 
mixed with an aqueous solution of hydrogen peroxide—H202—a deep blue 
liquid results, which is believed to contain perchromic acid—HCr04 or 
H2Cr208. The liquid decomposes rapidly, unless ether be added, which 
lengthens its existence. 
This test, for either Cr03 or H202, is exceedingly delicate, the ethereal 
solution of perchromic acid separating from the water and thus concentrating 
the color into a small bulk of ether. 
Chromates of the alkalies are soluble, while those of the other metals are 
chiefly insoluble, but have very brilliant colors. They are very poisonous, DETECTION.\ ETC., OF ACIDULOUS RADICALS. 
and are detected as follows (practise on solution of K2Cr04 and K2Cr207 
respectively):— 
1. Soluble chromates give a yellow precipitate with plumbic acetate 
or barium chloride, soluble in nitric acid, insoluble in acetic 
acid. The lead salt is darkened in color by alkalies, and 
dissolves by free excess of hot KHO. 
2. With argentic nitrate a dark red precipitate, also soluble in nitric 
acid, and in NH4HO, but not in acetic acid—HC2H302. 
3. Boiled with hydrochloric acid and alcohol, or any reducing agent, 
(for instance, sulphurous acid—H2S03), they turn green, owing 
to the production of chromic chloride (or sulphate). 
4. Treated with sulphuretted hydrogen, in the presence of hydrochloric 
acid, they turn green, and a deposit of sulphur takes place ; 
2K2Cr207 +x 6 HCI + 6H2S = 2Cr2CI6 + 4KCI + sS2 +14H20. 
5. Chromates, when treated with an acid, turn orange; and dichro- 
mates, when treated with potassium hydrate or any alkali, 
turn yellow. In this way they are mutually distinguished. 
6. Heated with strong H2SO4 they give off oxygen. 
7. Treated with an excess of sulphuric acid, and shaken up with 
ozonised ether (solution of hydric peroxide in ether), they give 
a gorgeous blue with the most minute traces. 
67. STANNIC ACID and STANNATES (Stannites ?). 
This is an unimportant compound, and is thrown down by an alkaline hydrate from a 
stannic salt. It is sometimes stated to be endowed with the composition Sn(HO)4, and at 
others, SnO(HO)2 (H2SnO3). 
Stannates are formed by the solution of the acid in an alkaline hydrate, and are detected in 
the examination for metals. 
Stannites are said to be formed by the solution of stannous hydrates in an alkaline 
hydrate. They decompose on boiling with KHO, forming stannates and throwing down 
metallic tin. 
This is the white precipitate having the composition HSb03, formed on adding strong HCI to 
potassium antimo7iiate; and it is detected in the examination for metals. 
58. ANTIMONIC ACID. 
59. FORMIC ACID and FORMATES. 
Formic Acid—HCH02—is the “ organic ” acid which contains the highest 
percentage of oxygen, and approaches most nearly in composition to the 
suppositious carbonic acid—H2C03. It is a tolerably stable liquid, boiling at 
the same temperature as water. Formates are all soluble in water, and behave 
as follows ; 
1. Heated to redness they decompose without blackening. 
2. Heated with H2S04 they evolve CO, which, being free from CO.„ 
gives no effect when passed through lime-water, but burns with 
the usual pale blue flame. The reaction is : 
H2S04, + HCH02 = H2S04 + CO + H2O. 
3. Readily reduce argentic nitrate, when boiled, metallic silver 
separating. 
60. DETECTION OF A FORMATE IN THE PRESENCE OF FIXED 
ORGANIC ACIDS WHICH REDUCE SILVER SALTS. 
Distil with dilute sulphuric acid at the heat of a water bath, neutralise the 
distillate with sodium carbonate, add a slight excess of acetic acid, and boil 
with argentic nitrate, when a dark deposit of metallic silver will form. A CETA TES— VA LERI ANA TES—S ULPHO VINA TES. 
5i 
61. ACETIC ACID and ACETATES. 
(Practise on sodium acetate.) 
This acid is characterised by its odor of vinegar. The strong acid chars 
when heated with strong H2S04. 
Acetates are without exception soluble in water (Ag2C9H302 and HgC2H302 
are sparingly dissolved). They are decomposed by a red heat, yielding 
acetone if the heat rise gently and the mass be not alkaline, and leaving a 
carbonate, oxide, or metal, according to the nature of the basylous radical. 
When heated with alkalies marsh gas—CH4,—is evolved. The reaction is of 
this type:— 
In the case of no hydrate or carbonate being present, the following is an 
example of the effect of heat on acetates : 
NaC2H302 + NaHO = Na2C03 + CH4. 
Acetates of easily reducible metals, such as copper, yield, when heated, a 
distillate of acetic acid, leaving a residue of the metal, or in some cases of 
oxide. The presence of acetates is analytically determined as follows ; 
1. By evolving an odor of acetic acid when heated with sulphuric acid. 
2. By a characteristic apple-like odor of “ acetic ether”— 
C 2H5(C2H302)— which they evolve when heated with sul- 
phuric acid and rectified spirit. 
3. By the deep red color which they produce with neutral ferric 
chloride—ferric acetate, Fe2(C2H302)6—dischargeable by both 
hydrochloric acid and mercuric chloride. 
8a(C2H302)2 = BaC03 + C 3H60 (Acetone). 
62. VALERIANIC ACID and VALERIANATES. 
Valerianic Acid is a liquid, which is— 
Volatile, malodorous, colorless, and oily. It reddens test-paper, 
and dissolves in most menstrica. 
The general characters of Valerianates are : 
1. A more or less strong odor of valerian root when warmed or 
moistened. 
2. They give, when heated with sulphuric acid, an odor of valerian 
and a distillate which, on the addition of solution of cupric 
acetate, forms, after the lapse of some time, an oily precipitate; 
gradually solidifying, by the absorption of water, into a greenish- 
blue crystalline solid. 
63. SXJLPHOVINATES (Ethyl sulphates). 
These salts, derived from ethyl hydrogen sulphate, behave as follows : 
1, Heated with strong sulphuric acid, they evolve a faint ethereal odor. 
2. They give no precipitate in the cold with barium chloride; but on 
boiling, a white precipitate of barium sulphate falls, and a smell 
of alcohol is perceived. The addition of a little solution of 
barium hydrate after the chloride and before boiling facilitates 
the reaction ; but in this case all metals precipitable by a fixed 
alkali must first, of course, be removed. 
3. Heated to redness, they leave a sulphate of the metal. 
4. Heated with sulphuric acid and an acetate, or with strong acetic 
acid, they evolve acetic ether with its characteristic apple odor. 52 
DETECTION, £7T., OP ACIDULOUS RADICALS. 
64. STEARIC ACID and STEARATES. 
This acid is usually so distinguished by its appearance and behaviour on 
being heated, that further tests are useless. The characters are : 
1. A white, odorless, fatty solid, melting by heat and soluble in absolute 
alcohol, the solution having an acid reaction. 
2. Giving, when dissolved in KHO and the solution as nearly neutral- 
ised as possible, a white insoluble precipitate of plumbic stearate 
—Pb(ClBH3so2)2—on the addition of plumbic acetate, which 
is insoluble in ether (distinction from plumbic oleate). 
Stearates of the alkalies are alone soluble in water. 
Any stearate heated with dilute HCI gives the free acid, which floats 
as an oily liquid, solidifying on cooling to a white mass. This 
test is applicable to the analysis of soap {,hard, containing Na, 
or soft, in which K is present). 
65. OLEIC ACID and OLEATES. 
Oleic Acid is usually an oily liquid, but remains solid below 590 F. when 
crystallised from alcohol. 
It does not dissolve in water, but is taken up by ether and by strong 
alcohol, the latter solution being acid in reaction. 
Oleates of K and Na alone dissolve in water. Acid oleates are all liquid and 
soluble in cold absolute alcohol and ether. 
1. They do not separate out from either of these solvents when a hot 
solution is cooled (distinction from stearates and pahnitates). 
2. Plumbic oleate is precipitable like plumbic stearate, but is separated 
and distinguished from it by dissolving in ether. 
66. LACTIC ACID and LACTATES. 
The pure strong acid resembles glycerine in appearance, liberates hydrogen 
on adding zinc, and on heating takes fire and burns away with a pale flame 
gradually becoming luminous. It dissolves in ether. It gives pure CO when 
heated with sulphuric acid. Boiled with solution of potassium permanganate it 
gives the odor of aldehyd. 
Lactates are not very soluble in water. They—- 
i. Are insoluble in ether. 
2. Argentic lactate—AgC3H503—when boiled gives a dark precipitate, 
which on subsidence leaves a blue liquid. 
3. Strong solution of an alkaline lactate, when boiled with HgN03, 
deposits crimson or pink mercurous lactate—HgC3H503. 
67. OXALIC ACID and OXALATES. 
(Practise on oxalic acid and on “ salts ot sorrel.”) 
The acid is very common, and is recognised,— 
1. By its colorless prismatic crystals, which are strongly acid, effloresce 
when exposed to dry air, and volatilise on heating with partial 
decomposition. 
2. By the complete discharge it effects of the color of a solution of 
potassium permanganate acidulated with dilute H2S04. SUCCINA TES—MALA TES—TARTRA TES. 
53 
3. By producing free H2S04 when added to solution of CuS04. (This 
is one of the very rare instances in which S04 is replaced by 
another acid radical and H2S04 liberated.) 
4. By giving the reactions of an oxalate. 
Oxalates of the alkalies are soluble, the others insoluble, in water. Insoluble 
oxalates dissolve in hydrochloric but not in acetic acid. They are known by— 
i. Not charring when heated, but only turning faintly grey; followed 
by a sudden glow of incandescence, which runs through the 
mass. 
2. Not charring when heated with sulphuric acid, but yielding CO and 
C02 with effervescence. 
3. Not effervescing with cold dilute sulphuric acid; but at once liber- 
ating C02 with effervescence on the addition of a pinch of 
manganese peroxide. 
4. With calcium chloride or barium chloride in a neutral or alkaline 
solution, they give a white precipitate of calcium or barium 
oxalate, i?isoluble in acetic acid, but soluble in hydrochloric acid. 
(For separation of oxalates from tartrates, etc., see No. 72.) 
This acid is a white crystalline solid. It is known,— 
1. By not charring with strong hot sulphuric acid. 
2. By subliming in a tube open at both ends, in silky needles, without giving off an 
irritating vapor (distinction from benzoic acid). 
3. By burning, when heated on platinum, with a blue smokeless flame. 
68. SUCCINIC ACID and SUCCINATES. 
Succinates are recognised as follows : 
X. With ferric chloride, a brownish-red precipitate of ferric succinate—Fe2(C4H404)3 
■—is formed. 
2. With hydrochloric and sulphuric acids no precipitate is produced [distinctionfrom 
benzoates'). With plumbic acetate, a white precipitate of plumbic succinate, 
soluble in succinic acid, succinates, and plumbic acetate. 
3. Barium succinate is soluble in hydrochloric acid, hence no effect results from the 
addition of succinic acid to barium chloride ; but alcohol and ammonium hy- 
drate give rise to a white precipitate [another point of distinction from benzoates). 
69. MALIC ACID and MALATES. 
Malic Acid—H2C4H40s—is a colorless, crystalline, very deliquescent acid, freely soluble 
in water and alcohol. Acid malates are most stable. The characters are : 
X. Calcium chloride, added to a neutral solution of a malate, gives no precipitate. 
Alcohol, however, even if added in small quantity, throws down a white 
precipitate ; and boiling aids the effect. 
2. Strong H2S04 gives no charring for some time [a tartrate is carbonised in a few 
minutes). 
3. Amorphous plumbic malate fuses below xoo° C. in water, but not in an air-bath. 
70. TARTARIC ACID and TARTRATES. 
Tartaric Acid—H2C4H406 is a strong acid, soluble in water and spirit. 
1. It forms usually oblique rhombic prismatic crystals, of an acid taste. 
2. It is decomposed by heat, giving off the odor of burnt sugar, and 
leaving carbon. A similar effect is produced by warming with 
strong H2S04, which blackens and carbonises it in a few minutes. 
3. With potassium acetate—KC2H302—it produces a white crystalline 
precipitate of potassium hydrogen tartrate—KHC4H406—in 
either an aqueous or an alcoholic solution, soluble in much 
water, but not in spirit. Stirring or violent shaking promotes 
the formation of the salt. 
(Practise upon the free acid and also upon “ Rochelle salt.”) 54 
DETECTION, ETC., OF ACIDULOUS RADICALS. 
The same compound is produced on adding any potassium salt, provided 
the liquid contain excess of free tartaric acid only. 
Tartrates of the alkalies are mostly soluble ; but the others are insoluble. 
The hydrogen tartrates of K and (NH4) are nearly insoluble. Tartrates are 
recognised by the following characters : 
1. Heated to dull redness they char rapidly and give off a smell of 
burnt sugar. The black residue contains the metal as car- 
bonate if it be K, Na, Li, Ba, Sr, or Ca; but the tartrates of 
other metals usually leave the oxides, or more rarely (as in the 
case of Ag2C4H406) the metal. 
2. Heated with strong sulphuric acid, they blacken rapidly, and give 
first a smell of burnt sugar, and afterwards evolve S02. 
3. Neutral solutions (free from more than a trace of ammonium salts) 
give, on adding calcium chloride, a white precipitate of calcium 
tartrate, which, when freed from other salts by washing, dissolves 
readily in cold solution of potassium hydrate, but is again pre- 
cipitated on boiling. The precipitate is soluble in NH4CI, 
but not in NH4HO. 
4. Mix a tartrate with sodium carbonate, and filter the slightly alkaline 
solution, so that the only metal present shall be sodium. If 
this clear solution, after slight acidulation with acetic acid, be 
mixed with argentic nitrate, the whole, on heating nearly to 
boiling in a clean tube, deposits a beautiful mirror of metallic 
silver upon the test-tube employed. 
5. A tartrate prevents the precipitation (more or less perfectly) of the 
salts of Pb, Bi, Cd, Cu, Pt, Fe2, Mn, Ni, Co, Cr, and Zn, by an 
alkaline hydrate in excess, or a phosphate. 
71. CITRIC ACID and CITRATES. 
(Practise upon the free acid and upon potassium citrate.) 
Citric Acid—H3C6H507—is soluble in water and alcohol, but insoluble in 
pure ether. It entirely burns away when heated to redness in the air; 
blackens slowly when heated with strong sulphuric acid; and when neutral- 
ised by ammonium hydrate, and the solution cooled, the solution gives 
no precipitate with calcium chloride until it has been boiled. Added to 
ferric, chromic, or aluminic salts in solution, it prevents their precipitation 
by ammonium hydrate. 
Citrates exhibit the following characters : 
1. Heated alone, they char slowly, and evolve an odor of burnt sugar, 
but not so intense as that of a tartrate. At a dull red heat, the 
citrates of K, Na, Li, Ba, Sr, and Ca leave their carbonates ; 
but those of most other metals leave the oxides. Argentic 
citrate leaves the metal. 
2. Heated with strong sulphuric acid, they slowly blacken, and evolve 
a slight odor of burnt sugar. 
3. Mixed in the cold with calcium chloride, in the presence of a slight 
excess of ammonium hydrate they give no precipitate; but on 
boiling, calcium citrate—Ca3(C6H507)2—separates as a white 
precipitate. If this precipitate be filtered hot, and washed with 
a little boiling water, it is found to be quite insoluble in cold 
solution of potassium hydrate, but readily soluble in neutral 
solution of cupric chloride. OXALATES, TARTRATES, CITRATES, AND MA DATES. 
55 
4. Mixed with argentic nitrate and boiled, no mirror of metallic silver 
is produced. 
72. SEPARATION OF OXALATES, TARTRATES, CITRATES, and 
MALATES. 
(Practise upon mixed solutions oxalic, tartaric, and citric acids.) 
If the solution be acid, neutralise it with sodium hydrate ; but if neutral or 
alkaline it is ready for use, and is treated as follows : 
A. Acidulate slightly but distinctly with acetic acid, bring the whole 
to the boil, and add a drop or two of calcium chloride; and if 
it produce a precipitate, add it till precipitation ceases. Keep 
the whole nearly boiling for a time, till the precipitate aggregates, 
and filter. The precipitate, after washing, should be quite in- 
soluble in cold solution of potassium hydrate. 
B. To the filtrate from (A) mixed with some more calcium chloride, 
ammonium hydrate is added in slight but distinct excess, 
and the whole thoroughly cooled. Calcium tartrate precipi- 
tates, and when it has settled clear, the liquid is poured off 
and preserved for (C). This precipitate, after washing, should 
be entirely soluble in cold solution of potassium hydrate, and 
reprecipitable by boiling. 
C. The liquid is slowly boiled for some time ; and if a precipitate does 
not form readily, a little more CaCl2 and NH4HO added, and 
the boiling resumed. The precipitate, when it begins to subside 
well, is filtered out whilst still hot. It should be (after washing) 
quite insoluble in cold solution of potassium hydrate; but 
soluble in perfectly neutral solution of cupric chloride. 
JD. To the filtrate add alcohol, when calcium malate will separate; 
but this portion of the separation is not infallible, and the 
precipitate must be carefully examined to see that it really is 
malate. 
73. MECONIC ACID and MECONATES. 
Meeonic Acid is a white powder, with a strongly acid reaction, soluble in water, 
alcohol, and ether, and giving the reaction for meconates. 
Meconates communicate a red color to ferric chloride solution. This color 
is not discharged by HgCL2 nor by dilute HCL By this means it is distin- 
guished from a sulphocyanate and an acetate. 
74. CARBOLIC ACID (or Phenol) and CARBOLATES (Phenates). 
The qualities of this body are very distinctive. 
1. It is a colorless, crystalline solid, melting at 940 F., and not 
volatile at 212° having the odor and taste of creasote, being 
very poisonous, and not reddening test-paper. 
2. The crystals deliquesce readily, forming a liquid which does not mix 
freely with water, but incorporates readily with alcohol, ether, 
and glycerine. 
3. Mixed with HQ and exposed to the air on a strip of deal, it becomes 
greenish blue. 
4. It coagulates albumen. It does not rotate polarised light. 56 
DETECTION,, ETC., OF ACIDULOUS RADICALS. 
5. Saturated with ammonia gas—NH3—and heated in a closed tube, 
aniline is formed : 
6. It does not decompose carbonates. 
7. NH4HO and CaOCl2 produce a blue liquid. 
8. It unites directly with strong H2S04 to form sulpho-phenic (or 
sulpho-carbolic) acid—C6HSHS04. 
9. With bromine water it gives a white precipitate of tribromophenol— 
CeH3Br30. 
c 6hsho+nh3=c6h5h2n+h20. 
Carbolates give the following reactions : 
1, When heated alone, they evolve the odor of carbolic acid and de- 
compose. 
2. Heated with strong sulphuric acid, they also smell of carbolic acid. 
3. Ferric chloride causes a reddish-violet color. 
Sulpho-Carbolates behave similarly, but also give the reactions of a sulphate 
with barium chloride. 
75. BENZOIC ACID and BENZOATES. 
Benzoic Acid is of characteristic appearance, being usually seen in light, 
feathery, flexible, nearly colorless crystalline plates or needles, and contain- 
ing a trace of an agreeable volatile oil, unless it is the artificial acid prepared 
from naphthalene, which is odorless. 
1. It is only slightly soluble in water, but dissolves freely in spirit, and 
in solutions of soluble hydrates. 
2. Heated in the air, it burns with a luminous smoky flame ; and when 
made hot in a tube open at both ends, sublimes in needles, 
giving off an irritating vapor. 
Benzoates possess the following general qualities : 
1. Heated with sulphuric acid they evolve the odor of benzoic acid, 
and darken. 
2. Ferric chloride, in a solution made slightly alkaline by ammonium 
hydrate, gives a reddish-white precipitate—ferric benzoate— 
Fe2(C7H502)6—soluble in acids (benzoic included). If this pre- 
cipitate be now filtered out and digested in ammonium hydrate, 
it is decomposed into a precipitate of ferric hydrate, and a solu- 
tion of ammonium benzoate, which is separated by filtration and 
treated as in 3. 
3. Strong hot solutions of benzoates yield crystals of benzoic acid when 
hydrochloric acid is added and the solution allowed to cool. 
76. SALICYLIC ACID (HC7HSO3). 
This acid occurs in prisms, when crystallised from a solution in alcohol in 
which it is readily soluble. It is freely dissolved by hot water, but not 
readily by cold, requiring 1,800 parts of the latter to completely dissolve it. 
1, Its aqueous solution gives with Fe2Cl6 a deep violet coloration. The 
compounds with methyl, ethyl, etc., give this reaction, as well 
as the ordinary salts. 
2. Its methyl salt, formed by warming a salicylate with sulphuric acid 
and wood spirit, has a very fragrant odor. 
From most other solid bodies it may be separated by taking advantage of 
its exceptionally great solubility in ether. In the event of its presence in an GALLIC; TANNLC, AND PYROGALLLC ACLDS. 
57 
organic liquid (such as milk) it or its salts may be procured in a pure condition 
by dialysis. The liquid is placed in a dialyser, and this floated on pure water. 
The salicylic acid or salicylate is found after some time to have entirely passed 
through the septum, and may be obtained by evaporating the aqueous solution 
and, when reduced in bulk, shaking with ether. 
77. DETECTION OE CARBOLIC ACID IN THE PRESENCE OF 
SALICYLIC ACID. 
Boil io grains in half an ounce of water, cool, decant the solution and add 
to it i minim of a saturated solution of KHC03, i minim of aniline, and 5 
drops of solution of chlorinated lime, when, if carbolic acid be present, a deep 
blue is produced. 
78. TANNIC, GALLIC, and PYROGALLIC ACIDS. 
Tannic Acid is soluble in water and alcohol, and very soluble in glycerine. It 
is insoluble in pure dry ether, but dissolves readily in ether containing 
a little water. 
Gallic Acid is slightly soluble in cold water, but readily in boiling; it is also 
freely soluble in glycerine, and slightly in alcohol and ether. 
Pyrogallic Acid is very soluble in water, the solution rapidly absorbing oxygen 
from the air and becoming brown. It also dissolves in alcohol and 
ether. 
DISTINCTION BETWEEN GALLIC, TANNIC, AND PYROGALLIC 
ACIDS. 
Behaviour of the 
Acid with 
Gallic. 
Tannic. 
Pyrogallic. 
Ferrous salts . 
A dark solution 
is formed, 
gradually de- 
positing a 
precipitate. 
The same effect 
as Gallic. 
A blue solution. 
Ferric salts . . 
Purplish pre- 
cipitate im- 
mediately 
formed. 
Same as pre- 
ceding. 
A red solution. 
Calcium hydrate 
in the form of 
Milk of Lime. 
A brownish pre- 
cipitate, be- 
coming deep 
brown in a 
few seconds. 
A white preci- 
pitate slowly 
changing. 
Instantaneous 
production of 
a purple solu- 
tion becoming 
brown by oxi- 
dation. 
Gelatine . . . 
No precipitate 
(except in the 
presence of 
gum). 
Immediate 
brownish 
precipitate. 
No precipitate. 58 
CHAPTER IV. 
QUALITATIVE ANALYSIS, AS APPLIED TO THE DETECTION 
OF UNKNOWN SALTS. 
§ I. GENERAL PRELIMINARY EXAMINATION. 
Under this head are included,— 
1. The observation of the physical properties of the substance sub- 
mitted for analysis. 
2. Its behaviour when heated, either alone or in the presence of 
reducing agents or fluxes. 
3. Its reaction with test-papers; the color it communicates to flame, 
etc. 
So particular and minute may this examination be, that in tVie larger works 
on chemical analysis many pages will be found devoted to it; but for the 
purposes of the analysis likely to come before the ordinary chemical student, 
it is sufficient only to carry it the length of a few readily obtainable and un- 
mistakable inferences. 
Step 1. If the substance given for analysis be a liquid, carefully mark its 
reaction with blue and red litmus paper, evaporate a little to dryness 
at a gentle heat on a clean porcelain crucible lid, observing the 
nature of the residue left, if any; and finally raise this residue to a 
red heat, carefully noting whether it is volatilised, blackened, or 
altered in color any way. If a solid, heat it directly to redness 
on a crucible lid and note effect; then shake a little up with distilled 
water and note its reaction with blue and red litmus paper. 
From a careful study of these points, the following simple inferences may 
safely be drawn ; any appearance not herein referred to being neglected as not 
affording a really distinctive indication 
A. Neutral, no odor, and leaving no residue whatever. Probably 
water. 
B. Strongly acid, leaving no residue. Probably an ordinary volatile 
acid, such as HCI, HNO-;, HC2H302, etc. 
C. Strongly acid, leaving a residue, fusible by heat and also strongly 
acid. Probably a non-volatile mineral acid, such as H3P04. 
D. Strongly acid, leaving a residue, which on heating chars, and en- 
tirely burns away. Probably free organic acid, such as H2C4H 06, 
H3C6H507, HC7H502j etc. 
Note.—Oxalic and formic acids do not char. 
E. Neutral or slightly acid, leaving a residue, which volatilises in 
fumes, but without blackening. Probably an ordinary salt of a 
volatile metal, such as NH4, Hg, As, Sb, etc. GENERAL PRELIMINARY EXAMINATION. 
59 
F Neutral or slightly acid, leaving a residue which on heating 
blackens and volatilises in fumes. Probably an organic salt of 
NH4, Hg, or other volatile metal. 
Note.—In this case it is best at once to test the original for NII, or Hg by boiling 
with KHO and SnCl2 respectively. 
G. Neutral or slightly acid, leaving a residue, which on heating 
changes color as follows 
Yellow while hot, white on cooling. Probably salt of Zn. 
Deep yellow while hot, yellow on cooling. Probably salt of Pb. 
Yellowish-brown wflflle hot, dirty light-yellow on cooling. Pro- 
bably salt of Sniv. 
Orange or red while hot, dull-yellow on cooling. Probably salt 
of Bi. 
Red while hot, reddish-brown on cooling. Probably salt of Fe 
or Ce. 
H. Neutral or slightly acid, leaving a white residue, which blackens 
on heating, burns, and leaves a black or greyish mass. Pro- 
bably an organic salt of a fixed metal. In this special case, 
proceed as follows:— 
Permanent brownish-black. Certain salts of Mn. 
Moisten the residue with a little water, and touch it with reddened litmus 
paper. If alkaline, the original substance was an organic salt of K, Na, or 
Li, in which case proceed by (a). If not alkaline, proceed by (b). 
(a) Boil the ash with the smallest possible quantity of water, filter, acidulate with 
HCI till effervescence ceases ; dip a perfectly clean platinum wire in the solu- 
tion, and try the flame test. If crimson, Li. Bright yellow, Na. Violet, K. 
Note.— The latter flame not being very easily seen in daylight, it is advisable to 
add to the solution PtCl4 and C 2H60. Shake well and cool. Yellow crystal- 
line precipitate of potassium platinochloride (PtCI42KCI). 
{b) The ash is covered with water and treated with HC2H302. If effervescence takes 
place, the original substance was probably an organic salt of Ba, Sr, or Ca ; 
and these metals may at once be tested for in the acetic acid solution. 
Note.—Oxalates, although'organic, do not blacken to any extent. If carefully observed, 
however, a slight greyish tint, followed by a distinct glow running through the 
mass, will be noticed at the moment of decomposition. To make certain, it is 
well to place a little of the original powder in one tube, and the residue, after 
ignition, in another; cover them both with water, and add a drop of acetic 
acid to each. If the residue effervesce, and the original powder does not, 
strong presumptive evidence is obtained of the presence of an oxalate of the 
alkaline or earthy metals. 
I. Neutral or slightly acid, leaving a residue, which takes fire and 
continues to burn even after removal from the flame, giving off 
clouds of white fumes and leaving a fixed white or pinkish 
residue. Probably a hypophosphite ; which fact should be noted 
as an aid to future information as to acidulous radicals. 
K. Strongly alkaline, leaving a fixed white residue, also alkaline. A 
hydrate, carbonate, bicarbonate, or sulphide of a fixed alkaline 
metal, or a hydrate or oxide of Ba, Sr, or Ca. In this case 
proceed as follows : 
Acidulate a portion of the original solution with HCI. 
{a) If it effervesces without smell, and is therefore a carbonate or bicarbonate, test 
at once by the flame for K, Li, Na, and also another portion of the original 
solution with HgCl2. If red, a carbonate ;if not, a bicarbonate. 
(b) Effervesces with smell of H2S. In this case it is a sulphide ; and if a deposit of 
S also takes place, a polysulphide. Add to a fresh portion of the original 
solution excess of HCI, boil till H2S is expelled, filter, if necessary, and test 
the solution for all metals of fourth and fifth groups. 
(c) Effervesces with smell of HCN. Probably an alkaline cyanide such as KCN. 6o 
QUALITATIVE ANALYSIS. 
(,d) It does not effervesce. In this case add to a fresh portion of the original solution, 
AgNOs. If a brownish-black precipitate be formed, it is a soluble hydrate. A 
portion of the original solution should be neutralised with HCI, and then 
examined for all metals of fourth and fifth groups. 
Note.—If AgN03 with original solution gives a yellow, a white, or a brick-red 
precipitate, the presence of a phosphate, borate, or arseniate of K or Na may 
be suspected. In the case of a complex solution in which a salt of some other 
metal is given dissolved in excess of an alkali, an intimation of the fact will be 
obtained on cautiously adding the HCI, as, at the moment of neutralisation, the 
dissolved substance appears as a precipitate before again dissolving in the excess 
of HCI. Basic plumbic acetate has an alkaline reaction. 
Step 2. Dip a clean platinum wire in the solution, or if a solid moisten the 
wire with HCI, dip it in the powdered substance, and heat in the 
inner Bunsen or blowpipe flame. The outer flame is colored as 
under:— 
Violet . . . Potassium. 
Golden-yellow . Sodium. 
Yellowish-green . Barium. 
Crimson . . Strontium or Lithium. 
Orange-red . . Calcium. 
Green . . . Copper or Boracic acid. 
Blue . . . Lead, Arsenic, Bismuth; 
also Copper as chloride. 
Step 3. Heat a little of the solid substance (or the residue left on evapora- 
tion if in solution) on charcoal before the blowpipe. 
Ordinary alkaline salts fuse and sink into the charcoal ; some decre- 
pitating (example NaCl, etc.), others deflagrating (as KN03, KCI03, 
etc.), but no sufficiently characteristic indications are usually obtained, 
except in one of the following cases : 
A. A white luminous residue is left. Moisten it when cold with a 
drop or two of cobaltous nitrate, and again apply the blowpipe, 
observing any change of color as follows : 
The residue becomes blue, indicating Al, Silicates, or Phos- 
phates. 
„ „ „ green, „ Zn. _ 
~ „ „ pink or flesh-colored, indicating Mg. 
B. A colored residue is left. Prepare a borax bead, and heat a little 
of the substance in it, both in the reducing and oxidising flame, 
and note any colors corresponding with the following list. 
Metal. 
In Oxidising Flame. 
In Reducing Flame. 
Cu 
Green (hot). Blue (cold). 
Red (cold). 
Co 
Blue. 
Blue. 
Cr 
Green. 
Green. 
Fe 
Red (hot). Yellowish (cold). 
Bottle-green. 
Mn 
Amethyst. 
Colorless. 
Ni 
Reddish-brown (hot). Yellow (cold). 
Same as oxidising flame. 
C. A metallic residue is left, with or without incrustation surrounding 
it. Mix a little of the substance with KCy and Na2COs, and 
expose on charcoal to the reducing charcoal flame. 
{a) Metallic globules are produced without any surrounding incrusta- 
tion of oxide. This occurs with Ag, Au, Cu, Fe, Co, and Ni, 
all easily recognisable. DETECTION OF METALS IN SALTS. 
61 
(b) Metallic globules are produced with a surrounding incrustation of 
oxide. This occurs with Sn, Bi, Pb, and Sb; the incrustation 
having the characteristic colors already described in Case 1., 
Step i, G. 
Note.—Sb often forms a white and distinctly crystalline crust. 
(c) The metal volatilises, and only leaves an incrustation of oxide. 
This occurs with As (garlic smell and white incrustation), 
Zn (yellow [hot], white [cold]), and Cd (reddish-brown). 
§ 11. DETECTION OF THE METAL PRESENT IN ANY SIMPLE 
SALT. 
Step 1. Preparation of the solution for analysis for the metal, if the 
substance be not already dissolved. 
i. Take a minute portion of the substance and boil it with water in 
a test-tube; should it dissolve, then take a large portion and 
dissolve for testing. 
2. Should the salt prove insoluble, take another small portion and heat 
with HCI, and add a little water and again heat. If it now 
dissolves, prepare a larger quantity of the solution for use in 
the same manner. 
3. Should it resist HCI, try another small portion with HN03 by 
heating, and then adding water. If this dissolves it, make up 
a larger quantity of a similar solution for testing. 
4. Should HN03 also fail, try another small portion with two parts 
HCI and one part HN03, warming and diluting as before; and 
if it succeeds, make up a larger amount of solution in the same 
manner. 
5. If all acids fail, then take another portion of the substance, mix it 
with several times its bulk of a perfectly dry mixture of sodium 
and potassium carbonates (prepared by heating Rochelle salt in 
an open crucible until the residue thoroughly ceases to evolve 
any gases, then extracting with distilled water, filtering, evapo- 
rating to dryness, heating the residue to redness, and preserving 
for use in a stoppered bottle. This reagent will hereafter be 
shortly described as fusion mixture). Place the whole in a 
platinum crucible, and fuse at a bright-red heat; when cold, 
boil with water and save the solution thus obtained for acidulous 
radicals. The insoluble matter is then to be drenched with 
strong HCI, slightly diluted and boiled, and the solution used 
for testing for the metal. Any insoluble white gritty matter still 
remaining is put down as silica. 
Step 2. Detection of the metal. 
The processes to be applied vary according to the limitation of the possible 
substances under examination, and the following tables are to be used accord- 
ingly, using the solution obtained in Step 1. Remember that even when we 
have apparently found out the metal by the table we should always proceed to 
perfect confirmation by applying (to fresh portions of the solution each time) all 
the tests for the metal given in Chapter 11. Unless otherwise directed, all 
confirmations referred to in the tables are intended to be tried upon fresh 
portions of the original solution. For brevity the said solution is in the 
tables indicated by a capital 0 in thick type, and the word precipitate is 
contracted to ppt. In simple salts we go through the groups until we 
get a result, and as soon as we do so we stop and go no farther with the 
groups, but simply confirm the result obtained by special tests. N.B.—ln using this Table, as soon as the Metal is discovered we go no further, and all confirmations, except where specially stated, are to be applied to 
fresh portions of the original Solution, hereafter represented by O. 
FULL TABLE FOR THE DETECTION OF THE METAL IN A SOLUTION CONTAINING ONE BASE ONLY. 
ist Group.—Add a drop of HC1, and if it produce a precipitate, add excess. 
Precipitate 
2nd Group.—To solution in which a drop of HC1 has failed to produce a ppt. add H2S, 
excess and warm. 
and if a discoloration appear, add 
May be either v - 
PbCl2 
Hg,.Cl2 ■ White. 
AgCl 
Precipitate 
May be either 
HgS As2S3 
PbS Sb2S3 
Bi2S3 SnS 
CuS SnS2 
CdS PtS2 
or 
Au2S3 
Let the precipitate settle, pour off 
3rd Group (Division A).—Evaporate a portion of original solution to dryness, and heat 
residue till any organic matter is destroyed; then dissolve in a few drops of HC1 with the 
addition of a drop or two of HNO,, dilute, and add NH4C1, and then NH4H0 in slight 
but distinct excess, and heat to boiling. 
Confirmations. 
Let ppt. settle, and pour 
i off supernatant liquid ; 
wash once by decanta- 
tion with cold water, 
and then proceed as 
follows;— 
(r.) Add some warm H20 
to ppt. and boil: if it 
dissolves and the solu- 
tion gives a yellow with 
K2Cr04=Pb. 
(2.) If ppt. insoluble in 
water, add to it excess 
of NH4H0. 
(a) The precipitate turns 
black=Hg2 (ous). 
(b) The precipitate dis- 
solves and is re-precipi- 
tated by HNOs=Ag. 
*Precipitate 
May be either 
Fe26HO = red-brown. 
Cr26HO = green. 
CeaHO \ 
Al26HO 6 
Insol. phosph. I 
of Fe, Cr, Al, [ 
Mn, Ba, Sr, 
Ca, and Mg./ 
Confirmations. 
(I.) If ppt. red. 
{a) Test O with K,FeCy,„ : 
dark blue= Fe. 
(b) Test O with K4FeCy4 : dark 
blue = Fe2. 
(II.) If ppt. green. 
Evap. portion of O on a porcelain 
crucible lid, add some KHO 
and a crystal of KN03, again 
evap. to dryness and fuse : 
yellow residue, sol. in H20 and 
precipitated yellow by PbaAc 
after acidulation by HAc = Cr. 
(HI.) If ppt. ivhite. 
(1.) Add to O, KHO ; white sol. in 
excess and re-precipitated by boil- 
ing with NH4C1 = A1. 
3rd Group (Division B).-—To the solution in which 
NH4H0 has failed to produce a precipitate, add 
NH4HS, and warm for some time. 
Precipitate 
May be either 
MnS—flesh colrd. 
ZnS—white. 
I black. 
NiS ) 
Confirmations. 
I. If ppt. white or 
flesh-coloured. 
(1.) Test O by eva- 
porating & fusing 
with KHO and 
KN03: green resi- 
due=Mn. 
(2.) Test O with 
K4FeCy„ : white 
=Zn. 
II. If ppt. be black, 
boil O with KHO. 
(a) Blueish ppt. turn- 
ing pinkish onboil- 
ing=Co. 
4th Group.—To same solution, 
add (NH4)2C03. 
as much of the supernatant liquid 
as possible, make the remainder 
alkaline by NH4HO and add a 
few drops of NH4PIS and warm. 
Insoluble. Soluble. 
CdS—yellow As S3 1 v 
HgS \ -c SnS2 | Yellow. 
PbS 1 n* Sb2S3—Orange 
Bi2S3 f S SnS 43 
CuS ) s PtS2 • jg 
Au2S3 S 
Confirmations, 
(1.) If ppt. yellow and insoluble in 
Cd. 
(2.) If ppt. black and insoluble in 
NH^HS. 
(a) Add to O, H2S04 : white=Pb. 
(b) Add to O, KHO : yeIlow=Hg; 
white=Bi; and blue--Cu. 
(3.) If ppt. yellow and soluble in 
NHtHS. 
Precipitate 
May be either 
BaC03 ) « 
SrCO., I '-S 
CaC03 ) £ 
Confirmations. 
Let ppt. settle, pour 
off as much super- 
natant liquor as 
possible, and dis- 
solve in HAc, 
then test succes- 
sively in the same 
liquid. 
(1.) WithK2Cr04: 
yellow—Ba. 
(2.) With a drop 
of dilute H2S04 
and fi t u otand : 
white=Sr. 
5th Group. 
(1). Divide into 
two portions ; 
test one with 
Na2HP04 : 
white=rMg. 
(2.) Evaporate the 
remainder to 
dryness, heat 
till fumes 
cease, dissolve 
residue in the 
smallest possi- 
ble quantity of 
water, and try 
the flame test. 
(a) Crimson flame 
=Li. 
(b) Violet flame 
= K. 
i 
1 
(a) Add to 0, KHO: white (sob in 
excess and not re-precipitated on 
boiling)=Sn (ic). 
(b) Add to O, KHO and Zn, boil 
and hold paper moistened with 
AgN03 over the tube: black 
stain=As. 
(4.) If ppt. orange, soluble in 
and re - precipitated 
orange by HCl=Sb. 
(5.) If ppt. brown or black, and 
soluble in NHtHS. 
(a) Add to O, HgCl2 and boil: 
grey=Sn (ous.) 
(b) Add to O, SnCl2 : purple=Au. 
(c) Add to O, KC1 and rectified 
spirit ; yellow = Pt, 
I2*) U PPT- wth KHO be insoluble 
in test O with (NH4)2Mo04 
dissolved in HNOs and boil. 
(a) If no precipitate forms, test O for 
Ce by evaporating and igniting 
and getting a red residue, which 
dissolves with difficulty in strong 
HC1, and the solution diluted 
and nearly neutralized gives a 
white with (NH4)2C204. 
(b) If a yellow precipitate forms, 
phosphoric acid is present, in 
which case proceed as follows :— 
Add to O, NH4H0 in excess, 
and then HAc until the solution 
is acid and boil. 
(a) A ppt. forms, it may be FeP04, 
CrP04, or A1P04, filter, wash, 
and treat on filter with boiling 
dilute KHO. 
* A reddish residue is left on 
filter = Fe (test O for Fe 
and Fe2. 
t A greenish residue is left on 
filter =Cr (fuse as above.) 
+ The ppt. dissolves = Al (con- 
firm by boiling filtrate with 
NH4C1.) 
(b) No precipitate forms. We may 
have in solution the phosphates 
of Ba, Sr, Ca, Mn, or Mg. Test 
the same solution with KsCr04: 
yellow = Ba. If no effect add a 
drop or two of dilute H2S04, and 
stand for a short time : white = Sr. 
If not Sr add (NH4)2C204 : 
white = Ca. If still not Ca cool 
and add excess of NH4HO : 
white= Mg or Mn. Fuse ppt. on 
porcelain with KHO and KN03: 
green residue = Mn. If no green 
then the ppt. was Mg. 
(6) Greenish ppt. un- 
altered by boiling 
(Both should be con- 
firmed by blowpipe 
bead.) 
i (3-) With 
(NH4)2C204: 
whi' “=C», 
(c) Yellow flame 
=iN a. 
Confirm K by Pt 
Cl4 and recti- 
fied spirit. 
Test for NH( 
by boiling O 
with KHO and 
smelling. 
*As Mn may sometimes precipitate through the solution absorbing oxvffen it k alwavs advisable r... e tU. ~ TT : 
KHO and KN03 ereen residue=Mn. 8 yg ’it is always advisable to filter out a little of this precipitate and fuse it with Table for the Detection of the Metal in a Simple Salt, the Metal present being limited to the Salts commonly used and included in 
the British Pharmacopoeia. 
(N.B.—Ppt. means precipitate ; 0 means the original solution.) 
ist Group.—Add a drop of HC1, and if it produce a precipitate, add excess. 
Precipitate. 
2nd Group.—To the solution in 
which HC1 has failed to give a ppt. add excess of IPS water and warm gently. 
May contain— 
Pb 1 
1 
Precipitate. 
3rd Group.—To a fresh portion of O add some NH.C1, then NH,HO in slight, but distinct excess, 
and observe effect; lastly, add 
a drop or two NH4HS and again observe. 
He (ous) > White. 
(1) Notice its color and add to it a ! 
Precipitate. 
4th Group.—To the solution which has failed to give a 
ppt. in the 3rd group add (NH4)2CG3. 
Ag ) 
drop of NH4HO to neutralise, and ! 
then add 10 drops of NH4HS and 
warm. Notice whether it dissolves 
or remains insoluble. Thus we 
Confirmations. 
Division I. 
A ppt. was caused by NH4HO, and 
Precipitate. 
5th Group.—To the solution in 
which (NH4)2C03 has failed 
to give a ppt. add Na2HP04, 
(i) Let ppt. settle; pour 
divide the group into two divisions, 
as follows :— 
was afterwards turned black by 
NH4HS. May be Fe, provided it 
May contain 
off liquid and add H20 
and boil. If it dis- 
Division I. 
it is readily bleached by HC1 [Ni 
Ba. 
and Co not so bleached). 
Ca. 
solves and gives a yel- 
(Insoluble in NH4HS.) 
Test O for Fe(ous) with K6Fe2Cy12. 
(Sr). 
Precipitate. 
6th Group. 
low ppt. with K2Cr04 
Hg) 
,, ,, Fe(ic) ,, K4Fe2Cye. 
To 0( first neutralised 
= Ph. 
c„ f = bi»*. 
Division II. 
if acid by N H4H 0, 
and then acidulated 
White = Mg. 
— 
(2) If not soluble in boil- 
Pb ! 
A ppt. is caused by NPi4HO not 
with acetic acid) 
(1) Test 0 for (NH4) 
' ing H20, add NHtHO. 
If now soluble = Ag, 
Cd = Yellow. 
altered in color by NH4HS. 
add, 
by boiling, with 
If the ppt. was black, then to 0 adda. 
Green = Cr (confirm by KHO). 
(1) K2Cr04 yellow 
KHO and smell- 
If turned black = Hg 
KHO. 
r ai. 
ppt. == Ba, 
ing for NH3. 
(ous). 
Yellow = Hg. 
White = I Ce. 
(2) (NH4)2C204white 
Blue = Cu. 
i Ca3(P04)3. 
ppt. = Ca. 
(2) Test O for K 
White (insoluble) = Bi. 
To O add KHO. 
with PtCl„ first 
White (soluble) = Pb. 
White (soluble in excess) = Al. 
Note. — If the O 
concentrating by 
Division II. 
White (insoluble in excess) = Ce 
gives a persistent 
evaporation and 
or Ca3(P04)2. 
red flame, Sr is to 
cooling: yellow 
(Soluble in NH4PIS.) 
Test specially for Ca3(P04)2(see § V.) 
be suspected, and 
= K. 
(Ce salts always leave a red residue on 
its absence must 
Sn(ous) = Brown. 
Ac ) 
heating). 
Division III. 
then be proved be- 
fore testing for Ca 
(3) Apply flame test. 
Yellow = Na. 
Sn(ic)) =Yellow- 
Ppt. with NH4HO instantly soluble, 
(see p. 25). 
Crimson = Li. 
Test O. (1) If ppt. brown :— 
but NH4HS produced a light- 
With HgCl2 for Sn(ous). 
colored ppt. 
Flesh-colored = Mn. 
(2) If ppt. yellow ; for As by Fleit- 
White = Zn. 
man’s test, and if not found then 
Add to O chlorine water and KHO. 
test specially for Sn(ic). 
Brown == Mn. 
(3) ppt. orange = Sb. 
White (soluble) = Zn. DETECTION OF INK NOWN SALTS. 
65 
§ 111. DETECTION OF THE METALS IN COMPLEX MIXTURES OF 
TWO OR MORE SALTS. 
Step I. Preparation of the solution for analysis in cases where the 
substance for analysis is not given in solution. 
Note.—By carefully applying this step and intelligently judging the results, we can 
often reduce a separation of two salts to the performance of two separate 
simple analyses, and so save much time and trouble. 
i. Boil some of the powdered substance with distilled water, and filter 
off from any insoluble matter. 
Evaporate a drop or two of the filtrate to dryness, at a gentle heat, on a 
slip of clean platinum foil, and if any residue be left, then save the balance 
of the filtrate for analysis as representing the portion of the original (if any) 
that is soluble in water* 
2. If anything remains insoluble from water, then wash it on the filter 
with boiling water until a drop of the washings leaves no marked 
residue on evaporation. Rinse the insoluble off the paper into 
a tube, and add hydrochloric acid drop by drop (noting carefully 
any effervescence or odor as indicating the presence of certain 
acidulous radicals, such as carbonates, sulphides, sulphites, 
cyanides, etc.), and warm. 
If it now all dissolves, save the fluid for analysis. If not, then separate 
the insoluble, test the filtrate by evaporation of a drop or two, to see whether 
anything has dissolved, and if so, save the fluid for analysis as representing 
the metals present in the form of salts insoluble in water, but soluble in HCI. 
Note. —This division of any mixture into salts soluble and insoluble in water gives 
the greatest assistance in the subsequent testing for the acidulous radicals. For 
example, if a metal of the sth group be found in the portion soluble in water, 
then any acidulous radical almost may be present; while if a metal of one of 
the other groups be found, then generally speaking only a nitrate, sulphate, 
chloride or acetate need be first searched for. If, on the other hand, the 
substance resists water and only goes into solution with HCI, then as a rule 
no metal of the sth group is present, and we might consider that we were 
probably dealing with a carbonate, oxide, phosphate, arseniate, oxalate, 
sulphide, sulphite, cyanide, ferro- or ferri-cyanide, or borate of a metal, not 
in the sth group. Certain tartrates and citrates, chiefly of the 4th group, 
would also come in this category. 
3. If the substance resists both water and HCI, try nitric acid, first alone, 
and then with the addition of hydrochloric acid. 
This treatment dissolves certain metals in the free state, such as Ag, Pb, 
Bi, Hg, and Cu, and also acts upon HgCl, HgS, and other insoluble sul- 
phides, and on Fe203 and some refractory oxides. Gold and platinum only 
dissolve in nitro-hydrochloric acid. 
Note.—When HNOs has been used as a solvent, the liquid should always be 
evaporated with HCI till all the HNG3 has been displaced, then allowed to 
get quite cold and any precipitate filtered out and treated as belonging to 
the Ist group, while the filtrate is directly treated with H2S. 
4. If anything still remains insoluble, it must be fused with fusion 
mixture (KNaCO3) at a bright red heat till action ceases, and 
the residue so obtained boiled with water and filtered. 
The filtrate is used for the detection of acidulous radicals; while the 
insoluble matter is dissolved (after washing) in nitric acid and used for 
finding the metals. The usual run of articles requiring this treatment are— 
sand, clay and other silicates, sulphates of Ba, Sr, Ca (latter not always) 
and Pb, the haloid salts of silver, Sn02 and Sb205. 
Step 11. Proceed to apply the following tables to the prepared solution 
from Step I. 
Note.—The whole of the first table for “separation into groups ” must be gone 
through, but if no effect be obtained in Groups I. or 11., a fresh portion of 
the prepared solution should be taken for Group 111., etc., so saving the 
time required for evaporating to a considerable extent. 66 
QUALITATIVE ANALYSIS. 
Add a drop of HC1 and if it produce a precipitate, add excess {Note i). 
_ 
which may contain 
PbCl2 
Hg2Cl2 
AgCl, 
is collected on a 
filter and examined 
by Table A 
To the filtrate add H2S water, and if it produce a discoloration, warm to blood-heat and pass H2S in excess. 
The precipitate is to be care- 
fully washed with boiling H20 
till quite free from HC1 {Note 2). 
It is then to be washed into a test- 
tube about half-full of H20, and 
from 10 to 20 drops of NH4HS 
having been added, the whole is 
warmed for a time and filtered 
(Note 5). 
(a) Insoluble poition, including 
possibly 
HgS 
PbS 
Bi2S3 
CuS 
CdS, 
is examined by Table B. 
(/>) Soluble portion, containing 
possibly 
Fvioorate filtrate to dryness in a platinum capsule, and heat till any organic matter present is 
decomposed. Moisten the residue with strong HC1, and then add H30and Jod (any insoluble 
(Note T if white Si02). Take a little of the solution, add PINOs and (NH4'2Mo04 and boil If 
Phosphates be present, a yellow precipitate will be produced (Note 4)- lake now the rest of the 
solution, warm it with a drop or two of HN03 and then add NH4C1 and NH4HO, the latter m slight 
but distinct excess ; boil and filter (a). Add to the filtrate N H4Hb in excess, boil and filtei (b). 
GEOUP I. 
(a) NH4HO 
Precipitate may (in 
absence of P04) con- 
tain 
Fe,6HO 
Cr26HO 
AU6HO 
Ce2HO 
W ash with boiling 
IPO and examine by 
Table D. 
(In presence of P04) 
(b) nh4hs 
Precipitate may con- 
tain 
MnS 
ZnS 
NiS 
CoS 
Wash with H20 con- 
taining NH4HS and 
examined by Table F. 
Add to filtrate (NH4)2C03 and boil. 
• 
Precipitate may con- 
tain 
BaC03 
SrC03 
CaC03 
examined by Table G. 
GROUP IV. 
Filtrate may contain 
Mg 
Li 
K 
Na 
examined by Table II. 
GROUP V. 
As2S3 
Sb2S3 
SnS 
SnS2 
Au2S3 
PtS2, 
is examined by Table C. 
GROUP II. 
It may contain 
FeP04 
A1P04 
CrP04 
Ce32P04 
Ba32P04 
Sr32P04 
Ca32P04 
Mn32P04 
Mg32P04 
W ash with boiling 
water and examine by 
Table E. 
Division (a). GEOt 
! 
IP III, Division (b). 
Notes. 
(1) Too much excess HC1 prevents the rapid 
precipitation of Cd by FI2S- 
(2) Known by testing washings with AgN03 
and continuing to wash and test till no precipitate 
is produced. 
(3) Cerium leaves a very dark red residue only 
soluble in strong acid. 
(4) A little patience here, as in dilute solutions 
the precipitate does not form instantly- 
(5) W,hen Cu is suspected from the Preliminary 
Examination, take care not to use yellow NII4HS 
as it always dissolves some CuS. 
TABLE FOR THE SEPARATION OF METALS INTO GROUPS. DETECTION OF UNKNOWN SALTS. 
6? 
Alter washing the precipitate once with cold water; put the funnel over a fresh tube and pour on some boiling water. 
The filtrate may contain 
PbCl2 
Test while still hot with K2Cr04 
Any precipitate remaining on the filter is washed with boiling water till all trace of Pb 
is removed, and then percolated with dilute NH4HO (i in 3). 
Yellow Precipitate = Pb. 
Any black precipitate 
which remains on the 
filter is NH2Hg.,Cl, 
and proves the pre- 
sence of Hg2. 
The filtrate is diluted with an equal bulk of water, and then 
cautiously acidulated with PINOs (to re-precipitate 
AgCl previously dissolved by the NH4HO). 
White precipitate = Ag. 
. 
Note.—Instead of filtering, the whole of this analysis may be done by decantation, as the precipitates are heavy and settle rapidly. 
TABLE A. 
SEPARATION OF METALS OF GROUP I. QUALITATIVE ANALYSIS. 
Wash precipitate with boiling -water, and then transfer it to a small porcelain dish, add a few dropa of HN03, and warm till red 
fumes cease, and repeat this heating with HN03 till an additional drop fails to cause any more red fumes. Now wash the 
contents of the basin into a tube with a little water (i), add H2S04 till no more precipitate forms, then cool and add an equal 
bulk of spirit of wine (methylated). 
Any Precipitate may contain HgS (2), 
and PbS04 Percolate with a strong 
To the Filtrate, which may still contain Bi, Cu, and Cd, add NH4HO in excess. 
solution of NH4C2H302, and test fil- 
trate with K2Cr04. Yellow = Pb. 
Any black residue now remaining in the 
filter will be HgS, and is to be con- 
firmed by dissolving in HC1 by the 
aid of a crystal of KC103, and (after 
boiling free from Cl) adding SnCl2, 
and boiling. Grey precipitate = Hg. 
Any Precipitate will be 
B13HO. and is to be 
confirmed by dissolv- 
ing in the least pos- 
sible quantity of HC1 
by the aid of heat, 
and pouring into 
H.,0. 
White -Bi. 
The Filtrate, if blue in colour, contains Cu for certain, 
and possibly also Cd. If not blue, no Cu is present, 
and Cd is to be directly tested for by adding NH4HS. 
Yellow - Cd. If Cu be present, then add KCy until 
the blue colour is discharged, and pass PI2S, when any 
Cd will be precipitated as yellow CdS, 
Note i.—Too much water added might precipitate any Bi, as Oxy-Nitrate. 
2.-—If any Cl have been left in the original group precipitate (through inefficient washing) the HgS will dissolve and be lost. 
! 
TABLE B. 
SEPARATION OF METALS OF GROUP II., DIVISION (a). DETECTION OF UNKNOWN SALTS. 
First Method\ in Absence of Gold and Platinum. 
Acidulate with HC1 to cause the reprecipitation of the sulphides. If a decided yellow, orange, or black precipitate separates, 
then proceed to filter out; but if only a cloud of precipitated sulphur forms (not separating readily, and nearly white in colour), 
no metals of this division are present. After washing the sulphides, suspend them in a cold solution of the B.P. ammonium 
carbonate, shake up for a few minutes, and filter. 
The filtrate may contain 
(NH4)3AsS3. Add HC1 
in excess, and if present 
As will be reprecipitated 
as yellow As2S3. Filter 
out and confirm by drying 
and heating with KCy 
and Na2C03 in a small 
tube, thus getting a mir- 
ror of metallic arsenic, 
or, if preferred, by Fleit- 
man’s test. 
Any orange or yellow precipitate still remaining may be sulphides of Sb or Sn(ic). Dissolve in 
strong boiling HC1, dilute a little, and put into a platinum dish with a rod of zinc so held that it 
dips in the fluid and touches the platinum outside the liquid. Electrolysis will set in and cause 
the Sb to deposit as a black stain closely adhering to the platinum, while Sn will deposit as loose 
metallic granules. Boil with HC1 (after washing) and the Sn will dissolve, forming SnCE and 
giving a precipitate with HgCl2; while the Sb will remain undissolved, and may be confirmed by 
oxidizing with a drop of HN03, then dissolving in solution of FEC4H406 and getting the 
characteristic precipitate with FES. 
Second Method in Presence of Gold and Platinum. 
When the precipitate from the NH4HS by dilute HC1 is dark in colour, either Sn(ous) Au or Pt must 
be present. In this case the separation had better be conducted as follows. Boil the mixed 
sulphides at once with strong HC1 as long as FES is given off; dilute slightly, and filter. 
Filtrate may con- 
tain SbCl3 and 
SnCl2, which are 
separated by elec- 
trolytic process 
above described. 
Precipitate may contain As2S3, Au2S3, and PtS2. If it be yellow, simply 
confirm the As by fusion in a tube as above; but if it be blackish, then 
Au or Pt are certainly present. In this case digest the precipitate with 
solution of ammonium carbonate as above. 
Filtrate may con- 
tain (NH4)3AsS3. 
Reprecipitate with 
HC1, and prove 
by fusion as above. 
Precipitate may be Au2S3 and PtS2. Dissolve in 
aqua regia; dilute, and test a portion for Au 
with SnCl2 (Purple = Au), and another for Pt by 
KC1 and S.V.R. Yellow = Pt. 
I 
TABLE C. 
SEPARATION OF METALS OF GROUP II., DIVISION (b). QUALITA LIVE ANAL YSIS. 
{Note i.) Wash and transfer to a platinum or silver dish, and fuse with KNaC03and KN03. Boil the residue in water and filter. 
insoluble portion may contain he and Ce. 
2.) Moisten with strong HC1, and 
then add HX) and boil. Test a por- 
tion of the solution for Fe by K4FeCy6 
Blue = Fe. To remainder add citric 
acid, and then excess of NH4HO, and 
finally (NH4)2C204. White - Ce. 
The solution (-which if yellozv contains Cr) is mixed with Na.2HP04 acidulated with 
HC>H302 and boiled. 
Precipitate is 
A1P04. 
Gelatinous white = Al. 
Filtrate treated with AgN03 gives a red, or with BaCb a 
yellow if Cr be present (Note 3). 
NOTES. 
1. If this group precipitate be deep reddish-brown, nothing is probably present but Fe. If it be at all greenish, Cr is present. If it 
be white or pale red, take a little on a watch-glass, and touch it with an excess of KHO and observe effect. 
Originally white and soluble, only Al. 
„ ,, insoluble ,, Ce. 
„ pale red, and becoming deep red, and partly dissolving, Fe and Al both present (probably). 
„ ,, „ not darkened by KHO, but darkened by NaCIO, Fe and Ce both present. 
2. If Ce be present, the red residue is with great difficulty soluble, even in strong HC1. 
3. Sometimes the NH4HO brings down Mn along with the Fe in this group; and both the residue and solution being then bright 
green, the yellow of the Cr is of course masked. In this case boil the filtrate with HC1 and S.V.R., when the green of the 
manganate will be removed, while the chromate will be reduced to Cr.2Cl6 and turned greenish. If therefore the originally 
green solution be entirely decoloured by HC1 and S.V.R. nothing but Mn was present; but if a green tint remain, then Cr was 
also present. This is of rare occurrence, but must always be kept in view when the original fusion gives a green residue. 
TABLE D. 
SEPARATION OF METALS OF GROUP III., DIVISION (a). {NoU I.) Dissolve precipitate in dilute HC1, add excess of Na2HP04 and then excess of NH4C2H3O2 and boil. 
Precipitate may be 
{Arote 2) FeP04, A1P04, Ce32P04 wash with 
boiling H.20 and percolate with some 
Filtrate, if green in colour, contains Cr. (but if perfectly colourless, that metal may be noted as absent). 
Add K2CrG4 and warm. 
boiling dilute KHO. 
Precipitate 
Filtrate must be tested for Sr by flame test (If present. Note 3), if absent, uroceed as 
Residue may contain 
Filtrate may contain 
BaCr04. 
Yellow = Ba. 
follows. Add (NH4)2C204. 
he and Ce 
Dissolve in HC1 and 
test a portion for 
Fe by K4FeCy6. 
A1P04 
supersaturate with 
HCJI3O0. 
White gelatinous = Ah 
Precipitate 
is CaC204. 
White = Ca. 
Filtrate is mixed with a little H3C6H507 
NH4HO added [Note 4). 
cooled and excess of 
Blue = Fe. 
To the remainder add 
citric acid and then 
NH4HO in excess. 
An immediate white 
or a white after ad- 
ding (NH4)2C204 
= Ce. 
Precipitate may contain 
Mn32P04 or Mg32PQ4 
(See Note 5). 
Separation, if necessary, by dissolving 
in dilute HC1, adding excess of 
NH4C,H30.,, boiling, and dropping 
in h e2Cl6 till a reddish tint is pro- 
duced. Fdter out the FeP04 thus 
produced, and to the filtrate add 
NH4C1, NH4HO, and NH4HS, to re- 
move Mn and Fe. Again filter, con- 
centrate to a small bulk, and test when 
quite cold for Mg by NH4HO and 
Na2HP04. 
Filtrate 
may contain 
Cr only , 
prove by fusion 
if necessary. 
..... NOTES. 
*• This precipitate, if free from Ce, Cr, and Mn, is much more simply worked. Therefore take a little before dissolving and put it on a porcelain crucible-lid with a few drops of strong 
KHO and a crystal of KN03 evaporate to dryneSs and fuse. If no bright yellow or green residue be formed Cr and Mn are respectively absent. Take another portion of the 
group precipitate on a white porcelain lid, and add some solution of chlorinated soda or lime ; if it does not turn yel ow, then Ce is absent (if Mn be present this last test will turn 
the precipitate brown) so that it is^only when it does not change colour at all that the positive absence of Ce can be insured. 
2. Here CrP04 should be found, as it is theoretically insoluble in acetic acid ; but in practice it is, when freshly precipitated, nearly entirely soluble, and passes on as shown in the Table 
If its presence is suspected, a little of the precipitate may be fused as above. F ' 
3. If Sr be present (known by its crimson flame, and distinguished from the mere orange-red of Ca) it must be removed by adding a little very dilute II,SO,, letting stand for twenty 
minutes in a warm place, and then filtering out the SrS04 formed. In this case excess of ammonium acetate must be added before proceeding to test for Ca 
4. If no Cr is present the citric acid need not be used, as it is*only added to prevent the precipitation of CrP04 by the NH4H0. 
5. If no Mn was found by the preliminary fusion {Note 1) this precipitate is all Mg ; but if Mn be present it must be first removed before Mg can be definitely proved. 
DETECTION OF UNKNOWN SALTS. 
71 
TABLE E. 
SEPARATION OF METALS OF GROUP III. (DIVISION a) IN PRESENCE OF PHOSPHORIC ACID. QUALITATIVE ANALYSIS. 
Case I.—If the group precipitate be white or flesh-coloured, nothing is present but MnS and ZnS; and it then only remains to 
dissolve in dilute HC1, add NaHO in excess, boil, and filter. 
The filtrate may contain 
Zn dissolved in excess of NaHO ; add 
excess of HC2H3Oa and then K4FeCy6. 
White = Zn. 
Any precipitate maybe Mn2HO, which must be confirmed by fusion on platinum foil 
with KNaC03 and KN03. Green residue — Mn. 
{Note.) The supposed precipitate of Mn must be confirmed, because any trace of Fe 
escaping precipitation in its own group might appear here as Mn. 
Case II.—If the group precipitate be dark in colour, then Co and Ni may also be present. In this case a black residue of NiS 
and CoS will remain insoluble in the diluted HC1. Any such residue must be filtered out and dissolved in strong boiling HC1, 
or Aqua Regia, if necessary ; then add excess of KCy, and boil in the fume chamber, adding more HC1 if necessary, until all 
further smell of HCy ceases to be developed. Then add KHO in excess. 
Any precipitate contains 
Ni; confirm by drying and heating in 
borax bead. 
The filtrate may contain Co; confirm by evaporating to dryness, and heating residue 
in borax bead. 
TABLE F. 
SEPARATION OF METALS OF GROUP III., DIVISION (b). DETECTION OF UNKNOWN SALTS. 
Dissolve the precipitate in HC3H3Q2 and add K2Cr04 in excess. 
Any precipitate is 
BaCr04. Y ello w = Ba, 
Take a small portion of the filtrate and add some saturated solution of calcium sul- 
phate, warming gently. If no precipitate should form, Ca only is present, and may 
be confirmed at once by adding (NH4)2C204 to the remainder of the filtrate. But 
if a precipitate be produced Sr is present, and must be separated by adding a 
few drops of very dilute HJSO to the said remainder, and letting the whole stand 
in a warm place for fifteen or twenty minutes. 
Any precipitate is SrS04; confirmed by 
being perfectly insoluble after di- 
gestion for some time at a gentle heat 
with a strong solution of (NH4)2S04 
and a little NH4HO (to remove any 
CaS04 accidentally precipitated). 
White residue giving crimson flame 
= Sr. 
The filtrate may contain Ca, confirmed 
by adding NH4HO and (NH4)2C204. 
White = Ca. 
(Note.) To ensure that Sr is fully sepa- 
rated, see that a portion of this filtrate 
gives no precipitate by warming with 
a saturated solution of Ca S04. 
1 
TABLE G. 
SEPARATION OF METALS OF GROUP IV. 74 
Q UALITA TIVE ANAL YSIS. 
Divide the solution into i and -|. Take the ± portion, and concentrate by evaporation if very dilute, cool perfectly, and add 
excess of NH4HO and Na2HP04. White-Mg'. Evaporate the filtrate to dryness on the water bath, and take up with boiling 
water, when any white insoluble residue is Li, provided it gives a crimson flame on a platinum wire previously dipped in HC1. 
Take the remaining and evaporate to dryness, and heat till all fumes of ammonium salts cease to be evolved. Take up the 
residue with the smallest quantity of boiling water (pouring off from and disregarding any insoluble matter). Then acidulate 
with HC1, dip in a wire and test flame, looking first at it with the naked eye, and then through a piece of blue glass (to cut off 
the sodium yellow). 
Red ..... Li (disregard if already found in the ± portion). 
Yellow . . . . . Na. 
Violet ..... K. 
Confirm K by adding PtCl4 to the rest of the acidulated solution, and getting when cold a yellow precipitate of PtCl42KCl. 
Test for NHt by boiling some of the original solution with KHO, and getting off NH;i. 
TABLE H. 
SEPARATION OF METALS OF GROUP V. DETECTION OF UNKNOWN SALTS. 
75 
§ IV. DETECTION OF THE ACIDULOUS RADICALS. 
Division A.—Preliminary Examination. 
Important Note.—We must always decide what metals or bases are 
present before we proceed to test for acidulous radicals. We 
must then note which bases are present as soluble and which 
as insoluble salts (in H2O). Lastly, we must consider what 
acids might be present in each case, and only test for such 
possible acids, because nothing leads to so many errors as testing 
for acids which could not possibly exist. We must also carefully 
note the information received in the former preliminary exami- 
nation, especially as regards the presence of organic matter, 
and remember that, if the original substance does not char on 
heating, we must never enter into the testing for organic acids, 
because none can possibly be present except oxalate, which is 
provided for in the inorganic portion of the course with this 
very object, together with a few others included for convenience. 
We must also remember to note what happens when we 
dissolve the original substance in HCI, provided such a step 
is necessary, and if any effervescence occurs we must be sure 
to smell the gas given off, because we may then at once detect 
the following:— 
. . effervescence without odor, and the evolved gas 
poured into lime-water renders it milky. 
. . odor of H2S (with deposit of S polysulphide). 
. . „ S02 ( ~ „ hyposulphite). 
. . „ HCN. 
Peroxide . . „ chlorine. 
Fe, Zn, or Sn (as metals)—no odor but hydrogen evolved. 
We must also remember that organic bodies, such as alkaloids or 
sugar, other than organic salts, might be contained in a mixture 
which would cause charring on heating, and so lead us to test for 
what was not there. It will be useful at this point to see how 
we can guard against two of the more commonly occurring of 
such cases. 
(i) Sugar. This will cause the soluble portion to be syrupy, and 
when warmed with dilute H2S04 it will rapidly darken, whereas 
organic salts, as a rule, require fairly strong H2S04 to char 
them. The solution will have a sweet taste, and after boiling 
with a drop or two of very dilute H2S04 it will reduce Fehling’s 
solution. 
(2) Alkaloids (nitrogenous organic bases). These will cause an odor 
like burning hair on heating to redness. The soluble portion of 
the mixture carefully treated with very dilute NH4HO will usually 
give a cloud (which may or may not dissolve in excess) and then 
the same liquid shaken up with chloroform, and the chloroform 
evaporated at a gentle heat, wall leave the alkaloid as a residue. 
If no residue be thus obtained then no alkaloid can be present 
except morphia, and this latter would never be put in a mixture 
unless specially intended for toxicological investigation, because 
* In soluble salts these effects will come on adding HCI in Group I. 76 
QUALITATIVE ANALYSIS. 
its detection requires altogether special work, which will be 
afterwards detailed. 
Having well considered all this, we now proceed to the actual 
work, carefully remembering that all the indications are merely 
preliminary, and that we are not to take notice unless we really 
get a distinct result. If we really do get one, then it may save us 
going so far through our actual acid course, but if we are not 
certain, then it is no use attempting to persuade ourselves and 
wasting time, but we should just note the probability and then 
at once pass on to confirm by the actual course hereafter 
detailed. 
No attempt is made to describe odors, because the student 
should simply put himself through a course of training for this 
preliminary examination on known salts, and learn to recognise 
all the odors, etc. This is a most important study, and should 
be carefully stuck to, until the nose and eyes have been quite 
trained to recognise the individual effects to be expected from 
each acid. 
Step I. Put a portion of the original solution in a tube, or if it be a 
solid cover it with some water, just acidulate with dilute H2S04 
and look for any effervescence or odor, then boil and smell. 
The following radicals may be thus recognised : 
Effervescence without odor . , . Carbonate. 
Effervescence with characteristic odors . -„u P .^e‘ 
Cyanide. 
Red fumes Nitrite. 
Step 11. Add another drop of H2S04, and again warm. 
Odor of vinegar ..... Acetate. 
„ ~ SOo with deposit of S . Hyposulphite. 
„ „ HCN „ ~ „ ' . Sulphocyanate. 
~ ~ HCN „ crystalline deposit, \ Ferro- or 
often bluish j Awr/-cyanide. 
„ ~ Valerian or sharp odor . . ■[ Valerianate, Ben- 
( zoate, Succinate. 
» » Carbolic acid . . . Carbolate. 
Note.—The effects of Step 11. will often come perfectly in Step 1., and 
then Step 11. may be considered as part of Step I. 
Step 111. Put a little of the original solid (or the residue left on evapora- 
tion if the original was a liquid) into a dry tube, cover it 
with strong H2S04, and warm, but not sufficiently to cause the 
H2S04 itself to fume. (See note, important to prevent accidents.) 
Thus we get;— 
(Chloride, r, , . f lodide. 
1 Nitrate, °f “lor | lodate. 
White fumes I Fluoride. f d colored Bromide, 
(characteristic of) 1 Benzoate. urnes (char- lgromate> 
I Succinate. actenstic of) chlorate> 
(Sulpho-carbolate. DETECTION OF UNKNOWN SALTS. 
77 
Effervescence on warming only, 
which persists after withdraw- 
ing from flame, but with no 
darkening in color and no 
odor. 
(Formates— give off CO only, and con- 
sequently the gas does not 
affect lime-water. 
Oxalates—give both CO and C02, and 
the gas therefore renders 
lime-water milky. 
/ Tartrates—rapid charring and smell 
I of burnt sugar. 
Lactates—not so dark, and peculiar 
/ odor. 
Citrates—slow darkening and peculiar 
sharp odor. 
Oleates—char and give odor of 
acrolein. 
Effervescence on warming, but 
the liquid darkens in color to a 
greater or less extent. 
' Meconate. 
Darkening in color without any J ai?Ina 6‘ 
very marked effervescence. 1 -Da aen . 
} Pyrogallate. 
i Salicylate {very slow darkening). 
No fumes—gelatinous deposit (or flaky)— Silicate. 
„ „—scaly crystals with pearly lustre—Borate (best seen on 
cooling). 
No change takes place at all with—Sulphate, phosphate, and arseniate. 
Chromates turn orange and then green—Bichromates turn green straight 
off. 
Note Important.—On adding strong sulphuric acid to any solid, one drop 
only should be first carefully applied, because chlorates, iodates, etc., 
are apt to explode on the first touch of the acid. 
If we get a decided indication of the presence of any acidulous radical 
as above, we may at once apply confirmatory tests for the radical found to 
our original substance, and so save going through the course, especially if 
the substance be soluble in water; but if insoluble a solution must always 
be specially prepared for acid testing. 
Division B.—Preparation of a Solution for Testing for Acidulous Radicals. 
The success of the course for the detection of acids depends in the highest 
degree upon the care with which the solution is first prepared. It may be 
taken as a general rule that no testing for acids is reliable unless they are 
present in the form of salts of alkaline metals. It is therefore necessary to 
transform our acids into such salts ; and, to do this successfully, the following 
rules must be closely adhered to : 
I. If the original is soluble in water, and absolutely neutral to test- 
paper, you may venture as a rule to use it as it is, and this will 
also apply, if it be alkaline, to test-paper. 
11. If the original be soluble in water, but in the least acid, we must 
drop in NaHO till it is rendered just alkaline, boil, and, if any 
precipitate should form, filter and use the filtrate for the acid 
course. 
111. The portion insoluble in water (or the whole of the original if all 
insoluble) must be boiled with a little NaHO, then diluted, 
filtered, and the filtrate only used for the acid course. 78 
QUALITATIVE ANALYSIS. 
Note.—If Al, Zn, Sb, Sn, Pb, or any metal whose hydrate is soluble in 
excess of NaHO has been found, then we must use a solution 
of Na2C03 instead of NaHO in both Cases 11. and 111. 
We must also take care to prepare plenty of our solution, 
because if the full acid course has to be gone through, we shall 
require possibly to employ eight to ten different portions before 
we have finished. 
This course now about to be explained is so devised that by working upon 
the prepared solution, in the presence successively of HCI, HN03,HC2H3C>2, 
H2S04 and absolute neutrality, we can insure the precipitation in each stage 
of certain given acidulous radicals only by reagents which, if used without 
such precautions, would precipitate many more than they do when so 
employed. 
Division C.—Course for the Detection of Inorganic Acids together with 
a few Organics included for certain reasons. 
Step I. Acidulate a portion of the prepared solution with HCI, and 
then to successive portions thereof apply the following tests : 
Reagent. 
i 
Effect. 
Acid Present. 
(a) Bads .... 
White ppt. insoluble in 
boiling HNO3 .... 
Sulphate. 
(*) Fe2Cl6 .... 
r Dark blue ppt. . . . 
j Blood red color dis- 
i charged by HgCls . . 
j Blood red color not dis- 
' charged by HgCl2 • . 
Ferrocyanide. 
Sulphocyanate. 
Meconate. 
(c) FeS04 .... 
Dark blue 
Ferricyanide. 
(d) Turmeric paper . 
f Dip in and dry over 1 
J the gas when the V 
[ paper turns pink J 
Borate. 
Step 11. Acidulate a portion of the prepared solution with HNO ~ 
add excess of AgN03, warm and shake, disregarding any precipi- 
tate that is not white or yellow and distinctly curdy. Thus we 
get the following : 
(a) Cyanide—Curdy white ; soluble in very dilute NH4HO, and also 
in boiling HN03. 
(h) Chloride—Curdy white; soluble in very dilute NH4HO, but in- 
soluble in boiling HN03. 
{c) Bromide—Curdy dirty white; slowly soluble in fairly strong 
NH4HO, but not in very dilute ; insoluble in HNOs. 
(d) lodide—curdy pale yellow ; insoluble even in strong NH4HO and 
also in HN03. 
Note.—Many other acids, such as ferrocyanide, oxalate, chromate, etc., are apt to come 
down with AgN03 in presence even of HN03, but the precipitates are (if 
white) not curdy, or they are colored red and so will be disregarded ; and we 
therefore deal only with the four acids mentioned giving curdy precipitates. DETECTION OF UNKNOWN SALTS. 
79 
To distinguish between these four acids we— 
(i) Filter out the precipitate with AgN03, wash it, and then percolate it 
several times with very dilute NH4HO (x in 20),‘when AgCl and 
AgCN will dissolve, and can be reprecipitated from the filtrate by 
HN03, while any Agßr or Agl will be left on the filter. 
Note.—lt is very important to have the dilute NH4HO exactly the correct strength, 
because, if stronger, then Agßr will also dissolve, and in any case a mere 
cloud on adding the HNO?l is to be disregarded, because if AgCl or AgCN be 
really present, they will reprecipitate in distinct curds, on adding HN03, 
warming and shaking. 
(2) If by (1) evidence of the presence of Cl or CN be obtained, then 
test a portion of the original prepared solution for CN by 
Scheele’s test, and if not present then the precipitate was all due 
to Cl. If CN be found, then another precipitate must be 
obtained by excess of AgNOs, filtered, washed, drained, and 
transferred to a tube with strong HN03 and boiled, when any 
AgCl will remain insoluble and also prove its presence. 
Note.—As HCN is so easily smelt in the preliminary examination we should always 
know before we begin the group whether it is there, and then if it be present 
the boiling with HN03 will be required, but if not, then we put it down at 
once as chloride if the NH4HO dissolves anything. 
(3) If, after treating with NH4HO (1 in 20), any residue be left on the 
filter, leading to the idea that Agßr or Agl may be present, we 
proceed as follows : To a small portion of our prepared solution 
a drop of mucilage of starch is added, and then one or two drops 
of chlorine water. If iodide be present we shall get a blue. 
Now we go on adding fresh chlorine water till all the blue 
has been bleached, and if the whole is now perfectly white only 
iodide is present; but if it remain at all yellow, then we add 
some chloroform and shake up, when an orange color in the 
chloroform will indicate bromide. This depends on the fact 
that free iodine combines with chlorine more readily than with 
bromine. 
Step 111. Acidulate a portion of the prepared solution with acetic acid, 
bring it to the boil, and then test successive portions while 
boiling as follows :—- 
Reagent. 
Effect. 
Acid Present. 
{a) CaCl2 .... 
White ppt. soluble in 
HC1 
Oxalate. 
(b) Fe2Cl6 (not in 1 
excess) 
White ppt 
j Phosphate or 
\ Arseniate. 
{c) Pb(C2H302)2 . . 
Yellow 
Chromate. 
To distinguish between phosphate and arseniate exactly 
neutralise a portion of the prepared solution with dilute HNO3 
and add AgN03. 
Yellow soluble in NH4HO = Phosphate 
Red do. do. = Arseniate 8o 
QUA LIT A TIVE ANAL VSIS. 
Step IV. Just acidulate a portion of the prepared solution with dilute 
H2S04, then add a strong and fresh solution of FeS04 and run 
some strong H2SO down the side of the tube so that it collects 
at the bottom. A dark ring where the liquids meet proves 
Nitrate. 
Note.—If iodide has been previously found, this test fails to be conclusive, and in such 
case we must take advantage of the power of nascent hydrogen to reduce 
nitrates to ammonia. If no salt of NH4 has been found in metal testing, we 
add to some of the prepared solution a fragment of zinc and sufficient HCI 
to cause a brisk effervescence. After ten minutes we add excess of KHO 
and boil, when an odor of NH, proves Nitrate. If NH4 salts be present 
we add a little KHO to the prepared solution, evaporate to dryness, heat 
the residue till no more fumes are evolved, and then dissolve in water and 
apply the zinc, etc., as above described. 
Extra Step. lodates being very difficult to detect in the preliminary, it is 
well to test for them specially (if they can possibly be present) 
by adding to the prepared solution KI and starch paste and 
acidulating with tartaric acid. This is not reliable in presence 
of nitrites. 
Division D.—Course for the Detection of Organic Acids. 
(Only to be entered upon in the event of the original substance being proved to 
contain organic matter by charring on heating in the preliminary examination.) 
The solution to be used is that prepared for acidulous testing, as already- 
described. 
Step I. Place a minute fragment of litmus paper in a little of the prepared 
solution, and add acetic acid drop by drop with agitation until 
the paper Just turns red, then take out the paper and add AgNOs 
in excess, lastly add a drop or two of very dilute NH4HO till 
the precipitate just commences to redissolve. Now warm the 
tube in the Bunsen flame, when a reduction to metallic silver, 
forming a mirror on the tube=Tartrate. 
Note.—The tube used must first be rendered chemically clean by boiling in it 
successively some dilute HN03 and then some dilute NaHO and rinsing 
with distilled water. Formates produce the same effects, but do not char on 
heating. 
Step 11. Place a minute fragment of test-paper into a portion of the 
prepared solution, and drop in dilute HCI till it just turns red, 
then dilute NH4HO till it just turns blue again, cool thoroughly, 
add some CaCl2 and shake well. If a precipitate forms (oxalate, 
tartrate, etc.) add excess of CaCl2, shake, and let it stand in 
cold water for ten minutes and filter. Now add to the filtrate 
a little more NH4HO and boil gently for some time, when a 
white precipitate=Citrate. 
Note.—If CaCl2 gives nothing in the cold of course we simply warm for the citrate 
straight off. As oxalate, tartrate, etc., have all been previously tested for, we 
shall know, before commencing to test for a citrate, whether we need to 
separate them in the cold or simply to add the NH4HO and CaCl, and boil 
straight away. 
The addition of rectified spirit to the solution in which boiling has failed 
to indicate citrate will bring down a Malate on cooling, but unless specially 
suspected this reaction is not a very certain one. 
Step 111. Place a fragment of test-paper into a portion of the prepared 
solution, and if alkaline, make it exactly neutral by carefully DETECTION OF UNKNOWN SALTS. 
81 
dropping in dilute HCI. Then apply the following tests to 
portions of this neutralised liquid : 
{a) Prepare some neutral ferric chloride, by adding very dilute NH4HO 
to a solution of Fe2Cle until a permanent cloud just forms, and 
filtering. 
Now add some of this reagent, and observe effect as follows: 
(i) Red color 
(3) Blue-black 
Acetate 
Sulphocyanate 
Meconate 
Pyrogallate 
Gallate 
Tannate 
(2) Purple color 
(4) Pinkish precipitate 
Carbolate 
Sulpho-carbolate 
Salicylate 
Benzoate 
Succinate 
Notes. 
(1) Acetate, red, is instantly discharged by a drop of HCI; pyrogallate is turned 
black by excess of KUO and exposure to air. Sulphocyanate and meconate 
have been already proved in the inorganic acid course, but distinguished by 
action of HgCl2 if desired. 
(2) Acidulate a portion of prepared solution with HCI and shake up with ether. 
Remove the ether by a pipette and evaporate it on a watch-glass at a very 
gentle heat. Carbolic acid is left an oily liquid readily recognised, while 
salicylic acid is left in characteristic crystals, as giving a beautiful violet 
with Fe2Cl6. (Also see page 57 for another separation.) Sulphocarbolic 
acid gives no immediate precipitate with BaCl2, but on evaporating with a 
little Na2Co3and KN03 and fusing, then the residue dissolved in H2O shows 
a sulphate with BaCI2 
(3) With excess of KHO a solution of gallic acid rapidly becomes dark on exposure 
to the air, while tannic acid gives a flocculent liquid not so rapidly changing. 
Tannic acid also precipitates solution of gelatine, and gallic does not. 
(4) Take a good quantity of the neutralised and prepared solution, add excess of 
Fe2Cl6, filter out the precipitate and wash it. Now percolate it with some 
dilute NH.,HO, evaporate the liquid so obtained to a IowT bulk, cool 
thoroughly, and acidulate with HCI. Benzoic acid will separate in silky 
crystals, and succinic acid will not. 
Step IV. If oleic, lactic, or sulphovinic (ethyl-sulphuric) acids be 
suspected, specially test for them as follows 
Oleic acid will have shown its presence by always floating to 
the surface as an oily liquid whenever the prepared solution is 
acidulated with any acid. To confirm and distinguish it from 
the other fatty acids (stearic, etc.) take some of the prepared 
solution and acidulate with HCI, warm and set aside till the 
oily layer floats up. Now remove the liquid beneath, as far as 
possible, with a pipette, add some water, boil and drop in small 
fragments of K2C03, until the oily layer is saponified and 
dissolves. Now put in a piece of test-paper and carefully add 
acetic acid to exact neutrality, then cool and precipitate, with 
excess of Pb(C2H3O2)2. Filter out the oleate of lead, wash it 
with boiling water, let it thoroughly drain, and then prove that 
it is soluble in ether (stearate and palmitate of lead are 
insoluble). 
Lactic acid. Acidulate the prepared solution with HCI and shake up 
with ether. Pipette off the ether into a porcelain capsule and let 
it evaporate at a gentle heat, when the acid will be left and may 
be recognised as follows ; (a) A portion heated burns at first 
with a blue flame, and then the flame becomes luminous as the 
temperature rises; (p) Another portion warmed with KvMn208 
gives the odor of aldehyd. 
Stilpho-vinates do not precipitate BaCl2 in the cold, but, on boiling, 
give a precipitate of BaS04 and an odor of spirit. QUALITATIVE analysis. 
Looking to the metals found, the question arises, what acidulous radicals could possibly be there, supposing the original substance to be soluble or insoluble in 
water or acids, or totally insoluble. Of the solubility of the commoner salts, the following table will show this, and a careful study of it will save much 
unnecessary and often misleading testing for acids. The usual radicals are in words and the rarer ones in symbols bracketed. 
If insoluble in acids, fuse with 
Metals found. 
If soluble in water, test for the following radicals. 
If insoluble in water but soluble in acids, test for the 
following radicals. 
KNaC03, extract with HaO, and 
test the solution for the following 
radicals. 
Silver 
Nitrate, Nitrite, Sulphate, Acetate (CIO, C103, 
Br03, S203) 
Oxide, Sulphide, Carbonate, Phosphate, Cyanide, 
Oxalate, Tartrate, Citrate (As04, Cr04, I03, 
S2°3) 
Oxide, Sulphide, Chloride, Iodide, Oxysulphate 
(P04, As04, C,04, Cr04l C4H4Or„ C6H507) 
Chloride, Iodide, Bromide 
Mercury (ous) 
Nitrate, Acetate, Sulphate (CIO, C103, I03, BrOq, 
NO. B03, C4H4Q6) 
Cljloride, Iodide, Bromide 
Mercury (ic) 
Chloride, Nitrate, Sulphate, Acetate (CIO, C103, 
I03, Br03, Cy, S203, C1O4, N02) 
Oxide, Sulphide, Iodide, Carbonate, Oxysulphate 
(P04, C204, As04, Cr04, C4ll406) 
Sulphide, Iodide 
Lead 
Acetate, Nitrate (Cl, I, CIO, C103, Br03, N02, 
c6h6o7) 
Oxide, Sulphide, Carbonate, Phosphate, Oxalate 
(Cl, I, Cy, S03, S0O3, I03, Br03, As04, Cr04, 
C4H4Og) 
Oxynitrate, Oxychloride, Oxysulphate, Oxide, 
Sulphide, Carbonate, Phosphate (Cr04, As04, 
B03. C204, I, S04, C4H4Ofi) 
Sulphate, Chromate, 
Chloride, Iodide 
Bismuth 
Nitrate, Chloride, Sulphate, Acetate (Br, I03, 
BrOa, CIO, C103, S 03, N02, C6H507) 
None 
Copper (ic) 
Chloride, Nitrate, Sulphate, Acetate (N0-2C103, 
S203, Cr04, CIO, Br, I03, Br03, I, C4H40c, 
c6h5o7) 
Oxide, Sulphide, Carbonate, Phosphate, Arsenite, 
Oxyacetate (As04, B03, Cy, S03) 
n 
Copper (ous) 
Sulphate (Cl,Br) 
Iodide (Cl, Br) 
Cadmium 
Chloride, Nitrate, Iodide, Sulphate (CIO, C103, 
Br, I03, BrOs, S03, S203, NO,, C2H302, 
c4h4o,;, c6h5o7, bo3) 
Oxide, Sulphide, Carbonate, Phosphate (BOs, C204, 
c4H4o8) 
it 
Antimony 
Chloride, Tartrate (C2H3C>2, C204) 
Oxide, Sulphide, Oxychloride (S04, P04, Cr04, I) 
Tin (Stannous) 
Chloride, Sulphate (CIO, C103, Br, N02, N03, 
s2o3, c2h3o2, c4h406) 
Oxide, Sulphide, Phosphate, Chromate (BO3, 02O4) 
«• 
SOLUBILITY. 
An important consideration before proceeding to the Acidulous Course. DETECTION OF UNKNOWN SALTS. 
83 
Tin (Stannic) 
Chloride (CIO,, CsH302, C204) 
Oxide, Sulphide (S03) 
None 
Gold 
Chloride 
Sulphide (Cy) 
Platinum 
Chloride 
Sulphide 
Iron (Ferrous) 
Chloride, Sulphate, Iodide (see Ferric, also S03, 
sao3) 
Oxide, Sulphide, Carbonate, Phosphate, Arseniate 
(QA, B03, Cr04, Cy, C4H406. AsOa) 
” 
Iron (Ferric) 
Chloride, Nitrate, Sulphate, Acetate (Br, I03, 
Br03, C10„ NOa, Cr04, C4H406) 
Oxide, Sulphide, Iodide, Phosphate, Arseniate 
(Ca04 (when dried), BO.„ and S04 (and NOa 
when basic) 
” 
Aluminium 
lake Iron 
Like Iron 
Cerium 
Chloride 
Oxide and Oxalate 
Oxide 
Chromium 
Chloride, Sulphate, Acetate, Nitrate (Br. CIO, 
CIO,. IO„ P.r03, S203, SOa, c.,04, C4II40(i, 
C6Ii507) 
Oxide, Phosphate, Arseniate (BOa, Cr04, Cy) 
Oxide 
Manganese 
Chloride, Sulphate, Acetate, Nitrate (Br, CIO, 
CIO3, IO„ Br03, S03, S,03, NOa, Cr04) 
Oxide, Sulphide, Carbonate, Phosphate (As04, 
CA, BO.„ Cy, C4II4Oe, C6HA) 
None 
Zinc 
1 
Chloride, Sulphate, Acetate, Nitrate (CIO, C103, 
Br, 10„ Br03, NOa, S203, SOa, CrG4, C6H-07) 
Oxide, Sulphide, Carbonate, Phosphate (Co04, 
BO„ AS04, Cy, C4H406) 
55 
j Nickel 
Chloride, Nitrate, Sulphate, Acetate (CIO, C103, 
JO* BrO„ SO.,, S203, Br, NO.,) 
Oxide, Sulphide, Carbonate, Phosphate (As04, 
BO3, Cr04, Cy, C4H406, C6Hs07. Ca04) 
” 
! Cobalt 
Chloride, Nitrate, Sulphate, Acetate (CIO, C103, 
I03, BrO* S03. Sa03, Br, NO* C6HsO?) 
Oxide, Sulphide, Carbonate, Phosphate (As04, 
BOj, CrO„ Ca04, Cy) 
” 
| Barium 
Chloride, Nitrate, Acetate, Oxide (slightly) (CIO, 
CIO.,, I, Br, IO* BrOa, S„03, NO* Cy. 
QH A, S) 
Carbonate, Phosphate, Oxalate, Chromate (O. 
As04, bo3, so3, c4h4o6) 
Sulphate 
Strontium 
Like Barium (except CetijOO 
Like Barium 
Sulphate 
Calcium 
Like Barium (except C6H507 soluble in cold but 
not in boiling water, CaS04 also slightly soluble) 
Like Barium (except SOa, which is soluble in HaO 
and CaS04 slightly soluble) 
Sulphate 
Magnesium 
lake Calcium 
Like Calcium 
None 
Lithium 
Oxide, Chloride, Sulphate 
Carbonate, Phosphate, Oxalate 
Potassium 
All radicals form soluble salts except those men- 
tioned opposite 
PtCl42KCl, KHC4H406, and KaSiF6 
5 5 
Sodium 
All radicals form soluble salts except 
Sodium Antimoniate 
Ammonium 
Like Potassium 
Note.—When a radical is mentioned in more than ope column, it means that it is so slightly soluble as to sometimes appear insoluble at first sight. 84 
QUALITATIVE ANALYSIS. 
§V.—SPECIAL PROCESSES FOR PROVING THE IDENTITY OF 
CERTAIN READILY RECOGNISABLE SUBSTANCES. 
(A) Salts of the Halogens. 
Chlorine water. Characteristic odor; entirely volatile; bleaches 
indigo; KI + starch paste gives blue; AgN03 gives curdy 
white. 
Hydrochloric acid. Slight fumes with sharp odor and strong acidity ; 
entirely volatile; AgN03 gives curdy white ; heated with Mn02 
evolves Cl2. 
Ferric chloride in solution. Orange-red liquid, not becoming milky 
with H2O ; test for ferric iron and for a chloride. 
Antimonious chloride in solution. Orange-red liquid, becoming milky 
when diluted with H2O ; milky liquid divided; one part 
becomes orange with H2S, and the other portion, after filtration, 
gives test for chloride with AgN03. 
Mercurous chloride. Heavy dull white powder, entirely volatile; turns 
grey when boiled with SnClg, turns black when boiled with 
dilute KHO, and, after filtration, the liquid gives test for 
chloride on acidulating with HN03 and adding AgN03. 
Mercuric-ammonium chloride. Opaque white powder, entirely volatile ; 
becomes grey when boiled with SnCl2-; boiled with KHO turns 
yellow and gives off NH3, and the liquid, after filtration, gives 
test for chloride on acidulating with HN03 and adding AgN03. 
Chlorinated lime. Dull white powder, having the odor of chorine; 
shaken up with water partly dissolves, and the solution, after 
filtration, gives with oxalic acid a white precipitate and evolves 
Cl2. 
Potassium chlorate. In crystalline plates, deflagrating on heating with 
evolution of oxygen and exploding when touched with HoS04 
with an odor of C1204; solution gives no precipitate with 
AgN03; evaporated to dryness, heated to redness and the 
residue dissolved in very little water, yields the tests for 
potassium with PtCl4 and for chloride with AgNOs. 
Mercurous iodide. Yellowish-green heavy powder, entirely volatile ; 
heated gently in a dry tube gives sublimate of Hgl2, leaving a 
globule of metallic Hg. 
Meratric iodide. A bright scarlet powder turning yellow and then 
volatilising when gently heated on a piece of paper; boil 
with dilute KHO, let settle, and pour off, when the liquid 
gives blue with starch paste and HN03, while the insoluble 
portion dissolved in HCI and boiled with SnCl2 gives grey. 
(B) Oxides, Carbonates, etc. 
Hydrogen peroxide. Colorless liquid with an odor similar to weak 
chlorine water; gives a blue with KI and starch paste, and the 
resulting liquid is alkalme to test-paper; no precipitate with 
AgNOs. SPECIAL PROCESSES. 
85 
Barium oxide or hydrate, and Calcium oxide or hydrate. Whitish 
powders which, when shaken up with a little water, do not appear 
to be soluble, but render the liquid strongly alkaline; add more 
water, shake and filter, and apply to the filtrate the tests for Ba 
and Ca, and in another portion prove soluble hydrate by getting 
a brown with AgNO:{; heated in a dry tube give off moisture 
if hydrates, but not if oxides. 
Magnesium carbonate or oxide. Light white powders not changing 
color on heating ; dissolve in dilute HCI (former effervesces, 
latter not), and then apply tests for Mg by adding 
NH4CI +(NH4)2C03 and getting no precipitate, and lastly 
adding Na2HP04 and getting a white precipitate. 
Zinc carbonate or oxide. White powders turning yellow while hot and 
white again on cooling; dissolve in dilute HN03 (effervescing 
or not), and apply tests for Zn. 
Plumbic carbonate. Heavy white powder, turning yellow on heating; 
dissolved in smallest possible excess of HNO3 effervesces, and 
the solution diluted with H2O does not become milky; apply 
tests for Pb. 
Plumbic oxide. Yellow or flesh-colored powder, heavy, and becoming 
yellow on heating; dissolves in HNOs without effervescence, 
and otherwise behaves as the carbonate. 
Red lead. Heavy red powder turning yellow on heating, but riot 
volatile; heated with dilute HN03 turns brown, and liquid 
poured off gives tests for Pb. 
Plumbic peroxide. Puce brown powder, turning yellow when heated ; 
heated with HCI evolves Cl2, and the residue dissolved in 
boiling water gives yellow with K2Cr04. 
Bismuth oxycaiPonate and oxide. Former white powder, latter lemon- 
yellow, and both turning deep orange while hot and pale yellow 
on cooling; dissolve in smallest possible excess of HN03, when 
former slightly effervesces and latter not, and the solution 
diluted with H2O becomes milky, proving Bi. 
Ferric oxide. Reddish-brown powder unchanged by heat; dissolves 
in HCI without effervescence or odor, and the solution diluted 
gives the tests for Fe2. Hydrated ferric oxide heated in a dry 
tube gives off moisture. 
Ferroso-ferric oxide. Blackish-brown powder, turned lighter by heat ; 
dissolves in HCI with effervescence or odor, and solution 
diluted gives tests for both Fe and Fe2. 
Potassium permanganate. Violet needles or prisms, giving off oxygen 
when heated and leaving a residue which when moistened is 
alkaline to test-paper; gives a fine violet solution turned 
colorless when warmed with HCI and spirit, the resulting liquid 
giving the tests for K and Mn. 
Potassium bichromate or chromate. The former is in orange crystals, 
evolving oxygen when heated, and the latter is in yellow crystals 
unaltered by heat. Both give the tests for chromate with 
AgN03 and Pb(C2H3O2)2, and when heated with HCI and 
spirit both turn green and the resulting liquid gives the tests for 
Cr and K. 86 
QUALITATIVE ANALYSIS. 
Chromic anhydride. In crimson needles, giving off oxygen when 
heated and leaving green Cr203. .A solution mixed with dilute 
spirit gives off the odor of aldehyd, and forms a deposit of 
green Cr203. 
Antimonious oxide. A greyish-white powder, readily fusible by heat; 
insoluble in HNOs, but soluble in heated strong HCI; the 
solution diluted with H2O becomes milky and then turns 
orange with H2S. 
Mercuric oxide. A yellow or red powder entirely volatile by heat; 
heated in a dry tube gives off oxygen and forms a sublimate of 
metallic Hg ; dissolve in dilute HCI and apply tests for Hg. 
Argentic oxide. An olive-brown powder, giving off oxygen and leaving 
metallic silver when heated; dissolve in dilute HN03 and 
apply the tests for Ag. 
(C) Sulphates, etc. 
Sulphur. A yellow or yellowish-white crystalline amorphous powder, 
which when heated takes fire, forms SO2, and entirely burns 
away; insoluble in H2O ; boiled with HNOs dissolves with 
evolution of red fumes, and solution diluted gives white with 
BaCl2. 
Stdphuretted hydrogen water. Colorless solution with odor of H.S 
and entirely volatile by heat; gives black with 
etc. 
Potassium polysulphide. A greenish deliquescent solid forming a 
greenish-yellow solution having the odor of H2S. Acidulated 
with HCI and boiled gives off H2S, deposits S2, and the solution 
gives test for K with PtCl4. 
Kermes mineral. {Antimony sulphide, etc.) An orange-red powder, 
which when heated burns, giving off S02 and leaving a lighter- 
colored residue ; entirely soluble in NaHO ; soluble in boiling 
HCI with evolution of H2S, and this solution diluted becomes 
milky and turns orange on adding H2S; original powder boiled 
with solution of KHC4H406 partly dissolves and the solution 
gives tests for Sb. 
Sulp/mrous acid. Colorless liquid having odor of S02 and entirely 
volatile by heat; BaCl2 gives no precipitate, or only a slight 
one, but on adding chlorine water a dense precipitate is pro- 
duced by BaCl2. 
Sulphjiric acid. A heavy, colorless, strongly acid liquid, which evaporated 
on a piece of paper chars it; entirely volatile by heat; BaCl2 
gives white precipitate; when diluted, dissolves metallic zinc 
with effervescence. 
Mercuric sulphate. White crystalline heavy powder, entirely volatile 
by heat; treated with water forms a yellow insoluble powder, 
the liquid poured off from which gives white with BaCl2; the 
yellow powder, dissolved in HCI, gives the tests for Hg. SPECIAL PROCESSES. 
87 
(Z>) Borates, Nitrates, Phosphates, etc. 
Boric acid. In minute tabular crystals, not volatile by heat, but 
fusible to a glassy residue which is acid to moistened test- 
paper ; not appreciably soluble in cold water; soluble in 
rectified spirit and the solution burns with a green flame. 
Nitric acid. A fuming liquid strongly acid and volatile by heat ; 
warmed with metallic copper gives off red fumes. 
Bismuth oxy-nitrate. Heavy white powder, turning orange on heating 
and becoming pale yellow on cooling; insoluble in water but 
soluble in HNO.g and the solution diluted becomes milky; 
dissolved in equal parts H2SO4 and H2O and a cold solution of 
FeS04 gently poured over the mixture, the characteristic nitrate 
ring is produced. 
Calcium and sodium hypophosphites. White granular powders which 
on heating take fire, giving dense white fumes ; if heated on 
platinum foil, go through it; dissolve and apply tests for Ca, 
Na, and hypophosphite. 
Phosphoric acid. Colorless strongly acid liquid leaving on evaporation 
a non-volatile glassy residue, also acid to moistened test-paper; 
no precipitate with AgNOg, but on carefully adding NH4HO 
a yellow precipitate is formed. 
Calcium phosphate. A light w'hite powder unaltered by heat; soluble 
in dilute HNOg, such solution giving a gelatinous precipitate 
with NaHO, insoluble in excess, but soluble in acetic acid ; 
the solution so obtained, when divided, gives, in one part, a 
white with (NH4)9C004, and in the other a gelatinous white with 
Fe2Cl6. 
Ferrous phosphate. A slate-blue powxler turned reddish by heat ; 
insoluble in HoO but soluble in HCI; a portion of this solution, 
diluted and divided, gives the tests for iron, and the remainder 
mixed with tartaric acid and then with excess of NH4HO gives 
a clear liquid which in turn yields a white precipitate with 
magnesia mixture. 
Arsenious acid. A heavy white crystalline powder entirely volatile by 
heat, slightly 'soluble and feebly acid; HCI-i-H2S gives 
reaction for arsenic; AgNOg and CuS04 give no precipitates, 
but on carefully dropping in very dilute NH4HO a yellow and 
a green precipitate are respectively produced. 
Ferrous arseniate. A pale yellowish-green powder turned dark red 
by heat; dissolved in HCI gives tests for Fe; boiled with 
dilute KHO and filtered, the filtrate after exact neutralisation 
by dilute HNOg gives a red precipitate with AgNOg. 
(.E) Organic Salt 
Salt of sorrel (Potassium binoxalate). A white crystalline powder 
burning when heated, but not charring to any extent, and 
leaving an ash that is alkaline to moistened test-paper; the ash 
dissolved in HCI gives test for K with PtCl4; the original 
dissolved in water by the aid of NH4HO gives the test for 
oxalate with CaCls- 88 
QUALITATIVE ANALYSIS. 
Cream of tartar (potassium bitartrate). A white gritty powder, charring 
by heat and leaving a black ash which is alkaline to moistened 
test-paper; the ash is tested by Kas in the last case; the 
original heated with H2SO4 chars strongly and gives the odor 
of burning sugar. 
Rochelle salt and neutral potassium tartrate. Both are freely soluble 
and char when heated, leaving an alkaline ash ; a strong cold 
solution acidulated with acetic acid lets fall a crystalline 
precipitate of KHC4H4O6, and the supernatant liquor gives 
with the former a yellow and with the latter a violet flame 
test. 
Tartar emetic (potassium antimonyl tartrate). Chars on heating, 
leaving an alkaline ash ; solution acidulated with HCI gives a 
white cloud soluble in excess, and H2S then gives an orange 
precipitate; the original gives the tests for a tartrate. 89 
CHAPTER V. 
QUALITATIVE DETECTION OF ALKALOIDS AND OF THE 
SO-CALLED “SCALE" MEDICINAL PREPARATIONS 
USUALLY CONTAINING THEM, WITH A GENERAL 
SKETCH OF TOXICOLOGICAL PROCEDURE. 
DIVISION A. COURSE FOR THE DETECTION OF THE ALKALOIDS 
AND ALKALOID SALTS USED IN MEDICINE. 
Note.—Aconitine and atropine are omitted because they can only be really detected 
by experiments upon animals, which are now illegal except by special 
licence. Salicine, although not an alkaloid, is included for convenience, 
as it may be mixed with quinine. 
In this course not more than two definite tests for each alkaloid are recorded, 
and for the remaining tests the reader is referred to the full table in Division D 
of this chapter. 
Step I. Heat on platinum foil. If the substance at once takes fire and 
burns away with a smoky flame and an odor of singed hair, it 
is probably an alkaloid. 
Step 11. Put a piece of red litmus paper on a watch-glass, lay on to this 
a little of the substance, and moisten it with a few drops of 
strong rectified spirit. If, on standing for a short time, the paper 
is rendered blue, we are dealing with a free alkaloid; if not, 
then it is an alkaloid salt, and in the latter case we shall have to 
search for the acid as well as the base. 
Note.—Acetates of alkaloids often become basic and consequently alkaline by 
keeping, so beware of this. 
Step 111. To a fragment of the substance on a watch-glass (placed over 
white paper) add a drop of strong H2S04, and stir :—a bright 
red= Salicine and a deep red=Vera trine. 
Confirm this latter by getting a yellow with HNOs and a 
blood-red on warming with HCI. 
Note.—In each step any colors other than those herein recorded are to be disregarded. 
Many alkaloids give pale dirty pinks with I 1.2S04. 
Step IV. To the liquid in which H2S04 has given no distinct red add a 
small fragment of powdered ammonium molybdate, and stir. 
{a) Greenish purple\—Morphine or Apomorphine. 
Greenish black j r r r 
Confirm by adding HNO-. to another fragment, when pale 
red=morphine and fine purple=apomorphine. Further con- 
firm morphine with Fe2Clc (blue) and with H2S04 + Na2HAs04 
(bluish-green). 90 
QUALITATIVE DETECTION OF ALKALOIDS, ETC. 
[V) Bright orange-red = Brucine, 
Confirm by testing another fragment with HNO3 and getting 
a bright red, turned to violet on warming with SnCB. 
(c) Bright greenish-blue=Codeine. 
Confirm by adding HNO3 to another portion = pale evanes- 
cent yellow. 
(d) A yellowish-green = Physostigmine. 
Confirm by adding HNO3 to another portions strong gamboge 
yellow. Further confirm by getting a red with KHO, becoming 
blue on evaporating to dryness on the water bath, and dissolving 
in HCI to a dichroic solution. 
Step V. Treat another fragment with a drop of H2S04 as before, then 
let another drop fall near it. Into the second drop put a fragment 
of powdered potassium bichromate, let it digest a moment and 
then stir the drops together. 
(a) Beautiful violet (evanescent) = Strychnine. 
(b) Emeraldgreen after standing some time = Caffeine or Pilocarpine. 
Test another portion for caffeine by adding a crystal ofKCiOs 
and a drop or two of HCI, evaporating to dryness and getting 
a red residue becoming purple with NH4HO. 
Note.—Do not decide too hurriedly about pilocarpine ; set the glass aside for half an 
hour, and then if the emerald green is qiiite distinct and no cinchona alkaloid 
is present you may conclude that pilocarpine is really there. 
(c) Dirty pale-yellowish pink= Cocaine. 
Note.—This test is not very good, but a minute drop of a dilute solution placed upon 
the tongue will cause tingling and numbness, and a strong solution will give 
a precipitate with (NH4)2COs soluble in excess. (Aconitine, which also 
tingles the tongue, is not precipitated by (NH4)2C03.) 
Step VI. Dissolve some of the original in water (using a drop or two of 
acetic acid to help solution if necessary) then add chlorine water 
and a gradual excess of NH4HO. A clear green solutions 
Quinine or Quinidine. A white precipitate=Cinchonine or 
Cinchonidine. 
Note.-—ln presence of salicylate the ordinary tests for quinine fail, and in this case it 
is necessary to dissolve in, dilute hydrochloric acid, shake up with ether to 
remove salicylic acid, and then draw off the watery solution from beneath 
the ether and test it for quinine. 
(a) To distinguish between quinine and quinidine. 
Dissolve in hot water with a drop of dilute H2S04 and cool, and 
if any crystals separate out they are probably sulphate of quinine 
and are rejected by filtration. (The proper proportion of 
water and alkaloid salt to start with is i of salt in about 25 of 
water. If you are dealing with a free alkaloid you must dissolve 
it in hot water with the smallest possible amount of dilute H2S04 
and then cool.) Now add very carefully dilute NH4HO until 
the solution is as nearly neutral as possible without producing 
a permanent precipitate, cool perfectly, and add a few drops of 
saturated solution of rochelle salts, and stir well or shake. This 
will precipitate quinine. If not, then add a little saturated solu- 
tion (or a small crystal) of KI, and shake, which will precipitate 
quinidine. 
Note.—lf on adding the chlorine water and then the ammonia gradually, a perfectly 
clear green solution results, then we need not search for quinidine, but 
put it down as quinine. The presence of quinidine always causes a milki- 
ness in the green. ANALYSIS OF SCALE PREPARATIONS. 
9i 
(b) To distinguish between cinchonine and cinchonidine. 
Dissolve in water, by aid of HCi if necessary, then cool and 
carefully make as nearly neutral as possible with very dilute 
NaHO (if necessary), and then add saturated solution of Rochelle 
salt and shake, when a cinchonidine. If not that, 
then add NH4HO : white precipitate = cinchonine. 
Note.—The general principles to keep in mind as to the cinchona alkaloids are : 
(l) That in a neutral solution rochelle salt precipitates quinine and cin- 
chonidine as tartrates, leaving the others in solution. (2) After filtration (if 
necessary) the addition of potassium iodide and a little spirit precipitates 
quinidine as iodide, leaving cinchonine and the amorphous alkaloids 
(quinoidine, etc.) in solution. (3) From this solution excess of ammonia 
precipitates both, and, on shaking with ether the amorphous alkaloid 
passes into the ether and the cinchonine remains as a precipitate. (4) The 
separation of quinine and cinchonidine may be roughly performed by 
shaking up with ether, in the presence of a very slight excess of NH4HO, 
and then corking the tube and letting it stand in cold -water for some hours, 
when cinchonidine, if present, deposits in crystals, and quinine remains in 
the ether. For this, the ether must be in very small quantity, just so as to 
form a distinctly visible layer. 
Step VII. If we believe that we are dealing with an alkaloid salt we must 
now proceed to test for the acid. The acid radicals usually 
present in alkaloidal salts of commerce are, chloride, sulphate, 
acetate, phosphate, citrate, meconate, nitrate and salicylate. 
The first step will be to dissolve a little of the alkaloid salt in 
very dilute HNOs, and test (1) for Cl by AgN03; (2) for S04 
by BaCl9 ; (3) for P04 by excess of ammonium molybdate and 
Hn°3. “ 
The next will be to dissolve in water only, and test with 
Fe2Cl6 for acetate or meconate (red) or salicylate (violet). 
(Acetate decolorised by boiling, meconate not so; also acetate 
gives no precipitate with Pb(C2H3OL,)2, and meconate does. ) 
Lastly, we must test in the usual way for a citrate (but unless 
the base be caffeine, this is not likely), and also for a nitrate 
(especially with pilocarpine and strychnine). 
DIVISION B. QUALITATIVE ANALYSIS OF SCALE PREPARATIONS. 
These commonly contain 
Metals 
Ammonium 
Iron 
Potassium 
Organic bases 
Quinine 
Cinchonine 
Cinchonidine 
Strychnine 
Beberine 
Acids 
Tartaric 
Citric 
Pyrophosphoric (or hypo-) 
Sulphuric. 
Step I. Heat a little to redness on platinum foil, and observe the 
following possible cases ; 
(a) If it entirely burns away we suspect Beberine sulphate. Test the 
original solution of the scale for sulphate by BaCl2, as usual; 
and for beberine with KHO, getting a yellowish-white precipitate 
entirely dissolved by agitating the liquid with twice its volume 
of ether. This ether separated and evaporated to dryness 
leaves a yellow resinous-looking residue entirely insoluble in 
dilute HCI. If beberine sulphate be thus proved, go no farther. 92 
QUALITATIVE DETECTION OF ALKALOIDS, ETC. 
(h) An ash is left: (a) Put a small fragment of the ash upon a piece of 
red litmus paper, moisten it with a drop of water, and, if it 
turns the paper blue, suspect potassium; (b) Dissolve the 
remainder of the ash in nitric acid, dilute and test with excess 
of ammonium molybdate for phosphoric acid. 
Note.—lf K be suspected, prove it by igniting some more of the scale, extracting the 
ash with very little boiling water, filtering, cooling, and adding PtCl4. 
Step 11. Make a weak solution of the scale, acidulate it with a drop of 
HCI, and test for ferrous iron with K6Fe2Cyi2, and for ferric 
with K4FeCy6. Also test another solution of the scale by 
adding excess of AgNOs, when a copious precipitate may form. 
Now add a drop of very dilute NH4HO till the precipitate just 
commences to dissolve and heat, when reduction to black or a 
m irror=Tartrate, 
Step 111. Make a fairly strong solution of the scale, add excess of NaHO, 
boil, and smell for ammonium. If neither phosphoric nor 
tartaric acid has been already found, filter out the precipitated 
ferric hydrate and use the filtrate for testing for acids as 
follows : 
(a) Test a portion for citric acid exactly as directed in the organic acid 
course (page 80). 
(b) Test another portion by exactly neutralising with HNO3 and adding 
AgNOg, when a white precipitate=pyrophosphate, and the same 
turning black=hypophosphite. 
Of course this step is never to be taken unless an indication 
of P be got in the ash with molybdate in Step I. 
Step IV. Make a solution of a fair amount of the scale, add a drop or 
two of very dilute NH4HO. and then add some strong NH4HO. 
Scales with strychnine only will not show a precipitate; with 
quinine they will give a precipitate with the dilute NH4HO 
and this precipitate will dissolve in the strong ; with cinchonine 
or cinchonidine a precipitate (white) will remain even with 
strong NH4HO. 
Case (A). There is either no precipitate, or it dissolves in strong 
NH4HO :—Add some chloroform and shake up. Separate the 
chloroform by a pipette, and evaporate it to dryness in two 
portions on separate white dishes. Test the one residue for 
strychnine with H2S04 and K2Cr207, and the other for quinine 
with chlorine water and NH4HO. 
Case {B). The NH4HO causes a permanent white precipitate:— 
Filter out precipitate, and dissolve it off the filter with a little 
warm water containing a few drops of acetic acid. Boil the 
solution down to a low bulk, cool, neutralise if necessary with 
very dilute NaHO, and then add a few drops of saturated 
solution of rochelle salts and shake, when a white precipitate 
= cinchonidine. If not that, then add NH4HO, when a white 
precipitate insoluble on shaking with ether=cinchonine. 
DIVISION C. GENERAL SKETCH OF THE METHOD OF TESTING 
FOR POISONS IN MIXTURES. 
This course is only carried down to the best method of preliminary 
procedure for the isolation of the poison, all the individual tests to be after- 
wards applied having been already fully described in this or former chapters. GENERAL METHOD OF TESTING POISONS IN MIXTURES. 
93 
Step I. If the liquid be very strong, acid effervesces violently with 
NaHC03, test for poisonous acids, specially for Nitric and 
Oxalic. 
Step 11. Acidulate with I of its bulk of HCI (filter if necessary), and 
apply Reinch’s lest for As, Sb, and Hg. 
Step 111. Burn to ash, dissolve this in HCI and test by ordinary 
course for poisonous metals, especially Pb, Cu, and Zn. 
Step IV. If the original, either alone or when heated with dilute 
H2SC>4, gives the odor of HCN or of carbolic acid, test 
specially for them. 
Step V. If the original has no odor of opium we proceed to apply Stas’s 
process for the detection of alkaloids as follows : 
If the original be a solid, it is operated upon directly, but, 
if a fluid, it is first evaporated to dryness on a water bath. 
Add some strong alcohol and a small crystal of tartaric acid, 
boil and filter. Evaporate the filtrate to dryness on the water 
bath, and take up with warm water slightly acidified with 
acetic acid, then cool and filter (if necessary), taking care that 
the liquid just remains acid. Now put this acid liquid into a 
separator (fig. 17), and shake it up with ether or benzene, and 
carefully separate the ether. (This ether may contain fat, certain 
bitter principles, and glucosides, and therefore, in a 
general investigation of a drug, it should not be rejected W 
but evaporated, and the residue examined.) Now make 
the liquid distinctly alkaline by the careful addition of ( ] 
Na2C03 or NatiO, and again shake up in the separator \ j 
with chloroform, which will take up all the alkaloids \ / 
except morphine The chloroform is separated, evapo- (-L 
rated at a very gentle heat, and the residue tested for Ju 
alkaloids by the course given in Division Aor by the I 
table given in Division Dof this chapter. Lastly, the r 
alkaline liquid is shaken up with amylic alcohol, which extracts 
morphine and leaves it upon evaporation. 
Note.—It is often better to get the alkaloids out from chloroform or amylic alcohol 
by shaking the separated solvent up with water acidulated with acetic acid 
or HCI, thus getting an aqueous solution and leaving any resinous matters 
in the chloroform. 
Step VI. When opium is suspected. Acidulate with acetic acid and 
filter, if necessary (any alcohol present being got rid of by 
boiling it off). Precipitate when cold with solution of plumbic 
acetate, filter and preserve the precipitate (a) for examination 
for meconic acid and the filtrate (b) for morphine. 
(a) Precipitate (a) is suspended in water and treated with H2S till per- 
fectly decomposed; the PbS filtered out, and the filtrate, after 
evaporation to drive off H2S, tested for meconic acid. If this 
be found, it is held to be sufficient proof of presence of opium 
taken in connection with the odor of the original. 
(b) Filtrate freed from Pb by H2S and filtering is evaporated to 
dryness with a slight excess of NaHC03 on a water bath. 
The residue will yield its morphine to alcohol, generally in 
a state sufficiently pure to evaporate a drop, and test. If not, 
then amylic alcohol must be used. 94 
QUALITATIVE DETECTION OF ALKALOIDS, ETC. 
DIVISION D. GENERAL RESUME OF THE TESTS FOR ALL THE 
CHIEF ALKALOIDS. 
The following tables are those given by DragendorfF in his “Pflanzenanalyse.” 
The author has carefully repeated these tests, and has found them to be fairly 
accurately described, except aconitine, for which the reactions given are not 
characteristic. Reference to such a list will rarely be necessary, the working 
by Division A already given being amply sufficient for all ordinary purposes. 
The following are the reagents used : 
1. Pure strong sulphuric acid free from nitrous fumes. 
2. 200 parts of sulphuric acid with i part of nitric acid. 
3. 'i gramme of sodium molybdate in 10 c.c. strong sulphuric acid 
(Frdhde’s test). 
4. 1 part alkaloid mixed with 5 parts powdered white sugar, and then 
strong sulphuric acid dropped on. 
5. Sulphuric acid and potassium bichromate used as already described 
in Division A. 
6. Nitric acid (strong 1.3 sp. gr.) 
7. Strongest fuming hydrochloric acid. 
8. Ordinary solution as neutral as possible. 
The reagents being generally added in turn to a fragment of the dry 
alkaloid, or to the residue left on evaporation of an alkaloidal 
solution. TABLE OF GENERAL REACTIONS OF THE ALKALOIDS. 
Alkaloid. 
Pure H.,S04. 
h2so4 
+ HN03. 
h2so4 
+ sugar. 
Frohde’s R. 
HN03. 
Cone. HQ. 
h2so4 
+ K2Cr207. 
F e2Cl6. 
Other Reactions. 
Aconitine.. .. 
grad, violet 
grad, violet 
fine red 
yellow- 
reddish- 
no effect 
in. aq. sol. 
A drop of a dilute solution causes tingling 
Atropine .. 
no effect 
no effect 
no effect 
brown 
no effect 
brown 
no effect 
no effect 
discolored 
yellow ppt. 
not pptd. 
and numbness on tongue. 
Dilates the pupil. 
Beberme .. 
olive-green 
olive-green 
brown-green 
brown-red 
Berberine 
olive-green 
olive-green 
brown-green 
brown-red 
The addition of a few drops of chlorine 
water to a solution of berberine in 
excess of hydrochloric acid produces a 
Brucine .. • 
no effect 
red 
no effect 
red 
red 
no effect 
orange 
red coloration. 
A solution in dilute sulphuric acid (i‘8) 
is turned fine red by bichromate of 
Caffeine .. .. 
no effect 
no effect 
no effect 
no effect 
no effect 
no effect 
no effect 
not pptd. 
potassium. 
The residue obtained by dissolving in 
chlorine water and evaporating is 
Calabarine 
colored red by ammonia. 
no effect 
no effect 
no effect 
( The precipitate-with potassio-mercuric 
Chelidonine .. 
Cinchonine .. 
Cinchonidine ., 
green 
no effect 
no effect 
no effect 
no effect 
no effect 
no effect 
no effect 
no effect 
no effect 
\ iodide is insoluble in alcohol. 
/ Remain colourless when treated as 
Codeine .. 
no effect 
grad, blue 
red 
grad, deep 
yellow 
olive-green 
no effect 
Warmed with sulphuric acid and ferric 
Colchicine 
yellow 
blue 
yellow 
blue 
yellow 
blue 
no effect 
green, then 
chloride turns blue. 
/ If the blue color produced by adding 
Colchice'ine 
yellow 
blue 
yellow 
yellow 
blue 
no effect 
brown 
green, then 
J KNO3 to the solution in H2S4 is al- 
1 lowed to fade, the residue is colored 
Coniine .. 
no effect 
no effect 
no effect 
no effect 
no eftect 
no effect 
brown 
i, red by potash. 
The hydrochloric acid solution leaves a 
Curarine .. 
red 
red 
red 
blue, then 
violet and 
crystalline residue when evaporated. 
Delphinine 
Delphinoidine 
no effect 
red 
no effect 
no effect 
no effect 
green 
no effect 
blood-red 
remain light 
remain light 
remain ligfit 
remain ligfit 
red 
/"Bromine colors the solution in Sul- 
'S phuric acid violet. 
Cone, hydrochloric acid colors the solu- 
Emetine .. 
brown-green 
brown-green 
red and 
brown 
Gelsemine 
yellow-red 
red 
green 
tion in Frohde’s reagent deep blue. 
Sulphuric acid and oxide of cerium color 
H yoscyamine.. 
Jervine 
no effect 
yellow, then 
no effect 
yellow, then 
no effect 
no effect 
no effect 
no eftect 
no effect 
no effect 
discolored 
not pptd. 
cherry-red. 
Dilates the pupil. 
Morphine.. .. 
light green 
no effect 
light green 
violet 
red 
violet 
yellow 
no effect 
brown 
blue 
Reduces iodates, liberates iodine from 
Narceine .. .. 
grad. grey. 
yellow, turn- 
brown- 
yellow 
no effect 
iodic acid. 
The crystals turn blue when moistened 
turning 
ing orange 
and blue 
with dilute solution of iodine. 
Narcotine 
blood-red 
grad, rasp- 
reddish- 
no effect 
Fine red is developed when the sol. in 
Nicotine .. 
berry 
no effect 
violet 
no effect 
no effect 
no effect 
no effect 
no effect 
dil. sulph. acid is evaporated. 
The hydrochloric acid solution leaves on 
Nepaline .. 
Papaverine 
grad, red 
no effect 
grad, red 
no effect 
grad, red 
orange 
red 
no effect 
reddish 
evaporation an amorphous residue. 
Turns blue, warmed with sulphuric acid. 
Physostigmine 
grad, red 
grad, red 
Solution of chloride of lime colors red. 
The precipitate with potassio-mercuric 
iodide is soluble in alcohol. Physo- 
Pilocarpine 
no effect 
no effect 
yellow, then 
brown 
green 
stigmine produces tetanus. 
Piperine .. 
grad, green 
grad, green 
01 ange 
ppt. in HC1. 
sol. 
Quinamine 
The ppt, with chloride of gold is rapidly 
Quinidine 
Quinine .. 
no effect 
no effect 
no effect 
no effect 
no effect 
no effect 
greenish 
greenish 
no effect 
no effect 
no effect 
no effect 
light yellow 
not pptd. 
decomposed with red coloration. 
Like quinine. 
The chlorine-water solution is colored 
green by ammonia, red-brown with 
ammonia and ferricyanide of potas- 
Sabadilline 
grad, fine 
grad, fine 
grad, rfid" 
dish-violet 
grad. fed‘ 
dish-violet 
grad, red- 
yellow 
wine-red 
slum. 
Sabatrine.. 
cherry-red 
grad, fine 
cherry-red 
cherry red 
grad, fine 
cherry-red 
dish violet/ 
grad, red- 
dish violet 
yellow 
margin blue 
wine-red 
f Much weaker in physiological action 
j’ than veratrine. 
Solanine .. 
light red- 
dish 
light red- 
dish 
A hot mixture of equal volumes of alcohol 
and sulphuric acid is colored red by 
Staphysagrine 
no effect • 
no effect 
firown 
violet- 
no effect 
solanine. 
Strychnine 
no effect 
no effect 
no effect 
no effect 
no effect 
no effect 
blue,passing 
brownish- 
The blue coloration produced by H2SG4 
quickly to 
green ppt. 
and oxide of cerium is finer than with 
violet and 
red 
bichromate. 
Taxine 
red 
The double chloride of taxine and gold is 
Thalictnne 
Theobi'omine .. 
Thebaine .. 
no effect 
deep green 
no effect 
no effect 
no effect 
orange 
no effect 
yellow 
no effect 
yellow 
no effect 
not pptd. 
easily soluble. 
Like caffeine. 
Veratrine.. 
grad, fine 
grad, fine 
grad- blue 
grad, cherry- 
red 
grad, cherry- 
yellow 
red 
reddish- 
ppt. in HC1. 
Veratroidine .. 
cherry-red 
grad, fine 
cherry-red 
grad, fine 
grad, vio^t 
yellow 
red 
brown 
sol. 
cherry-red 
cherry.red 
red 
• PART II. 
QUANTITATIVE ANALYSIS. 
CHAPTER VI. 
WEIGHING, MEASURING, AND SPECIFIC GRAVITY. 
I. WEIGHING AND MEASURING. 
All bodies mutually attract each other. As the earth is the largest body 
within our atmosphere, it follows that its attraction is always greater than that 
of any surrounding matter. The force thus developed is called the attraction 
of gravitation, and its exercise is the cause of weight. Weighing is performed 
by means of the well-known appliance called the balance. Figure 18 
illustrates a chemical balance of the modern short-beam type, his the 
handle by which the balance is put into action, and R is the appliance for 
Fig. 18. 
placing rider weights upon the graduated beam, aided by weights made either 
according to the English or the metrical system, as follows: 
(a) The English system.—ln weights of precision, any amount above 10 
grains is usually represented by a series of small brass cylinders, from 10 to 
1000 grains ; then follow 6, 3, 3, 2 and 1 grains in platinum wire, and afterwards 
'6, '3, '3> ’2j and ‘i of a grain in platinum, or, more frequently, in aluminium 
wire. Quantities of less than TE grain are weighed by a small rider of gold 
wire placed on the beam of the balance. The foundation of the English system 
is the inch. One cubic inch of distilled water, measured at 6o° F. and 30 
inches barometrical pressure, weighs 252 45 grains, or 252F grains nearly. There 96 
WEIGHING, MEASURING, AND SPECIFIC GRA VITY. 
are 437*5 grains in an ounce, and 16 ounces (or 7000 grains) in a pound. 
Measure of capacity is obtained by weighing out 10 lb. of water at 6o° Fahr. 
and 30 inches bar., when the whole measures one gallon. The gallon is in 
turn divided into 8 pints ( =2O ounces, or 8750 grains of water, per pint) ; 
the pint into 20 fluid ounces ( =437-5 grains of water per fluid ounce); the 
fluid ounce is divided into 8 fluid drachms ( =54-68 grains of water per fluid 
drachm); and, lastly, the fluid drachm is divided into 60 minims ( =-91 grain 
of water in each minim). 
{,b) The Metrical system.—The metrical weights of precision above one 
gramme are in brass; and then we have -5, "2, -i, *i, and following them 
•05, -02, -or, -ox, all in platinum or aluminium foil. The quantities below -ox 
(one centigramme) are weighed by a rider on the beam. The combination of 
5, 2, 1 and 1 has been chosen because they have 
been found to give the greatest number of possible 
combinations with the fewest weights. Figure 19 
shows such a box of metrical weights as usually 
employed in quantitative analysis. The metrical 
system is founded upon the metre. The metre is multiplied and divided 
entirely by 10, thus 
Fig. 19. 
Kilo-metre ...... iooo1 
Hecto-metre ...... loo' 
Deca-metre ...... xo‘ 
Metre T 
Deci-metre . . . . . . 1 
Centi-metre . . . . • . . -oi 
Milli-metre -oox 
The metre taking the practical place of the English yard, the decimetre 
consequently lakes the place of the foot, and the centimetre of the inch ; and 
just as weight is got in our system from the cubic inch, so it is got metrically 
from the cubic centimetre, only much more simply, because 1 cubic centimetre 
of distilled water, measured at 40 C. and 760 millimetres bar., weighs one 
gramme. The gramme is multiplied and divided exactly as the metre, thus;— 
Kilo-gramme ...... 1000. 
Hecto-gramme ..... 100. 
Deca-gramme ...... 10. 
Gramme 1. 
Deci-gramme ...... .1 
Centi-gramme ...... .01 
Milli-gramme ...... .001 
One kilogramme (1000 grammes) of water at the standard temperature and 
pressure measures one litre (or 1000 cubic centimetres), and we have therefore 
the following simple relation of weights and measures of water. 
Weight. Measure. 
1000 grammes . . . • 1 litre or 1000 cubic centimetres 
100 ~ . . • • 1 deci-litre or 100 ~ ~ 
10 ~ .... 1 centi-litre or 10 ~ „ 
1 gramme . . . • 1 milli-litre or 1 cubic centimetre. 
So we see that using water at 4°C., a gramme by weight and a cubic centi- 
metre by measure amount to the same thing; as likewise do a kilogramme 
by weight and a cubic decimetre (or litre) by measure. The relation between 
the two systems is easily calculated from the following standards : 
Metrical. English. 
1 Gramme = 15‘432 grains. 
1 Kilogramme = 2'205 lb. (or 15,432 grains). 
1 Litre == 176 pints (or 35 fl. oz. 2 drachms 11 minims). 
1 Metre = 3977 inches. 
So that 1 decimetre is, as nearly as possible, 4 inches ; and 1 decilitre, a 
trifle over 35 fluid ounces. SPECIFIC GRAVITY. 
97 
11. SPECIFIC GRAVITY 
may be generally explained to be the weight of anything as compared 
with that of an equal volume of something else taken as a standard. For 
liquids and solids the standard is distilled water at a temperature of 6o°. An 
acquaintance with the various cases which may occur in the taking of specific 
gravity is of great importance, as it forms an exceedingly ready method of 
testing the purity and strength of many substances. A knowledge of the 
specific gravity of the various bodies also enables the chemist to tell at once 
what any given volume of a liquid ought to weigh, or conversely, what size of 
a vessel will be required to contain any given weight. The following are the 
chief varieties of cases which may occur in taking : 
{A) Specific Gravity of Liquids. 
Case x. To take the specific gravity of a fluid.—A small bottle of thin 
glass is procured, and counterpoised upon a balance. It is then filled with 
distilled water at 6o° F., and the weight of the water thus introduced noted. 
The bottle, having been emptied and dried, is filled with the liquid to be 
tested, also at 6o° F., and the whole is again weighed. By this means, 
having ascertained the weight of equal bulks of water and fluid, it only 
remains to divide the weight of the fluid by the weight of the water, and 
the quotient will be the specific gravity required. To make the calculation 
clear, observe the following examples : 
A counterpoised bottle filled with distilled water weighs 1000 grains ; the same bottle 
filled with sulphuric acid weighs 1843 grains, then : 
-1--- = I 843, the specific gravity of the acid. 
Again, the same bottle, carefully washed, and filled with rectified spirit, weighs 838 grains, 
then:— 
= -838, the specific gravity of rectified spirit. 
1000 
In practice, bottles are sold with perforated stoppers, which, when entirely 
filled with the liquid, and the stopper dropped in, so that no bubbles of air 
are allowed to remain between the stopper and the liquid, exactly hold a 
given weight of water. A counterpoising weight for the empty bottle is 
also provided ; so that there is nothing further to be done but simply to 
place the counterpoise in one scale, and the bottle, filled with the liquid under 
examination, in the other; and having ascertained the weight, to divide by 
the known weight of water for which the bottle was constructed. Fig 20 
shows a specific gravity bottle in its case, with the counterpoise in a little 
Fig. 20. 
Fig. 21. 
box on the lid. Fig. 21 shows a specific gravity bottle the stopper of which 
is a thermometer, thus enabling us to observe the exact temperature of the 
liquid a t the moment of weighing. 98 
WEIGHING, MEASURING, AND SPECIFIC GRA VITY. 
Case 2, To take the specific gravity of a liquid by means of the hydro- 
meter.—The hydrometer depends for its action on the theorem of Archimedes. 
If a solid body be immersed in a liquid specifically heavier than itself, it 
continues to sink until it has displaced a bulk of fluid equal to its own weight, 
and then it becomes stationary. Suppose an elongated body with a weight at 
its base to cause it to float upright, which has a specific weight exactly half 
that of water, be immersed in that fluid, it will sink to exactly half its length, 
because its whole weight is counterpoised by a bulk of fluid equal to half its 
size. Hydrometers are long narrow glass or metal tubes with a bulb near the 
bottom filled with air, and another smaller bulb beneath containing a sufficient 
quantity of mercury to weight it and cause it to float upright. There are two 
kinds of hydrometers: (1) for fluids heavier than water, and (2) for fluids 
lighter than water. The graduation of the former- is performed by immersing 
the instrument in water and introducing such a quantity of mercury as will 
cause it to sink, so that only about one inch remains unsubmerged, and 
marking this point 1. The instrument is then plunged successively into 
several liquids heavier than water, the specific gravities of which are known, 
and the points to which it rises are marked and numbered. By this means 
a scale can be made between those points, indicating any gravity from 1 
upwards. In hydrometers for fluids lighter than water, the first sinking in that 
quid is continued by weighting until only the upper bulb is immersed ; and this 
point having been marked 1, the instrument is placed successively in known 
fluids lighter than water, the points to which it sinks marked, and by this 
means a whole scale is obtained. The method of using the 
hydrometer is readily seen from the illustration (fig. 22), in which 
(a) is the hydrometer, and (b) is a thermometer also placed in the 
liquid to show the temperature. Most hydrometers being made to 
indicate specific gravity at 6o° F., it follows that the liquid must 
either be first brought to that temperature before using the instru- 
ment, or else the temperature employed must be noted, and a 
calculation made, based upon the coefficient of expansion of the 
liquid in question. 
By Act of Parliament Sykes’s hydrometer is used by the officers 
of excise to indicate the strength of spirituous liquors, and thus 
facilitate the collection of the revenue. It is a short brass instrument with the 
stem graduated from o to 10, and a series of nine weights to place beneath 
the bulb. By thus being able to change the weight, the length of the stem 
is only of that it would need to be with a permanent weight, and so the 
instrument will work in a proportionately smaller quantity of liquid. In using 
it, the thermometer must also be employed ; and by observing (1) the tem- 
perature, (2) the weight put oh, and (3) the point to which it sinks on the 
stem, and referring to a book of tables which is sold with the hydrometer, 
the strength of the spirit is ascertained. 
Another modification of the instrument is found in Twaddell’s hydrometer, 
which is used in this country for testing the density of liquids having a greater 
specific gravity than water. It is so graduated that the reading of any indi- 
cated degree, multiplied by 5 and added to 1000, gives the specific gravity 
as compared with water. Specific gravity beads form the only other variation 
of the hydrometric idea. These are small loaded bulbs of known specific 
gravities, which are thrown into the liquid to be tested, when the number 
marked upon the bead, which just floats underneath the surface and shows 
no tendency to sink or rise, gives the specific gravity required. Hydrometers 
in any form must in accuracy rank considerably beneath that of the specific 
gravity bottle; but in commercial operations, where an approximation only to 
correctness is required, these little instruments are invaluable. 
Fig. 22. SPECIFIC GRA VITV. 
99 
Case 3. To take the specific gravity of a liquid by weighing a solid 
body in it.—Take the weight of a glass stopper, or other suitable plummet, 
by suspending it from the hook provided for the purpose in all balances of 
modern type (see fig. 12, page 6). Put a wooden stool (also provided with 
all modern balances) over the pan, and upon this place a beaker containing 
distilled water at 6o° F. Let the plummet hang beneath the surface of the 
water and again weigh, and then empty out the water, substitute the fluid 
(also at 6o° F.), immerse the plummet as before, and once more weigh. By 
deducting respectively the weights in water and in fluid from the weight in 
air, we get the loss of weight sustained by the plummet in each case. It is 
evident that the lighter the liquid, the more the plummet will weigh ; therefore 
we divide the loss of weight in the fluid by the loss of weight in water, which will 
give the specific gravity of the liquid. This rule is now practically applied in 
all modern laboratories by means of the Westphal balance (fig. 23). By this 
a small thermometer (a), adjusted to a counterbalancing weight (b), is placed 
in the liquid, and the loss of weight is restored by little rider weights placed 
on the beam, which are so contrived as to readily indicate the specific gravity 
without calculation. 
{B) Specific Gravity of Solids. 
insoluble in and heavier than water.—The method 
by which this process is conducted was suggested by 
a theorem attributed to Archimedes, which may be 
thus expressed :—A solid on being immersed in a 
liquid is buoyed up in proportion to the weight of 
the fluid which it displaces, and the weight it thus 
apparently loses is equal to that of its own bulk of 
the liquid. A piece of the solid substance to be tested 
is weighed, and is suspended by means of a fine 
thread from one arm of a balance so that it dips 
Case i. To take the specific gravity of a solid body in mass which is 
under the surface of a vessel containing distilled water 
at 6o° F., when its weight is again noted. Its weight 
Fig. 23. 
in water is deducted from its weight in air, and the weight in air is divided 
by the difference so obtained, which gives the specific gravity. 
Example. 
A piece of marble weighs . . . 300 grains. 
Immersed in distilled water . . . iBB-9 ~ 
Difference in weight Ul'l ~ 
By dividing 300 by mi we obtain the quotient 27, which is the specific gravity of the 
marble. The practical arrangement has been already described above (Liquids, Case 3). 
Case 2. To arrive at the specific gravity of a powder which is insoluble 
in and heavier than water.—Weigh a portion of the powder in air, then 
introduce it into a counterpoised specific gravity bottle constructed to hold 
a known weight of water. Let the bottle be carefully filled with distilled 
water, gently agitating to insure that no minute bubbles of air shall remain 
attached to the particles of powder ; then weigh the whole. From the weight 
of the powder in air, plus the known weight of water which the bottle should 
contain, deduct the weight obtained in the second operation, and divide the 
original weight of the powder by this difference. ; - WEIGHING, MEASURING, AND SPECIFIC GRAVITY. 
Example.—2o grains of a powder are weighed out, and poured into a counterpoised 
specific gravity bottle, constructed to hold 1000 grains of water. The bottle thus charged is 
found to weigh 1012 grains ; then, 
20 grains + 1000 grains = 1020 grains. 
Weight of the bottle when charged) 
with powder and water . . .) ” 
Difference . . . . . 8 ~ 
Therefore, 20 grains divided by 8 grains will give 2'5 as the specific gravity of the powder. 
Case 3. To take the specific gravity of a substance in mass, insoluble in 
but lighter than water.—The difficulty met with in this case consists in the 
impossibility of weighing such a substance alone in water, because it floats on 
the surface of that liquid. It therefore becomes necessary to attach a piece 
of lead sufficiently heavy to sink it, and thus a complication is introduced. 
The light substance is first weighed in air in the ordinary manner, and is then 
attached to a sinker, and suspended from one arm of a balance under the 
surface of distilled water, when the combined weight of both is ascertained. 
The light body is now detached, and the weight of the sinker alone in water 
noted. By these means we obtain the following data:— 
i. The weight of the light body in air. 
ii. The weight of the sinker in water. 
hi. The weight conjointly of the light body and sinker in water. 
We then deduct the weight of both in water from the weight of the sinker in 
water; add the weight of the light substance in air; and divide the weight of 
the light body in air by the product so obtained. 
Example.—A light substance weighs 120 grains in air; being attached to a piece of lead 
and weighed in distilled water the united weight amounts to 40 grains, while the weight of 
the lead alone in water shows 50 grains. Then : 
Weight of lead in water .... 50 grains. 
Weight of both in water . . . 40 ~ 
Difference 10 ~ 
Add weight of light body in air . . . 120 ~ 
Sum 130 ~ 
Dividing 120, the weight in air, by 130 obtained as above, we arrive at the decimal fraction 
•923 as the specific gravity of the light substance tested. 
Case 4. To obtain the specific gravity of a substance soluble in water.— 
Proceed exactly in the same manner as in Case 2 or 3, according as the body 
is in mass or in powder; but instead of water, use oil of turpentine or some 
other liquid in which the solid is insoluble. Having obtained the specific 
gravity of the substance by calculating just as if water had been used, multiply 
the result by the known specific gravity of the oil of turpentine or other fluid 
employed. 
Example.—A lump of sugar weighing 100 grains was found to weigh when immersed in 
oil of turpentine 45 '62 grains. Then 
The weight of the sugar in air was . . . ,100 grains. 
~ ~ oil of turpentine . . 45 62 
Difference 54-38 
Dividing 100 grains by 54'SS grains yields l'B4 as the specific gravity as if water had been 
used ; and by multiplying this result by ’B7, the specific gravity of oil of turpentine, we obtain 
I "6 as the actual specific gravity of the sample of sugar operated on. 
Having thus considered in detail the various complications which may arise SPECIFIC GRAVIIY. 
101 
in taking the specific gravity of liquids and solids, it only remains to point out 
how the foregoing may be rendered subservient to commercial purposes. 
(C) Practical Applications of Specific Gravity of Solids and Liquids. 
Case i. The specific gravity of a body being known, it is desired to as- 
certain the weight of any given volume of the substance. Find the weight 
of the given bulk considered as water, and multiply this amount by the 
specific gravity. 
Example i. —What would be the weight of a fluid ounce of oil of vitriol ? We know that 
a fluid ounce of distilled water weighs 437'5 grains, and the specific gravity of oil of vitriol is 
I ’843 ; so, if we multiply the former figures by the latter, we obtain 806 ‘3l grains, which is the 
weight of a fluid ounce of this acid. 
Example ii.—How much should a litre of chloroform weigh ? The weight of a litre of 
water is 1000 grammes ; and by multiplying 1000 by i-49, the specific gravity of the chloroform, 
we obtain 1490 grammes, as an answer to the question. 
Example iii.—How much should a fluid ounce of pure ether weigh ? The specific gravity 
is 72, and a fluid ounce of distilled water weighs 437’5 grains ; multiplying the one number 
by the other gives 315 grains. 
Case 2. Given the weight of any known bulk of a liquid, to find its 
specific gravity. Divide the weight by that of the given bulk considered as 
distilled water. 
Example.—A pint of spirit weighs i6| ounces;—is it rectified or proof spirit? By 
dividing this weight by 20 ounces, the ascertained weight of a pint of distilled water, we 
obtain as an answer 'B3B. We know, therefore, that the spirit thus tested must have been 
rectified. 
Case 3. To find the amount of solid matter, in grammes, present in 100 c.c. 
of a solution of given specific gravity. So far as any ordinary rule can 
be laid down, especially with regard to saccharine liquids, for which this 
calculation is generally used, we multiply the gravity by 1000, and then, having 
deducted 1000 from the product, we divide by 3'95- 
Example.—A saccharine solution has a gravity of i'OH4 : how much solid matter in 
grammes does it contain in each c.c.? 
i'OU4 X iooo = 1011-4 1000 = 11-4.*. 114 = 2-886 grammes per 100 c.c. 
3‘95 
{£>) Specific Gravity of Gases. 
Taking the density of gases and vapors involves many more complicated 
considerations than are required in the methods applicable to the specific 
gravity of liquids and solids. The standard adopted for such bodies is 
hydrogen, measured at a temperature of o° C. and a barometrical pressure 
of 760 millimetres. 
When taking the specific gravity of liquids or solids, it is easy to obtain the 
water or other fluid required at the exact temperature necessary, by the use of 
cooling or heating appliances. With a gas we need exercise no such manipu- 
lation, because the coefficient of expansion of all gases and vapors is alike and 
well ascertained. The measurement of gases is therefore conducted without 
any attempt to modify these conditions; but the indications of the thermo- 
meter and barometer being carefully noted at the time of the experiment, a 
simple series of calculations enables us to ascertain how much the volume of 
gas would have measured had the test been conducted at a standard of tem- 
perature and pressure. The following are specimens of such calculations : 
x. Correction of the volume of gases for temperature.—This calculation 
is based upon Charles’s law, viz. : gases expand or contract one two-hundred- 
and-seventy-third part of their volume for each degree of temperature, 102 
WEIGHING, MEASURING, AND SPECIFIC GRA VITY. 
Centigrade, through which their heat has been respectively raised or lowered. 
Therefore As 273 plus the temperature at the time of measurement is to 
273 phis the required temperature, so is the volume of the gas at the period of 
measurement to the required volume. 
For example :—The volume of a gas at 150 C. was xoo cubic centimetres : what would it be 
at the standard temperature of o° C. ? Then,— 
As 273 273 
!5 o 
288 : 273 : : 100, 
which gives, as an answer. 94/795 cubic centimetres, the volume of the gas at standard 
temperature. 
2. Correction of the volume of gases for pressure.—This calculation is 
based upon Boyle’s law, viz. : gases expand or contract in volume in inverse 
proportion to the increase or diminution of the pressure,—that is to say, the 
greater the pressure the less the volume of gas, and the less the pressure the 
greater the volume of the gas. 
For example :—At the moment of measuring 100 cubic centimetres of a gas, the barometer 
stood at 752 millimetres: what would the volume of the gas be at the standard pressure of 
760 millimetres ? Applying the rule of inverse proportion, we have :—As the required pressure 
is to the observed pressure, so is the observed volume to the required volume : then 
760 : 752 :: 100, 
which gives, as an answer, 98'95, the volume of the gas at standard pressure. 
The manner in which the specific gravity of a permanent gas was formerly 
obtained was by exhausting a thin glass globe by means of the air pump and 
weighing it; then filling it with air at known temperature and pressure, and 
weighing ; and lastly, pumping out the air, filling the globe with the gas at a 
similar temperature and pressure, and again weighing. After deducting the 
weight of the empty globe from each of the two latter weights, the weight of 
the gas was divided by that of the air. 
Now, however, in modern laboratories all that is practically done away with, 
and the standard taken for the density of gases and vapors is hydrogen ; because 
(1) it is the lightest known gas, and {2) we know the weight of any given 
volume of it without the necessity of weighing each time. Therefore to take 
the density of a gas or vapor we weigh a given number of cubic centimetres of 
the gas, noting the temperature and pressure at the moment of weighing, and 
having corrected the volume so obtained to o° C. and 760 m.,m. bar. we 
divide this by the weight of the same number of c.c. of hydrogen. A litre of 
hydrogen at o° C. and 760 m.m. weighs ‘0896 gramme bar. ; therefore each c.c. 
of H will weigh ‘0000896 gramme. 
{E) Vapor Density. 
After finding the percentage composition of organic bodies, and from that 
calculating an empirical formula (which is done by dividing the percentage of 
each element by its own atomic weight, then, taking the lowest of these 
answers as unity, dividing all the others by it and expressing the mutual 
ratios in the simplest full numbers) it is often necessary to prove whether the 
sum of such formula is the truemolecular weight. Upon the theory that all 
molecules occupy a space double that of an atom of hydrogen, we can prove our 
case by taking the density of a volume of the substance in vapor (if volatile) 
as regards hydrogen, and then this vapor density x 2 the true molecular 
weight. This research acts as a check upon our formula obtained by analysis, 
and may or may not lead to our having to double it. VAPOR DENSITY. 
103 
(.a) Dumas’ process.—A thin, clean, dry glass globe, about three inches in 
diameter, is employed. Its neck having been drawn out to a fine tube in the 
blowpipe flame, it is weighed, and the temperature and pressure noted. By 
gently heating the bulb and dipping the open end into the volatile liquid a 
suitable quantity is drawn into the globe by the contraction of the air. Attach- 
ing a handle by means of wire, the sphere is plunged into an oil bath furnished 
with a thermometer, and is then heated somewhat above its volatilising point. 
When all vapor has ceased to issue from the globe, the orifice is hermetically 
sealed, and the temperature and pressure again noted. The apparatus is 
allowed to cool, separated from the handle, cleansed, weighed, and the 
weight noted. The last step is to break off a fragment of the neck beneath the 
surface of a sufficiency of mercury, when, should the experiment have been 
carefully performed, the liquid enters the globe, completely filling it, and the 
capacity is ascertained by emptying its contents into a graduated glass 
measure. Supposing the experiment to have been perfectly successful, we 
have the following five data : 
1. Weight of globe filled with air. 
2. Temperature and pressure at the time of weighing. 
3. Weight of globe plus vapor. 
4. Temperature and pressure at sealing. 
5. Capacity of the globe. 
Proceeding from these data, the first point is to find the actual weight of the 
globe. This is done by calculating the capacity of the globe from the tempera- 
ture and pressure at the time of weighing to o° C. and 760 mm. bar., 
and then multiplying the true volume thus found by '001295, which 
is the weight of a cubic centimetre of air (1 litre at o° C. and 
760 m.m. bar.= i' 295 gramme). Having thus obtained the weight 
of the air, it is deducted from the weight of globe and air, and the 
difference gives the true weight of the globe ; and by deducting this 
latter from the weight of the globe plus vapor, we obtain the actual 
weight of the vapor. But as this weight is that of the volume of vapor 
to the temperature and pressure at the moment of sealing, it must be 
corrected to standard temperature and pressure, and the weight of an 
equal volume of hydrogen ascertained. To do this, the capacity of 
the globe is once more put down, and reduced from the temperature 
and pressure at sealing to o° C. and 760 m.m. bar., and the resulting 
volume is multiplied by '0000896, which is the weight of 1 cubic 
centimetre of hydrogen. The product, which gives the actual weight 
of an equivalent volume of hydrogen, is then taken, and divided into 
the weight of the vapor already found, and the answer is the density. 
(h) V. Meyer’s Method.—This is the simplest and most rapid process. 
The apparatus used is illustrated in fig. 24. The inner tube (a) is closed 
with a cork and arranged so that its bent delivery tube just dips under the 
surface of mercury contained in a trough. Any suitable liquid, which boils 
at a constant temperature, is placed in the outer tube (b), together with 
a thermometer, and heat being applied so as to boil the fluid, the air 
in the inner tube expands and passes off through the mercury. When 
bubbles of air cease to pass (showing that the air in the tube has been fully 
expanded to its proper volume at the given temperature), some water is 
poured upon the surface of the mercury, and a graduated “ gas collecting 
tube ” is filled with water and inverted over the delivery tube. A known 
weight of the substance is then introduced into the inner tube (a) by rapidly 
raising the cork, dropping the substance in, and instantly closing again. The 
vapor produced now displaces an equivalent volume of air, which passes into 
Fig. 24. WEIGHING, MEASURING, AND SPECIFIC GRA VITY. 
the measuring tube. When action ceases, the cork is opened to prevent 
back suction, and the air in the tube is measured, noting temperature and 
pressure. This volume in centimetres corrected to N.T.P., and multiplied 
by ‘0000896, gives the weight of a volume of hydrogen equal to that of the 
vapor, and then by dividing the weight of the substance taken by such 
weight, we obtain the vapor density. The coefficient of expansion of all 
gases being equal, it is quite the same thing whether we measure an actual 
volume of vapor at a given temperature, or that of an equivalent volume 
of air displaced at the same temperature. Such a minute quantity of the 
substance must be taken as shall not, when in vapor, more than displace 
the air contained in the inner tube of the apparatus (which should hold 
about xoo c.c.), otherwise the whole process manifestly fails. 
Methods of measuring gases at fixed temperature and pressure are given 
in Chapters IX. (Estimation of Nitrogen), and XII. (Analysis of 
Gases). io5 
CHAPTER VII. 
VOLUMETRIC QUANTITATIVE ANALYSIS. 
I. INTRODUCTORY REMARKS. 
Volumetric analysis is that in which the quantity of any reagent required to 
perform a given reaction is ascertained, and the amount of the substance acted 
upon is found by calculation. The process of adding the reagent from a 
graduated measure is called Titration. 
(A) Volumetric or standard solution is a solution of definite strength 
made by dissolving a given weight of a reagent in grammes in a definite 
volume of water in cubic centimetres (or in grains and fluid grains). Such 
solutions are usually made by dissolving either a molecular weight of a 
reagent in grammes, or some decimal fraction of such weight, in 1000 c.c. 
(one litre) of water. The following abbreviations are used to express the 
strength of standard solutions 
N == a normal solution having i molecular weight in grammes per litre. 
—= a semi-normal „ I „ „ ~ „ 
2 
a deci-normal ~ „ ~ „ ~ 
10 
= a viginti-normal „ jV » >• „ „ 
(.B) An indicator is a substance added to enable us to ascertain, by a 
change of color (or other equally marked effect), the exact point at which a 
given reaction is complete. 
The principal indicators employed are as follows : 
(a) Solution of litmus, which turns red with acids and blue with 
alkalies. 
(//) Alcoholic solution of phenol-phthalein, which is colorless with acids 
but red with alkalies. 
(c) Starch mucilage, which turns blue in presence of free iodine. 
\d) Solution of potassium chromate, which gives a red with AgN03, but 
not until any halogen present has entirely combined with the 
silver. 
(e) Solution of potassium ferricyanide, which ceases to give a blue color 
when any iron present has been fully raised to the ferric state. 
(C) General modus operand!. A known weight of the substance to be 
analysed is accurately weighed, and having been dissolved or diluted with 
water (if necessary), the solution is placed in a flask, the indicator is added 
and the standard solution of the reagent is dropped in until the desired effect 
is attained. 
The volume of the standard solution used is then noted; and its strength 
per 1000 c.c. being known, the actual amount of solid reagent that has been VOLUMETRIC QUANTITATIVE ANALYSIS. 
really added is easily found and calculated, by means of the equation for the 
action in question, to the amount of the substance under analysis it represents, 
as follows : 
Suppose, for example, we desire to ascertain the strength of a sample of 
caustic soda, and that we have weighed out 1 gramme, dissolved it in water, 
added litmus solution and found that it required 24 c.c. of standard solution 
N 
of oxalic acid =63 grammes per 1000 c.c.) to just cause the color to change 
from blue to violet red (i.e. to neutralise it). Now, by the equation : 
11./:,04 • 2ll20 + 2NaHO - Na2C,04 + 4H20 
2)126 2)80 
63 40 = grammes of NaHO, equivalent to 1000 c.c. of oxalic 
acid solution (its strength being 63 grammes per 
1000 c.c.). 
Knowing this, we now ascertain how much NaHO is represented by the 
24 c.c. of acid used; thus : 
40 X 24 _ .gg gramme of real NaHO present in the 1 gramme of caustic soda 
1 °°° weighed out for analysis. 
Then, if the results are to be expressed in percentage, we multiply the 
amount of the real article found by 100 and divide by the quantity weighed 
out for analysis, thus : 
96 x I0S? =96 per cent., strength. 
Expressing the above calculations in rules to commit to memory, we have 
the following four steps : 
I. Write out the equation and reduce the first side of it to figures in 
molecular weights. 
11. Cancel these weights down to equivalent weights corresponding to 
the indicated strength of the standard solution used {i.e. if 
- divide by 2, if divide by 10, if divide by 20, etc.), 
2 TO 20 
thus obtaining the equivalent of the substance under analysis 
to 1000 c.c. of the standard solution. 
111. Multiply this equivalent by the number of centimetres of standard 
solution used and divide by 1000. 
IV. If percentage be required, multiply the last result by 100 and divide 
by the weight of substance taken for analysis. 
Note.—lt must be remembered that all waters of crystallisation must always be 
added to each substance containing them, in writing the equation for 
volumetric calculations. 
(Z>) The apparatus specially employed in volumetric analysis. 
1. The measuring flask, so constructed as to hold a definite amount of 
fluid (say 1000 or 100 c.c.) when filled up to the mark on the 
neck (fig. 25). 
2. The test mixer, a cylindrical vessel, to hold 1 litre of fluid 
graduated in measures of 10 c.c. each (fig. 26). 
3. The burette, a graduated tube, usually containing 100 c.c. and 
graduated in divisions of x c.c., for containing and delivering 
the standard solution. This is fitted with a clamp or stopcock 
at the bottom, which, when pressed or turned, allows the 
contained liquid to run out at any regulated speed desired. It 
should also be furnished with an appliance called “ Erdmann’s 
float,’’ which enables us to read the quantity of fluid delivered INTRODUCTORY REMARKS. 
107 
more accurately. (Fig. 27 shows two burettes in their stand as 
usually employed.) 
4. The pipette is an instrument graduated to deliver a fixed volume of 
liquid (say 10, 20, 50 or 100 c.c.). Fig. 28 shows a set of such 
instruments arranged in a convenient stand. 
Fig. 25. 
[E) Weighing Operation. The student should have a tared watch-glass for 
weighing out solids and a small stoppered bottle for weighing volatile 
liquids. By carefully keeping these much trouble is saved. 
(1) To weigh a solid. Place the tared glass on the scale, and put on 
it what is judged to be a sufficient quantity of the article to be 
weighed, then weigh the whole and note the weight thus:— 
Fig. 26. 
Fig. 27. 
Fig. 28. 
Glass + substance . . . . 5 "63 2 grammes. 
Known tare of glass . . . . 5' 132 ~ 
Weight taken for analysis .... '5OO ~ 
(2) To weigh a volatile liquid. Fill the small stoppered bottle with the 
liquid and weigh ; pour out what is judged to be sufficient into 
the flask containing the indicator and some water, replace the 
stopper and again weigh, noting each weight at the time thus : 
Total weight of bottle + fluid . . . 20-982 grammes 
Weight of bottle + fluid after pouring out . 15‘482 ~ 
Weight of fluid taken ..... s's°° » 
Note.—It is most important always to take the weights directly down in a note-book 
from the balance, and to cultivate the habit of always replacing the weights 
in their proper holes in the weight box when finished. This enables us to 
have a double check, (1) from the weights in the pans, and (2) from looking 
at the empty holes in the weight box. In weighing, brass weights are used 
from 50 to 1 gramme; flat platinum weights from -5 to -oi gramme, and 
the rider on the beam is used for milligrammes (i.e. ‘OO9 to ‘ooi). Before 
weighing, see that all the weights are in their right places in the box. At 
the conclusion of the weighing, read off the weights and put them down in 
a note-book, and then check that reading by putting them back into the 
box, looking, as you do so, at the note already made. Always close the 
case of the balance before using the rider, so as to prevent currents of air 
affecting the weight. 
Having thus given a general idea of the mode of working, we now 
commence to practise with the chief standard solutions as follows. VOLUMETRIC QUANTITATIVE ANALYSIS. 
11. STANDARD SDLUTION OF OXALIC ACID. 
Strength grammes per 1000 c.c. 
2 
(A) Preparation. 
This is made by powdering some pure oxalic acid, pressing it between the 
folds of blotting-paper (to remove any chance moisture), and weighing out 
exactly 63 grammes in a tared beaker. The powder is then washed out with 
distilled water from the beaker into the litre measuring flask, which is nearly 
filled with water and slightly warmed to aid solution. When all is dissolved, 
more water is poured in till the solution arrives at the mark in the neck of 
the flask, and finally the whole is cooled down to 6o° R, and is once more 
exactly made up to the line with water. 
This solution may then be used for the following purposes in the manner 
described under each case. 
Check.—To check the strength of the standard oxalic acid itself. Take 
some pure NaHCOg, and ignite it in a crucible for 15 minutes at a red heat, 
cool and weigh off 2‘65 grammes of the resulting Na2COs, and this should take 
exactly 50 c.c. of acid if truly f. The process is described below at {C). 
(B) Estimation of Alkaline Hydrates. 
By weighing out a definite quantity of the substance, diluting with, or 
dissolving in, water in a flask, adding a few drops of solution of litmus, 
and dropping in the standard acid from a burette until the last drop added 
just causes the blue to change to violet-red, the flask being agitated after 
each addition of the acid. In this way we should examine : 
{a) Liquor ammonia, fort, and liquor anunonice. 
Take about 3 grammes, and use the equation : 
H,C204.2H„0 + 2NH3 . H,O = (NH4)2C204 + 4H..0 
Srms- NH3, equivalent to 1000 c.c. oxalic acid solution. 
f ) Potassium hydrate or sodium hydrate or their solutions. 
Take about 1 gramme of solid, or about 10 grammes of solution, and 
use the equations:— 
H2C204.2H..0 + 2NaHO = Na2C204 + 4H20 
2)126 2)80 _ mg_ reai NaHO, equivalent to 1000 c.c. acid. 
63 40 2 
H2C204.2H20 + 2KHO = K2C304 + 4H20 
2)126 = grins. KHO, equivalent to 1000 c.c. acid. 
63 S6 2 
(e) Metallic sodium (thrown on water and the resulting solution titrated). 
Take under *5 gramme, and use the equation : 
H2aO,. 2H.0 + Na2 == Na2C204 + 2H..0 + H2 
2)126 2)46 ...... N ~ 
—— grms. Na2, equivalent to 1000 c.c. acid. STANDARD SOLUTION OF OXALIC ACID. 
109 
(d) Lime-water and liq. calcis sacch. 
H2C204 . 2H.fi + CaO + H,O = CaC204 + 4H20 
2)126 2);6 
63 28 = grammes CaO, equivalent to 1000 c.c. acid. 
(e) Borax. 
Take about 25 grammes, and use the equation;— 
Take between 2 and 3 grammes, and use the equation:— 
H2C204.2H20 -f Na2B407. ioH20 = Na2C204 + H2B407 + i 2H20 
2)126 2)382 
63 191 = grammes borax, equivalent to 1000 c.c. acid. 
2 
(C) Estimation of Alkaline Carbonates. 
By a similar process to (A), only conducted at a boiling temperature, so as 
to drive off all CO2, and the standard acid to be added until two minutes’ 
boiling fails to restore the blue of the litmus. Another and better method 
is to add a given volume of standard acid, more than sufficient to neutralise 
all the carbonate, then to boil until all carbon dioxide has passed off, and to 
titrate back with standard soda, using phenol-phthalein as indicator. The 
difference between the number of c.c. of acid taken and that of soda used 
will give the acid equivalent to the carbonate analysed. 
{a) Crystallised sodium carbonate. 
Take about 3 grammes, and use the equation : 
H2C.,04.2H20 + Na2C03 . ioH20 = Na2C204 + C02 + 13H20 
2)126 2)286 
63 143 = grammes Na2C03ioH20, equivalent to 1000 c.c. 
acid. 
2 
(I?) Dried sodium carbonate. 
Take about x gramme, and use the same equation less the 10 H2O on 
each side : 
2)126 2)106 N 
63 + 53 = grammes Na2C03, equivalent to 1000 c.c. - acid 
(c) Sodium bicarbonate. 
Take about 3 grammes, and use the equation : 
H2C204.2H20 + 2NaHC03 = Na2C204 + 2CO, + 4H20 
2)126 2)168 
63 84 = grammes NaHC03. equivalent to 1000 c.c.— acid. 
(1d) Potassium carbonate (commercially considered as always holding i6°/0 
of moisture). 
Take about 2 grammes, and use the equation : 
H,c204 . 211..0 + K2C03. i6%H20 = K2C20., + C02 + 
2)126 2)^64-28 
63 82-14 = grammes commercial K2C03, equivalent to 
N 
1000 c.c. acid. 
2 VOL UME TRIG Q UANTITA LIVE ANA L YSIS. 
(e) Potassium bicarbonate. 
Take about 2 grammes, and use the equation ; 
H2C204.2H20 + 2KHCO, = K2C,O, + 2C0., -f 4H.,0 
2)126 2)200 
63 Too = grins. KHCO3, equivalent to 1000 c.c. - acid. 
{/) Commercial “ carbonate of ammoniaC1 
Take about 1 gramme, do not boil too violently, and use the equation : 
3(H2C204, 2H,p) + = 3(NH4)2C204 + 4C02 + 8H20 
6)378 6)3i4 n 
63 52-3 = grins., equivalent to 1000 c.c. acid. 
[D) Estimation of Lead. 
Weight out the substance, dissolve it in plenty of water (the flask i full), 
with a drop or two of acetic acid to clarify it, and then carefully drop in the 
standard acid till precipitation ceases. Thus we operate upon 
(a) Plumbic acetate. 
Take 3 grammes, and use the following equation : 
II2C204.2H20 + Pb(C2H3O2)2. 3H20 = PbC204 + 2HC2H302 + 5H20 
2)126 2)379 N 
63 189'5= grms., equivalent to 1000 c.c.— acid. 
{b) Liquor plumbi subacetatis. 
Take about 10 grammes, and use the equation ; 
2(h2c204 . 2H.0) + Pb2o(c2H3y = 2Pbc.,o4 + 2HC2h30, + 5H20 
4)252 4)548 x 
63 137 = grins., equivalent to 1000 c.c. acid. 
2 
[E) Estimation of Organic Salts of the Alkalies. 
Organic salts of potassium or sodium are examined by weighing out about 
2 grammes in a tared platinum or porcelain crucible, and then heating to 
redness in contact with the air until all is perfectly charred. The crucible 
is now cooled, and its contents dissolved in boiling water and filtered into 
a flask, and the filter washed with boiling water until the washings do not 
affect red litmus paper. The contents of the flask are then colored by litmus 
solution and titrated at boiling temperature with the standard acid, as already 
described in the case of alkaline carbonates. The ignition causes the 
conversion of the organic salt into an alkaline carbonate. Thus we should 
operate upon : 
(rt) Cream of tartar. 
2KHC4H406+ s02= K2C03 + 7C02 + SHX) ; 
376 138 
then K,C03 + H2C204.2H„0 = K,C204 + C02 + 3HX); 
138 126 
therefore IJ2C204.2H20 = 2KHC4H406 
2)126 2)376 
63 = 188 = grins, of KHC4II406, equivalent to 1000 cc. 
acid. 
2 STANDARD SOLUTION OF OXALIC ACID. 
(p) Neutral potassium tartrate. 
2K„C,H ,06 • H,,0 + 50. = 2K,C03 + 6C0., + 4H,0 ; 
488 276 
then 2H2C.,0(. 2H..0 + 2K,,C03 = 2K..C..0, + 2CO, + 4H,0 ; 
252 276 
therefore 2H.,C204.2H20 = 2K2C2H406 . H*o 
4)252 4)4?8 
63 = i 22 = grins, of K2C4H406. H2O, equivalent to 
1000 cc. acid. 
2 
(c) Rochelle salt. 
2(KNaC4H406.4H..0) + 50, 6C(X + 8H20 ; 
564 244 
then 2KNaC03 + 2(H.,C204.2H.0) = 2KNaC204 + 2<ZO, +4H2O ; 
244 252 
therefore 2(H.2C„04.2HX)) = 2KNaC4H406 
4)252 4)564 
= 141 = grms. of KNaC4H406.4H20, equivalent 
* N 
to 1000 c.c. acid, 
2 
{d) Potassium citrate. 
2K3C6H507 + 90, =^3K2COa + 9CO, + 5H20 ; 
612 4H 
then 3K2C03 + 3(H2C204 • 2H20) 3K2C204 + 3C02 + ; 
414 378 
therefore 3(H2C„04.2H20) = 2KsC6Hj07 
6)378 6)6i2 
63 = 102 = grins, of K3C6H507, equivalent to 1000 cc 
acid. 
2 
(/c) B.P. Standards of Strength by Oxalic Acid, 
ARTICLE B.P. STRENGTH 
I.iq. Amnion, fort. .... 32% NH;j. 
Liq. Ammon. . ■ • ■ • 10% NH3. 
Officia ammon. carb. .... 100% N.iH11C205. 
Borax pure (100%). 
Plumbic acetate ..... pure (100%). 
Liq. plumbi subacetatis .... about 24% IL.fJ (Cfl f).,).,. 
Lime-water ...... 5 grains CaO in 10 fluid ounces. 
Sodium (metallic) 957%- 
Potassium and sodium hydrates . • 90 to ico%. 
Potassium carbonate . . . . 97 to 100% of K,C03 + i 6% H2O. 
Crystallised sodium carbonate . . 96 to 100% of NaXO, .10 H^O. 
Potassium and sodium bicarbonates . . pure (100%). 
Potassium tartrate and rochelle salt . . 99°/ - 
Cream of tartar 92% KHC4H406 in the salt dried at 21 z° 
remainder only calcium tartrate. 
Potassium citrate ..... pure (100%). 
Liquor potasste. ..... 5'^4%- 
Liquor sodae 4’IO/7 VOLUMETRIC QUANTITATIVE ANALYSIS. 
111. STANDARD SOLUTION OF SODIUM HYDRATE. 
N— 4° grammes NaHO in 1000 c.c. 
{A) Preparation and Check. 
As commercial soda is not pure, this solution has to be made as follows : 
Dissolve 45 grammes of ordinary caustic soda in 1 litre of distilled water, 
and let it cool to 6o° F. Now place 20 c.c. of standard solution of oxalic 
acid in a flask, add litmus, and run in some of this crude soda solution from a 
burette until neutrality is produced. Note the number of c.c. of soda used, 
put 50 times that volume of the crude solution into a test mixer, and make 
up to the 1000 c.c. mark with distilled water. On again checking, 20 c.c. of 
the acid should take exactly 20 c.c. of the perfected soda for exact neutralisation. 
(B) Acidimetry. 
Soda solution is used for taking the strength of acids by simply weighing 
out a quantity of the acid, and then running in the soda in presence of the 
litmus indicator if the acid be inorganic, or of phenol-phthalein if it be 
organic. We operate, as a rule, upon about 1 gramme of a strong or a solid 
acid, and from sto xo grammes of a diluted acid. The following are some 
of the more important equations : 
(«) NaHO + HCI = NaCl + HaO 
40 36-5 grms. of HCI, equivalent to 1000 c.c. NaPIO. 
(i) NaHO + HN03 = NaNOs + H2O 
40 63 = grms. of HN03, equivalent to xooo c.c. NaHO. 
(c) NaHO + HC.,H:jO, = NaC,H302 + H,,0 
40 60 = grms. of HC2H302, equivalent to 1000 c.c. NaHO. 
(d) 2NaHO + H2S04 = Na2S04 + 2H20 
2)8o 2)98 
40 = 49 = grms. of H2S04, equivalent to 1000 c.c. NaHO. 
{e) 2NaHO + H2C4H406 = Na2C4H4Oe + 2H20 
2)8o 2)150 
40 75 = grms. of H2C,,H,06, equivalent to 1000 c.c. NaHO. 
(/) 3NaHO + H3C6H507‘H20 = Na3C6H507 + 4H20 
3)120 3)21° 
40 70 = grms. of H3C6H307. H2O, equivalent to 1000 c.c. NaHO. 
(C) List of Strengths of B.P. Acids taken by Soda. 
Acetic (glacial) .... 99% HC2H30.^ 
„ (ordinary) .... 33% ~ 
„ (dilute) ..... 4'27% >? 
Citric pure. 
Hydrochloric ..... 32% HCI. 
~ (dilute) • • • 10-5&% » 
Lactic 75% HC3H503. 
„ (dilute) 13% m 
Nitric ...... 7°% HN03. 
~ (dilute) *7’44% >, 
Nitro-hydrochloric . . . 32 grins, should neutralise 883 c.c. NallO 
Sulphuric . . . . . 98% H2S04 
„ (dilute) .... I 3'65%.) 
~ (aromatic) . . • 12'5% ~ 
Tartaric 99% H2C4H406. 
Hydrobromic . . . . . 10% HBr. STANDARD SOLUTION OF ARGENTIC NITRATE. 
113 
IV. STANDARD SOLUTION OF ARGENTIC NITRATE. 
N 
=l7 grammes per 1000 c.c. 
10 
Dissolve 17 grammes pure AgNOs in distilled water, and make up to 1 litre 
(1000 c.c.) 
Check.—As argentic nitrate is not always pure, the solution when thus 
made should be standardised by weighing out 'i (one decigramme) of pure 
powdered sodium chloride, dissolving it in water in a small beaker, adding 
sufficient solution of potassium chromate to color it yellow, and then running 
in the silver solution, with constant stirring, until the last drop just causes the 
color to change from yellow to pink. This should take 17’! c.c. of silver 
solution if it be of correct strength, because : 
(A) Preparation. 
AgNOg + NaCl = AgCl + NaNOa 
10)170 10)58-5 N 
17 5-85 = grms. of NaCl, equivalent to 1000 c.c. jQAgNO3. 
(B) Estimation of Soluble Haloid Salts 
The silver solution is used for the estimation of haloid salts by weighing 
out any quantity ranging between -i and ‘2 (one or two decigrammes), dis- 
solving and titrating, K2CrC>4 being used as the indicator, exactly as above 
described. Thus we should operate upon : 
(a) Potassium bromide. 
AgN03 + KBr = Agßr + KNO, 
io)i7q_ io)_ri9 N 
17 11-9 grms. of KBr equivalent to xooo c.c AgNOg. 
(/;) Ammo7ihim bromide. 
AgNOs + NH4Br= Agßr + NH4N03 
10)170 10)98 N 
17 9’B = grms. of NH4Br equivalent to 1000 c.c. ~ AgNOs. 
(c) Sodium bromide, potassium iodide, and sodium iodide, all by similar 
equations. 
Naßr -f KI + Nal 
10)103 10)166 10)150 
103 i6'6 is'o all respectively = 1000 c.c. Agl\03. 
Note.—Bromides, if adulterated with iodides, will take less silver than they ought, but, if 
the impurity be chloride, they will take more. Therefore they must neither take less nor 
mors than the correct amount. 
(C) Application of Volhard’s Method to the Analysis of Chlorides, 
This process is, in certain cases, a much better method for the estimation of 
chlorides than the direct method with the chromate indicator, because it may 
be used in the presence of nitric acid, thus enabling a chloride to be estimated 
in presence of a phosphate or other acid which precipitates silver in a neutral 
solution. It depends upon entirely precipitating the chloride in the presence 114 
VOLUMETRIC QUANTITATIVE ANALYSIS. 
of nitric acid by a known volume of standard solution of silver, and then esti- 
mating the excess of silver, left uncombined with the chloride, by standard 
solution of ammonium thiocyanate (sulphocyanate) using a drop of solution of 
ferric alum as an indicator. The thiocyanate solution is checked against the 
silver so as to correspond with it c.c. to c.c. As soon as the thiocyanate 
has precipitated all the silver it will strike a blood-red with the ferric salt 
due to the formation of ferric thiocyanate. The difference between the volume 
of standard silver solution originally added and that of the thiocyanate used 
will give the c.c. of silver equivalent to the chloride present. 
(D) Estimation of Hydrocyanic Acid. 
Silver solution is also used for taking the strength of hydrocyanic acid. 
This is done by weighing out about 5 grammes, adding a drop of solution of 
litmus, and then a few drops of NaHO so as to cause strong alkalinity. Now 
carefully drop in the silver solution from the burette, with constant agitation, 
until a faint permanent cloud of AgCN is produced. If, during the operation, 
the litmus becomes red, more NaHO must be added to keep it blue. At 
the moment that the permanent cloud appears the following reactions are 
complete : 
2HCN + 2NaHO = 2NaCN + 2H20 
54 9§ 
2NaCN + AgN03 = AgCN • NaCN + NaN03 
98 iyo 
therefore— 2HCN = AgN03 
10)54 io)i7o_ 
5’4 = 17 0 
N 
so that 1000 c.c. AgN03 are equivalent to 5 ‘4. grms. of HCN. 
On adding more silver AgCN would be precipitated thus : 
and the first appearance of this precipitate therefore shows that the action to 
be calculated upon is complete. 
Potassium cyanide is done in the same way, using about '2 gramme, and 
AgN03=2KCN—i.e., 17 grammes (ioooc.c.) = 6-5 grammes KCN. 
NaCN • AgCN + AgN03=2AgCN + NaN03; 
(E) Standards of Strength by Silver Solution. 
Hydrocyanic acid ....... . 2/. 
, Potassium cyanide 95%* 
Potassium iodide . . • • • • ■ • • to 99%. 
Sodium iodide ......... 99/• 
Potassium bromide ....•••• 9$ to 100%. 
Sodium bromide ....••••■ 99/b- 
Ammonium bromide pure. 
V. STANDARD SOLUTION OF lODINE. 
127 grammes per litre (1000 c.c.) 
10 
(A) Preparation. 
Weigh out 127 grammes of pure iodine and place it in a litre flask with 
18 grammes of potassium iodide and about 200 c.c. of water, agitate till 
dissolved, and make up to one litre with water. STANDARD SOLUTION OF SODIUM THIOSULPHATE. 
Check.—To standardise the strength of the solution (if desired), test it 
against ‘2 gramme (2 decigrammes) of pure AS2O3, as hereafter described. 
(B) Estimation of Arsenions Acid. 
This solution is used : 
For arsenious acid and the solutions thereof weigh out one to two deci- 
grammes of the As2Os, and dissolve it in boiling water by the aid of five 
times its weight of NaHCOs- Let it cool, add some mucilage of starch, and 
run in the iodine solution until a faint permanent blue color is obtained. 
Then apply the equation : 
2l„ + As2Os + 5H..0 = 2H3As04 + 4HO 
4)5°8 4)i98 
10)127 10)49-5 N 
127 4-95 grms. of As203, equivalent to 1000 c.c. iodine. 
For liquor arsenicalis use 10 grammes and ’3 gramme NaFICOs. 
For liquor arsenici hydrochloricus use to grammes and ’6 gramme NaHCOs. 
(C) Estimation of Sulphurous Acid. 
For sulphurous acid weigh out about one gramme from a stoppered bottle, 
and largely dilute it with water. Add starch mucilage, and run in the iodine 
solution until the faintest possible permanent blue appears. Then apply the 
equation :—- 
I. + H,O + S02 • H„0 H2S04 + 2HI 
2)254 2)64 
10)127 10)32 N 
127 3'2 grms. S02, equivalent to 1000 c.c. -- iodine. 
For sodium thiosulphate (hyposulphite) use about -5 gramme, dissolve in 
water, add starch, and titrate as above. 
i2’7 1=24-8 “ hypo.” 
lyD) Estimation of Thiosulphates 
VI. STANDARD SOLUTION OF SODIUM THIOSULPHATE (“HYPO.”) 
Strength 24-8 “ hypo ” • SH-20)5H-20) per litre (1000 c.c.) 
10 
(.A) Preparation and Check. 
Dissolve about 28 grammes of commercial “hypo” in a litre of distilled 
water. Now place 20 c.c. of standard solution of iodine slightly diluted with 
water in a beaker, and run in the rough “ hypo ” solution until the color 
changes to that of pale sherry. Then add mucilage of starch, and continue 
to run in the “ hypo” till the last drop just discharges the blue color. Note the 
number of c.c. of “ hypo ” used, put 50 times that number into a test mixer, 
and make up with distilled water to 1000 c.c. 
This solution may be used for ; 
By weighing out ‘2 gramme (2 decigrammes), dissolving in a little water 
by the aid of potassium iodide, and then running in “ hypo ” till the color 
(B) Estimation of Free lodine. VOLUMETRIC QUANTITATIVE ANALYSIS. 
is reduced to that of a pale sherry ; lastly, adding starch mucilage, and going 
on till the blue is just bleached. Then by the equation;— 
2(Na„5„035H20) + I„ = 2NaI + Na2S40,- + ioH„0 
V w 1 v—' 
2)496 2)254 
10)248 IO)l27 
24‘8 = 127 grins. I, equivalent to 1000 c.c. -- “hypo.” 
For chlorine water or bromine water. 
(C) Estimation of Free Chlorine or Bromine. 
Weigh about xo grammes from a stoppered bottle, pouring it directly into 
a flask containing 2 grammes of potassium iodide dissolved in 50 c.c. of 
water, and then titrate with “ hypo ” as already described. 
The Cl first liberates an equivalent quantity of iodine from the KI, and 
the “ hypo ” then acts upon the I 2 so set free, thus ; 
ci, + 2KI = 2KCI + r2 
20)71 20)254 
355 127~ 
2Na2S2035H20 + I, = 2NaI + Na2S406 + ioH„0 
v 1 V-v- 
-20)496 20)254 N 
24-8 = 127, therefore 375 grms. Cl = 1000 c.c. “hypo.” 
On the same principle, 
I, = Br2 
20)254 20)160 N 
127 8-o, so that 8 0 grms. Br is equivalent to 1000 c.c. —“ hypo.” 
(B) Estimation of Available Chlorine. 
Use ‘5 gramme of the solid or 5 grammes of the liquor. Put it into a 
flask with I*s gramme of KI dissolved in 100 c.c. of water, and then drop 
in HCI in excess. Lastly, titrate with “ hypo,” as already described. Then 
by the equations : 
For chlorinated lime and its solution. 
{a) CaO Cl 2 + 2HCI=CaCI2 + HsO + Cl 2, 
{b) Cl2 + 2KI=2KCI + 12,I2, 
(<r) 2(NasSso3 -5H20) + L=2Nal + Na2S406 + ioH20, 
we come to the result already shown for chlorine-water—namely, that 
2{Na2S.A-5H20) = Cl2 
20)496 20)254 2°)71 
24-8 = 127 = 3'55 
N 
therefore, 1000 c.c. —— “ hypo” represent 3'55 grammes “ available chlorine ’’ 
IO 
in all chlorinated compounds. 
Liquor sodce chlorinates. 
Use about 5 grammes, and proceed as for chlorinated lime. The action 
and calculations are the same, only differing in the first equation, which is 
Na2OCl2 + 2HCI=2NaCI + H2O + Cl 2. STANDARD SOLUTION OF POTASSIUM BICHROMATE. 
117 
{£) List of B. P. Standards by lodine and “ Hypo.” 
Sulphurous acid . . 5%502. Chlorine water . . . '6% Cl. 
Arsenious acid . . pure. Chlorinated lime . . • 33% Cl. 
Arsenious liquors . . i%As2O3. Liquor calcis chlor. . . 2to 3% Cl. 
Sodium hyposulphite . pure Liquor sodas chlor. . . 27% Cl. 
lodine sol. “ Hypo ” sol. 
VII. STANDARD SOLUTION OR POTASSIUM BICHROMATE. 
Strength = 1475 grammes IC2Cr207 in 1000 c.c. 
20 
(A) Preparation. 
Dissolve 1475 grammes pure K2Cr207 in one litre of water. 
Check.—If desired to standardise, we do so by performing an estimation 
upon -5 gramme (5 decigrammes) of pure iron (pianoforte) wire, dissolved in 
dilute H2S04 as described below. 
Principle of the process.—K2Cr207, when heated with an acid (say H2S04), 
gives 
therefore, each molecule of bichromate gives three atoms of nascent oxygen, 
which possesses the power of raising six atoms of iron from the ferrous to the 
ferric state, because 
K2Cr207 + 4H2504=K2504 -f Cr2 (504)3 + 4H20 + 03; 
6FeO + 03=3Fe203. 
(B) Estimation of Ferrous Salts, 
Bichromate solution is to be used for the following estimations : 
(a) Metallic iron. 
•5 gramme of the metallic wire or filings is dissolved by the aid of heat 
in dilute sulphuric acid, using a flask fitted with a cork through which passes 
a small tube to allow the exit of steam and hydrogen, but to prevent as far as 
possible ingress of air. While the iron is dissolving, 2 ounces of water are 
placed in a basin over the gas, and a burette charged with bichromate solution 
is arranged over it. A porcelain slab is also got ready at the right-hand side 
of the basin, and is covered over with spots, from a glass rod, of freshly made 
solution of potassium ferricyanide. When dissolved, the iron solution is 
rinsed from the flask into the basin, and immediately titrated with the 
bichromate, until a drop taken from the basin on the stirring rod just ceases 
to give a blue color when brought into contact with one of the spots of 
potassium ferricyanide on the slab. The number of c.c. of bichromate 
solution used is read off, and the following equations applied : 
6Fe + 6H2SG4 = 6FeS04 + 3H2 
20)336 20)912 
i 6-8 45’6 
6FeS04 + K2Cr207 + 7H2SQ4 = 3Fe2(504)3 + K2S04 + Cr2(S04)3 + ;H2O ; 
20)912 20)295 
' 45-6 14 7 5 
therefore 1475 K2Cr207=i6-8 Fe grammes, equivalent to 1000 c.c. 
20 
bichromate. 118 
VOLUMETRIC QUANTITATIVE ANALYSIS. 
(b) For ferrous sulphate, fenous phosphate, ferrous arseniate, and ferri 
carhonas saccharata. 
Use about r gramme in each case, dissolve in water by the aid of sulphuric 
or hydrochloric acid, then add a good excess of dilute H2SO4 or HCI, 
and titrate with bichromate solution as already described. Apply the 
equations as under : 
(1) Crystallised ferrous sulphate. 
K2Cr„07 + 6FeS04 • 7HaO + 7H2504 = 3Fe2(504)3 + K2S04 + Cr2(S04)3 + 14H..0 
20)295 20)1668 -j^T 
14-75 83-4 = grms., equivalent to xooo c.c. bichromate. 
(2) Real ferrous sulphate. 
K2Cr.p7 + 6FeS04 + 7H2504 = 3Fe2(504)3 + K2S04 + Cr2(S04)3 + 7H20 
20)295 20)912 N 
14'75 45 6 = gnus., equivalent to 1000 c.c. bichromate. 
(3) Ferrous phosphate. 
K2Cr207 + 2Fe3(P04)2.8H20 + 7H20 + 7H2504 = Fe2(S04)3 + 2Fe2(P04)2 + 
' ' [K2SO4 + Cr2(S04)3 + i 5H20 
20)295 20)1004 
1475 50-2 = grins., equivalent to 1000 c.c. 1 bichromate. 
20 
(4) Ferrous arseniate. 
K2Cr2Or + 2Fe3(As04)2 + yH.,O + 7H2504 = Fe2(S04)3 + 2Fe„(AsO4)2 + 
1 v ' [KoSO., + Cr2(S04)3 + 7F120 
20)295 20)892 
1475 44-6 = grms., equivalent to 1000 c.c. bichromate. 
20 
(5) Ferri carb. sacch. (dissolve in HCI, because H2S04 would char the 
sugar):— 
K2Cr207 + 6FeCO;{ + 26HCI = 3Fe2CI6 + 2KCI + Cr2Cl6 + 6C02 + 13BUO 
20)295 20)696 
1475 34'& = grms., equivalent to 1000 c.c. —bichromate. 
20 
The process may be applied to hcematite or any form of ferric iron by 
dissolving in and acidulating with hydrochloric add, and then dropping in 
zinc so as to evolve H2 and reduce the iron to the ferrous state. When all 
Zn has dissolved, and the solution has ceased to give a red with KCNS, it 
is litrated with bichromate in the usual way. 
(C) Estimation of Ferric Salts. 
(£>) B.P. Standards by Bichromate Solution. 
Iron ....... pure. 
Crystallised ferrous sulphate . . . 54-13% real FeS04 (=99% crystals). 
Granulated ~ ~ 54 real FeS04 (=lOO% crystals). 
Dried ~ ~ . . . 87-0% real FeS04. 
Ferrous phosphate 47% Fe3 (P04)2, 8H20. 
Ferrous arseniate 10% Fe3 (Aso4)2 
Ferrous carbonate sacch. . . . about 33% FeC03 
Instead of bichromate we may use a standard solution of potassium 
permanganate to estimate iron, simply running it in (in presence of excess of STANDARD SOLUTION OF POTASSIUM BICHROMATE. 
119 
H2S04) until a permanent pink color remains. Each molecule of K2Mn208 
gives 05, and therefore equals ten atoms of Fe in oxidation. 
VIII. FEHLING’S STANDARD SOLUTION OF COPPER. 
{A) Manufacture and Check hy the Ordinary Method. 
This solution is used for the estimation of sugars, and is made as follows : 
Dissolve 34'65 grammes of pure crystallised sulphate of copper in 250 c.c. 
water. Dissolve 173 grammes rochelle salt and 60 grammes KHO in 500 c.c. 
water. Mix the two solutions, and make up, when quite cold, to 1000 c.c. 
Each xo c.c. of this liquid will represent— 
Glucose .......... 'O5 gramme. 
Maltose .......... ’OB2 „ 
Inverted cane sugar '°475 » 
Inverted starch ......... ’045 ~ 
To check Fehling’s solution, weigh out -q75 gramme of pure sugar candy 
and dissolve it in 100 c.c. of water in a small flask; add 3 drops of strong 
HCI, and boil briskly for ten minutes to invert the cane sugar into glucose. 
Let it cool, neutralise with KHO, and then make up exactly to 100 c.c. with 
distilled water. Place this liquid in a burette arranged over a basin placed 
over the gas, and containing 10 c.c. of Fehling’s solution and 50 c.c. of 
water. When the contents of the basin are boiling, run in the sugar solution 
until all blue color is destroyed. Then note the number of c.c. of sugar 
solution used, and whatever that number may be, it will contain the equiva- 
lent in sugar of 10 c.c. of “Fehling.” If the “ Fehling” be correct, 10 c.c. 
of the standard sugar will be used to entirely precipitate it. 
It is usually necessary to do the estimation twice, first roughly and 
then accurately, using the second time drops of K4FeCy6 acidulated with 
acetic acid, on a slab, as an indicator for the disappearance of the last trace 
of Cu from solution. 
{B) Manufacture and Check by Pavy’s Method. 
Cuprous oxide dissolves in ammonia, forming a colorless liquid. Taking 
advantage of this point, Pavy treats an ammoniacal cupric solution at a 
boiling temperature with sufficient saccharine solution to exactly discharge 
the blue color. The advantage of this method over that above described 
lies simply in the fact that there is no bulky red precipitate to interfere with 
the ready observation of the end reaction. To prepare the test solution, 
dissolve 20-4 grms. of rochelle salt and the same weight of caustic potash 
in distilled water; dissolve separately 4-158 grms. of pure cupric sulphate in 
more water with heat; add the copper solution to that first prepared, and 
when cold, add 300 c.c. of strong ammonia, and distilled water to 1 litre. 
The process is conducted as follows: 10 c.c. of the ammoniated cupric solution 
(=O-005 grm. of glucose) are diluted with 20 c.c. of distilled water, and 
placed in a small flask. This is attached by means of a cork to the nozzle of 
a burette, fitted with a glass stopcock, and previously filled with the saccharine 
solution previously diluted to a fixed bulk. The cork of the flask should be 
traversed by a small bent tube, to permit steam to escape. Now heat the 
flask until the blue liquid boils. Turn the stopcock in order to allow the 
saccharine solution to flow into the hot solution—which should be kept at the 
boiling point—at the rate of about 100 drops per minute (not more nor much 
less), until the azure tint is exactly discharged. Then stop the flow, and note 
the number of cubic centimetres used. That amount of saccharine solution 120 
VOLUMETRIC QUANTITATIVE ANALYSIS. 
will contain 5 milligrammes of glucose. To render the determination as 
accurate as possible, the solution for analysis should be diluted to such an 
extent that not less than 4 nor more than 7 c.c. are required to decolorise the 
solution. 
To find the percentage of sugar, multiply 0-005 by the original total 
bulk (in c.c.) of the solution started with, and divide the product by the 
number of cubic centimetres of solution used from the burette. To observe 
easily the exact end-reaction, a piece of paper or other white body should be 
placed behind the flask. Mr. Stokes uses the half of an ordinary opal gas 
globe fixed in the proper position. If the operator objects to the escape of 
the waste ammoniacal fumes, they may be conducted by a suitable arrange- 
ment into water or dilute acid. For a special apparatus for this purpose 
see the Analyst, vol. xii. 
(C) Estimation of Sugar. 
The sugar weighed must not exceed -5 gramme, and must be dissolved 
in xoo c.c. of water. If the sugar be either glucose or maltose or lactose it 
is titrated directly ; but if cane sugar, it is first inverted as above described. 
By always placing 10 c.c. of “Fehling” in the basin, then whatever 
number of c.c. of sugar solution we use, that number will contain the 
equivalent of 10 c.c., and we have only to calculate : 
As No. of c.c. used : Total volume of sugar solution Equivalent of 10 c.c. “Fehling” of 
the sugar in question : Real sugar present in the quantity weighed out for analysis. 
(D) Estimation of Starch. 
Starch is weighed and boiled in a flask with water containing dilute hydro- 
chloric acid, under an upright condenser, for some hours. It is then cooled, 
neutralised with potassium hydrate, diluted to a fixed volume (not stronger 
than 1 in 200), and then the solution so made is titrated into 10 c.c. of 
“ Fehling.” A much improved process will be found in Chapter X. 
IX. ESTIMATION OE PHOSPHORIC ACID 
is performed by means of a standard solution of uranic nitrate in the presence 
of sodium acetate. The necessary solutions are, 
1. Standard solution of uranic nitrate, made by dissolving 70 grammes in 
900 c.c. of water, and then, after ascertaining its strength by performing an 
analysis on 50 c.c. of the standard phosphate solution, diluting with water so 
that 50 c.c. will correspond exactly to 50 c.c. of that solution. If absolutely 
pure uranic nitrate were obtainable, theory requires the solution of 71 grammes 
in one litre of water to yield a solution which will balance the standard phos- 
phate (each 1 c.c. = 1 gramme of PsOj). 
2. Standard phosphate solution, made by dissolving 50-42 grammes of 
perfectly pure disodium hydrogen phosphate in one litre of water, when each 
1 c.c. will equal *i gramme of P205. 
3. A solution of 100 grammes of sodium acetate and 100 grammes of acetic 
acid in water, and the whole diluted to one litre. 
4. Finely powdered potassium ferrocyanide. 
To perform the process, the solution of the phosphate in about 50 c.c. of 
water is placed in a basin on the water bath, mixed with 5 c.c. of solution 
No. 3 (sodic acetate), and No. 1 (uranic nitrate), is run in from a burette, 
until a drop taken from the basin on to a white plate just gives a brown color, 
when a little powdered ferrocyanide is cautiously dropped into its centre. The STANDARD SOLUTION OF BARIUM CHLORIDE. 
121 
number of c.c. of uranic solution used having been noted, the usual calcula- 
tions are to be applied. 
After repeated trials upon 50 c.c. of the standard phosphate solution, so 
as to thoroughly adjust the strength of the uranic solution, and at the same 
time accustom the eye to observe the exact moment of the appearance of the 
brown coloration, the process may be practically applied to Manures. 
The best method of preparing the solution of the manure is to heat 10 
grammes to dull redness for 15 minutes, and when cold to reduce it to a fine 
powder in a mortar, and add gradually 10 grammes of sulphuric acid diluted 
to 200 c.c. with water. Rinse the whole into a stoppered bottle, and make 
up with water to one litre. Shake up occasionally for an hour, and having 
then let all settle for three hours, draw off 100 c.c. (= 1 gramme manure) for 
analysis. To this add a little citric acid (10 drops of a cold saturated solution), 
and slightly supersaturate with ammonium hydrate. Again acidify with acetic 
acid, add 10 c.c. sodium acetate solution, and then use the uranic solution as 
usual. If all these quantities be rigorously adhered to, each c.c. of uranic 
■solution used can, without further calculation, be taken as indicating 1 
per cent, of tricalcium phosphate in the manure. 
This process is highly recommended by Mr. Sutton of Norwich, and elabo- 
rate details will be found in his work on Volumetric Analysis. 
X. STANDARD SOLUTION OF BARIUM CHLORIDE. 
This is used for taking the amount of a soluble sulphate, by adding it to a 
known weight of the sulphate ; dissolve in water acidulated with hydrochloric 
acid, until precipitation ceases. The process, however, is tedious, and the 
end of the reaction is not sharp, and it is therefore rarely employed. The 
following is a specimen of the reaction using magnesium sulphate : 
Semi-normal—104 grammes per 1000 c.c. of Bad?. 
MgSO.i" 78120 T BaCl2 BaSCV -h MgCl2 -h 7H20. 
Each c.c. of the standard solution equals '04503 or ’O4B SO4. 
The solution is made by dissolving 104 grammes of pure barium chloride 
dried at 220° F. in 1 litre of water. 
Made by dissolving i 3"546 grammes of pure mercuric chloride and 
grammes of potassium iodide in water, and then making up to 1000 c.c. 
This solution is used for the estimation of alkaloids, which should be free 
from any mucilaginous matter and preferably dissolved in a little dilute 
sulphuric acid. The reagent is added till precipitation ceases. In the 
author’s hands the process has not worked very well, except for the amount 
of emetine in ipecacuanha, which may be rapidly ascertained as follows ;—- 
15 grammes of ipecacuanha are treated with 1-5 c.c. of dilute sulphuric 
acid, and sufficient rectified spirit of wine added to make the whole bulk up 
to 150 grammes. The whole is allowed to stand for 24 hours, and 100 c.c. are 
decanted off for analysis. The liquid is evaporated until all the alcohol is 
driven off, and then brought under the burette containing the test solution, 
which is run in until it ceases to give a precipitate. The final point of the 
reaction is ascertained by filtering off a drop or two into a watch-glass placed 
on black paper, and adding a drop of the reagent, when, if no cloudiness 
appear, the precipitation of the alkaloid is complete. The number of c.c. of 
the test used multiplied by ‘OIB9 gives the amount of alkaloid in 10 grammes 
XI. STANDARD MAYER’S SOLUTION. 122 
VOLUMETRIC QUANTITATIVE ANALYSIS. 
of the sample, which again multiplied by 10 gives percentage. A full list of 
the equivalents of the various alkaloids to Mayer’s solution is found in the 
“ coefficient ” table at the end of this chapter. 
XII. ANALYSIS BY THE NITROMETER. 
{A) General Remarks. 
This useful instrument is illustrated in fig. 29. It consists of a measuring 
tube (a) graduated in cubic centimetres, having a funnel-shaped cup (c) 
connected to it by means of the stopcock (d). This cock is a “ three-way 
one, and according to the direction in which it is turned, it can make 
connection and discharge the contents of the cup either into the tube a 
or out in the waste opening at e ; or it can make, or quite shut off, all 
connection between (a) and the outer air through e. Connected to aby a 
piece of flexible indiarubber tube is the ungraduated control tube B. The- 
object of the apparatus is the rapid and accurate measurement, at definite 
temperature and pressure, of gases evolved during any reaction ; and it takes, 
its name from the fact that it was first used to measure the nitric oxide given 
off by the decomposition of nitric acid. Suppose that we 
fill the instrument with a fluid (say mercury) right up to 
the top : having closed the tap d, we lower the tube b 
and then admit a little carbonic anhydride through e ; by 
opening and again closing the top, we have a volume of gas. 
in the measuring tube which we desire to measure under 
definite condition. If (1) we allow the instrument to stand 
until its contents must have assumed the temperature of 
the room, then a centigrade thermometer suspended to the 
same stand will give the temperature of the gas ; (2) If we 
now raise or lower the control tube so that the level of the 
liquid both in it and in the measuring tube is the same, 
it is evident that the pressure inside a is the same as in 
the room, and reference to a barometer standing near 
will give that pressure. It now only remains to read off 
the volume of the gas in the measuring tube, and 
having corrected it to normal temperature and pressure by Charles’s and 
Boyle’s laws respectively, to calculate it from its volume in c.c. to its weight 
in grammes by multiplying the number of c.c. of volume at N.T.P. by the 
weight of 1 c.c. of the gas in grammes. This latter is easily obtained by 
multiplying the crith ('0896 gramme, weight of 1 litre of H) by the atomic 
weight of an elementary or half the molecular weight of a compound gas, and 
then dividing by 1000. Suppose, for example, that in the analysis of a 
nitrate or nitrite we have obtained 20 c.c. of nitric oxide at 150 C. and 750* 
m.m. barometer, and we require to know the weight of NO so got, that we 
may afterwards calculate therefrom the weight of the nitrate present, we 
should say : 
Fig. 29. 
(a) (273 +o) x 75° * 20_-_: 18788 c.c., corrected volume at N.T.P. 
(273 + 15) x 7t>o 
{/>) •°B9,6_>L_is = -001344 grm., weight of I c.c. NO. 
xooo 
(V) 18788 x -001344 = ‘0253 grm., weight of NO found. 
The various possible applications of this instrument are so numerous that 
an exhaustive detail would be impossible in the present work ; but the following, 
should be practised as typical instances of its use : ANALYSIS BY THE NITROMETER. 
123 
(B) Estimation of the Strength of Spirit of Nitrous Ether. 
The active principle of this drug is ethyl nitrite. Nitrites when mixed 
with excess of potassium iodide and acidulated with sulphuric acid cause 
a liberation of iodine and evolve all their nitrogen in the form of nitric oxide, 
thus ; 
CoH5 • N02 +KI + H2S04= C 2H5 •HO + KHSO4 +1 + NO. 
The process (originally due to Mr. Allen) has been recognised officially for 
the assay of the spirit, and is thus conducted. The nitrometer is filled 
with saturated solution of sodium chloride, with which owing to its density a 
strong spirit will not readily mix, and so we save the expense of mercury; 
5 c.c. of the sample to be tested is placed in the cup of the nitrometer, 
and the control tube having been lowered, the spirit is allowed to enter 
through the tap, taking care that no air gets in at the same time. 5 c.c. 
of a strong solution of potassium iodide is next allowed to enter, and this 
is in turn followed by 5 c.c. of dilute sulphuric acid. Effervescence 
immediately occurs, and if the tube be vigorously agitated at intervals, the 
reaction completes itself in 10 minutes. The level of the liquid in the 
control tube of the instrument is adjusted to equal that in the measuring 
tube, and the volume of nitric oxide is read off and calculated. For official 
purposes it is however sufficient to see that the resulting gas is seven times 
(or at all events not less than five times) the volume of the spirit started 
with. The least trace of air allowed to enter with the liquids vitiates the 
results of the process, because the nitric oxide would be thereby converted 
into a higher oxide of nitrogen and so become soluble in the fluid with 
which the instrument is charged. 
(C) Estimation of Nitric Acid in Nitrates. 
This depends on the fact that when a nitrate is shaken up with excess of 
sulphuric acid and mercury the following reaction takes place 
2 KNOg + 4H2504 + sHg= 3 HgS04 4- K2S04 +2N 0 + 4H20,— 
thus showing that each molecule of the nitrate radical N03 gives off a 
molecule of NO. If any chlorides or other haloid salts be present they are 
first removed by adding a slight excess of argentic sulphate to the solution 
and filtering. No quantity of a nitrate exceeding 2 decigrammes should be 
used, otherwise more gas may be evolved than the instrument will con- 
veniently hold. The nitrometer is charged with mercury, and the nitrate 
solution, which should not exceed 5 c.c., is put into the cup and passed 
therefrom into the measuring tube followed by excess of strong sulphuric 
acid. The instrument is well agitated for some time, and when action has 
ceased and the contents have cooled down to the temperature of the room, 
the level is adjusted and the volume of NO read off and calculated. All 
the precautions already mentioned must be observed. If any nitrites be 
present, they affect the accuracy of the estimation, being also decomposed 
to nitric oxide. 
{£>) Estimation of a Soluble Carbonate. 
This has been proposed for use in taking the strength of the medicinal 
solution of ammonium carbonate in the spirit known as spiritus ammonia 
aromaticus. A given volume of the spirit is placed in the cup and introduced 124 
VOLUMETRIC QUANTITATIVE ANALYSIS. 
into the nitrometer charged with mercury. This is followed by an excess of 
dilute hydrochloric acid, and the carbon dioxide evolved by the action of the 
acid upon the carbonate is measured. From this the percentage of ammonium 
carbonate may be calculated, or an empirical comparison of volume on the 
principle of that already described for spirit of nitrous ether may be applied. 
According to Mr. Gravill, the originator of the test, good aromatic spirit of 
ammonia should give off seven times its volume of carbon dioxide after allowing 
a correction for the slight solubility of the gas in the liquid with which it is 
inclosed. 
This depends upon the fact that, when hydrogen peroxide acts upon 
potassium permanganate, acidulated with sulphuric acid, oxygen is evolved. 
One half of this oxygen is due to the peroxide and the other to the 
permanganate. The nitrometer should be charged with concentrated solution 
of sodium sulphate (which in this case is better than brine), and one cubic 
centimetre of the solution is introduced from the cup followed by excess 
of a strong solution of potassium permanganate acidulated with sulphuric 
acid. The contents of the measuring tube, after the reaction is complete, 
must remain colored violet, thus showing that sufficient permanganate has 
been employed. A solution commercially described as of 10 per cent, 
strength by volume should when thus treated give off twenty times its volume 
of oxygen. 
(E) Estimation of the Strength of Solutions of Hydrogen Peroxide. 
(F) Estimation of Urea in Urine. 
This process depends on the fact that when urea is decomposed by an 
alkaline hypobromite or hypochlorite, it gives off its nitrogen in the free 
state. A small flask is fitted with a tight cork through which passes a funnel 
tube closed by a clamp and reaching to the bottom of the flask and also 
a bent delivery tube just passing through the cork. 5 c.c. of the urine is 
placed in this flask, and the nitrometer having been filled with water the flask 
is attached to the tap of the nitrometer at the end e (see fig. 29, page 122). 
An excess of a solution of bromine in sodium hydrate solution is then placed 
in the funnel and allowed to run into the urine, and the clamp immediately 
closed. At the same moment the tap of the nitrometer is so placed as 
to establish connection between e and the measuring tube. A little warm 
water in a basin is applied to the flask to hasten the reaction, and when no 
more gas is evolved, the tap is closed, the temperature and pressure adjusted, 
and the volume read off as usual. Each c.c. of gas at N.T.P. represents 
•0029 gramme of urea present in the 5 c.c. of urine acted upon. 
XIII. COLORIMETRIC ANALYSIS. 
General Remarks. 
This is a variety of volumetric analysis in which the amount of a substance 
present in solution is found by adding, to a given volume, a fixed quantity of 
a reagent and observing the color produced. This color is then matched by 
adding, to an equal volume of distilled water, the same mixed quantity of 
reagent, and running in a volumetric solution of the pure substance until the 
same tint is produced. Evidently when this point is reached the amount of 
substance present in the solution under analysis equals that in the volumetric COLORIMETRIC ANALYSIS. 
125 
solution used for the comparative experiment. The applications commonly 
occurring of this method are ; 
{A) Estimation of Ammonia by “Nesslerising.” 
For this process the following solutions and apparatus are required : 
(a) Nessler’s solution. Dissolve 35 parts of potassium iodide in 100 
parts of water. Dissolve 17 parts of mercuric chloride in 300 
parts of water. The liquids may be heated to aid solution, but 
if so must be cooled. Add the latter solution to the former 
until a permanent precipitate is produced. Then dilute with a 
20 per cent, solution of sodium hydrate to 1000 parts; add 
mercuric chloride solution until a permanent precipitate again 
forms; allow to stand till settled, and decant off the clear 
solution. The bulk should be kept in an accurately stoppered 
bottle, and a quantity transferred from time to time to a small 
bottle for use. The solution improves by keeping. 
if) Standard ammonia solution. Dissolve 3'146 grammes pure ammo- 
nium chloride in 1000 c.c. of distilled water free from ammonia. 
For use dilute 10 c.c. of this solution to 100 c.c. with ammonia- 
free distilled water. Each c.c. of the diluted solution will then 
contain *i milligramme of NH3 (i.e. -oooi gramme). 
(c) Two narrow cylinders of colorless glass, of perfectly equal height 
and diameter, holding about 150 c.c., and graduated at 100 c.c. 
These should either have a milk glass foot or should stand 
upon perfectly white paper. 
(d) A pipette to deliver i- c.c. 
(e) A quantity of ammonia-free distilled water. This is obtained by 
placing a litre of ordinary distilled water in a retort attaching 
a condenser (see Chap. 1., page 4), and distilling until what 
passes over ceases to give any color with “Nessler’s solution,” 
The remaining water in the retort is then cooled and bottled 
for use. 
The liquid in which ammonia is to be estimated (usually a distillate ob- 
tained in water analysis) is first made up to a fixed bulk, and the bulk noted. 
It must be so diluted that it only gives a color and not a precipitate with 
“Nessler.” 100 c.c. of this solution are placed in a cylinder, and ir|c.c. 
of “ Nessler ” having been added by the pipette, and the whole stirred with 
a perfectly clean rod, the color produced is observed. A little experience 
soon teaches the operator to judge the probable amount of ammonia solution 
required to produce a similar tint. Let us suppose, for example, that the 
color is judged to be equal to 2 c.c. of ammonia, then we proceed to confirm 
our idea : 2 c.c. of the standard ammonia solution are run from a burette 
into the other cylinder, ammonia-free water is added to 100 c.c., then the 
1 i c.c. of “Nessler,” and the whole stirred with the clean rod. If now, after 
a few minutes, the colors match, we are correct; but if not, then we must try 
again and again with more or less standard ammonia until we get an exact 
match between the colors in the two cylinders. This having been attained, 
the calculation is very simple, and will be best explained by an example. 
Suppose that we start with a distillate containing ammonia and made up 
to 200 c.c., and that we employ 5 c.c. of standard ammonia solution in the 
comparison experiment, to match the color produced by “Nessler” in 100 c.c. 126 
VOLUMETRIC QUANTITATIVE ANALYSIS. 
of such distillate. Then 5 c.c Xt = *5, and ‘5 x 2=ro ; therefore the 
whole 200 c.c. of distillate contained 1 milligramme of NH3. Beginners 
should train their eyes by observing the colors produced by adding various 
quantities of standard ammonia to 100 c.c. of ammonia-free water and then 
introducing the “ Nessler,” T- of a c.c. of standard ammonia will produce 
a very faint yellow, while larger amounts will increase the color to orange, 
and finally to deep orange-red. We should always wait 3 minutes before 
observing, as the full color does not appear under that time. 
(B) Estimation of Salicylic Acid. 
The substance containing the salicylic acid is slightly acidulated with 
hydrochloric acid, and then shaken up with ether in a separator. The ether 
is drawn off and evaporated, and the residue is dissolved in water and 
diluted to a fixed bulk until it gives a suitable violet color, with a few 
drops of ferric chloride. 100 c.c. of the solution are then treated with 
10 drops of solution of ferric chloride; and the color having been observed, 
it is imitated in the other cylinder by a very dilute standard solution of pure 
salicylic acid made to 100 c.c. with distilled water and a similar number of 
drops of ferric chloride, exactly like the nesslerising process above described. TABLE OF COEFFICIENTS. 
127 
XIV. TABLE OF COEFFICIENTS REQUIRED IN THE VOLUMETRIC 
ANALYSIS DESCRIBED IN THIS CHAPTER. 
Standard Acid Solution." coeff. 
Oxalic acid . . . . . ‘063 j 
Sulphuric acid .... "049 
NH3 -017 
NH4HO -035 
NH4HC03.NH4NH2C02 . . -0523 
Na2B207. ioH20 . -191 
Pb(C2H302)23H20 .... -1895 
Pb.,0(C.,H3b2)2- .... -137 
CaiHO -037 
CaO -028 
CaC03 -05 
Ba(HO).? -0855 
Ba(H0)28H20 . . . -1575 
BaC03 -0985 
MgO -02 
MgCOa -042 
KHO 056 
K2C03 -069 
K2C03 +l6 °/0 Aq . . . -08214 
K0C4H4b6 (converted into K.,C03) . -113 
(tC.,H406)2H20 . . ‘ . . -H75 
KHC4H4Os -188 
K3C6H507 -IC2 
kc2h3o2 . . . . . 098 
K2Mn208 (by oxalic acid) . . -0314 ■ 
KNaC,H4O6 -141 
NaHO ...... -04 
Na2C03 -053 
Na.2C03. xoH,;O . . . . -143 
NaHC03 -084 
Standard Soda Solution. 
Sodium hydrate . . . . "04 
HC2H302 -06 
h3c6h5o7h„o . . . . -07 
HCI ’0365 
HBr -0808 
HI -128 
HN03 ’063 
H2S04 -049 
H2C4H406 ..... -075 
HC3HSO3 (lactic) .... -09 
H2C2042H20 063 
Standard Nitrate of Silver Solution. 
Argentic nitrate . . . -017 
CN -0052 
HCN -0054 
KCN -01302 
NH4CI -00535 
KCI ’00745 
NaCl ’00585 
KBr 0119 
Naßr -0103 
Na.,HAs04 -0064 
Cl" -00355 
Standard lodine Solution, coeff. 
lodine . . . . . ‘0127 
502 -0032 
H2S03 -0041 
As„03 ’00495 
Na2S20s5H20 -0248 
Na2S03yH20 ‘0126 
K2S032H20 -0097 
Standard Bichromate of Potassium. 
Potassium bichromate . . . ‘01475 
Fe( Ferrous) -oi6B 
FeSO, ‘0456 
FeS042H20 ‘O5l 
FeSOjH'O . . . . -0849 
Fe3(AsO,)„ -0446 
Fe3(P04)2 ’ ‘0358 
FeC03 ‘0348 
Fe304 ‘0696 
FeO ‘0216 
Standard Hyposulphite Solution. 
Hyposulphite of sodium . . . -0248 
I -0127 
Cl -00355 
Br . , . . . . . ‘OOBO 
Standard Barium Chloride Solution, 
Barium chloride (BaC!„) . . ‘lO4 
BaCUH.,O . . ' . - . ‘122 
H.,S04 '. -049 
S04 ‘O4B 
503 ‘O4O 
Standard Mayer’s Solution. 
Aconitine ..... ‘0267 
Atropine (1-200) .... -0097 
Nepaline ..... ‘O3BB 
Hyoscyamine (1-200) . . . -00698 
Emetine ...... -0189 
Coniine ...... -0125 
Nicotine ...... -00405 
Strychnine . . . . . -0167 
Brucine -0197 
Colchicine (1-600) . . . . -0317 
Morphine "02 
Narcotine ..... -0213 
Veratrine ..... "oaqb 
Sabadilline ’°374 
Sabatrine ..... "03327 
Physostigmine .... "01375 
Berberine ..... "0425 
Nitrometer Analysis. 
{ ‘00282 HN03 
\ -00262 N2O- 
- ‘00452 KN03 
•00336 C 2H5. NO, 
( ‘OO2O Urea 
Each cc. of NOatN.T.P. 
equals gramme of 
Each cc. of C02 at N.T.P.) 
equals gramme of ( 
•0043 (NH4)2co3 128 
CHAPTER VIII. 
GRAVIMETRIC QUANTITATIVE ANALYSIS OF METALS 
AND ACIDS. 
DIVISION I.—PRELIMINARY REMARKS. 
Gravimetric quantitative analysis is that method by which the substance to 
be estimated is converted into some chemically definite compound, weighed as 
such, and the amount of the original substance obtained from this weight by 
calculation. The same definite compound will answer both for the estimation 
of its metal and of its acid. For example, if we precipitate a known weight of 
argentic nitrate with hydrochloric acid we obtain insoluble argentic chloride 
which may be filtered out and weighed and the amount (x) of Ag in the 
quantity started with calculated therefrom, because,— 
AgCl: Ag : : weight of AgCl found: x. 
143-5: 108: : » >» » •' x. 
If, on the other hand, we start with a known weight of hydrochloric acid, 
precipitate it with argentic nitrate, and collect and weigh the argentic chloride 
formed, we can find the amount (x) of real HCI actually present in quantity 
started with, because,— 
AgCl: HCI; : weight of AgCl found : x. 
143'5 : •' •' » » » :.*• 
Before giving the individual processes for the quantitative estimation of the 
various metals, we must first say something about the preparation of filters, 
and the washing, drying, and weighing of precipitates, which will serve as 
general directions and so save continual repetition of details. 
(A) The Preparation of Filters. 
Ready-cut filters may be procured from the dealers in chemical apparatus. 
The kind known as Swedish is the best for all cases where the precipitate is 
finely divided or pulverulent. For gelatinous precipitates, such as ferric hydrate 
and calcium phosphate, the white English filters are preferable ; but they 
should never be used, say, for barium sulphate or calcium oxalate, as those 
bodies would very likely pass through the pores of the filter, and so cause a 
loss in the analysis. The only drawback to Swedish papers is their filtering 
rather slowly. Whatever paper be used, the size for quantitative operations is, 
for the larger sort, six inches in diameter, for the smaller, about two inches. 
The small sort is used where we have to deal with traces of precipitate only, 
or when a small quantity of fluid has to be filtered. The paper should yield 
nothing to dilute acids, and if the ash exceed one milligramme per large filter 
it will in most cases be remedied by placing, say, 100 cut filters for some PRELIMINARY REMARKS. 
129 
hours in a basin filled with a mixture of one volume of HCI and eight volumes 
of water. They must then be repeatedly washed with distilled water till quite 
free from acidity, otherwise they would crumble to pieces when being folded. 
The washing is a very tedious operation indeed, and having been completed, 
the basin is put on to a water bath till the filters are perfectly dry. 
(.B) Estimation of the Ash of Filters. 
This is most conveniently done by folding ten filters in a small compass, 
twisting a long platinum wire round the packet so as to form a cage, holding 
the free end in the hand and the paper over a previously weighed platinum 
crucible while touching it with the flame of a Bunsen burner. The paper 
burns and the ash drops into the crucible, while any particles of carbon which 
have escaped combustion are quite consumed by exposing the crucible for 
some time to a red heat till the ash gets perfectly white. The crucible after 
cooling is re weighed, and its increase is the ash of ten filters. Divided by 10, 
we get the ash of one filter; and in every case where both filter and precipitate 
are burned, the ash of the filter thus found must always be deducted from 
their total weight, and the difference is then the actual weight of the 
precipitate. 
(C) The Collection and Washing of Precipitates. 
When the precipitate has been fully formed and the supernatant fluid has 
become quite clear, the latter is poured on the filter (which is either previously 
tared or not according to circumstances), care being taken not 
to disturb the precipitate. This is done by holding a glass rod 
in a perpendicular position over the filter, placing the lip of the 
beaker against it and causing the liquid to flow steadily down 
the rod into the filter. When the latter is three-fourths full, the 
beaker is turned into an erect position and the rod drained 
against the inside of the lip and then laid across the top of the 
beaker until it is time to refill the filter. After thus pouring off 
as much as practicable, the precipitate remaining in the beaker 
is treated with water and well stirred. When the whole has once 
more settled, the clear fluid is again passed through the filter. 
This operation having been repeated three or four times, the 
precipitate is allowed to pass on to the filter, any particles which stick to 
the sides of the beaker being removed with a feather, or a rod tipped with a 
small piece of black india-rubber tubing ; and the whole having been thus 
collected, the washing is continued by means of a washing-bottle (fig. 30), till 
the precipitate is quite freed from its soluble impurities. For instance, in 
estimating sulphuric acid, the barium sulphate is washed till the filtrate no 
longer gives a turbidity with argentic nitrate. 
Many bodies, as ferric and aluminic hydrate, most phosphates, barium sul- 
phate, and some of the carbonates, are best washed with boiling water. Others, 
on the contrary, must be washed with cold water,— such as plumbic sulphate, 
for which we use cold water acidified with some H2SO4; magnesium 
ammonium phosphate, for which cold dilute ammonium hydrate is used, etc. 
Fig. 30. 
After the precipitate has been thoroughly washed and perfectly drained, 
the funnel containing it is loosely covered over with filter paper and then put 
into the water oven or air bath till dry. Most precipitates are dried at a 
temperature of 2120 F., but some of them require a heat of 220° F. before 
(Z>) Drying of Precipitates. 130 
QUANTITATIVE ANALYSIS OF METALS. 
becoming constant in weight. Prolonged and repeated drying is only necessary 
when the precipitate is weighed on the filter, as described below. Fig 31 
shows a water oven for drying at 2120 F., while fig. 32 shows an air bath for 
drying at higher temperatures. This bath is fitted with an apparatus for 
automatically controlling the gas supply, and consequently the temperature. 
(£) Igniting and Weighing of Precipitates. 
Fig. 31. 
Fig. 32. 
Most precipitates must first be ignited before they can be weighed. This 
is to drive off water, which they may still retain after drying at 2120 F., or 
carbonic anhydride and water. For instance, zinc is best weighed as oxide, 
and therefore the precipitate, consisting of oxycarbonate, is first ignited. Iron 
is precipitated as hydrate, but the composition of that body not being constant, 
it is ignited and so made into pure oxide before weighing. As soon, therefore, 
as the precipitate appears dry, it is carefully detached from the filter and 
put into a previously ignited and weighed crucible, the filter is burned on the 
lid (which has been weighed together with the crucible), the ash is thrown into 
the crucible, and the latter covered with the lid. The crucible is now sup- 
ported by a pipe-clay triangle, and gently ignited at first, to prevent spurting 
from the sudden evolution of steam or other gases. The lid is now taken 
off, and the crucible inclined a little, so as to give a free access of air. The 
ignition is continued for some minutes, and the crucible, having been again 
covered with the lid, is allowed to cool and weighed. For accurate estima- 
tions it is best to let it cool under a desiccator. Such an arrangement is 
shown in fig. 33, in which a is a vessel containing strong sulphuric acid to 
keep the air under the glass shade always free from moisture. 
The heat of an ordinary Bunsen burner is generally sufficient for all pur- 
poses ■ but the conversion of calcium carbonate into oxide requires the aid of 
a gas blowpipe; while argentic chloride must be heated with a rose Bunsen 
or spirit lamp until it just begins to fuse. The filters are, as already shown, 
burned separately, to prevent any reduction of the precipitate by the carbon of 
Fig. 33. 
Fig. 34. 
Some precipitates are not ignited but weighed on a previously tared filter. 
Before weighing the filter —for which purpose a weighing tube (fig. 34) is used, PRELIMINA R V REM A RES. 
131 
or the filter is placed between two closely-fitting watch-glasses provided with a 
clamp to hold them together—it must first be dried for fifteen minutes at 
2120 F. After drying the precipitate, the filter is again placed in the tube or 
between the glasses and reweighed; the increase shows, of course, the weight 
of the substance. It is well to replace the filter in the bath for, say, half an hour, 
and to weigh again. Should the weight be considerably less, it must be once 
more put into the bath and reweighed. Another method of weighing precipi- 
tates on a filter is to prepare two filters of equal size, a and b. Cut off the 
bottom point of B, so that a will go inside it with its point projecting through 
the opening. Now put bon the weight scale of the balance, and cut off minute 
slices from the top of a until the two are exactly counterbalanced. Place A 
inside b, and then, having put both in the funnel, collect the precipitate, wash, 
and dry as usual, and cool under the desiccator. Lastly, detach b, and use 
it for a tare, putting it into the weight pan, and then the weights required to 
balance a and its contents will be the weight of the precipitate, because both 
filters having been exposed to the same conditions the tare is accurate. 
{F) Estimation of Moisture. 
A watch-glass is exactly tared on the balance, and then 2 grammes of the 
substance (in powder if possible) are carefully weighed upon the glass, and the 
total weight noted. The glass, with contents, is then placed in the drying 
oven and heated therein for an hour, at the expiration of which it is removed 
to the desiccator, and wrhen cold, is weighed and the weight noted. It is 
then replaced in the oven for half an hour, and the cooling and weighing 
repeated. If the two weights do not agree within, say, 2 milligrammes, the 
process is repeated until two concordant weighings are obtained. The weight 
after drying deducted from the total weight of glass + substance started with 
gives the moisture, which figure multiplied by 50 gives percentage. 
[G) Estimation of the Ash of Organic Bodies. 
This determination is necessary in every analysis of a vegetable or animal 
substance. A platinum dish is heated to redness, cooled under the desiccator, 
weighed, and the weight noted. A suitable quantity, say sto 10 grammes of 
the substance, is weighed into the dish, which is then arranged on a triangle 
support over a Bunsen burner and heated to dull redness. If after fumes 
cease the substance is seen to have assumed a coke-like form, it is removed 
from the dish into a small dry mortar, and having been carefully powdered, 
the powder is replaced in the dish and maintained at a dull red heat until it 
has become perfectly white, or at least until all carbon has been burned off. 
If the burning proves very tedious and the last traces of carbon are very 
difficult to burn, the addition of a light sprinkling of ammonium nitrate will 
cause the process to complete itself more rapidly. The dish is now cooled 
under the desiccator and weighed, and the weight of the empty dish having 
been deducted, the difference gives the weight of the ash, which is then cal- 
culated to percentage. The heat should not be allowed to rise to bright 
redness, because potassium and sodium chlorides, which are very common 
constituents of the ash, would be thereby volatilised to some extent and so 
lost. 
(M) Analytical Factors for Calculating the Results of Analyses. 
To save the working out of a rule of three sum on the result of each 
analysis it is customary to employ factors. These are obtained by dividing 
the weight of the required body by the equivalent weight of the form in QUANTITATIVE ANALYSIS OF METALS. 
which it is precipitated. Thus, supposing we are estimating the amount of 
argentic nitrate present in a solution containing ‘6 gramme of the salt, and 
have precipitated and weighed the same in the form of argentic chloride, we 
have : 
Molecular weight of AgNOa 170 .... 
Equivalent weight of AgCl 14.3-5 ~ analytical factor. 
It now only remains to multiply this factor by the weight of the precipitate 
to obtain the answer. Let us further suppose that the weight of the precipi- 
tate was '5 gramme, then nSq) x -5 = ‘59235 real AgNOg present in the 
X 100 
•6 gramme taken; then NzS? = 9873 per cent, real AgNOg present 
•6 
in the sample. 
DIVISION 11. GRAVIMETRIC ESTIMATION OF METALS. 
1. ESTIMATION OF SILVER. 
{A) As Argentic Chloride. 
(Practise upon ‘5 gramme pure AgNOg dissolved in 100 c.c. H20.) 
Silver is most conveniently weighed as chloride, because this body is per- 
fectly insoluble in water and dilute acids, and separates readily. The silver 
solution to be estimated is acidified with nitric acid, and hydrochloric acid is 
dropped in until no more precipitate forms. It is best to have the solution 
warm, and to stir till the supernatant liquid has got perfectly clear. The clear 
fluid is now poured off through a filter, and the chloride is washed by decan- 
tation with boiling water, always pouring the washings through the filter, till 
every trace of acid is removed, and subsequently brought upon the filter. The 
filter and contents is then dried in the water oven, and the chloride transferred 
into a weighed porcelain crucible, and heated till it just commences to fuse. 
The filter is burned on the crucible lid, and the ash treated with a drop of 
aqua regia, the resulting chloride dried, the lid placed upon the crucible, and 
the whole weighed. The tare of the crucible and lid having been deducted, 
the balance is AgCl, from the quantity weighed out for analysis. 
(B) As Metal. 
If silver is required to be estimated in organic salts, and other bases are 
absent, the analysis is performed by igniting a weighed quantity of the salt, 
and weighing the ash, which will consist of pure metallic silver. 
In alloys the pure metal is obtained by cupellalion, as follows :—The weighed 
alloy is wrapped in lead foil, placed on a little cup or cupel made of bone ash, 
and heated to bright redness in a muffle furnace. The lead oxidises and 
sinks into the cupel, carrying the impurities with it, and leaving a button of 
pure silver, which is cooled and weighed. 
2. ESTIMATION OF LEAD. 
(.A) As Plumbic Oxide. 
(Practise upon -5 gramme pure plumbic acetate.) 
The solution containing the substance to be analysed is precipitated with 
ammonium carbonate in the presence of a little ammonium hydrate. The 
precipitated plumbic carbonate is then collected on a small filter, washed, and ESTIMATION OF MERCURY. 
dried. The dry precipitate is removed as completely as possible from the 
filter-paper, and introduced into a weighed porcelain crucible. The filter 
having been burned on the lid, and its ash added to the contents of the 
crucible, the whole is ignited, cooled, and weighed. By ignition, the oxide 
is formed ; and after deducting the weight of the crucible, the balance is PbO, 
from the quantity weighed out for analysis. Organic salts of lead require 
simply to be ignited in a tared porcelain crucible, with free access of air, 
adding towards the end a sprinkling of ammonium nitrate, and weighing the 
resulting PbO. 
(b) As Plumbic Chromate. 
(Practise upon ‘5 gramme of plumbic nitrate.) 
The solution is mixed with excess of sodium acetate and precipitated with 
potassium chromate. The precipitate is collected, washed with water, acidu- 
lated with acetic acid, dried and ignited in a platinum crucible with the usual 
precautions. The filter is burned on the lid, treated with a drop or two of 
nitric acid, dried and again ignited. The crucible and contents are weighed, 
and the tare of the crucible having been deducted, the balance is PbCrCL, from 
the quantity weighed out for analysis. 
Lead may also be precipitated as PbSCb, dried, ignited and weighed as such. 
3. ESTIMATION OF MERCURY. 
(a) As Metal. 
(Practise upon 1 gramme of “white precipitate,” which should yield tj‘s % Hg.) 
Take a combustion tube of hard glass closed at one end, and put in : (x) a 
little magnesite—MgCOs; (2) the white precipitate mixed with excess of quick- 
lime ; (3) a few inches of quick-lime ; (4) a loose plug of asbestos. Draw out 
the open end of the tube before the blowpipe and bend it down at a right angle. 
Give the tube a tap or two on the table to insure a free passage along the upper 
part for gases, and place it in a combustion furnace, with its open end dipping 
under the surface of some water in a small flask. Apply heat to the front part 
of the tube and go gradually backwards until the whole is heated to redness 
and the CO2, given off by the MgCOs, has swept all the mercury vapor out of 
the tube. The mercury collects as a globule under the water in the basin, and 
is transferred to a tared watch-glass, perfectly dried by pressure with blotting- 
paper, and weighed. 
(/;) As Mercuric Sulphide. 
(Practise upon ‘5 gramme of mercuric chloride.) 
Through the solution of the mercuric salt a current of H2S is passed till 
the liquid is saturated. It is necessary the mercury should be all in the mer- 
curic state, and not contain other metals precipitable by H2S. The precipitate 
is collected on a weighed filter, washed first with water, then with absolute 
alcohol, and finally, to remove any free sulphur, with a mixture of equal parts 
of ether and carbon disulphide. After drying at 2120 F. and weighing, the 
balance is HgS from the quantity weighed out for analysis. 134 
QUANTITATIVE ANALYSIS OF METALS. 
4. ESTIMATION OF CADMIUM. 
(Practise upon -5 gramme of CdC03 dissolved in diluted HCL) 
As Sulphide. 
The solution is precipitated with ammonium hydrate and ammonium suh 
phide. The cadmium sulphide is collected in a weighed filter, washed, dried 
at 2i2° F., and weighed. This process is only applicable in the absence of 
metals also precipitable by ammonium sulphide. In the presence of metals of 
the fourth group the solution must be slightly acidified with hydrochloric acid 
and precipitated by a current of sulphuretted hydrogen. 
5. ESTIMATION OF COFFEE. 
(a) As Cupric Oxide. 
(Practise upon *5 gramme of pure CUSCVSH2O.) 
The solution (freed from other metals if necessary) is boiled with a slight 
excess of sodium hydrate. The precipitate is filtered out, washed, and dried. 
It is then carefully removed from the paper to a weighed crucible, and the 
filter having been burned on the lid and the ash added to the contents of the 
crucible, the whole is well ignited, cooled in a desiccator, and weighed rapidly, 
because cupric oxide is very hygroscopic. To make sure that the oxide con- 
tains no cuprous oxide, it is moistened with a little fuming nitric acid, dried 
with the lid on, ignited for ten minutes, and then reweighed. This operation 
requires care, being liable to involve loss by spurting. 
(h) As Metallic Copper. 
The solution, which must be free from metals precipitable by electrolysis, is 
introduced into a weighed and very clean platinum basin. It must contain a 
slight excess of sulphuric acid, but on no account nitric acid. The dish is 
then attached to the wire from the zinc plate of a galvanic cell, thus becoming 
the cathode. The other wire is connected to a piece of platinum wire to form an 
anode, and this latter is then immersed in the liquid. After a short time the 
fluid will become quite colorless, and the basin will be coated with metallic 
copper. The fluid is now poured off, and the copper repeatedly washed with 
boiling water till all acidity is removed. The basin is finally rinsed with 
absolute alcohol, quickly dried, weighed, and the tare of the basin having been 
deducted the difference is metallic copper in the quantity weighed out for 
analysis. 
The use of a battery may be dispensed with and a fragment of pure zinc 
used to precipitate the copper on the basin with sufficient acid to dissolve all 
the zinc before pouring off. 
6. ESTIMATION OF BISMUTH. 
(a) As Bismuth Oxide. 
The solution for analysis (freed, if necessary, from other metals) is diluted 
with water, and precipitated with a slight excess of ammonium carbonate. 
The precipitated bismuthous oxycarbonate is collected, washed and dried. 
It is then separated from the filter paper, and the latter having been burned 
on the lid of a weighed crucible, the whole is introduced into the crucible, 
and ignited, cooled, and weighed. ESTIMATION OF GOLD, PLATINUM, AND TIN. 
135 
(b) As Bismuth Sulphide. 
(Practise upon 75 gramme of bismut hi et ammonia citras B. P.) 
This process (although employed in the 8.P.) cannot be much recommended, 
as the sulphide is apt to increase in weight on drying, owing to the absorption 
of oxygen. A current of sulphuretted hydrogen is passed through the acid 
bismuth solution ; the resulting sulphide is collected on a tared filter, dried at 
2120 F., and weighed. 
7. ESTIMATION OE GOLD. 
As Metallic Gold, by Cupellation 
The alloy containing the gold is treated exactly as described under silver. 
The resulting metallic button is rolled out into a flat foil, and is then digested 
with nitric acid, which dissolves any silver, and the resulting gold is re-fused 
into a button and weighed. 
8. ESTIMATION OF PLATINUM. 
As Metallic Platinum. 
The solution, which must contain the platinum as chloride, is concentrated 
and precipitated with excess of ammonium chloride. The precipitate is well 
washed with spirit of wine, dried, ignited, and weighed, as metallic platinum. 
9. ESTIMATION OF TIN. 
(a) As Stannic Oxide. 
Alloys containing tin, but free from antimony or arsenic, are treated with 
nitric acid, which converts the tin into oxide and other metals into nitrates. 
The acid fluid is evaporated nearly to dryness, the residue taken up with 
water and a little nitric acid; the oxide is washed by decantation, collected 
on a filter, completely washed and dried. It is then as completely as possible 
detached from the filter, the latter is burned on a lid, the ash added to the 
contents of the crucible, and the whole ignited. After cooling the oxide is 
moistened with a little nitric acid, dried (with the lid on), and again ignited, 
when, after cooling, it is ready for weighing. 
Where we have to deal with tin in solution, the following method is 
applied ; 
The solution, which must be free from metals of the first three groups, is 
precipitated with sulphuretted hydrogen, the resulting sulphide is washed with 
solution of ammonium acetate, which will prevent the stannic sulphide from 
passing through the filter. After drying, the sulphide is transferred to a 
weighed crucible, the filter burned on the lid, its ash added to the contents of 
the crucible, and the whole ignited, at first very gently, until fumes of 
sulphurous anhydride cease, and then at a very high temperature, with the 
addition of a fragment of ammonium nitrate. 
This process depends on the conversion of the sulphide into SnC>2 by 
ignition; but it must be conducted with care, as a too rapid application of 
heat would cause the change to take place suddenly, and the whole would 
ignite. 
This process, which is only applicable to tin stone, consists in fusing a 
known quantity of the pulverised ore with potassium cyanide in a porcelain 
{b) As Metallic Tin. 136 
QUANTITATIVE ANALYSIS OF METALS. 
crucible, when a small button or granules of metallic tin will be obtained on 
treating the mass .with water. The tin is washed, dried, and weighed. 
10. ESTIMATION OF ANTIMONY. 
As Antimonious Sulphide, with or without Subsequent Conversion into 
Antimonious Antimonic Oxide. 
(Practise upon -5 gramme of “ tartar emetic.’') 
The acid solution is mixed with tartaric acid, to prevent the precipitation of 
an oxysalt, diluted with water, and precipitated with sulphuretted hydrogen, 
the sulphide collected on a weighed filter, dried at 220° F., and weighed. 
The conversion of the sulphide into oxide is done by igniting it in a porcelain 
crucible, heating gently at first; then dropping on nitric acid until red fumes 
cease, and finally igniting very strongly. The remaining Sb204 is then 
weighed. 
11. ESTIMATION OF ARSENIC. 
(a) As Arsenious Sulphide. 
The solution must contain the arsenic as arsenious acid. After adding 
some HCI, a current of sulphuretted hydrogen is passed through the liquid till 
the latter acquires a strong smell. The excess of gas is now removed by 
warming the fluid and passing a current of carbonic anhydride through it. 
The sulphide is collected on a weighed filter, washed, dried at 2120 F., and 
weighed. 
(Practise upon -5 gramme As205.) 
(1b) As Magnesium Ammonium Arseniate. 
If the substance be arsenious acid it is dissolved in some hot solution of 
sodium carbonate, excess of hydrochloric acid is added, and the fluid gently 
heated with potassium chlorate till it smells distinctly of chlorine, even after 
half an hour. Arsenic and sulphur compounds, on the other hand, are dissolved 
in hot potassium hydrate and treated with excess of chlorine gas to convert 
them into arsenic acid. The solution of arsenic acid thus obtained by either 
of the foregoing methods is mixed with large excess of ammonium hydrate, and, 
after being allowed to cool, precipitated with magnesia mixture (a fluid prepared 
by adding ammonium hydrate to a solution of magnesium sulphate and re- 
dissolving the precipitate with ammonium chloride). After standing for at 
least twelve hours, the precipitate is collected on a weighed filter, washed with 
a mixture of one volume of ammonium hydrate and three volumes of water 
till free from chlorine, dried for three hours at 220° F. and weighed. If only 
dried at 2120 F. the drying will occupy a considerably longer time. The 
results are usually a trifle too low. 
12. ESTIMATION OF COBALT. 
As Potassium Cobaltous Nitrite. 
The solution is concentrated to a small bulk, the excess of acid is neutralised 
with potash, and excess of potassium nitrite and a little acetic acid (to keep 
the solution slightly acid to test-paper) are then added. After the lapse of 
twenty-four hours all the cobalt will have crystallised out as potassium cobaltous 
nitrite. This salt is quite insoluble in the mother liquor, but slightly so in ESTIMATION OF NICKEL, MANGANESE, ZINC, AND IRON. 
137 
pure water. For the washing, a 16% solution of potassium acetate is used, 
wherein the salt is also insoluble, and the acetate is afterwards removed by 
washing with alcohol. A weighed filter is used and the precipitate dried at 
2T2°. 
13. ESTIMATION OF NICKEL. 
As Metal. 
The solution is precipitated with excess of sodium hydrate and boiled. 
The precipitate is washed with boiling water, dried, ignited, and weighed. 
The ignited residue, or a known portion of it, is now introduced into a 
weighed glass tube and reduced at red heat by a current of hydrogen. The 
reduced metallic nickel is afterwards weighed. 
14. ESTIMATION OF MANGANESE. 
As Manganese -manganic Oxide. 
(Practise upon 75 gramme of pure MnS04 * 7H20.) 
The solution for analysis, if strongly acid, is neutralised with ammonium 
hydrate and precipitated by ammonium sulphide. The precipitated manganous 
sulphide is washed with water containing ammonium sulphide, and dissolved 
in acetic acid. Chlorine gas is passed through the liquid until all the 
manganese precipitates as manganic peroxide, which is then collected, washed, 
and calcined in a weighed crucible to bright redness This forms Mn304; 
the crucible with the contents is then cooled and weighed. 
15. ESTIMATION OF ZINC. 
As Zinc Oxide. 
(Practise upon 75 gramme of pure ZnSCVyH^O.) 
The solution of the zinc salt (freed from other metals if necessary) is pre- 
cipitated boiling with sodium carbonate, and the solution boiled well. The 
precipitate is allowed to settle, washed by decantation with boiling water, 
filtered out, and dried. It is then introduced into a weighed crucible, 
ignited for some time at a bright red heat, cooled, and weighed. The ignition 
changes the precipitated zinc carbonate to oxide, and it is weighed as such. 
Or the solution is precipitated with ammonium sulphide, the zinc sulphide 
collected on a filter, washed with dilute ammonium sulphide, dried, ignited, 
and finally weighed as oxide. This latter method is useful when only small 
quantities of zinc are present. 
16. ESTIMATION OF IRON. 
As Ferric Oxide. 
(Practise upon 75 gramme of pure FeS047H20.) 
The solution (freed if necessary from other metals, phosphates, and organic 
matter) is boiled with a few drops of nitric acid, to insure that the whole 
of the iron is in the ferric state. Excess of ammonium hydrate is added, 
the whole boiled, and rapidly filtered. The precipitated ferric hydrate is 
washed with boiling water, dried, and ignited in a weighed crucible for some 
time. 138 
QUANTITATIVE ANALYSIS OF METALS. 
In the presence of organic matter, such as citric or tartaric acids, the iron 
must first be separated by precipitation with ammonium sulphide, the precipi- 
tate washed with dilute ammonium sulphide, redissolved in hydrochloric acid, 
boiled, oxidised by potassium chlorate, and then precipitated with ammonium 
hydrate, as directed. In the presence of manganese the solution should be 
nearly neutralised by ammonium hydrate and then boiled with excess of 
ammonium acetate, and the resulting ferric oxy-acetate collected, washed, 
dried, and ignited to Fe2os. 
17. ESTIMATION OF ALUMINIUM. 
As Aluminic Oxide. 
(Practise upon i gramme of pure alum.) 
The solution containing the alum or other salt of the metal (which must be 
free from iron and earthy phosphates) is precipitated with a slight excess of 
ammonium hydrate, and boiled until it only smells very faintly of ammonia. 
The precipitated aluminic hydrate thus obtained is filtered out, washed with 
boiling water, and dried. The dry filter and its contents are transferred to a 
weighed platinum crucible, and ignited to bright redness for some time, allowed 
to cool, and weighed. 
18. ESTIMATION OF CHROMIUM. 
As Chromic Oxide. 
Salts of chromium are at once precipitated with ammonium hydrate, and the 
precipitate washed, dried, ignited, and weighed as 0203. Soluble chromates 
are first reduced by means of hydrochloric and sulphurous acids (or, instead 
of the latter, spirit of wine may be used), and the chromium precipitated as 
hydrate by ammonium hydrate ignited and weighed as 0203, all as described 
above for aluminium. 
19. ESTIMATION OF BARIUM. 
(Practise upon -5 gramme of BaClg. 2H20.) 
As Barium Sulphate. 
To a solution in boiling water add excess of sulphuric acid, boil rapidly for 
a few minutes, and set aside to settle. 
The clear liquor is poured off as closely as possible, and the precipitate 
collected on a filter of Swedish paper, and washed with boiling water. The 
filter and precipitate are next dried and ignited in a weighed platinum crucible 
(the precipitate being removed as perfectly as possible from the paper, and 
the latter first burned separately on the crucible lid, and the ash added to the 
contents of the crucible, to avoid the reduction of BaS04 to BaS by the carbon 
of the paper). The crucible and its contents having been weighed, and the 
weight of the crucible deducted, the difference equals the BaSOq. 
20. ESTIMATION OF CALCIUM. 
As Calcium Carbonate or Calcium Oxide. 
(Practise upon *5 gramme of powdered calc-spar dissolved in dilute HCI.) 
The solution of the lime salt is mixed with ammonium chloride, and is then 
made alkaline by ammonium hydrate. Should any precipitate (for instance. ESTIMATION OF MAGNESIUM, POTASSIUM, AATJ SODIUM. 
139 
calcium phosphate) form, it is redissolved by means of acetic acid, and any 
insoluble residue is removed by filtration. Ammonium oxalate is now added 
in excess. The precipitated calcium oxalate is boiled for a few minutes, 
filtered, the precipitate washed until free from oxalates, and the filter and 
contents dried at 2120 F. The precipitate is now carefully transferred to 
a tared platinum crucible and gently ignited. It is then moistened with a 
solution of pure ammonium carbonate, evaporated to dryness, heated until 
no more fumes are evolved, and then weighed as carbonate. 
21. ESTIMATION OF MAGNESIUM. 
(Practise upon ’5 gramme of pure MgSO-4' 7H20.) 
As Magnesium Pyrophosphate. 
The solution, which must be strong, is mixed with some ammonium 
chloride, and then with one-third of its bulk of ammonium hydrate, entirely 
cooled, excess of di-sodium hydrogen phosphate added, and the whole set 
aside for some hours. Care must be taken not to touch the sides of the 
beaker with the stirring rod, as otherwise particles of the triple phosphate 
will adhere to them so tenaciously that they can only be removed with great 
difficulty. The precipitate is collected on the filter and washed with a 
mixture of one volume of ammonium hydrate and three volumes of water, 
till the washings are free from chlorine, and dried. The precipitate is now 
detached from the filter and put into a weighed platinum crucible, the filter 
is burned in the lid, the ash added to the contents of the crucible, and the 
whole ignited by means of a Bunsen burner; and, when a large quantity of 
phosphate has been obtained, finally ignited before the blowpipe. 
It sometimes happens that the phosphate, even after prolonged ignition, is 
very black. In that case it is, after cooling, thoroughly moistened with nitric 
acid, carefully dried, and re-ignited, when it will be found to be perfectly 
white. 
22. ESTIMATION OF POTASSIUM. 
As Potassium Platino-Chloride. 
The solution is placed in a small porcelain basin, and mixed with a good 
excess of solution of platinic chloride. The whole is evaporated to dryness 
on a water bath kept at a temperature of about 200° F. When quite dry it is 
again digested with a few drops of platinic chloride solution, to make sure 
that all the sodium will be in the state of sodium platino-chloride. This 
sodium compound and the excess of platinic chloride are now removed by 
spirit of wine of 60 0.P., the precipitate is collected on a weighed filter, washed 
with alcohol till the washings appear quite colorless, dried at 2i2°F., and 
weighed. 
(To be practised upon ‘2 gramme of pure KCl.j 
23. ESTIMATION OF SODIUM. 
(Practise upon -5 gramme of pure NaCl.) 
As Sodium Sulphate. 
This method is applicable where we have to deal with a sodium salt con- 
taining a volatile acid. The solution is mixed with excess of sulphuric acid 
and evaporated in a weighed platinum basin. When fumes of sulphuric acid 140 
QUANT IT A TIVE ANA L Y SIS OF ME TA LS. 
become visible, the basin is covered over with a lid or foil which has been 
weighed together with the crucible, and gradually heated till fumes cease. 
While red-hot the foil is lifted up a little, and a small lump of ammonium 
carbonate put in the crucible, which operation is repeated after a few minutes, 
and the residual Na2S04 is cooled and weighed. The object of introducing 
the ammonium carbonate is to remove the last traces of free sulphuric acid. 
ESTIMATION OF POTASSIUM AND SODIUM IN PRESENCE OF 
METALS OF FOURTH GROUP. 
(Practise upon the residue left on evaporating i litre of ordinary drinking- 
water, and redissolved in a little dilute HCI.) 
The solution, which must be free from other metals, but may contain 
calcium, magnesium, and sodium compounds (as their presence does not 
interfere with the process), is first of all precipitated with excess of barium 
chloride, which throws down sulphuric, phosphoric, etc., acids. Barium 
hydrate or some milk of lime is now added in slight excess, when any 
magnesia will also be thrown down. To the filtered liquid excess of am- 
monium carbonate is added, the precipitate is separated by the filter and the 
fluid evaporated in a platinum crucible to dryness, best on the water bath. 
When quite dry it is covered with a platinum lid and gently heated as long as 
white ammoniacal fumes are visible. The residue, which will now consist of 
potassium chloride, together with perhaps sodium chloride, is however not 
quite fit for weighing, and must be purified. This is done by redissolving 
in water and adding a little ammonium carbonate, when a slight precipitate 
will form. After filtering, the fluid is evaporated, this time in a weighed 
platinum basin covered with a weighed lid, on the water bath, and when dry 
the residue is gently heated to faint redness for a minute, cooled and weighed. 
When no sodium is present it will now be pure potassium chloride; but 
should it also contain sodium chloride, then it must be redissolved, the 
potassium estimated by PtCl4, and the sodium obtained by difference. This 
process is one of the most commonly occurring operations, because it is 
required in every full analysis of water, and also of the ash of all vegetable 
and animal substances, where both potassium and sodium have always to 
be estimated in presence of Ca, Mg, phosphates, etc. It is therefore a very 
important one to thoroughly master. 
25. ESTIMATION OF AMMONIUM. 
As Ammonium Platino-Chloride, 
If the solution contains other basylous radicals, a known quantity of it is 
distilled with some slaked lime in a suitable apparatus, and the distillate 
received into dilute hydrochloric acid. About three-fourths is distilled over. 
The distillate is then evaporated to dryness with excess of pure platinic 
chloride (free from nitro-hydrochloric acid). The dry residue is now treated 
with a mixture of two volumes of absolute alcohol and one of ether, collected 
on a weighed filter, washed with the said ether mixture, dried at 2i2°F., 
and weighed. The following calculation is now applied : 
Weight of the double chloride x 36 _ 1 ammonium in the quantity 
442 i taken for analysis. CHLORIDES, lODIDES, BROMIDES, CYANIDES, ETC. 
141 
DIVISION 111, GRAVIMETRIC ESTIMATION OF 
ACIDULOUS RADICALS. 
1. CHLORIDES. 
As Argentic Chloride. 
(Practise upon •? gramme pure NaCl.) 
The solution containing the chloride is precipitated with argentic nitrate. 
Nitric acid is then added, and the whole warmed and stirred till the liquid is 
perfectly clear. The precipitate is now treated as directed (see Silver, p. 132). 
After weighing the chloride it is calculated to Cl. 
2. lODIDES. 
3. BROMIDES. 
4. CYANIDES. 
The process for each of these is practically the same as for chloride. The 
argentic cyanide is, however, collected and weighed upon a weighed filter. 
The argentic iodide and bromide are treated like the chloride ; but if a filter 
is used, it must be a weighed one. The filter is afterwards reweighed, and 
the increase in weight is the amount of argentic iodide or bromide lost during 
the washing by decantation. 
5. ESTIMATION OE AN lODIDE IN THE PRESENCE OF A CHLORIDE 
AND A BROMIDE. 
Palladium, 
The solution, slightly acidified, is precipitated with excess of palladious 
chloride or nitrate. The jvhole is then allowed to stand in a warm place for 
twenty-four hours, so that the precipitate may thoroughly settle. The super- 
natant liquor is poured off, and the precipitate having been collected on a 
filter, and washed, is placed in a weighed platinum crucible and ignited. 
The whole is then again weighed, and the weight, less that of the crucible, 
equals the amount of metallic palladium left after ignition. Now, 100 parts of 
the metal combine with 239-6 parts of iodine in the precipitate, therefore the 
weight of the metal left after ignition x amount of iodine in the 
weight of the sample taken for analysis. 
6. MUTUAL ESTIMATION OF CHLORIDE, BROMIDE, AND 
lODIDE IN THE PRESENCE OF EACH OTHER. 
(Practise upon -2 gramme each of KCI, KI, and KBr dissolved 
together in 150 c.c. of water.) 
Observation has revealed that if argentic chloride be digested with potassium 
bromide it is thereby converted into argentic bromide ; again, if argentic 
bromide be digested with potassium iodide it is in turn changed to argentic 
iodide. 
This being recognised, and a solution of a known quantity of the mixed 
salts being made, divided into three equal volumes, and slight excess of 
argentic nitrate added to each, three precipitates are obtained, which are to be 142 
QUANTITATIVE ANALYSIS OF METALS. 
washed till free from soluble matter. The first of these must then be dried 
and weighed; the second digested with solution of KBr, washed, dried, and 
weighed ; the third digested with solution of KI, washed, and also, after 
being rendered free from moisture, weighed. From these three results the 
amounts of Cl, Br, and I are to be deduced by a calculation based on the 
difference of the molecular weight of AgCl, Agßr, and Agl. 
The first weighing is— 
AgCl + Agßr + Agl. 
The second is— 
Agßr + Agl, and is consequently increased as 35*5 is to 80. 
The third is entirely Agl, and is consequently increased as 80 is to 127. 
Conversion into Sulphate. 
7. SULPHIDES. 
(Practise upon ’5 gramme of purified “black antimony.”) 
Are analysed by fusion with a large excess of a mixture of potassium nitrate 
and carbonate, extracting the fused mass with water, filtering, acidulating 
with hydrochloric acid, adding excess of barium chloride, and proceeding 
as for a sulphate; but calculating at the last to sulphur instead of sulphuric 
acid. Some sulphides can be dissolved in nitric acid with the addition of 
successive small crystals of potassium chlorate. Excess of hydrochloric acid 
is then added, and the whole evaporated to dryness. The mass is then boiled 
with dilute hydrochloric acid, filtered, and the filtrate precipitated with barium 
chloride as above. 
8. SULPHATES. 
As Barium Sulphate. 
(Practise upon -5 gramme of MgS04 • 7H20.) 
To the solution of the sulphate hydrochloric acid is added, then excess 
of barium chloride, and the whole boiled. When quite clear, a little more 
barium chloride is added, to ascertain whether all the sulphuric acid has 
precipitated. The precipitate is now treated precisely as in the barium 
estimation. 
9. NITRATES. 
(A) In Alkaline Nitrates. 
If nitric acid be required to be estimated in, say, ordinary nitre, the sample 
must first be heated to fusion to remove moisture, and then be quickly 
powdered. A known quantity of it is now mixed in a platinum crucible with 
(exactly) four times its weight of plumbic sulphate. The mixture is ignited 
till it ceases to lose weight, and the loss will just represent the amount of 
nitric anhydride in the sample taken for analysis. 
If plumbic sulphate is used, the reaction is represented by the following 
formula : 
PbS04 + 2KN03 = PbO + K2S04 + 2N02 + O. 
(.B) By Conversion into Nitric Oxide. 
Already described at page 123. PHOSPHA TES. 
(C) By Conversion into Ammonia. 
The nitrate is converted into ammonia by the action of nascent hydrogen, 
thus— 
HN03 + 4H2=NH3 + 3H20. 
The nascent hydrogen may be applied in various ways, as follows ; 
1. By distillation with sodium hydrate and metallic aluminium, and 
receiving the evolved ammonia into a known volume of 
standard acid. 
2. By acting on the nitrate for 12 hours with zinc or iron and dilute 
sulphuric acid, and then adding excess of sodium hydrate, and 
distilling off the ammonia into a known volume of standard 
acid. 
In any case, the standard acid used is then volumetrically checked back by 
standard sodium hydrate, and the excess of acid used over that of alkali gives 
the amount of standard acid neutralised by the ammonia. This amount, 
having been multiplied by the strength of the acid in each c.c., is calculated 
to ammonia. Then— 
Ammonia found X 54 _ J amount of anhydrous nitric acid in 
[ the quantity taken for analysis. 
10. PHOSPHATES. 
(A) Estimation of the Strength of Free Phosphoric Acid. 
7-38 grammes of the acid are evaporated in a weighed dish with iB-o 
grammes of pure litharge, and the dry residue ignited and its weight noted. 
Thus treated, strong B.P. acid should yield 21-5 grammes of residue. 
(B) As Magnesium Pyrophosphate in Alkaline Phosphates. 
(Practise upon 75 gramme of pure Na2HPO4 * 12H0O.) 
They are at once precipitated with ammonium hydrate and magnesia 
mixture, and the precipitate is treated as directed under Magnesium. Should 
they contain the acid as meta- or pyro- acid, they must first either be boiled 
with strong nitric acid for one hour, or be fused with potassium sodium car- 
bonate. 
(Q As Magnesium Pyrophosphate in the Presence of Lime and Magnesia. 
(Practise upon -5 gramme of pure Ca3(P04)2 dissolved in dilute HCI.) 
The solution (which must contain orthophosphoric acid, or, failing that, 
should be boiled with HN03 as above) is precipitated with ammonium 
hydrate, the precipitate redissolved in the smallest amount of acetic acid, the 
lime precipitated with ammonium oxalate, and the phosphoric acid pre- 
cipitated in the filtrate by adding ammonium hydrate and magnesia mixture, 
and proceeding as already described for magnesium. Before precipitation this 
filtrate should be evaporated to a bulk of 3 ounces. This process is suitable 
for determining the “ soluble phosphates ” in an artificial manure. 144 
QUANTITATIVE ANALYSIS OF METALS. 
(D) As Magnesium Pyrophosphate in the Presence of Iron and 
Aluminium. 
(Practise upon 75 gramme of B. P. Ferri phosphas dissolved in dilute HCI.) 
The solution is mixed with excess of ammonium acetate, boiled, and ferric 
chloride added till a dark-brown precipitate forms. This is washed with 
boiling water and redissolved in a small quantity of dilute HCI. About five 
grammes (or more) of citric acid are now added, and ammonium hydrate is 
added to the whole in large excess, and, after cooling, magnesia mixture and 
the precipitate treated as for magnesium already described. If the addition 
of excess of NH4HO does not produce a clear lemon-yellow solution then 
enough citric acid has not been added. 
[E) Estimation as Phosphomolyhdate. 
If necessary, the acid solution is heated and precipitated with H2S to 
remove arsenic. The excess of H2S is boiled off, and large excess of nitric 
acid is added. An excess of ammonium molybdate and ammonium nitrate 
dissolved in nitric acid is now poured in, the liquid boiled, and finally allowed 
to stand for some hours in a warm place. The precipitate is filtered off, 
washed with dilute alcohol until free from acidity, redissolved in dilute 
ammonium hydrate, and this solution evaporated in a weighed dish on the 
water bath and dried in the water oven. Its weight-4-28-5 = P205 present. 
This process is the best for determining small amounts of total phosphates in 
cast iron, waters and soils. 
11. ESTIMATION OF TOTAL AND SOLUBLE PHOSPHATES IN AN 
ARTIFICIAL MANURE OR OF TOTAL ONLY IN SOIL. 
(.A) Total Phosphates. 
About two grammes of the finely powdered substance are weighed accurately, 
transferred to a beaker and decomposed with HCI, and where necessary with 
the addition of a drop or two of HNO3. The solution is then evaporated to 
dryness in a water bath, taken up with HCI, and after digestion the insoluble 
silicious matter is separated by filtration ; a weighed quantity of citric acid is 
added ; the solution heated up nearly to boiling point, and a weighed quantity 
of ammonium oxalate added. The quantities used must vary with the 
substance under examination, the knowledge only being acquired by ex- 
perience ; but it is seldom necessary to add more than 2 grammes citric acid 
or 2-5 grammes ammonium oxalate. The free acid is then just neutralised 
with dilute ammonia, and acetic acid added, to decidedly acid reaction. The 
liquid is kept simmering for a few minutes with constant stirring, and after 
standing a short time the calcium oxalate is filtered out. Great care must 
be observed not to have too large an excess of ammonium oxalate 
present, as magnesium oxalate in an ammoniacal solution is somewhat easily 
precipitated. To the filtrate ammonia of 'BBo sp. gr. is added to about one- 
fourth of the bulk ; and to the liquid, which must remain clear, or only slowly 
throw down a small precipitate, due to the magnesia present, magnesia 
mixture is added in moderate excess. The liquid must be set aside with 
occasional stirring for the precipitate to form—the time required being 
principally determined by the quantity of alumina present. It is best, 
however, to allow it to stand overnight, although in cases where the alumina 
is absent, or small, the precipitation will be found to be complete in two ARSENIATES AND CARBONATES. 
145 
hours. The precipitate is then separated from the liquid by filtration, 
dissolved in as little HCI as possible, and reprecipitated with one-third of its 
bulk of ammonia. After allowing to stand for two hours with occasional 
stirring, it may be filtered, and after drying converted, by ignition in a weighed 
platinum crucible, into Mg2P207, and weighed as such. 
The calcium oxalate is converted into CaC03 by gentle ignition, weighed, 
dissolved in HCI, and tested for P205, which may be present in small 
quantities, and which should be determined. 
The Mg2P207 is calculated to Ca3(PO4)2 unless a full analysis is being 
made, when it is calculated to P205 and divided pro rata among the bases 
actually found to be in combination with it. 
Five grammes of the manure are well triturated in a mortar with distilled 
water, washed into a stoppered 250 c.c. flask and made up to the mark with 
water. After standing with occasional shaking for two hours 100 c.c. (=2 
grammes of sample) is drawn off by a pipette into a beaker, 2 grammes of 
citric acid and grammes of ammonium oxalate are dissolved in the liquid, 
which is then treated with ammonia, acetic acid, etc., as above described. If 
the amount of soluble calcium comes out low, the process should be repeated, 
using such a weighed quantity of ammonium oxalate as will just remove it 
from solution, This is because the great source of error in phosphate 
estimations is the use of excess of oxalate, causing the precipitation of 
magnesium oxalate with the magnesium ammonium phosphate. The Mg2P207 
is calculated to Ca3(PO4)2 and reported as “ phosphate made soluble.” 
(B) Soluble Phosphates. 
12. ARSENIATES 
are estimated precisely like phosphates ; but the precipitate of ammonium 
magnesium arseniate is dried at 220° F. on a weighed filter, as already directed 
under arsenic. The precipitate thus dried is 2(MgNH4As04) • H2O ; or, for 
simplicity of calculation, MgNH4As04 * |H2O. 
13. ARBONAS. 
A carbonate is estimated by the loss of weight it undergoes by the dis- 
placement of its carbonic anhydride by an acid. A small and light flask is 
procured, and fitted with a cork through which passes a tube (c) containing 
Fig. 35. 
Fig. 36. 
fragments of calcium chloride (see fig. A weighed quantity of the 
carbonate is introduced into the flask with a little water, and a small test-tube 
(t) about two inches long is filled with sulphuric acid and dropped into the 
flask, so that, being supported in an upright position, none of the acid shall 
mix with the carbonate. The cork is put in, and the weight of the whole 146 
QUANTITATIVE ANALYSIS OF METALS. 
apparatus having been carefully noted, it is inclined so as to allow the acid to 
run from the small tube into the body of the flask. Effervescence sets in, the 
carbonate is dissolved, and the CO2, escaping through the calcium chloride 
tube, is deprived of any moisture it might carry with it. When all action has 
ceased, and the whole has cooled, it is once more weighed. The difference 
between the two weights gives the amount of CO2 evolved. 
A better apparatus is that figured (No. 36), in which (c) is the flask, (a) the 
tube to contain HCI to decompose the carbonate, and (b) a tube containing 
strong H2SO4 through which the evolved CO2 must pass, and so be perfectly 
deprived of moisture. 
14. OXALIC ACID. 
As Calcium Carbonate. 
The solution containing the acid, or its potassium or sodium salt, is made 
alkaline with ammonium hydrate, and precipitated with, calcium chloride. 
The precipitate is washed till free from chlorides, dried, ignited, and finally 
weighed as carbonate. (See Estimation of Calcium.) 
15. TARTARIC ACID. 
As Calcium Oxide. 
The solution (which must contain no other bases than Ka, Na, or NH4) is 
made faintly alkaline by ammonium hydrate, and precipitated by excess of 
calcic chloride. The precipitate is washed, dried, ignited (with the blowpipe), 
and weighed as calcic oxide. 
16. SILICIC ACID. 
[A] In olnble Silicates. 
By soluble silicates are meant those which are either soluble in water or 
in hydrochloric acid. The solution (which must contain some free HCI) is 
evaporated to dryness on the water bath, and the residue dried for an hour 
at 248° F. After cooling, the mass is moistened with strong hydrochloric 
acid, and then boiled with water, thus leaving an insoluble residue of pure 
silica—SiC>2—which is collected on a filter, washed, dried, ignited, and 
weighed. 
(B) In Insoluble Silicates. 
These bodies must be decomposed by mixing a weighed quantity of the 
finely powdered substance with four times its weight of sodium potassium 
carbonate, and fusing the whole for about half an hour. (When alkalies have 
to be estimated, a separate special fiision must be made with barium hydrate, or 
pure lime mixed with ammonium chloride, instead of the double carbonate?) The 
crucible must be well covered during fusion. After cooling, the residue is 
treated with dilute and warm HCI until efiervescence ceases, evaporated to 
dryness, and treated as above described at 248° F., etc. 
DIVISION IV. QUANTITATIVE SEPARATIONS. 
This department is beyond the scope of the present edition. When the 
student has practised all the contents of the book up to this point, he will 
already have a sufficiently general idea of chemical analysis to enable him to 
fix the line of work he desires to make his speciality. If this be mineral QUANTITATIVE SEPARATIONS. 
147 
analysis, he must pass to a larger book such as “ Fresenius ” to complete his 
knowledge. So as to give, however, some idea of how the preceding pro- 
cesses may be joined in performing the full analysis of a mixture, we take 
the following example, because it is a standard one, and give a sketch of 
the manner of working in performing— 
The Full Analysis of the Mineral Contents of a Sample of Ordinary 
Potable Water. 
Step I. Take the total solid residue of 100 c.c. (calculated in grains per 
gallon) as directed in Chapter X., to serve as a check on the results ; then 
ignite and again weigh : loss=organic and volatile matter. 
Step 11. Evaporate 2000 c.c, of the water to dryness in a large porcelain dish, 
and heat gently till fumes of NH3 cease to be evolved. Moisten the residue 
with 10 c.c. of distilled water, and then add 200 c.c. of proof spirit; having 
gently detached it all from the dish, filter and wash with proof spirit till 
practically nothing more dissolves. This procedure is useful because it 
separates the salts present thus : 
(a) The filtrate may contain all salts of K and Na, chlorides and 
nitrates of Ca and Mg, and the sulphate of Mg. 
{&) The insoluble residue may contain the sulphate and carbonate of 
Ca and the carbonate of Mg, together with any iron silicous 
matter present. 
(1) Analysis of the filtrate. 
(a) Evaporate till the spirit is driven off, cool, transfer to a 250 c.c. 
flask, and make up to the mark with distilled water. Divide 
into two portions of too c.c. and 150 c.c. respectively, marking 
them (a) and (b). 
(b) To (a) add NH4CI, NH4HO and (NH4)2 C 204, to precipitate the 
Ca, and estimate as usual as CaCO3. Calculate to CaO and 
thenx 2-5 = CaO present as Cl or NO3 in the original 2000 c.c. 
of water taken. 
(<r) To filtrate and washings from (b), concentrated to 50 c.c, and 
cooled, add Na2HP04 to precipitate Mg, treat as usual, and 
weigh as Mg2P207. Calculate to MgO, and then x 2’5 = MgO 
present as Cl or N03 in the original 2000 c.c. of water. 
(d) To (b) acidulate with HCI and add BaCl2 to precipitate sulphate. 
Treat as usual and weigh as BaSO4. Calculate to S03 and then 
X 2'5 -r- I's = total S03 present in the original 2000 c.c. of 
water taken in combination with K or Na. 
(e) The filtrate and washings from (d) are evaporated to a low bulk 
rendered alkaline with pure Ca(HO)2, the separation for alkalies 
given at page 140 gone through, and the K and Na present 
both estimated as chlorides. Results X 2-5 -f- I*s = total K 
and Na present in the 2000 c.c. of water started with. 
(/) The residue from (e) is dissolved in a little water and the K 
estimated thereon by PtCI4 in the usual manner and calculated 
to K2O (see page 139). An equivalent amount of KCI (calcu- 
lated from this KsO) is then deducted from residue (g) and the 
balance is NaCl, which is calculated to Na20. 
(2) Analysis of tin insoluble portion. 
(a) This is washed from the filter with distilled water and then boiled 
with 100 c.c. of H2O and HCI added till effervescence ceases. 148 
QUANTITATIVE ANALYSIS OF METALS. 
Any insoluble is filtered out, washed with boiling H2O, dried, 
ignited and weighed—silicious matter in the 2000 c.c. of water 
started with. 
(I) The filtrate and washings are warmed with a drop or two of 
HNO3 and mixed with NH4CI+ NH4HO, and the iron estimated 
if present asFe203, and result calculated to Fe=total Fe in the 
2000 c.c. of water taken. 
(I) Divide filtrate and washings into two equal parts, a and B. 
(1d) The portion ais precipitated with (NH4)2C204, and the calcium 
estimated as CaCOs and calculated to CaO=total CaO as 
carbonate or sulphate in the original 2000 c.c. of water taken. 
(e) The filtrate from (d) is concentrated to a low bulk, cooled, and 
Na2HP04 added with excess of NH4HO, and the Mg estimated 
as usual as Mg2P207 and calculated to MgO. Result x2= total 
MgO present as carbonate or sulphate in the original 2000 c.c. 
of water. 
(/) The portion b is acidulated with FICI, and the sulphate estimated 
by Bads, weighed as BaS04 and calculated to S03. Result 
x 2 = total SO3 in combination with Ca or Mg in the original 
2000 c.c. of water. 
Step 111. Evaporate 250 c.c. of the water to a bulk of 2 c.c. and treat in the 
nitrometer to estimate the nitric acid (see page 123). Resulting NO calcu- 
lated to N205 and xB= total N205 present in 2000 c.c. of water. 
Step IV. Take the amount of chlorides volumetrically (page 113) in 100 c.c. 
of the water. Result x2o=Cl in 2000 c.c. of water. 
Step V. Calculation of results. 
{a) All our results being in grammes or fractions of the same from 
2000 c.c. of water, each must be multiplied by 35, which will bring 
them all to grains per gallon (parts in 70,000). Now we state 
out our analysis thus (example taken from actual practice);— 
A sample of water yielding 20 • I grains of total solids per gallon, of which '45 grain was 
“ organic and volatile matter,” and the balance (i9'65 grains) was mineral matter, showed on 
analysis:— 
(a) In the portion soluble in spirit : 
grains per gallon 
Potassium oxide 
•2704 
Sodium oxide . 
1-4097 
Chlorine .... 
i’2i33 
Sulphuric anhydride 
•6803 
Calcium oxide . 
none. 
Magnesium oxide 
none. 
Nitric anhydride 
none. 
(6) In the portion insoluble in spirit: 
Calcium oxide . 
7-3953 
Magnesium oxide 
1 -oooo 
Sulphuric anhydride . 
17647 
Silicious matter 
•2000 
Ferric oxide 
•0500 
Total found 
13-9837 
From this residue is now to be always deducted an amount of oxygen equivalent to the 
chlorine found, because all the bases have been calculated to oxides, while haloid salts con- 
tain no oxygen. The chlorine found is 1'2133, and— 
1 2133>< oxygen, equivalent to Cl found. 
7i 
Performing this deduction, we have : 
13’9537—"2737 = 137100 grains of solid matter actually found. Q UA NT IT A TIVE SEP A RA TIONS. 
149 
The total residue, after driving off organic matter, was 19 ‘65 grains per gallon, and the 
difference is due to C02 unestimated, thus : 
Adding now this CO, to the substances actually estimated, we get : 
Total substances found-fC02 = ig'6s, 
Actual residue found = 19 ‘65, 
which proves our analysis to be correct. 
It now remains to calculate how these bases and acids are probably combined as salts 
actually present, by the following general rules of affinity, thus : 
(a) In the portion soluble in spirit. (l) Any sulphuric anhydride will prefer the bases in 
the following order ;K, Na, Ca, Mg. (2) Chlorine will prefer the bases in the same order 
after the S03 is satisfied. Therefore we first calculate our K2O to K2S04, which gives ’5O and 
uses up '2296 of our S03, and the balance of SOs (*4507) we calculate to Na2S04. This gives 
•80 Na2S04, and leaves i-0604 Na20 not as sulphate and therefore existing as chloride. Calcu- 
lating accordingly, we get 2-oo of Nad, which just uses up all our chlorine. Therefore this 
portion contained altogether : 
19’65 —1371 = 5'94 grains of COa per gallon. 
Potassium sulphate 'So 
Sodium sulphate ...... ‘Bo 
Sodium chloride ...... 2-oo 
(b) In theportion insoluble in spirit: (1) The S03 found will all be present as CaSO.,, and 
the balance of CaO and all the MgO will be as carbonates. Therefore 17647 S03 calculated 
to CaS04 becomes 3-oo and uses up T2353 of CaO, leaving 6’i6 to be calculated to CaC03. 
This yields iroo CaC03, and the roo of MgO found calculated to MgCOs gives 2-io. Thus 
this portion contains : 
Calcium sulphate 3 -oo 
Calcium carbonate ..... ii'oo 
Magnesium carbonate . . . . . 2'lo 
Putting now the whole analysis together, we have 
Potassium sulphate ..... ’5O 
Sodium sulphate . . . . . . -8o 
Sodium chloride ...... 2-oo 
Calcium sulphate ...... 3-oo 
Calcium carbonate . . . . .11 -oo 
Magnesium carbonate . . . . . 2'lo 
Ferric oxide ....... 'O5 
Silica . ... . . '2O 
Organic and volatile matter . '45 
Total residue 20 ’io. ISO 
CHAPTER IX. 
ULTIMATE ORGANIC ANALYSIS. 
This process consists in estimating the amount of each element present in 
any organic compound, as distinguished from proximate analysis, which 
estimates the amounts of the compounds themselves. 
i. A combustion furnace, which is a series of Bunsen burners arranged 
in a frame so as to gradually raise a tube placed over them to a 
red heat. The tube lies in a bed made of a series of fire-bricks, 
I. LIST OF APPARATUS REQUIRED. 
which confine the heat and make it play all round the tube (see 
%• 37)- 
2. Combustion tubes made of hard glass, not softening at a red heat. 
These tubes are closed at one end by drawing out before the 
Fig 38. 
Fig. 39. 
Fig. 37. 
Fig. 40. 
blowpipe and turning up. The mode of doing this is illustrated 
in fig. 38. 
3. (J tubes packed with perfectly dry calcium chloride in small 
fragments, so as to allow the free passage of gases (illustrated 
in fig. 39), and hereafter referred to for brevity as “ CaCl2 
tubes.” 
4. Bulbs charged with strong solution of potassium hydrate (1 in 1), 
hereafter for brevity referred to as “ KHO bulbs.” Two 
common forms of such bulbs are illustrated in fig. 40. ESTIMATION OF CARBON AND HYDROGEN. 
5. Bulbs for absorbing ammonia and intended to be charged with 
dilute acid of known strength, and hereafter referred to as 
“ nitrogen bulbs ” for brevity. Two common forms of such 
bulbs are illustrated in fig. 41. 
6. Graduated tubes closed at one end to hold 50 c.c., and graduated 
from the closed end downwards in of a c.c., used for 
collecting gases and measuring them after collection, hereafter 
referred to as “gas collecting tubes ” for brevity (fig. 42). 
7. A deep cylindrical vessel of glass filled with water and furnished 
with a thermometer dipping in the water. The whole 
sufficiently high to permit of the entire immersion of the gas 
measuring tubes, and wide enough at the top to admit the 
hand, as shown in fig. 43. This is hereafter called the 
“ measuring trough ” for brevity. 
8. Glass towers, filled in one limb with fragments of CaCl2 to absorb 
moisture, and in the other with fragments of soda lime to 
Fig 41. 
Fig 42. 
Fig 43. 
Fig 44. 
absorb carbon dioxide. Thesetare illustrated in fig. 44, and are 
used for freeing any air which may be caused to pass through 
them from moisture and C02 *, hereafter called “air purifying 
towers ” for brevity. 
This process is performed by heating a weighed quantity of the substance in 
a tube with some body readily parting with oxygen at a red heat, such as 
cupric oxide or plumbic chromate, by which the hydrogen and carbon of the 
organic body are respectively oxidised into water and carbonic anhydride. 
These products are passed first through a previously weighed tube containing 
calcium chloride, which retains the water, and then through a bulb apparatus 
containing potassium hydrate, which absorbs the carbonic anhydride and has 
also been previously weighed. After the experiment is finished, the increase 
in weight of the tubes is calculated thus : 
11. ESTIMATION OF CARBON AND HYDROGEN. 
As H2O : H2: : increase in CaCl2 tube :x. 
As C02 ; C : : increase in KHO bulbs ; x. 
The details of the actual process are as follows : 
Cupric oxide is prepared by heating cupric nitrate to bright redness in a 152 
ULTIMATE ORGANIC ANALYSIS. 
crucible ; it is reduced to powder while still warm, and preserved in a well- 
stoppered bottle. A combustion tube is procured, having a bore of about 
half an inch and a length of fifteen to eighteen inches. Sufficient cupric 
oxide to fill it is measured out, heated in a hard glass flask to expel any 
moisture (as it is very hygroscopic), well corked, and allowed to cool. About 
4 decigrammes of gently fused and cooled potassium chlorate is first dropped 
into the combustion tube, and then when cold a little oxide is introduced. 
About '4 gramme of the organic substance having been weighed out, it is rubbed 
up in a warm mortar with enough cupric oxide to half fill the tube, and the mix= 
tore is quickly transferred to that apparatus; sufficient cupric oxide to nearly 
fill the tube is then introduced, and lastly a loose plug of asbestos is inserted to 
keep all in place. To this charged tube is then attached by means of a good 
cork a previously weighed “ CaCl2 tube,” and to this is in turn fixed by an 
indiarubber joint a set of “ KHO bulbs ” also previously weighed. The tube 
is now placed in the furnace, the glass attachments supported outside of it by 
appropriate stands, and made perfectly air-tight. Heat is now applied to the 
front portion of the tube by lighting the first five or six burners, and when 
that part is quite red-hot the next burner is turned on. The heat is thus 
applied gradually, taking care that it is so regulated as to produce a regular 
slow passage of the evolved gases, so that the bubbles may be distinctly 
counted as they pass through the “ KHO bulbs.” When the whole tube is 
heated from end to end the potassium chlorate at the back gives off a little 
oxygen, which sweeps the last traces of moisture and carbonic anhydride into 
the bulbs, which are then detached, weighed, and the increase in weight of 
each noted. 
Weight of sugar taken ...... ‘475 gramme. 
Potash bulbs after combustion weighed . . . 79' l 13 grammes. 
„ ~ before ~ ~ ... 78-382 ~ 
Difference, due to C02 . . . -731 ~ 
Calcium chloride tube after combustion weighed . 23 ’605 grammes. 
>, ~ before ~ „ . 23-330 ~ 
Difference, due to H2O . . . '275 ~ 
(C) 12 X -731 „ , (PL) 2 X -275 , . , 
(C67)44 “ 1994 “rb°n (H,O) .8 ”" °3°56 h>'droß“- 
Total sugar taken . . . . . . . -475 
Total C and PI found ...... -22996 
Difference, due to oxygen . . "24504 
Or, in percentage—Carbon 41-98 
Pfydrogen ....... 6-43 
Oxygen 51 59 
10000 
When the organic matter is a liquid, it is introduced into a small drawn-out 
tube previously tared; the end is hermetically sealed by the blowpipe and the 
whole again weighed, thus obtaining the weight of the liquid. A little oxide 
having been first put into the combustion tube, the sealed one is dropped in, 
its end broken by a wire, and the whole of the rest of the oxide poured in. 
The heat is applied till six or seven inches of CuO are bright red, and then 
the burner underneath the spot where the tube with the liquid lies is 
cautiously turned on, so as to volatilise the vapor and cause it to pass over 
the red-hot cupric oxide and so suffer combustion. Fats and other bodies 
which cannot be mixed with the oxide are weighed in a small platinum boat, 
which is dropped in and treated like the tube of liquid already referred to. ESTIMA TION OF NITROGEN. 
153 
Special Notes to tlie Foregoing Process. 
(a) Substances containing sulphur, phosphorus, arsenic, chlorine, or any 
halogen, are best mixed with fused and powdered plumbic chromate 
instead of cupric oxide, so as to avoid the formation of volatile cupric 
compounds. 
(Z>) When the substance also contains nitrogen, the front part of the 
combustion tube must be plugged with a roll of bright copper gauze 
about 4 inches long instead of the asbestos. This is to reduce any 
oxide of nitrogen, which if allowed to pass into the potash would be 
absorbed and count as carbon dioxide. The copper, however, takes 
the oxygen, and only leaves nitrogen, which passes unabsorbed. 
(1c) Very refractory bodies should be burned in a current of air or of 
oxygen carefully deprived of any moisture or carbon dioxide by causing 
it to pass through “purifying towers” (see page 151) before entering 
the tube. 
111. ESTIMATION OF NITROGEN. 
The estimation of nitrogen in all compounds, not being nitrites or nitrates, 
is conducted as follows ; 
(a) The Method of Varrentrapp and Will. This depends for its success 
on the fact that when nitrogenous substances are strongly heated with sodium 
hydrate, they are decomposed, forming a carbonate and oxide with the oxygen 
from the hydroxyl, and liberating hydrogen, which then combines with the 
nitrogen to form ammonia. 
So as to prevent fusion of the glass tubes employed, solution of sodium 
hydrate is evaporated to dryness with calcium oxide, and the resulting mixture, 
known as soda-lime, is heated to redness and preserved for use. 
About "5 gramme of the perfectly dry nitrogenous substance is mixed 
in a warm wedgwood mortar, with sufficient soda-lime to fill about three- 
quarters of a combustion tube. The mortar is rinsed with a little more 
soda-lime, and the rinsings also put into the combustion tube. More soda-lime 
is then put into the tube, until it is filled to within two inches of its open end, 
and then an inch of asbestos in shreds packed loosely in front of all, so as to 
prevent the passage of fragments of lime along with the evolved gases. A 
set of “ nitrogen bulbs,” containing a little tolerably strong hydrochloric acid, 
is adapted to the mouth of the combustion tube by means of a well-fitting 
cork, and the tube is placed in the combustion furnace, so that the bulbs and 
about an inch of the tube project outside. A few front burners having been 
lighted, and the free part of the tube having become red-hot, the heat is 
gradually applied until the whole of it has been heated to bright redness. 
When this point is attained, and bubbles of gas cease to pass through the acid 
in the bulbs, the end of the tube is broken off, and some air sucked through 
the apparatus by means of a small tube attached to the outer end of the bulbs. 
The contents of the bulbs are then transferred into a small basin, the bulbs 
washed out into it, first by means of a little alcohol, and afterwards repeatedly 
with distilled water. An excess of platinic chloride is then added, the whole 
evaporated to dryness in a water bath, and the precipitate, having been 
moistened with a little alcohol, is washed on to a weighed filter. The washing 
with alcohol is continued until it passes colorless, and the precipitate is dried 
at 2120 and weighed. The weight of the filter having been deducted, the 
balance is PtCl4(NH4CI)2, which is then calculated to N2. ULTIMATE ORGANIC ANALYSIS. 
A more simple plan, adapted to the estimation of nitrogen in manures and 
other commercial products, may be thus followed out:— 
The ammonia is received into 20 c.c. of semi-normal volumetric solution of 
oxalic or sulphuric acid, which is placed in the bulb apparatus. The ammonia 
which passes into the bulbs during the combustion neutralises a portion of 
this acid, and at the conclusion of the operation the amount of acid still 
remaining free is ascertained by means of a corresponding normal volumetric 
solution of sodium hydrate (see Volumetric Analysis, p. 112). The difference 
between the amount of acid originally placed in the bulbs and that remaining 
free, as thus ascertained, evidently corresponds to the amount of sulphuric acid 
neutralised by the ammonia produced during the combustion. The strength 
of the acid being known, a simple calculation enables us to ascertain the 
amount of the nitrogen evolved in the form of ammonia. 
(b) The Process of Dumas. This consists in measuring the amount of pure 
nitrogen evolved, and is suitable for certain organic bases and for compounds 
containing nitrosyl (NO) or nitryl (NO2), in which the soda-lime fails to con- 
vert all the nitrogen into ammonia. 
The combustion tube (which in this case is twenty-six to twenty-eight inches 
long) is packed (1) Avith six inches of dry sodium hydrogen carbonate; (2) 
with a little pure cupric oxide; (3) with the weighed substance mixed with 
CuO; (4) with more pure CuO ; and lastly with a considerable length of pure 
spongy metallic copper ; and the whole is closed by a good cork through which 
passes a bent delivery tube dipping under the surface of mercury in a small 
pneumatic trough. Heat is first applied to the very end portion of the 
NaHC03 until sufficient C02 has been given off to entirely drive all the air 
out of the apparatus, which is ascertained by collecting a little of the gas 
passing off and seeing that it is entirely absorbed by solution of potassium 
hydrate. A graduated “ gas collecting tube ” is then filled, one-third with 
strong solution of KHO, and the remainder with mercury, and carefully 
inverted into the mercury trough so that no air is admitted, and placed over 
the mouth of the delivery tube. Combustion is now commenced at the front 
of the tube and gradually carried backwards as usual. The gases evolved are 
C02 and N, the former of which is absorbed by the KHO and the latter 
collects in the graduated jar. When the heat reaches the back of the tube 
the remainder of the NaHCOs is decomposed, and the carbonic anhydride 
given off chases any trace of nitrogen out of the tube. The collecting tube 
is then closed by a small cup containing mercury, and transferred to the 
“measuring trough,” and entirely immersed therein. After leaving it until its 
contents have acquired the temperature of the water, it is raised so that the 
level of the water inside and outside the tube is equal, and the volume is read 
off. The temperature and pressure being noted, the Aveight of the nitrogen is 
obtained by the species of calculation already described at page 101. 
(c) Kjeldahl’s Process.—This method is rapidly superseding combustion, 
being almost universally employed in Germany. It is as follows : 
The substance, whether solid or liquid—and, if solid, it need not even be 
powdered—is weighed or measured into a small flask, in which the subsequent 
treatment is executed. In the case of substances containing about 10 per 
cent, of nitrogen, about on to o-2 grm. are sufficient; if less is present, up 
to 1 grm. may be taken. Ten c.c. of strong sulphuric acid, known to be 
free from ammonia, are now introduced by means of a pipette, the flask, 
in an inclined position, placed upon wire gauze over a gas flame, and the 
contents heated for one or two hours to near the boiling point of the acid, 
which may be known from the occasional slight bumping. If the substances 
retain their nitrogen very tenaciously, such as quinine, morphine, etc., a little ESTIMATION OF SULPHUR, PHOSPHORUS, ETC. 
155 
fuming sulphuric or anhydrous phosphoric acid may be added to the contents 
of the flask in the beginning. When the action of the acid is completed, 
which usually results in a solution of the solid, the flame is removed, and a 
fine spray of finely powdered permanganate of potassium, contained in a tube 
closed with a fine wire gauze and inserted in the neck of the flask, is made to 
rain down upon the acid in the flask until the latter assumes a green color. 
This step is only, however, necessary when the substance is specially difficult 
to oxidise, most ordinary bodies being sufficiently attacked by fuming sul- 
phuric acid. The flask is then cooled, the contents diluted with water, 
40 c.c. of a solution containing 35 per cent, of rochelle salt and 30 per 
cent, of sodium hydrate are added, and the flask immediately connected with 
and its contents distilled into a well-cooled condenser, provided with a 
receiver containing standard volumetric acid. If the original flask is too 
small, the contents may be transferred to another, water being used in portions 
to wash the original flask carefully. The estimation of the ammonia, by 
finding the amount of unsaturated acid, is conducted by volumetric soda, 
as already described in the soda-lime combustion. The ammonia found is 
calculated to nitrogen. Any substance likely to give off nitrous fumes should 
be first mixed with twice its weight of sugar. Nitrates require dilution with 
three times their bulk of benzoic acid. The rochelle salt takes no part in 
the reaction, but is a device to prevent bumping. 
IV. ESTIMATION OF CHLORINE. 
Chlorine is estimated by combustion of the substance in a tube filled with 
pure calcium oxide, when it displaces oxygen and turns part of the oxide into 
soluble calcium chloride. After combustion the contents of the tube are 
digested in water, filtered, excess of argentic nitrate added, and the precipitate 
washed, dried, and weighed, as already directed (see Gravimetric Estimation 
of Chlorine, p. 141). 
Sulphur, phosphorus and arsenic, are estimated by fusing in a silver crucible, 
with twelve times the bulk of pure potassium nitrate, a little mixed carbonate 
and nitrate being first put into the crucible, heated to fusion, and the mixture 
added a little at a time, waiting between the additions till action ceases. 
After fusion the sulphur and phosphorus, which have been converted into 
sulphuric and phosphoric acids respectively, are estimated by dissolving the 
residue in water and proceeding by precipitation as barium sulphate and 
magnesium ammonium phosphate respectively. (See Gravimetric Estimation 
of Sulphuric and Phosphoric Acids.) 
V. ESTIMATION OF SULPHUR, PHOSPHORUS AND ARSENIC. 156 
CHAPTER X. 
THE ANALYSIS OF WATER, AIR, AND FOOD. 
DIVISION I. THE SANITARY ANALYSIS OF WATER. 
In the following instructions, the lines laid down by the Water Committee 
of the Society of Public Analysts (of which the author was a member) have 
been followed. 
1. Collection of the Sample. 
This is to be taken in a clean stoppered “ Winchester quart ” bottle, 
previously entirely filled with the water, and emptied before finally filling up 
and introducing the stopper. The sample should be kept dark, and analysed 
with as little delay as possible. 
2. Color. 
This is to be taken by looking at a column of water in a colorless glass 
tube 2 feet long, and held over white paper. The presence of a greenish- 
yellow color is an adverse indication. 
3. Odor. 
An 8-ounce wide-mouthed stoppered bottle, free from odor, is half filled 
with the water, warmed in the water bath to xoo° Fahr., shaken, and then the 
stopper is removed and the odor instantly noted. Peaty waters, and those 
containing marked amounts of sewage, can frequently be thus detected by 
a practised nose. 
Heat a platinum basin of about 130 c.c. capacity to redness, cool it under 
the desiccator and weigh. Introduce 100 c.c. of the water, and evaporate 
over a low gas flame until reduced to about 10 c.c.; then place it on the 
water bath till dry. Finally, heat it in the air bath at 220° Fahr. until it 
ceases to lose weight, cool under the desiccator, and weigh. Having deducted 
the tare of the basin, the difference in milligrammes x 10 = total residue in 
parts per million, or the same x 7-=- io=grains per gallon. Example ; 
4. Total Solid Residue. 
Weight dish + residue . . . 89'336 
Tare of dish ..... 89-300 
■036 or 36 mfUigrammes-; 
then ——? =25 '2 grains per gallon. 
The residue should now be gradually heated to redness, and the presence 
of organic matter carefully looked for as indicated by charring; also the THE SANITARY ANALYSIS OF WATER. 
157 
nature of the same, by whether the odor on burning is purely carbonaceous 
(like burning sugar) or nitrogenous (like burning hair). This latter is an 
especially unfavorable indication. 
5, Chlorine, 
Solutions required:— 
(a) 4789 grammes pure crystallised argentic nitrate, dissolved in xooo c.c. of dis- 
tilled water. Each c.c. of this solution=’ooi (one milligramme) of chlorine. 
(J>) 5 grammes potassium chromate dissolved in 100 c.c. distilled water, and a weak 
solution of argentic nitrate dropped in until a slight permanent red precipitate 
is produced, which is allowed to settle in the bottle. 
Process.—Put 100 c.c. of the water into a white basin, add a few drops of 
the chromate solution, and titrate with the silver solution from a burette, 
graduated in Jg- of c.c., until a faint permanent change of color is produced, 
as already described (Chap. VII. p. 113). Note the number of c.c. used, 
multiply by 10, and the result will be chlorine in milligrammes per litre (or 
parts per million), or multiply by 7 and divide by xo, which will give grains 
per gallon (or parts per 70,000). The water itself must be perfectly neutral; 
if acid it must be first shaken with a little pure precipitated chalk. 
6. Phosphoric Acid. 
Solution required:— 
One part pure molybdic acid is dissolved in 4 parts ammonia, sp. gr. '960. This 
solution, after filtration, is poured with constant stirring into 15 parts of nitric 
acid of 1-20 sp. gr. It should be kept in the dark and carefully decanted from 
any precipitate which may form. 
Process.—The ignited total residue, obtained as directed in No. 4, is to 
be treated with a few drops of nitric acid, and the silica rendered insoluble 
by evaporation to dryness. The residue is then taken up with a few drops of 
dilute nitric acid, some water is added, and the solution is filtered through 
a filter previously washed with dilute nitric acid. The filtrate, which should 
measure 3 c.c. (or say 50 grains), is mixed with 3 c.c. of molybdic solution, 
gently warmed, and set aside for fifteen minutes at a temperature of Bo° Fahr. 
The result is reported as “traces,” “heavy traces,” or “very heavy traces,” 
when a color, turbidity, or definite precipitate are respectively produced, 
after standing for fifteen miuutes. 
7. Nitrogen in Nitrates. 
(,a) Cnm Process.—This is the best process where a nitrometer is available. 
250 c.c. of the water must be evaporated to a small bulk, the chlorine pre- 
cipitated with saturated solution of argentic sulphate, filtered, and the filtrate 
concentrated in a basin to 2 c.c. A nitrometer is charged with mercury, and 
the three-way stopcock closed, both to measuring tube and waste pipe. The 
concentrated filtrate is poured into the cup at the top of the measuring tube, 
and the vessel which contained it rinsed with 1 c.c. of water, and the contents 
added. The stopcock is opened to the measuring tube, and, by lowering 
the pressure tube, the liquid is sucked out of the cup into the tube. The 
basin is again rinsed with 5 c.c. of pure strong sulphuric acid, and this is also 
transferred to the cup and sucked into the measuring tube. The stopcock 
is once more closed, and 12 c.c. more sulphuric acid put into the cup, and 
the stopcock opened to the measuring tube until 10 c.c. of acid have passed 
in. The excess of acid is discharged, and the cup and waste pipe rinsed with 
water. Any gas which has collected in the measuring tube is expelled by 
opening the stopcock and raising the pressure tube, taking care no liquid 
escapes. The stopcock is closed, the measuring tube taken from its clamp 158 
THE AHA LYSIS OF WATER, AIR, AND FOOD. 
and shaken by bringing it slowly to a nearly horizontal position and then 
suddenly raising it to a vertical one. This shaking is continued until no more 
gas is given off, the operation being, as a rule, quite complete in fifteen 
minutes. Now prepare a mixture of one part of water with five parts of 
sulphuric acid, and let it stand to cool. After an hour, pour enough of this 
mixture into the pressure tube to equal the length of the column of acidulated 
water in the working tube, bring the two tubes side by side, raise or lower 
the pressure tube until the mercury is at the same level in both tubes, and 
read off the volume of the nitric oxide. This volume expressed in c.c.’s 
and corrected to normal temperature and pressure gives, when multiplied by 
•175, the nitrogen in nitrates, in grains per gallon, if 250 c.c. of the water 
have been used. According to some authorities the precipitation of the 
chlorides is not necessary. 
(b) Copper-Zinc Process.—This must be carried out as follows :—A wet 
copper-zinc couple is prepared by taking a piece of clean zinc foil, about 
3 in. by 2 in., and immersing it in a solution of copper sulphate, containing 
about 3 per cent, of the pure crystallised salt. A copious and firmly adherent 
coating of black copper is speedily deposited upon the surface of the zinc, 
which must be allowed to remain in the solution until the deposit is thick 
enough, but not for too long a time, or it will become pulverulent and not 
adhere firmly to the zinc,—three or four minutes will generally be sufficient. 
The zinc coated with copper must then be removed from the solution, which 
may be bottled for subsequent use, and the couple thoroughly washed first 
with distilled water, and finally with the water to be analysed, in order that 
this may replace the adhering distilled water. It is then put into a clean 6 
or 8-ounce wide-mouth stoppered glass bottle, and covered with 100 c.c. of the 
water to be analysed. If the water be very soft a small addition, say one part 
per 1000, of sodium chloride, will accelerate the reaction. The stopper must 
then be inserted in the bottle and the water allowed to remain overnight in a 
warm place. If still greater speed be necessary the temperature may be raised 
to 90° or ioo° F. (320 or 38° C.). With hard water it is preferable to add a 
small quantity of pure oxalic acid to precipitate the lime and quicken the 
reaction. When the reduction is complete the fluid contents of the bottle are 
to be transferred to a retort with 200 c.c. of ammonia-free distilled water, and 
the retort having been attached to a condenser, the contents are distilled till 
the distillate which comes over gives no color with “Nessler.” The distillate 
is then “ nesslerised,” as already described (Chapter VII., page 125), and the 
number of milligrammes of NH3 found are calculated to N (x 14 -f- 17), and 
then the resulting milligrammes of N x 7 -Mo = grains per gallon, or x 10 
only = parts per million. 
8. Ammonia and Albuminoid Ammonia. 
These two indications are successively taken on the same quantity of water. 
The former is an estimation of the ammonia present in the water in the form 
of ammonium salts or similar compounds readily decomposed by a weak 
alkali, while the latter shows the ammonia derived from the decomposition of 
nitrogenous organic matter under the joint influence of an oxidising agent 
(KMnO4) and a hydrating agent (KHO), and is therefore a measure of the 
nitrogenous, and consequently presumably dangerous, organic matters con- 
tained in the water under examination. 
The solutions and apparatus required are : 
(a) Sodium, carbonate. 
A 20 per cent, solution of recently ignited pure sodium carbonate. 
(b) Alkaline potassium permanganate solution. 
Dissolve 200 parts of potassium hydrate and 8 parts of pure potassium per- THE SANITARY ANALYSIS OF WATER. 
159 
manganate in 1200 parts of distilled water, and boil the solution rapidly till 
concentrated to 1000 parts, cool, and keep in a well stoppered bottle. 
(e) Distilled water which is free from Ammonia. 
Distilled water which gives no reaction with Nessler test is pure enough. But, if 
this is not available, take the purest distilled water procurable, add pure ignited 
sodium carbonate in the proportion of 1 part per 1000, and boil briskly until 
at least one-fourth has been evaporated. 
(d) A 40-ounce stoppered retort with a neck small enough to pass loosely into the 
internal tube of a Liebig’s condenser to the extent of 6 inches (see illustration 
Chapter I. page 4). The joint between the retort and condenser is made by 
an ordinary indiarubber ring—such as those used for the tops of umbrellas— 
which has been previously soaked in a dilute solution of soda or potash—being 
stretched over the retort tube in such a position that when the retort tube is 
inserted in the condenser it shall fit fairly tightly within the mouth of the tube 
about half an inch from the end. 
(e) All the materials for “ Nesslerising ” (see Chapter VII. page 125). 
The process is as follows : 
(,a) For free ammonia.—First test a little of the water with tincture of 
cochineal, to see if it shows an alkaline reaction. Put 500 c.c. of distilled 
water into the retort and distil until 50 c.c. of the distillate gives no color 
with i| c.c. of Nessler, thus rendering the whole apparatus “ammonia-free.” 
Let the whole cool, pour out the distilled water (which may be saved for 
ammonia-free water), put in 500 c.c. of the water to be analysed, and if it had 
not an alkaline reaction make it alkaline with a drop or two of the sodium car- 
bonate solution. The distillation should then be commenced, and not less 
than 100 c.c. distilled over. The receiver should fit closely, but not air-tight, 
on to the condenser. The distillation should be conducted as rapidly as is 
compatible with a certainty that no spurting takes place. After 100 c.c. have 
been distilled over, the receiver should be changed, that containing the distil- 
late being stoppered to preserve it from access of ammoniacal fumes. 100 c.c. 
measuring flasks make convenient receivers. The distillation must be con- 
tinued until 50 c.c. more are distilled over ; and this second portion of the 
distillate must be tested with Nessler’s reagent to ascertain if it contains any 
ammonia. If it does not, the distillation for free ammonia may be discon- 
tinued, and this last distillate rejected; but, if it does contain any, the distilla- 
tion must be continued still longer, until a portion of 50 c.c., or say 700 
grains, when collected, shows no coloration with the Nessler test. The whole 
of the distillates must be nesslerised in the usual manner, and the total 
number of milligrammes of ammonia found having been added together are 
multiplied by 2, which gives milligrammes per litre (parts per million). This 
number in turn multiplied by 7 and divided by 100 gives grains per gallon of 
free ammonia. 
{b) For albuminoid ammonia.—As soon as the distillation above referred to 
has been started, 5c c.c. of the alkaline potassium permanganate solution are 
placed in a flask with 150 c.c. of distilled water and boiled gently during the 
whole time that the free ammonia is distilling, adding some ammonia-free 
water if necessary to prevent too much concentration. The object of this is to 
insure the entire evolution of any trace of ammonia present in the alkaline 
permanganate, thus avoiding a check analysis, as usually recommended. When 
the distillation of the free ammonia is complete, take out the stopper of the 
retort and pour in this boiled alkaline permanganate by means of a perfectly 
clean funnel with a long limb. Now replace the stopper and continue the 
distillation, when the albuminoid ammonia will begin to come over. After 
200 c.c. have been distilled change the receiver and take off 50 c.c. at a time, 
as already described, until the last 50 comes over ammonia-free. Mix the 
distillates, nesslerise and calculate as for the free ammonia, noting the total 
result as albuminoid ammonia in parts per million or grains per gallon. Great THE ANALYSIS OF WATER, AIR, AND FOOD. 
care must be taken that no ammonia is kept in the room devoted to water 
analysis, and that all receivers used are first insured to be perfectly ammonia- 
free by proper rinsing with ammonia-free water and testing with Nessler. 
9. Oxygen required to oxidise the Organic Matter. 
Solutions required ; 
(a) Standard solution of Potassium permanganate. 
Dissolve ’395 parts of pure potassium permanganate in 1000 of water. Each c.c. 
contains ‘ooor gramme available oxygen. 
(b) Potassium lodide solution. 
One part of the pure salt recrystallised from alcohol, dissolved in 10 parts distilled 
water. 
(c) Dilute Sulphtiric acid. 
One part by volume of pure sulphuric acid is mixed with three parts by volume of 
distilled water, and solution of potassium permanganate dropped in until the 
whole retains a very faint pink tint, after warming to Bo° F. for four hours. 
(d) Sodium hyposulphite— 
One part of crystallised sodium hyposulphite dissolved in 1000 parts of water, 
(e) Starch water. 
One part of starch to be intimately mixed with 500 parts of cold water, and the 
whole briskly boiled for five minutes, and filtered, or allowed to settle. 
The Process.—Two separate determinations have to be made : viz., the 
amount of oxygen absorbed during 15 minutes, and that absorbed during four 
hours ; both are to be made at a temperature of Bo° F. It is most convenient 
to make these determinations in 12-oz, stoppered bottles, which have been 
rinsed with sulphuric acid and then with water. Put 250 c.c. of the water 
into each bottle, which must be stoppered and immersed in a water bath 
until the temperature rises to Bo° F. Now add to each bottle 10 c.c. of the 
dilute sulphuric acid, and then 10 c.c. of the standard potassium perman- 
ganate solution. Fifteen minutes after the addition of the potassium perman- 
ganate, one of the bottles must be removed from the bath and two or three 
drops of the solution of potassium iodide added to remove the pink color. 
After thorough admixture, run from a burette the standard solution of sodium 
hyposulphite, until the yellow color is nearly destroyed, then add a few drops 
of starch water, and continue the addition of the hyposulphite until the blue 
color is just discharged. If the titration has been properly conducted, the 
addition of one drop of potassium permanganate solution will restore the blue 
color. At the end of four hours remove the other bottle, add potassium 
iodide, and titrate with sodium hyposulphite as just described. Should the 
pink color of the water in the bottle diminish rapidly during the four hours, 
further measured quantities of the standard solution of potassium perman- 
ganate must be added from time to time so as to keep it markedly pink. The 
hyposulphite solution must be standardised, not only at first, but ..(since it is 
liable to change) from time to time in the following way :—To 250 c.c. of pure 
redistilled water add two or three drops of the solution of potassium iodide, 
and then 10 c.c. of the standard solution of potassium permanganate. Titrate 
with the hyposulphite solution as above described. The quantity used will be 
the amount of hyposulphite solution corresponding to 10 c.c. of the standard 
potassium permanganate solution, and therefore representing 1 milligramme of 
oxygen consumed. The difference between the number of c.c. of hyposulphite 
used in the blank experiment and that used in the titration of the samples of 
water multiplied by the amount of available oxygen contained in the perman- 
ganate added (= 1 milligramme if 10 c.c. have been used), and the product 
divided by the number of c.c. of hyposulphite corresponding to the latter as 
found by the check experiment, is equal to the amount of oxygen absorbed 
by the water. THE SANITARY ANALYSIS OF WATER. 
161 
Finally, the amount in milligrammes of oxygen absorbed thus found is 
multiplied by 4 for parts per million, and that result x 7 and -f- xoo = grains 
per gallon. 
10. Clark’s Process for Hardness. Total before boiling and permanent 
after boiling. Solutions, etc., required. 
(«) Standard solution of Calcium chloride. 
Dissolve 8 decigrammes of pure crystallised calc-spar in dilute hydrochloric acid 
in a platinum dish, adding the acid gradually, and taking precautions to 
prevent loss by spurting. When all is dissolved, evaporate to dryness in 
a water bath, add a little distilled water and again evaporate to dryness. 
Repeat several times, to insure the expulsion of all the acid. Lastly, dissolve 
in water and make up to 700 c.c. For use, dilute to 10 times its volume : 
the result will be standard water ofB° of hardness. Or, instead of making the 
solution thus, dissolve "1376 gramme pure crystallised selenite in 700 c.c. 
water, and that will be the standard water ofS°of hardness. 
(f) Standard Soap solution. 
Take 15 gi-ammes lead plaster (Emplastrum Plumbi, 8.P.), rub in a mortar with 4 
grammes dry potassium carbonate ; when fairly mixed add 660 c.c. of rectified 
methylated spirit, rub well, and after a time filter. To the nitrate add 
440 c.c. of recently boiled distilled water, and mix. Now place 100 c.c. of 
the standard water (a) in an 8-ounce wide-mouthed stoppered bottle, and add 
from a burette the standard soap I c.c. at a time. After each addition, shake 
the bottle vigorously for about a quarter of a minute. As soon as a lather 
is produced, lay the bottle on its side after each addition, and observe if the 
lather remains permanent for five minutes. To ascertain this, at the end of 
five minutes roll the bottle half-way round; if the lather breaks instead of 
covering the whole surface of the water, it is not permanent; if it still covers 
the whole surface, it is permanent : now read the burette. Repeat the 
experiment, adding the full quantity of soap solution employed in the first 
experiment, less about 2 c.c. ; shake as before, add soap solution very 
gradually till the permanent lather is formed, and note the number of c.c. of 
soap used. If this be exactly 18 c.c. then the soap is correct, but if less, 
then it must be diluted with proof spirit until 100 c.c. of standard water 
exactly takes 18 c.c. of soap. This method of dilution has been already 
discussed under Volumetric Analysis in Chapter VII. (see Manufacture of 
Soda Solution, page 112). 
The Process.—(a) For total hardness. Put 100 c.c. of the water into the 
bottle and add the soap from a burette exactly as above described; note the 
number of c.c. of soap used, and refer to the following table : 
HARDNESS C.C. OF SOAP USED DIFFERENCE 
o° o*9 i*o 
1° 2'9 2'5 
2° 5'4 2'3 
3° 77 2'2 
4° 9'9 21 
l2*o 2*o 
6° 14*0 2.0 
70 . . . 16*0 2*o 
8° rB*o 
and so on, after this point each 2 c.c. of soap used representing 1 additional degree of hardness. 
Example to show use of this table.—Suppose 8 c.c. of soap to have been used, which comes 
between 77 and g~g, then 8 77 = 7 ; =• -33 ; lastly '33 + 3°= 3'33° correct de- 
gree of hardness. 
If magnesium salts are present in the water the character of the lather will 
be very much modified, and a kind of scum (simulating a lather) will be seen 
in the water before the reaction is completed. The character of this scum 162 
THE ANALYSIS OF WATER, AIR AND FOOD. 
must be carefully watched, and the soap test added more carefully, with an 
increased amount of shaking between each addition. With this precaution 
it will be comparatively easy to distinguish the point when the false lather 
due to the magnesium salt ceases, and the true persistent lather is produced. 
If the water is of more than i 6° of hardness, mix 50 c.c. of the sample with 
an equal volume of recently boiled distilled water, which has been cooled in 
a closed vessel, and make the determination on this mixture of the sample 
and distilled water. In this case it will of course be necessary to multiply 
the figures obtained from the table by 2. 
(b) For permanent hardness. To determine the hardness after boiling, boil 
a measured quantity of the water in a flask briskly for half an hour, adding 
distilled water from time to time to make up for loss by evaporation. It is 
not desirable to boil the water under a vertical condenser, as the dissolved 
carbonic acid is not so freely liberated. At the end of half an hour, allow the 
water to cool, the mouth of the flask being closed; make the water up to its 
original volume with recently boiled distilled water, and, if possible, decant 
the quantity necessary for testing. If this cannot be done quite clear, 
it must be filtered. Conduct the test in the same manner as described 
above. 
The hardness is to be returned in each case to the nearest half-degree. 
11. Judging the Results. 
No definite rule can be laid down for judging all the results on one 
uniform scale, because the analyst must have special information as to the 
locality, nature of the soil, or depth of the well, before giving a reliable 
opinion. For example, nitrates, which have in river and shallow surface 
waters the highest significance, as indicating the presence of previous sewage 
contamination, entirely lose such force in waters from deep artesian wells, 
because these are naturally rich in such salts. The same thing may be said 
of ammonia, which, although highly unfavourable in shallow waters, is yet 
always found in artesian wells, most probably from the metal pipes acting 
as reducing agents upon the nitrates. Again, with upland peaty waters we 
always find a large reduction of permanganate, and consequently an excess 
of “oxygen consumed,” although the organic matter so acting cannot be 
viewed as dangerous. 
Setting aside, however, all questions of mineral constituents, and only 
looking at the indications of the presence or absence of organic matter, the 
author has devised a valuation scale, originally presented by him in a paper 
read before the Society, and which has proved since that time, in the hands 
of his various students dealing with sanitary examinations, as nearly correct 
as any general scale can be. The principle (which was originally proposed 
by the late Mr. Wigner) is to divide the amount of each figure found in the 
analysis by a fixed divisor, and where the quotient exceeds 10 to double all 
figures over that number. Let us suppose that, for example, a water yielded 
•012 grain of albuminoid ammonia per gallon, and that the divisor fixed 
for this indication is ’OOO7 ; then we have 
•012 
:= i7’i; then xyi —lO 7*l, and 7-i x 2 14*2 ; 
•0007 
therefore 14-2 + 10 = indicated degree of impurity. 
To prevent the production of enormous figures, likely to startle non-pro- 
fessional persons, the indicated degree of impurity is expressed as a decimal 
by dividing it by 100. Thus, it is only when the article is very bad indeed 
that the indication comes into full numbers. THE SANITARY ANALYSIS OF AIR. 
163 
Taking, then, the whole scale, it stands as follows : 
Grains per Gallon. 
Ammonia each ’OOl5 = 1. 
Albuminoid Ammonia . . . . . „ -0007 1. 
Oxygen consumed in 15 minutes . . . ~ -004 =l. 
Oxygen consumed in 4 hours . . . ~ -oio =l. 
Parts per Million. 
Ammonia ....... each -02 = i. 
Albuminoid Ammonia . . . . ■ ~ -oi = i. 
Oxygen in 15 minutes . . . • • „ -057 
Oxygen in 4 hours . . . . • ~ ‘143 = . 
When any number exceeds 10, then all over 10 is to be doubled and added 
to the original number, and the total valuation is to be divided by 100 and 
noted as “ comparative degree of organic impuritv.” Then, supposing no 
other consideration intervenes to modify the analyst's opinion of the sample, the 
following limits should be observed :—■ 
Ist Class Water . . . . . . zip to '25 degree. 
2nd ~ ~ (more or less questionable) . up to '4O ~ 
Undrinkable Water ..... over ‘4O ~ 
DIVISION 11. THE SANITARY ANALYSIS OF AIR. 
For sanitary purposes it is not necessary to make a full analysis of air, but 
should such be desired the processes described in Chapter XII. must be 
followed. The chief points are : 
1. Estimation of Carbon Dioxide. 
This is done by the method of Pettenkofer, which consists in standardising 
100 c.c. of lime or baryta water with standard oxalic acid grammes per 
litre of which 1 c.c. = -oor (1 milligramme of CaO). The air to be 
examined having been collected in a large bottle of known capacity, 100 c.c. 
of the same lime-water are added, the bottle is closed and well shaken for 
some time. The CO2 is absorbed, forming CaCOs. The resulting milky 
liquid is titrated in the bottle with the same acid. The indicator used is 
turmeric paper, or phenol-phthalein. The difference between the two titra- 
tions gives the amount of CaO precipitated as carbonate by the C02 in the 
air, and this is then calculated thus ; 
c.c. used x -ooi x 44 . , . . . 
-—— ———= CO2 present m the volume of air taken. 
56 
In strict analyses, the volume of air taken must be corrected for observed 
temperature and pressure to its volume at N.T.P. Pure air contains about 
•04 per cent, of C02. 
2. Estimation of Organic Matter. 
A known volume of air is sucked by an aspirator through a specially 
arranged apparatus containing ammonia-free distilled water, and'the resulting 
liquid is analysed for “ free ” and “ albuminoid ” ammonia like a water. 
3. Testing for Gaseous Impurities. 
The odor will generally detect these when present in notable proportions. 
Blotting-paper dipped (a) in tincture of turmeric, turns red-brown in presence 
of ammonia; (h) in solution of subacetate of lead—black with sulphuretted 
hydrogen; (c) in solution potassium iodide mixed with starch paste—blue with 164 
THE ANALYSIS OF WATER, AIR AND FOOD. 
chlorine or ozone; (d) weak solution of indigo is decolorised by chlorine and 
sulphurous acid gas ; (e) red litmus paper dipped in solution of potassium 
iodide becomes blue with ozone and not with chlorine. 
DIVISION 111. FOOD ANALYSIS. 
Here we will only attempt to consider a few of the more commonly occur- 
ring cases, always choosing the simplest and most rapid process. 
1. Milk. 
(1) Specific Gravity. Take the specific gravity with great care at 6o° F. 
If not at 6o°, take the temperature and refer to the table opposite. 
(2) Total Solids. Heat a small flat platinum dish about i| inch in 
diameter to redness, cool it under the desiccator and weigh. Put in about 
5 c.c. of the milk and again weigh. The difference=milk taken. Now dry 
on the water bath for 3 hours (or until seemingly dry), then transfer to the 
drying oven at 2120 for 2 hours, cool under the desiccator and weigh. Put it 
back in the oven for an hour, repeat the cooling and weighing, and if the 
difference does not exceed a milligramme or two it is dry, if it does, then repeat 
the drying. The weight of the dry residue minus the tare of the dish equals 
the total solids ; then— 
weight solids x 100 , , ~j 
—2 = per cent, of total solids. 
quantity taken 
(3) Fat. May now be calculated by Fleishmann’s formula thus it total 
solids : = specific gravity :/= fat) ; 
f— t '833- 2' 2 —-o~f ~ -lO° 
s 
Deducting the fat thus found from the total solids, we get the “ solids not fat.” 
If a more accurate process be required, the fat may be estimated by Adams’ 
method as modified by Thompson thus ; 
A strip of good filtering paper (not blotting) is procured, 21 in. long by 2\ in. 
wide. Two small pieces of ordinary stirring rod are taken, the one rather longer 
than the other. These are fixed together by stretching a section of indiambber 
tubing over each end of the rods. The two rods are separated from each 
other by the fingers, and the end of the strip of filter paper placed between 
them. The longer rod may be conveniently held by an iron clamp on a 
retort stand. 5 c.c. of the milk are taken in a pipette, having a long stem 
under the bulb, and whilst the left hand holds the free end of the strip of 
paper, thus giving it an almost horizontal position, a small portion of the milk is 
allowed to run from the pipette which is held in the right hand, with the 
finger closing the top, so as to make a line of milk across the strip of paper 
within about an inch of the fixed end. More milk is then allowed to flow on 
to the centre of the strip, and is then spread equally all over the surface with 
the stem of the pipette, which is held almost horizontally at right angles to 
the strip. By this means the milk may be transferred entirely to the 
strip of paper, about an inch or an inch and a half at the end being left 
unmoistened, upon which the stem of the pipette is wiped dry. The strip of 
paper thus moistened with 5 c.c. of milk may now be taken between the 
hands, and dried in 2 or 3 minutes over an ordinary Bunsen burner. The 
flame may be allowed to play directly on the paper, which is moved rapidly 
backwards and forwards over it. The strip of paper thus treated is then coiled 
on a stirring rod, the rod withdrawn, and the coil without any further manipula- 
tion placed in a Soxhlet’s tube for extracting the fat (see Chapter 1., page 2). FOOD ANALYSIS—MILK. 
Observed 
Specific 
DEGREES OF 
THERMOMETER 
[Fa hr.). 
Observed 
Specific 
Gravity. 
50 
51 
52 53 
( 
54 
55 
56 
57 
58 
59 
60 
61 
62 
63 
64 65 
66 
67 
68 
69 
70 
Gravity. 
10200 
ig-2 
19-3 
19-4 19-4 
19-5 
19-6 
197 
19-8 
19-9 
19.9 
1020'0 
20 T 
20‘2 
20'2 
20-3 20'4 
20-5 
20-6 
207 
20-9 
21-0 
10200 
10210 
20-2 
20'3 
20-3 20*4 
20-5 
20-6 
207 
20-8 
20-9 
2Q'9 
1021-0 
21 * 1 
21-2 
21-3 
21 '4 .'21 "5 
21-6 
217 
21-8 
22-0 
22-1 
10210 
10220 
21 2 
21-3 
21'3 21-4 
21-5 
21-6 
217 
21'8 
21'9 
21-9 
1022-0 
22'I 
22-2 
22-3 
22 "4 !22 ‘5 
22-6 
227 
22-8 
23-0 
23-I 
10220 
10230 
22‘2 
22-3 
22'3 22-4 
22-5 
22-6 
227 
22-8 
22-8 
22'9 
1023-0 
23-1 
23-2 
23-3 
23-4 237 
23-6 
237. 
23 8 
24-0 
24-1 
10230 
10240 
23-2 
23-3 
23d 23-4 
23-5 
23-6 23-6 
237 
23-8 
23-9 
1024-0 
24-1 
24-2 
24-3 
24-4 24-5 
24-6 
247 
24-9 
25-0 
25-I 
10240 
10250 
24-1 
24*2 
24-3 '24-4 
24'5 
24-6 
24-6 
247 
24-8 
243 
1025-0 
25-1 
25-2 
25-3 
25-4 257 
25-6 
257 
25-9 
26‘0 
26-1 
1025 0 
1026 0 
25-1 
25-2 
25-2 25-3 
254 
25 ‘5 
25-6 
257 
253 
25'9 
1026-0 
26'! 
26-2 
26-3 
267 z6‘6 
267 
26-8 
27-0 
27-1 
27-2 
10260 
10270 
26*1 
26-2 
26-2 26-3 
26-4 
26-5 
26-6 
267 
263 
26-9 
1027-0 
27-1 
273 
27-4 
27-5 27-6 
277 
27-8 
28 'O 
28-1 
28-2 
10270 
10280 
27-0 
27'I 
27 2 27-3 
27-4 
27-5 
27-6 
277 
27-8 
27-9 
1028-0 
28-1 
287 
28-4 
287 28-6 
287 
28-8 
29-0 
29-1 
29-2 
10280 
1029 0 
28-0 
28-1 
28-2 28-3 
28-4 
28-5 
28-6 
287 
28-8 
287 
1029-0 
29-1 
297 
29-4 
29-5 29-6 
29-8 
29-9 
30-1 
30-2 
30-3 
10290 
1030 0 
29-0 
29-1 
29-1 29-2 
29-3 
29-4 
29-6 
297 
29-8 
29'9 
1030-0 
3°"i 
30-3 
3°"4 
30-5 307 
30-8 
3°"9 
31 1 
31"2 
31-3 
1-030-0 
10310 
29-9 
3°"° 
30-1 30'2 
303 
30-4 
3° 3 
30-6 
3°-8 
3°'9 
1031-0 
31-2 
SI'S 
3I-4 
3i-S 317 
31-8 
32-0 
32-2 
32-2 
32-4 
] 0310 
10320 
30-9 
31-0 
31'1 31-2 
313 
3r4 
3i3 
31-6 
3r7 
3i'9 
1-032-0 
32-2 
323 '32'5 
32-6 327 
32-9 
33 
33'2 
337 
33’4 
10320 
10330 
Si'S 
3i'9 
320 32-1 
323 
32'4 
323 
32'6 
327 
32-9 
10330 
33'2 
33 3 33‘5 
33-6 133-8 
33‘9 
34-o 34-2 
34-3 
34-5 
10330 
10340 
327 
32-9 
33’o 33-1 
33‘2 
333 333 
33'6 
337 
33'9 
1034-0 
34-2 
34'3 34‘5 
34-6 34-8 
34‘9 
35-° 
35-2 
35‘3 
35‘5 
10340 
1035 0 
33-6 
33'8 
33'9 34-0 
34'2 
343 343 
34-6 
347 
34’9 
1035-0 
35-2 
35'3 35'5 
35-6 35-8 
35'9 
36-1 
36-2 
36-4 
367 
10350 166 
THE ANALYSIS OF WATER, AIR AND FOOD. 
(4) Added Water. The limit for the strength of milk is at present based 
upon that of the poorest possible natural milk. Average milk will show:— 
Fat . . . 3*oo 
Solids not fat 9*oo 
Total 12*00, 
If, however, a milk has only— 
Fat 30 
Solids not fat . . . 8-5 
Total 11-5, 
it will not be considered as definitely proved to be adulterated. The amount of 
water added should, however, always be calculated upon the average standard of 
9 per cent. “ solids not fat,” provided the milk is certainly well below the limit 
of 8 '5%. The “ solids not fat ” are used for the basis of calculation because 
they are a fairly constant quantity, the fat being variable. The amount of 
pure standard milk present in any sample may be calculated thus : 
solids not fat x ico 0/ r •„ 
= f0 ol pure milk present, 
and the difference between this result and 100 is of course added water. 
(5) Ash. The total solids in the platinum dish are burned over a low flame 
at dull redness till quite white, and the ash is weighed. The ash should be 
about '70%, and it will never, as a rule, fall below *67 in an unwatered milk. 
2. Butter. 
Undoubtedly the best process for the detection of foreign fat in butter is : 
Reichert's Process.—This process is based upon the presence in butter-fat 
of one constituent (tributyrin), which yields by appropriate treatment an acid 
(butyric acid) that is relatively much more volatile than the other acids yielded 
by any of the practicable substitutes for butter-fat. As will be seen, the method 
is based on operations that admit of no arbitrary variation; to secure reliable 
and comparable results exactly similar steps must be followed by all operators. 
2*5 grammes of the filtered melted fat are weighed into a flask of about 
150 c.c. capacity, 20 c.c. of a solution of potassium hydrate in methylated 
spirit—50 grammes KHO in 1000 c.c.—and the whole heated to gentle 
ebullition on a water bath until the fat is entirely saponified and all the alcohol 
expelled. The soap should form an almost dry mass, that can scarcely be 
detached from the bottom of the flask by shaking ; the last traces of alcohol 
being removed by occasionally sucking the air out of the flask with a tube. 
Afterwards 50 c.c. of water is added to dissolve the soap (the solution is hastened 
by gentle heating), and when the soap is completely dissolved, 20 c.c. of dilute 
sulphuric acid (100 c.c. H2SO4 in 1000 c.c. of water) is added to decompose 
the soap. The flask is then connected with a small but efficient Liebig’s con- 
denser, and the contents heated to moderate boiling, with addition of two or 
three bits of broken tobacco pipe to prevent bumping. The distillate, which 
contains some insoluble acids, must be passed, as it drops from the condenser, 
through a small wet filter into a 50 c.c. measure. The distillation is con- 
tinued until exactly 50 c.c. has come over, which is at once titrated with 
decinormal soda solution, phenol-phthalein being used as the indicator. 
Reichert’s formula for determining the percentage of butter-fat in mixed fat 
is B = 7'3 {n —o*3); n being the number of cubic centimetres of decinormal 
alkali used in neutralising the distillate from 2*5 grammes of the fat. 
Thus treated, pure butter never yields less acidity than is represented by FOOD ANALYSIS. 
167 
12 c.c. of decinormal soda (4 grammes real NaHO per litre). Butter made from 
the milk of one single individual cow has been known to fall to 11*5 c.c., but 
average butter, as produced from the mixed milk of a herd of cows, takes 
14 c.c. Every time a fresh lot of alcoholic potash (1 in 20) is made, a blank 
experiment must be gone through without any fat, and the amount of alkali 
used must be noted on the potash bottle and deducted as a check from each 
actual analysis. This is necessary when we employ methylated spirit, and such 
check may range up to 2 c.c. with certain spirit. 
3. Bread. 
The only common impurity in bread detectable by chemical means is alum, 
which is tested for as follows : A piece of the crumb of bread, cut from the 
centre of the loaf, is steeped in a mixture of 5 c.c. freshly made tincture of 
logwood, 5 c.c. of solution of ammonium carbonate, and 20 c.c. of water. The 
liquid is poured off and the basin placed on the top of the water oven. If 
alum be present a fine blue color will be developed. This test is, however, 
only very strong presumptive evidence ; and to absolutely confirm it in legal 
cases 100 grammes of the bread should be dried and incinerated in a large 
platinum basin, the ash dissolved in hydrochloric acid, and the amount of 
alumina present estimated by the ordinary methods of quantitative analysis. 
Proper precautions should be taken for separating silica and iron, and an 
allowance should be made on the alumina found from the amount of silica 
present, to avoid the estimation of A1203 accidentally present as clay. The 
alumina is best precipitated and weighed as phosphate in the presence of 
ammonium acetate and excess of acetic acid, the solution being boiled 
and filtered hot. 
4. Estimation of the Alcoholic strength of Spirits, Beer, Wines, and 
Tinctures. 
(1) In a Pure Spirit, If the sample be simply a dilute spirit which leaves 
no residue upon evaporation, the percentage may be ascertained by taking 
the specific gravity. Great care must be taken that the contents of the 
specific gravity bottle are exactly at a temperature of 6o° F., and in taking 
such specific gravities it is better to perform the operation, say, three times, 
and take the average of such determinations, as a very small error makes 
a great difference in the commercial value of the sample under examina- 
tion. Reference to the alcohol table appended will now give the required 
information. 
(2) In a Wine, Beer, Tincture, or Colored or Sweetened Spirit. The 
specific gravity of the sample is taken at 6o° F. and noted. 100 c.c. are 
measured off at 6o° F., and evaporated on the water bath or over a low 
gas flame, so as just to boil very gently, till all odor of alcohol has passed 
off. The liquid thus left is poured back into the measuring flask, the beaker 
is rinsed with a little distilled water, and the rinsings added to the flask. The 
whole is cooled to 6o° F., made up to the 100 c.c. mark with distilled water, 
and the specific gravity of this non-alcoholic fluid is then taken, also at 6o° F. 
Lastly, we calculate : 
Gravity before boiling _ specific gravity of the contained spirit. 
Gravity after boiling 1 
The gravity so found gives by the table the percentage of alcohol in the 
sample. (3) Table for ascertaining the percentages respectively of Alcohol by 
Weight, by Volume, and as Proof Spirit, from the Specific Gravity. 
Condensed from the excellent Alcohol Tables of Mr. Hehner in the “Analyst,” vol. v., pp. 43—63. 
Specific 
Absolute 
Alcohol 
Absolute 
Alcohol 
Proof 
Specific 
Absolute 
Absolute 
Proof 
Specific 
Absolute 
Absolute 
Proof 
I5'5°* 
by w’ght. 
Per cent. 
by vol'me 
Per cent 
Per cent. 
gravity, 
I5‘5°- 
by w’ght. 
Per cent. 
by vol’me 
Per cent. 
Spirit. 
Per cent. 
gravity, 
15‘5°. 
by w’ght. 
Per cent. 
by vol’me 
Per cent. 
Spirit. 
Per cent. 
I -ooco 
O'O O 
O’OO 
000 
•9289 
45-14 
52-82 
92-56 
•8599 
75-18 
81-44 
142-73 
•9999 
0-05 
0-07 
0-12 
•9279 
45'59 
53-29 
93-39 
•8589 
75-64 
81-84 
143-42 
.9989 
0-58 
0-73 
I -28 
•9269 
46-05 
5377 
94-22 
•8579 
76-08 
82-23 
144-10 
.9979 
I" 12 
I-42 
2-48 
•9259 
46-50 
54-24 
95-05 
•8569 
76-50 
82-58 
144-72 
.5969 
175 
2-20 
3-85 
•9249 
46-96 
54-7i 
95-88 
•8559 
76-Q2 
82-93 
145-34 
.9959 
2-33 
2-93 
5-13 
•9239 
47-41 
55-i8 
96-70 
•8549 
77-33 
83-28 
145-96 
.9949 
2-89 
3-62 
6-34 
■9229 
47-86 
55-65 
97-52 
•8539 
7775 
83-64 
146-57 
.9939 
3'47 
4-34 
7'6l 
•9219 
48-32 
56-11 
9874 
•8529 
78-16 
83-98 
147-17 
.9929 
4-06 
5-08 
8-90 
•9209 
4877 
56-58 
99-16 
•8519 
78-56 
8471 
14775 
.9919 
4-69 
5 -86 
10-26 
•9199 
49-20 
57-02 
99'93 
•8509 
78- 
79- 
84-64 
148-32 
.9909 
5 ‘31 
6-63 
11-62 
•8499 
84-97 
148-90 
•9x98 
.9899 
5’94 
7-40 
12-97 
49-24 
57-06 
xooooPs 
•8480 
7976 
85-29 
85-63 
149- 
150- 
.9889 
6-64 
8-27 
14-50 
•8479 
80-17 
■9189 
.9879 
7'33 
9-13 
I5-99 
49-68 
57-49 
100-76 
•8469 
80-58 
85-97 
150-67 
9869 
8-oo 
9’95 
17-43 
•9179 
50-13 
57'97 
xox-59 
•8459 
8i-oo 
86-32 
151 '27 
.9859 
871 
10 82 
18-96 
•9169 
50-57 
58-41 
102-35 
•8449 
81-40 
86-64 
151 "83 
.9849 
9‘43 
1170 
20-50 
•9159 
51-00 
58-85 
103-12 
•8439 
8x-8o 
86-96 
152-40 
.9839 
10-15 
12-58 
22 -06 
•9^9 
5172 
59-26, 
103-85 
•8420 
82-19 
87-27 
152"95 
9829 
10-92 
13-52 
23-70 
■9139 
5I-83 
59-68 
104-58 
•8419 
82-58 
87-58 
153-48 
.9819 
11-69 
14-46 
25-34 
•9129 
52-27 
6o-I2 
105-35 
•8409 
82-96 
87-88 
154-01 
9809 
12-46 
15-40 
26-99 
-9119 
52-73 
60-56 
106-15 
•8399 
83-35 
88-19 
I5474 
9799 
13-23 
i6'33 
28-62 
•9109 
53-17 
61-02 
106-93 
•8389 
83-73 
88-49 
155-07 
9789 
14-00 
17-26 
30-26 
•9099 
53-6i 
61-45 
107-69 
•8379 
84-12 
88-79 
x5 5 "61 
9779 
14-91 
18-36 
32-19 
•9089 
54-05 
61-88 
108-45 
•8369 
84-52 
89-11 
156-16 
9769 
1575 
1979 
33-96 
•9079 
54-52 
62-36 
109-28 
•8359 
84-92 
89-42 
15671 
9759 
16-54 
20-33 
35-63 
•9069 
55-oo 
62-84 
110*12 
•8349 
85-31 
8972 
157-24 
9749 
1733 
21-29 
37-30 
•9059 
55-45 
63-28 
110-92 
•8339 
85-69 
90-02 
157-76 
9739 
18-15 
22-27 
39-03 
•9049 
55-9i 
63-73 
111-71 
•8329 
86-08 
90-32 
158-28 
9729 
18-92 
23-19 
40-64 
•9039 
56-36 
64-18 
112-49 
•8319 
86-46 
90-61 
15879 
97x9 
1975 
24-18 
42-38 
-9029 
56-82 
64-63 
113-26 
•8309 
86-85 
QO-QO 
I593I 
•9709 
20-58 
25-17 
44-12 
•9019 
57-25 
65-05 
113-99 
•8299 
87-23 
91-20 
159-82 
9699 
21-38 
26-13 
4579 
•9009 
57-67 
65-45 
114-69 
•8289 
87-62 
91-49 
160-33 
■9689 
22-15 
27-04 
4779 
•8999 
58-09 
65-85 
iiSHi 
•8279 
88-oo 
91-78 
160-84 
•9679 
22-92 
27-95 
48-98 
■8989 
58-55 
66-29 
iifrxS 
•8269 
88-40 
92-08 
161-37 
■9669 
23-09 
28-86 
50-57 
•8979 
59-oo 
6674 
116-96 
■8259 
88-8o 
9279 
161-91 
•9659 
24-46 
29-76 
52-16 
•8969 
5 9'43 
67-15 
117-68 
•8240 
89-19 
92-68 
162-43 
•9649 
25-21 
30-65 
5371 
•8959 
59-87 
67-57 
118-41 
•8239 
89-58 
92-97 
162-93 
■9639 
2573 
31-48 
55-i8 
•8949 
60-29 
67-97 
119-12 
•8229 
8q-q6 
93-26 
163-43 
■9629 
26-60 
32-27 
56-55 
•8939 
60-71 
68-36 
119-80 
•8219 
90-32 
93-52 
163-88 
•9619 
27-29 
33-o6 
5774 
•8929 
61-13 
68-76 
120-49 
•8209 
90-68 
93-77 
164-33 
•9609 
28-00 
33-89 
59-40 
•8919 
61-54 
69-15 
I2I-i8 
•8199 
91-04 
94-03 
164-78 
•9599 
28-62 
34-61 
6o-66 
•8909 
61-96 
69-54 
121-86 
■8189 
9I-39 
94-28 
165-23 
■9589 
29-27 
35-35 
61-95 
•8899 
62-41 
69356 
122*61 
•8179 
91-75 
94'53 
165-67 
■9579 
29-93 
36-12 
6370 
•8889 
62-86 
70-40 
I2336 
•8169 
92-11 
94'79 
i66'I2 
•9569 
30-50 
3676 
64-43 
•8879 
63-30 
70-81 
124-09 
•8159 
Q2-48 
95-06 
166-58 
•9559 
31-06 
37-41 
65-S5 
•8869 
63-74 
71-22 
124-80 
•8149 
92-85 
95-32 
167-04 
•9549 
31-69 
38-11 
66-8o 
•8859 
64-17 
71-62 
•8139 
93-22 
95-58 
167-50 
'9539 
3271 
38-82 
68-04 
•8849 
64-61 
72-02 
126-22 
•8129 
93’59 
95-84 
167-96 
•9529 
32-94 
3974 
69-29 
1 -8839 
65-04 
72-42 
126-92 
•8119 
93-96 
96-11 
168-24 
•9519 
33'53 
40-20 
70-46 
■8829 
65-46 
72-80 
1257-59 
■8109 
94-3I 
96-34 
168-84 
•9509 
34-10 
40-84 
7I-58 
•8819 
65-88 
73-19 
128-25 
•8099 
94-66 
96-57 
169-24 
9499 
3477 
41-37 
72-50 
•8809 
66-30 
73-57 
128-94 
•8089 
95'00 
96-80 
169-65 
■9489 
35-05 
41-90 
73'43 
•8799 
6674 
73-97 
129-64 
•8079 
95-36 
97-05 
170-07 
•9479 
35'55 
42-45 
74'39 
•8789 
67-17 
7437 
130-33 
■8069 
95-7I 
97-29 
17050 
•9469 
36-06 
43-oi 
75'37 
•8779 
67-58 
7474 
130-98 
•8059 
96-07 
97’53 
170-99 
9459 
36-61 
43-63 
76-45 
•8769 
68-oo 
75-X2 
I3X-64 
1 -8049 
96-40 
97'75 
171-30 
•9449 
37-17 
44-24 
7773 
I -8759 
68-42 
75-49 
132-30 
•8039 
96-73 
97-96 
171-68 
‘9439 
3772 
44-86 
78-61 
•8749 
68-83 
75-87 
132-95 
•8029 
97-07 
98-18 
172-05 
•9429 
38-28 
45-47 
79-68 
•8739 
69-25 
76-24 
133-60 
•8019 
97-40 
9839 
172-43 
•9419 
38-83 
46-08 
8075 
•8729 
69-67 
76-61 
I34-25 
•8009 
97-73 
98-61 
172-80 
■9409 
39’3S 
46-64 
81-74 
•8719 
70-08 
76-98 
134-90 
•7999 
98-06 
98-82 
173"I7 
■9399 
39-85 
47-18 
82-69 
•8709 
70-48 
7772 
T35 "51 
•7989 
9837 
qq-oo 
173-50 
■9389 
40-35 
47-72 
83-64 
•8699 
70-88 
77-67 
136-13 
•7979 
98-69 
99-18 
173-84 
•9379 
40-85 
48-26 
84-58 
•8689 
71-29 
78-04 
136-76 
•7969 
QQ'OO 
9977 
174-17 
•9369 
41-35 
48-80 
85-53 
•8679 
71-71 
78-40 
137-40 
•7959 
99-32 
99'57 
I74-52 
‘9359 
41-85 
49-34 
86-47 
•8669 
72-13 
7877 
138-05 
•7949 
99^5 
9977 
174-87 
'9349 
42-33 
49-86 
8777 
•8659 
72-57 
79-16 
13872 
'7939 
99-97 
99-98 
175-22 
■9339 
42-81 
50-37 
88-26 
•8649 
73'oo 
79-54 
r39"39 
•9329 
•9319 
43-29 
4376 
50-87 
5178 
89- 
90- 
•8639 
•8629 
73-42 
73-83 
79- 
80- 
140-02 
140-65 
Absolute Alcohol. 
•9309 
44-23, 
5I-87 
90-89 
•86x9 
74-27 
80-64 
Hi-33 
•9299 
44-68 
52-34 
91-73 
•8609 
74-73 
81-04 
142-03 
•7938 
100-00 
100-00 
I75-25 FOOD ANALYSIS. 
169 
5. Mustard. 
This is chiefly a microscopical matter for the exact identification of impuri- 
ties, but the following chemical operations may be performed : 
(1) Test a cooled decoction for starch with solution of iodine. 
(2) If starch be found, extract a weighed portion in the “ Soxhlet ” 
with petroleum spirit or ether. Distil off the spirit dry, and 
weigh the oil. Mustard contains as an ordinary minimum 
33 % of oil, and the amount of genuine mustard in the sample 
will then be found thus ; 
°/ of oil found x 100 0/ , , 
= /„ Pennine mustard ; 
33 
by deducting this from 100 the difference is added starch or 
flour. 
(3) Moisten the mustard with a little ammonia, when the turmeric brown 
will be developed if that coloring agent be present. 
6. Pepper. 
This is also examined microscopically for extraneous starches (especially 
rice), and also for poivrette, which is chiefly ground olive stones. 
(1) Dry at 2120, weigh out 5 grammes of the dried pepper, and take 
the ash. This should not exceed g'o per cent, even in the 
most inferior black pepper, which has been previously dried at 
2120. Treat the ash with HCI, add water, bcil, filter, wash, 
dry, ignite, and weigh the sand. This should not exceed 4 per 
cent, on the dried pepper. 
(2) If the microscope reveals starch other than that of pepper, estimate 
it on 2 grammes of the dried pepper by the method given in 
Section 8. 
7, Colored Sweets, 
The poisonous colors are nearly all mineral and insoluble. They may be 
scraped off, washed with water, and identified by the ordinary methods given 
in Chapter IV. As a rule, at present only aniline colors are used, and they 
are added in such minute proportions as not to be considered dangerous. 
8. Direct Estimation of Starch in Cereals, Mustard, Pepper, and all 
Foods and Drugs containing it. 
This depends upon the fact that starch forms an insoluble compound with 
barium. If an excess of baryta water of known strength be added to starch 
which has been gelatinised in water, a portion of the barium will combine with 
the starch, and then by estimating the excess of baryta water left unabsorbed 
we can find the amount taken up by the starch. The formula of the starch- 
baryta compound is Co4H40O20 BaO, and it therefore contains ig'x per cent, 
of BaO. 
The materials required are : 
(1) Decinormal hydrochloric acid, containing 3'65 grms. real HClper xooo c.c. = '00765 
BaO for each c.c. 
(2) Baryta water kept in a special jar with a burette permanently attached, as shown in 
the illustration (overleaf). Ais the jar for the baryta water, having a tube attached 
containing lumps of quicklime to prevent the entrance of CO„ from the air. 
The burette B is attached to the bottom neck of the jar by a tube having a 
pinchcock (a) to admit the reagent, and a tube (n) filled with lumps of caustic 
potash to prevent entrance of C02. 
(3) Alcoholic solution of phenol-phthalein as an indicator. THE ANALYSIS OF WATER, AIR AND FOOD. 
The Process.—The substance is powdered or finely ground in a mill, and 
3 grammes weighed out for analysis. If (as in the case of mustard, pepper, 
etc.) it contains oil or resinous bodies, these are first extracted by percolation 
with petroleum spirit or ether in the “Soxhlet.” The powder is then well 
rubbed in with successive quantities of water until thoroughly disintegrated, 
the liquid being transferred to a 250 c.c. flask, and 100 c.c. of water in all being 
used to entirely transfer the powder from the mortar to the flask. In dealing 
with very hard substances, like beans, peas, etc., the water should be used 
boiling. The flask and contents are now heated on the water bath for half an 
hour, with frequent shaking, to entirely gelatinise the starch. The whole is 
then cooled, and 50 c.c. of standard baryta water having been added from the 
burette, the flask is corked, well shaken for two minutes, proof spirit is added 
up to the 250 c.c. mark, and the whole again shaken, tightly corked, and set 
aside to settle. While settling a check is made on 50 c.c. of the baryta water 
by shaking up with 100 c.c. of freshly boiled distilled water in a 250 c.c. corked 
flask, and then titrating with the decinormal HCI, in the presence of two drops 
of phenol-phthalein. The number of c.c. of acid used is recorded, giving the 
total strength of 50 c.c. of the baryta water employed. When the main 
analysis has settled, 50 c.c. of the clear liquid are drawn off with a pipette, 
rapidly titrated with the decinormal acid and phenol-phthalein, as in the check, 
and the number of c.c. of acid used is multiplied by 5 and set down as strength 
of baryta water remaining uncombined. This latter amount is deducted from 
the total check strength, and the difference in c.c. of acid is multiplied by 
■00765, which gives BaO combined with the starch. This result now multiplied 
by 4’2353 gives the amount of starch in the 3 grms. taken = x : then 
Fig. 45. 
——^lO°- percentage of starch. FOOD ANALYSIS. 
171 
9. Free Sulphuric Acid in Vinegar. 
(1) B. P. Process.—lf ten minims of solution of barium chloride be added 
to a fluid ounce of the vinegar, and the precipitate, if any, be separated by 
filtration, a further addition of the test will give no precipitate (absence of 
more than Ty per cent, of sulphuric acid). 
(2) Improved Method.—The official test given above is entirely valueless in 
the case of vinegars containing much sulphate, from being made with water 
rich in that ingredient; it is therefore necessary, if the vinegar appear to be 
adulterated when thus tried, to proceed as follows : 50 c.c. of the vinegar are 
mixed with 25 c.c. of volumetric solution of sodium hydrate, made decinormal 
by diluting the official volumetric solution to ten times its bulk with water. 
The whole is evaporated to dryness, and incinerated at the lowest possible 
temperature. 25 c.c. of decinormal solution of oxalic acid (made to exactly 
balance the sodium hydrate solution) are now added to the ash, the liquid 
heated to expel C02, and filtered. The filter is washed with hot water, and 
the washings having been added to the filtrate, litmus solution is added, and 
the amount of free acid ascertained by running in decinormal soda from a 
burette. The number of c.c. of soda thus used multiplied by '0049 gives the 
amount of free sulphuric acid in the vinegar. This process depends on the 
•fact that whenever the ash of vinegar has not an alkaline reaction, free mineral 
acid was undoubtedly added. CHAPTER XI. 
ANALYSIS OF DRUGS, URINE AND URINARY CALCULI. 
DIVISION I. ANALYSIS OF DRUGS. 
1. General Scheme. 
The analysis of drugs is so large a subject that only a few of the more 
commonly occurring problems can be discussed in the present volume. It 
will, however, be interesting, before proceeding to the consideration of special 
matters, to give a sketch of the general method of analysing a vegetable sub- 
stance used in medicine, following the lines laid down by Dragendorff, but 
somewhat modified by the author as the result of experience. 
Step I. Dry the substance in the water oven until it ceases to lose weight. 
Step 11. Pack the dried and powdered substance, mixed with a little 
sand, in a “ Soxhlet ” apparatus, thoroughly exhaust it with 
petroleum spirit, and cork up and save the fluid extract so 
obtained, marking it A. 
Step 111. Spread the solid left from Step 11. out to dry on a plate of glass 
on the top of the water oven, and when all odor of petroleum 
has passed off, replace it in the Soxhlet, and exhaust it this time 
with perfectly anhydrous ether. Cork up the ethereal extract 
obtained and mark it b. 
Step IV. Spread out as before, and when all odor of ether is gone, repack 
and extract with purified commercial methyl alcohol, as sold for 
making methylated spirit. This is more volatile than common 
alcohol, and is as a rule a better solvent of the articles required 
in this group, while it does not so readily extract glucose, etc. 
It is an article of commerce, and can be specially ordered 
through a purveyor of chemicals, as “commercial methol, highest 
strength.”—Save this alcoholic extract and mark it c. 
Step V. Extract the insoluble matter from Step IV. with distilled water 
at a temperature not exceeding 120° Fah., and filter. Wash 
with cold water and save the filtrate d. 
Step VI. Wash the insoluble off the filter into a large flask, with plenty of 
water, acidulated with 1 per cent, of hydrochloric acid, and boil 
it for an hour under an upright condenser. Let it settle, 
pour off the liquid as close as possible (saving it), and then 
collect the insoluble on a filter and wash with boiling water, 
adding the washings to what was poured off. This extract is 
marked e. ANALYSIS OF DRUGS. 
173 
Step VII. Once more wash the insoluble from the filter into a beaker and 
boil it up for an hour with plenty of water rendered distinctly 
alkaline with sodium hydrate. Collect on a weighed filter, wash 
first with boiling water, acidulated with hydrochloric acid, and 
then with plain boiling water, till no trace of a chloride remains; 
dry in the water oven and weigh, deducting the tare of the filter. 
Lastly, ignite the filter and its contents in a weighed platinum 
basin, and deduct the ash so found from the first weight, and the 
difference will be the woody fibre in the drug. 
Step VIII. Make a nitrogen determination by Kjeldahl’s method (page 154) 
on a fresh portion, and the nitrogen found (after deducting any 
due to alkaloids present) multiplied by 6‘33 will give the amount 
of albuminous bodies present. 
Treatment of the Separate Solutions.—Each liquid is made to a definite 
number of c.c. with the same solvent, and then an aliquot part, say 
10 c.c., is taken and evaporated, and the residue weighed, to find the total 
matter soluble in each solvent. The bulk of the liquids are then treated as 
follows:— 
Liquid A. This will contain chiefly fixed and volatile oils. The spirit is 
allowed to evaporate spontaneously, and the residue is distilled 
with water, when the volatile oil passes over, leaving the fixed oil 
in the retort. 
Liquid B. This chiefly contains resins, together with some bitters, alkaloids 
and organic acids. The solution is evaporated to dryness on 
the water.bath with sand, and the residue, having been powdered, 
is boiled with water slightly acdulated with HCI. A portion 
of this watery solution is tested for benzoic, cinnamic, salicylic, 
gallic, and other free organic acids, and the remainder is saved 
for subsequent use in Group C. The portion insoluble in water 
now chiefly represents any resins present in the drug, which are 
soluble in ether. These may be further divided and examined 
by the action of alcohol. Resins are recognised by their odor 
on warming, and by the action of H2S04, HN03, HCi, etc., on 
spots of the solid resin left by evaporating the solutions. This 
matter requires special experience, but a full description of the 
nature and reaction of all the principal resins will be found in 
the author’s work on “ Pharmaceutical and Medical Chemistry,” 
or in his book on “ Organic Materia Medica.” 
Liquid C. Is evaporated to a low bulk, and then poured into water faintly 
acidulated with hydrochloric acid. Any insoluble matter is 
probably a resinous body insoluble in ether, and is to be 
filtered out and examined as a resin. A portion of the aqueous 
solution is to be tested for tannin, and the remainder is to be 
mixed with the reserved liquid from b, the whole gently evaporated 
to a convenient bulk and treated by immiscible solvents as 
follows : 
Step I, The liquid (which must still retain a slightly acid reaction) is 
shaken up successively with chloroform and ether in a separator 
(see fig. 23, page 93). The solvents are drawn off and evaporated, 
and the residues so obtained tested for glucosides and bitter ANALYSIS OF DRUGS, ETC. 
principles, of which latter bodies the following are some of the 
more commonly occurring : 
(i) Extracted by chloroform from acid solutions : 
Absinthin (wormwood). 
Anthemin (chamomiles). 
Colchicine (colchicum), imperfectly. 
Colocynthin (colocynth, or bitter apple), imperfectly. 
Calurabin, and probably some berberine (calumba), bright yellow, and 
highly fluorescent. 
Gentipicrin (gentian), very imperfectly. 
Picric acid (artificial), yellow, imperfectly. 
Picrotoxin {cocculus indicus), with difficulty. 
Quassiin (quassia wood). 
(2) Subsequently extracted by ether from acid solutions : 
Chiratin (chiretta). 
Colocynthin (colocynth, or bitter apple). 
Gentipicrin (gentian). 
Picric acid, yellow. 
Picrotoxin (cocculus indicus). 
Note.—The alkaloid colchicine comes out with the glucoside in this division. 
Step 11. The liquid remaining in the separator is now rendered alkaline 
with sodium hydrate and shaken up again with chloroform. 
This extracts nearly all the alkaloids. The chloroform is 
evaporated and the residue tested for alkaloids (see Chap. V.). 
Step 111. The liquid still remaining in the separator is shaken up with 
amylic alcohol, which takes out morphine and leaves it on 
evaporation, when any residue is tested for its presence. 
Liquid D. Is evaporated to a low bulk and then mixed with twice its 
volume of rectified spirit, when gums precipitate insoluble, and 
may be examined, and sugars dissolve and may be estimated by 
“ Fehling.” Saponin also may be found with the sugars. 
2. Analysis of Cinchona Bark. 
Step I. Extraction. Mix 20 grammes (or 200 grains) of the bark in 
fine powder (No. 60) with 6 grammes (or 60 grains) of calcium 
hydrate in a mortar. Slightly moisten with 20 c.c. (or half a 
fluid ounce) of water, and mix intimately ; allow the mixture to 
stand for an hour or two, when it will present the characters of a 
moist, dark brown powder, in which there should be no lumps 
or visible white particles. Transfer this powder to a 6-ounce 
flask, add 130 c.c. (or 3 fluid ounces) of benzolated amylic 
alcohol, boil them together for about half an hour under an 
upright condenser, decant and drain off the liquid on to a 
filter, leaving the powder in the flask; add more of the 
benzolated amylic alcohol to the powder, boil and decant as 
before; repeat this operation a third time : then turn the 
contents of the flask on to the filter, and wash by percolation 
with more of the benzolated amylic alcohol until the bark is 
exhausted. (If an upright condenser be not available, a funnel 
may be placed in the mouth of the flask, and another flask 
filled with cold water placed in the funnel. This will form a 
convenient condenser, which will prevent the loss of more than 
a small quantity of the boiling liquid.) Introduce the collected ANALYSIS OF DRUGS. 
175 
filtrate, while still warm, into a stoppered glass separator; add 
to it 2 c.c. (or 20 minims) of diluted hydrochloric acid, 
mixed with 12 c.c. (or 2 fluid drachms) of water; shake them 
well together, and when the acid liquid has separated draw it 
off, and repeat the process with distilled water slightly acidulated 
with hydrochloric acid, until the whole of the alkaloids have 
been removed (which is known by a few drops of the liquid 
ceasing to give any precipitate with sodium hydrate). The 
acid liquid thus obtained will contain all the alkaloids as 
hydrochlorates, and excess of hydrochloric acid. 
Step 11. Separation of the Quinine and Cinchonidine from the 
Quinidine, Cinchonine, and Amorphous Alkaloids.—The 
acid fluid from Step I. is to be carefully and exactly neutralised 
with ammonia while warm, and then concentrated to the bulk 
of 18 c.c. (or 3 fluid drachms). I*s gramme (or 15 grains) 
of tartrated soda, dissolved in twice its weight of water, 
is added to the neutral liquid, and the mixture stirred with a 
glass rod. Insoluble tartrates of quinine and cinchonidine will 
separate completely in about an hour ; and these collected 
on a filter, washed, and dried in the water oven, will contain 
eight-tenths of their weight of the alkaloids, quinine and 
cinchonidine, which multiplied by 5 (or if grains have been 
taken, divided by 2) represents the percentage of those 
alkaloids. The other alkaloids will be left in the mother- 
liquor. 
Step 111. For total Alkaloids.—To the mother-liquor from the preceding 
process add solution of ammonia in slight excess. Collect, 
wash, and dry the precipitate in the water oven, which will 
contain the other alkaloids. The weight of this precipitate 
multiplied by 5 (or, if grains have been taken, divided by 2) 
gives the amount of cinchonine, quinidine, and amorphous 
alkaloids. This weight, added to that of the quinine and 
cinchonidine from Step 11., gives the total alkaloids. 
Step IV. Separation of Quinine and Cinchonidine.—This is an 
operation to effect which with absolute accuracy requires 
special experience, and to give the detailed instructions 
and solubility allowances by which alone it can be carried out 
to within tenths of a per cent, would be beyond the scope of 
the present work. It may, however, be generally stated that it 
is accomplished by dissolving the precipitate from Step 11. in 
a little water acidulated with hydrochloric acid, then adding 
excess of sodium hydrate and shaking up with ether. After 
standing for some hours the ethereal layer is separated and 
evaporated to dryness. The residual quinine (now con- 
taining only a little cinchonidine) is dissolved in a fixed 
quantity of alcohol by the aid of a slight excess of dilute 
sulphuric acid, the alcohol is evaporated off, the residue is 
dissolved in a fixed quantity of water and brought to the 
boil. While hot, this solution is rendered as nearly neutral as 
possible by dropping in dilute ammonium hydrate (but not so 
as to produce a permanent precipitate) and set aside for twelve 
hours, when crystals of sulphate of quinine (C20H24N202) * 
H2S04 • iSH2O deposit, leaving sulphate of cinchonidine in 176 
ANALYSIS OF DRUGS, ETC. 
solution. These crystals are then collected and weighed with 
certain special precautions. The use of animal charcoal to 
perfectly decolorise is also necessary. 
Step V. Separation of the quinidine, cinchonine and amorphous alkaloid. 
The precipitate from Step 111. is digested in cold proof spirit, 
which dissolves the quinidine and amorphous alkaloids, and 
leaves the cinchonine insoluble for collection, drying and 
weighing. The alcoholic solution is rendered acid with acetic 
acid and evaporated to dryness on the water bath. The 
residue is dissolved in a very small quantity of water, and a 
little spirit and some solution of sodium iodide is added, which 
precipitates the quinidine as iodide. This is weighed and the 
weight multiplied by 718 = quinidine. The amorphous 
alkaloids are then found by difference. 
3. Estimation of Morphia in Opium. 
Dry the opium in the water oven, powder it, and once more dry it at 2120 
till the weight is constant. Take 14 grammes (or 140 grains) of this powder, 
and 6 grammes (or 60 grains) of fresh slaked lime, and triturate them 
together with 40 c.c. (or 400 grain-measures) of distilled water in a mortar 
until a uniform mixture results ; then add 100 c.c. (or 1000 grain-measures) 
of distilled water and stir occasionally during half an hour. Filter the 
mixture through a plaited filter about three inches in diameter in a wide- 
mouthed bottle or stoppered flask, having the capacity of about six fluid 
ounces and marked at exactly 104 c.c. (or 1040 grain-measures), until the 
filtrate reaches this mark. To the filtered liquid, representing 10 grammes 
(or 100 grains) of opium, add 11 c.c. (or no grain-measures) of rectified 
spirit, and 50 c.c. (or 500 grain-measures) of ether, and shake the mixture; 
then add 4 grammes (or 40 grains) of ammonium chloride, shake well and 
frequently during half an hour, and set it aside for twelve hours. Counter- 
balance two small filters ; place one within the other in a small funnel, and 
decant the ethereal layer as completely as practicable upon the inner filter. 
Add 20 c.c. (or 200 grain-measures) of ether to the contents of the bottle, and 
rotate it; again decant the ethereal layer upon the filter, and afterwards 
wash the latter with 10 c.c. (or 100 grain-measures) of ether added slowly 
and in portions. Now let the filter dry in the air, and pour upon it the 
liquid in the bottle in portions, in such a way as to transfer the greater 
portion of the crystals to the filter. When the fluid has passed through the 
filter, wash the bottle and transfer the remaining crystals to the filter, with 
several small portions of distilled water, using not much more than 20 c.c. 
(or 200 grain-measures) in all, and distributing the portions evenly upon the 
filter.* Allow the filter to drain, and dry it, first by pressing between sheets 
of bibulous paper, and afterwards at a temperature between 1310 and 140° F. 
(550 and 6o° C.), and finally at 1940 to 2120 F. (96° to ioo° C.) Weigh 
the crystals in the inner filter, counterbalancing by the outer filter. The 
crystals should weigh 1 gramme (or 10 grains), corresponding to 10 per cent, 
of morphine in the dry powdered opium. It is considered that anything 
between 97 and 107 per cent, is correct for official opium. 
* When it is desired to obtain the morphine in a state of absolute purity, the precipitate 
should be washed first with water saturated with morphia, and then with rectified spirit 
similarly saturated. ANALYSIS OF DRUGS. 
177 
IV. Estimation of the Alkaloidal Strength of Extracts. 
Dissolve 1 gramme (or 10 grains) of the extract in 20 c.c. (or half a fluid 
ounce) of water, heating gently if 'necessary, and add 6 grammes (or 1 
drachm) of sodium carbonate previously dissolved in 20 c.c. (or half a fluid 
ounce) of water and 20 c.c. (or half a fluid ounce of chloroform; agitate, 
warm gently, and separate the chloroform. Add to this 20 c.c. (or half a fluid 
ounce) of dilute sulphuric acid with an equal bulk of water; again agitate, 
warm, and separate the acid liquor from the chloroform. To this acid liquor 
add now an excess of ammonia, and agitate with 20 c.c. (or half a fluid 
ounce) of chloroform; when the liquors have separated, transfer the chloro- 
form to a weighed dish, and evaporate the chloroform over a water bath. 
Dry the residue for one hour at 2120 R, and weigh. Thus treated, extract of 
mix vomica should show 15 per cent of total alkaloids, and the process may 
be extended to almost any extract containing alkaloids except opium. No 
standards have, however, yet been fixed, except that for mix vomica. 
V. Examination of a Tincture or other Alcoholic Liquor for the Presence 
of Methylated Spirit. 
For the purpose of testing tinctures or any alcoholic liquors, they must 
first be distilled until a part of the spirit has passed over. The distillate is 
treated as follows ; 
A small flask is fitted with a cork and a tube having two right-angular 
bends, with the end dipping into a test-tube kept cold by immersion in water; 
and in it is put,— 
(1) About half a drachm of the spirituous liquid required to be tested, 
(2) An equal quantity of potassium dichromate and of pure sulphuric acid. 
(3) Four or five times as much water. 
The mixture, after standing for twenty minutes, is distilled at a gentle heat, 
until nearly the whole has passed over. Sodium carbonate having been added 
to the distillate till it is slightly alkaline, the liquid is evaporated in a porce- 
lain basin to about half its bulk, and having been acidulated slightly by acetic 
acid, is transferred to a test-tube, heated gently with twenty drops of a 5 per 
cent, solution of argentic nitrate for a few minutes, when any decided opacity 
(due to the discoloration of the fluid and the separation of a blackish precipi- 
tate of metallic silver), indicates the presence of methyl hydrate in the sample 
thus tested. In the oxidation of ordinary alcohol a mere trace of formic acid 
is formed by secondary decomposition, consequently a distinct precipitate 
must be obtained before the spirit can, with certainty, be pronounced to be 
methylated. 
The operation of the above process depends on the fact that by a short 
oxidation with sulphuric acid and potassium dichromate, aldehyds and acids are 
produced, which, by being boiled with sodium carbonate, yield sodium acetate 
and formate, the former from the ordinary “ alcohol ” and the latter from the 
wood spirit. Upon the addition of argentic nitrate, argentic formate is pro- 
duced, which is easily reduced by boiling to metallic silver, while argentic 
acetate is not so affected. If the oxidation be too powerful, the formic 
acid in turn becomes oxidised to C02 and FL,O and lost. Thus the 
process is not always satisfactory, and must be completed within half an hour 
or so. 178 
ANALYSIS OF DRUGS, ETC. 
When this process has to be applied to sweet spirit of nitre, the ethyl nitrite 
must be first got rid of, as follows ; 
Take a little of the spirit and place it in a bottle with some dry potassium 
carbonate, and shake up. Let it settle, and take about two drachms of the 
strong spirit which separates. Saturate this with calcium chloride, and distil 
on a water bath, rejecting the distillate (ethyl nitrite, etc.). Add a little 
water to the contents of the retort and distil again, when the pure spirit will 
come over, and a portion may then be tested as above directed. 
VI. Estimation of the Strength of Resinous Drugs. 
Take 5 to 10 grammes of the drug in powrder, and place it in a strong glass 
flask with 100 c.c. of pure methylated spirit (6o° O.P. and free from resin). 
Close the flask with a good cork, and digest it in a warm place at about 
1200 F. for 12 hours, shaking from time to time. Pour or filter off 80 c.c. 
(representing of the total drug taken), place it in a weighed beaker, and 
evaporate to 25 c.c. on the top of the water bath. Now add 50 c.c. of 
distilled water and boil gently over a low gas flame till all the alcohol is 
driven off. Let it cool and perfectly settle, pour off the supernatant liquor, 
wash the deposited resin by decantation with hot distilled water, and then 
dry the beaker and its contents in the air bath at 220° F. and weigh, 
deducting the tare of the beaker. Thus treated, jalap, for example, should 
show 10 per cent, of resin, but for other resinous drugs no official standard 
has yet been laid down. 
VII. Testing the Purity of Quinine Sulphate. (Official Directions.) 
Test for Cinchonidine and Cinchonine.—Heat 100 grains of the sulphate of 
quinine in five or six ounces of boiling water, with three or four drops of 
diluted sulphuric acid. Set the solution aside until cold. Separate, by 
filtration, the purified sulphate of quinine which has crystallised out. To 
the filtrate, which should nearly fill a bottle or flask, add ether, shaking 
occasionally, until a distinct layer of ether remains undissolved. Add 
ammonia in very slight excess, and shake thoroughly, so that the quinine 
at first precipitated shall be redissolved. Set aside for some hours, or during 
a night. Remove the supernatant clear ethereal fluid, which should occupy 
the neck of the vessel, by a pipette. Wash the residual aqueous fluid and 
any separated crystals of alkaloid with a very little more ether, once or twice. 
Collect the separated alkaloid on a tared filter, wash it with a little ether, 
dry at 2120 F. (ioo° C.), and weigh. Four parts of such alkaloid correspond 
to five parts of crystallised sulphate of cinchonidine or of sulphate of cin- 
chonine. 
Test for Quinidine.—Recrystallise fifty grains of the original sulphate of 
quinine, as described in the previous paragraph. To the filtrate add solution 
of iodide of potassium, and a little spirit of wine to prevent the precipitation 
of amorphous hydriodates. Collect any separated hydriodate of quinidine, 
wash with a little water, dry, and weigh. The weight represents about an 
equal weight of crystallised sulphate of quinidine. 
Test for Cupreine.—Shake the recrystallised sulphate of quinine, obtained 
in testing the original sulphate of quinine for cinchonidine and cinchonine, 
with one fluid ounce of ether and a quarter of an ounce of solution of 
ammonia, and to this ethereal solution, separated, add the ethereal fluid and 
washings also obtained in testing the original sulphate for the two alkaloids ANALYSIS OF DRUGS. 
179 
just mentioned. Shake this ethereal liquor with a quarter of a fluid ounce 
of a 10 per cent, solution of caustic soda, adding water if any solid matter 
separates. Remove the ethereal solution. Wash the aqueous solution with 
more ether, and remove the ethereal washings. Add diluted sulphuric acid 
to the aqueous fluid heated to boiling, until the soda is exactly neutralised. 
When cold collect any cupreine sulphate that has crystallised out on a tared 
filter, dry and weigh. 
Quinine sulphate should not contain more than 5 per cent, of other cinchona 
alkaloids. 
VIII. Estimation of the Alkaloidal Strength of Seale Preparations. 
Dissolve 5 grammes in 30 c.c. of water, place the solution in a separator, 
add 20 c.c. of chloroform, and then a slight excess of ammonium hydrate. 
Shake well and allow it to stand. When the chloroform has separated off clear, 
run it off into a small weighed flat-bottomed flask, and repeat the shaking 
successively with 10 c.c. and 5 c.c. of chloroform, always running it off into 
the same flask. Attach the flask by a cork to a condenser and distil off the 
chloroform, and then dry the residue for half an hour in the air bath at 
220° R, and weigh. Thus treated, citrate of iron and quinine should show 
15 per cent, of alkaloidal residue, which should be soluble in ether. 
IX. The Estimation of Phenol. 
The following is the method for determining the phenol quantitatively in 
crude carbolic acid:—2o c.c. of potassium hydrate solution (sp. gr. 1-25—1-30) 
are added to 20 c.c. of the crude carbolic acid. The whole is well shaken up, 
and, after half an hour, the mixture is made up to litre by the addition 
of water. The tarry constituents of the carbolic acid separate out and are 
removed by filtration. The residue is washed with lukewarm water till the 
wash-water is no longer alkaline. The whole filtrate is then treated with 
hydrochloric acid till faintly acid (this point is also indicated by the liquid 
changing color and turning brown), and made up to 3 litres. The small 
quantity of tarry matter left in the filtrate does not interfere in the titration 
which follows. The dilution is necessary, for, in titrating, the carbolic acid 
solution must not contain more than 1 gr. in 25 c.c. 50 c.c. are now taken, 
and 150 c.c. of a solution containing 2-040 grs. sodium bromate and 6-959 grs- 
sodium bromide to the litre are added, together with 5 c.c. of concentrated 
hydrochloric acid; bromine is evolved and tribroraophenol precipitated. 
After 20 minutes, during which the mixture is shaken up frequently, 10 c.c. 
potassium iodide solution (125 gr. potassium iodide to the litre) are added ; 
potassium bromide is formed with the excess of free bromine, and iodine 
liberated. After about 5 minutes (not longer) starch solution is added, and 
the free iodine titrated with a sodium thiosulphate solution (“hypo”), con- 
taining 9-763 grs. per litre. The experiment should be first done upon 
•2 gramme of pure crystallised carbolic acid dissolved in 50 c.c. of water, and 
the number of c.c. of the “ hypo ” solution used should be noted. A blank 
experiment on 150 c.c. of the bromide-bromate solution, with 5 c.c. of HCI 
and 10 c.c. of the iodide solution, should also be titrated. By deducting the 
c.c. of “ hypo ” used in the first check from that in the second, the number 01 
c.c. of “ hypo ” equivalent to -2 gramme real carbolic acid is ascertained, and 
the equivalent value of each c.c. of “hypo” in carbolic acid is calculated. 
In every analysis the number of c.c. of “hypo” used is deducted from that 
employed in the blank experiment, and the difference is calculated to carbolic 
acid present in the sample. ANALYSIS OF DRUGS, ETC. 
X. Estimation of the Fatty Acids in Soap. 
Two grammes of the soap, in fine shavings, are shaken up in a separator, with 
a slight excess of dilute sulphuric acid to liberate the acids. Ether is then 
added, and the fatty acids which have been liberated are dissolved up in it. 
When the decomposition of the soap is complete, the liquid below the 
ethereal solution is removed. With a little care this can be done very 
completely without any loss of the ethereal solution. The ether is then 
shaken up with distilled water, and the latter drawn off as before, and this 
process of washing repeated three times more. When all but a few drops of 
the wash-water have been drawn off, a few drops of barium chloride solution 
are added, the mixture shaken up, and the last traces of sulphuric acid thus 
removed. With a little practice so little water is left below the ethereal 
solution that the latter can be directly drawn off and evaporated in a weighed 
dish, and the residue finally dried in the water oven and weighed. The fatty 
acids obtained are perfectly free from sulphuric and hydrochloric acid, and do 
not get brown at ioo° C. 
XI. Estimation of Oleic Acid. 
One gramme of the impure fatty acid is saponified in a basin by heating 
with a slight excess of alcoholic potash till dissolved, and then diluted with 
water. This solution is treated with acetic acid drop by drop, until on stirring 
a faint permanent turbidity ensues. Dilute solution of potassium hydrate is 
then stirred in drop by drop till the liquid just clears up, and then solution of 
plumbic acetate is stirred in until precipitation ceases. The precipitate having 
been allowed to settle, the supernatant liquor is poured off and the soap 
washed once with boiling water. A little clean sand is rubbed up with the 
soap in the basin, and the whole scraped out and transferred to a “ Soxhlet,” 
in which it is thoroughly exhausted with 90 c.c. of pure ether. The ethereal 
solution (which now contains only plumbic oleate, the plumbic palmitate and 
stearate being left insoluble in the Soxhlet) is transferred to a special apparatus, 
sold by apparatus vendors as “ Muter’s oleine tube.” This is a graduated and 
stoppered tube holding 120 c.c., and having a spout and stopcock at 30 c.c. 
from its base. Previously to introducing the ether, place 20 c.c. of dilute 
hydrochloric acid (1 in 3) into the tube, and then make up the whole with 
ether rinsings of the basin to the 120 c.c. mark. Close the tube, shake well 
and set aside. When settled, note the full volume of the ethereal solution 
of oleic acid, and run off an aliquot part from the tap into a weighed dish, 
evaporate, dry in the water oven and weigh. Finally calculate this weight to 
that of the whole bulk of ethereal solution previously noted, thus getting the 
amount of real oleic acid present in the gramme of crude acid started with. 
XII. Estimation of Glycerine. 
This process depends on (i) obtaining the glycerine free from other oxi- 
disable bodies, such as alcohol sugars, etc.; (2) oxidising it with potassium 
bichromate in the presence of sulphuric acid to carbon dioxide and water by the 
following equation : 
3C,H6(0H)8 + 7K2Cr207 + 28H2S04 = i4Cr2(SO4)3 + yK2S04 +9CO. + 40H20 ; 
and (3) estimating the amount of CO2 evolved. 
The relation between carbon dioxide and glycerine is that 396 parts by 
weight of C02 represent 276 parts of glycerine, or in other words the weight 
in grammes of C02 found multiplied by '69697 gives the amount of glycerine MICRO-CHEMICAL IDENTIFICATION OF DRUGS. 
181 
in the quantity weighed out for analysis. The process is conducted in an ordi- 
nary apparatus for the estimation of carbon dioxide like that figured on page 145, 
fig. 36. The fluid containing the glycerine is first tested for the presence of 
sugars, both cane and glucose, and if they are absent a measured quantity, 
(say 100 c.c.) is evaporated on the water bath with 3 c.c. of milk of lime and 
2 grammes of pure sand, till a fairly detachable residue is obtained. This is 
then scraped from the basin and extracted in the “ Soxhlet ” with absolute 
alcohol of B.P. strength. The alcohol is distilled off in a weighed flask and 
the weight of the residue taken. The residue is then dissolved in a little dis- 
tilled water, and such an aliquot part taken for analysis as shall not contain 
more than *5 gramme of glycerine. This is introduced into the apparatus 
with 4 grammes of potassium bichromate in saturated solution, and into the 
acid reservoir are placed 10 c.c. of strong sulphuric acid, the absorbing tube 
being also charged with the same acid. The apparatus is weighed, and then 
the acid in the reservoir is allowed to mix with the glycerine and bichromate. 
Action sets in, and after standing for three hours in a warm place, the whole 
is heated to gentle ebullition, cooled and weighed. The loss of weight equals 
the C02 evolved, and this is then calculated to glycerine as above and lastly 
corrected from the aliquot part to the whole. In the presence of sugar the 
liquid must first be inverted by boiling with dilute hydrochloric acid (if cane 
sugar be present) and then evaporated with an excess of barium hydrate 
instead of lime. This will either decompose the sugars, or render them 
insoluble in the alcohol subsequently applied. 
DIVISION 11. MICRO-CHEMICAL IDENTIFICATION OF DRUGS. 
Many of the active principles of drugs are best identified by first isolating 
them by suitable processes, and then dissolving in alcohol, ether, water or some 
other solvent, and allowing a drop or two of the liquid to crystallise on a 
microscope slide. 
This is a subject of study possessing the utmost fascination, and with which 
familiarity is only acquired by practice. 
Experience is necessary in selecting the most suitable solvent from which to 
crystallise an alkaloid, as the duration of the evaporation may have a marked 
effect upon the form of the crystals. In some cases evaporation may be 
accelerated by the aid of heat; in others, such a proceeding is fatal to success. 
The addition of alcohol to ether, and of water to alcohol appears to be the 
best means of retarding the process when necessary. To take the case of 
cocaine. From chloroform no crystals are deposited ; from ether they are 
ill defined; but from alcohol, allowing evaporation to proceed very slowly, we 
get the best results. Always employ polarised light by which to view the 
crystals, either with or without the addition of a selenite plate. Here, again, 
the duration of evaporation has a marked effect, also the strength of the solu- 
tion. If the substance is deposited in a thin film it may be altogether invisible 
without polarised light. Thick crystals frequently produce color without the 
selenite, and those that are very thick may depolarise without any coloration. 
This being borne in mind, no difficulty is experienced in practice, as it is easy 
to compare with an alkaloid of known purity crystallised under the same 
conditions. In the accompanying plates (drawn by Mr. A. Percy Smith, 
F.1.C.) are given representations of various substances crystallised under the 
best conditions, with the name of the solvent and the linear magnification. 
The letter B signifies a black field (ordinary polarised light) and V a violet 
field produced by the selenite. 184 
ANALYSIS OF URINE, ETC. 
DIVISION 111. ANALYSIS OF URINE. 
The following are the chief points on which information is usually required 
by the physician who submits urine for examination to an analyst;— 
1. Take the specific gravity, which should range from 1-015 to 1*025 at 
6o° F. 
Note.—In diabetes the gravity is too high, sometimes reaching 1 ’O6O, while in albuminuria 
it is abnormally low, even occasionally falling to 1-005. 
2. Examine the reaction, which should be very faintly acid. 
3. Set a portion to settle in a long glass, and examine the deposit under 
the microscope for calcium oxalate or phosphate, uric acid or urates, pus, 
casts of kidney tubes, etc., etc. 
Note.—The nature of the deposit may also be confirmed chemically as follows : 
(a) Warm the urine containing the sediment, when, if the latter should dissolve, it 
consists entirely of urates. In this case let it once more crystallise out, and 
examine it by the ordinary course for Ca, Na, and NH4, to ascertain the 
bases. 
{/>) If the deposit be not dissolved by heating, let it settle, wash once by decantation 
with cold water, and warm with acetic acid. Phosphates will dissolve, and 
may be reprecipitated from the solution by excess of NH4HO filtered out, 
well washed with boiling H2O, dissolved in HC2H302 and examined for Ca 
or Mg by the usual course for these metals in presence of P0.,. 
(c) If the deposit be insoluble in acetic acid, warm it with HCI. Any soluble 
portion is calcium oxalate, which may be precipitated by NH4HO. 
(d) If the deposit be insoluble in HCI it is probably uric acid. In this case apply 
the murexid test as follows. Place it in a small white dish, remove moisture 
by means of a piece of bibulous paper, add a drop or two of strong HN 0:, 
and evaporate to dryness at a gentle heat. When cold add a drop of 
NH4HO, which will produce a purple color deepened to violet by a drop of 
KHO. 
4- Test for albumin, as follows : 
(a) Boiling test.—Filter the urine, place 10 c.c. in a narrow test-tube, 
and add one drop of acetic acid. Heat the tube over a small 
flame in such a way that the upper portion of the liquid only 
shall be heated. Coagulation will take place, and the presence 
of albumin will be evident from the formation of a turbidity 
ranging from a faint cloud to a dense coagulum, but always 
strongly contrasted with the clear liquid beneath, which was 
not heated. Mucin also precipitates with this test. 
(I?) Nitric test.—To five volumes of cold saturated solution of magnesium 
sulphate add one volume of nitric acid (sp, gr, 1*42), and 
preserve this reagent for use. Pour some perfectly clear filtered 
urine into a tube and carefully add an equal volume of the 
reagent delivered gently from a pipette so that the liquids shall 
not mix. An opalescent zone will form at the point of 
contact either immediately or within twenty minutes, according 
to the quantity of albumin present. This zone should not 
dissolve on gently warming, but should be a distinct ring at the 
bottom of the urine and not a general haze near the top, which 
latter indicates mucin. ANALYSIS OF URINE. 
185 
(c) Picric acid test.—Dissolve grammes of pure crystallised trinitro- 
phenol (picric acid) in 500 c.c. of water, let it stand for some 
days to perfectly clarify, pour off and preserve the reagent for 
use. Mix some of the filtered urine in a tube with an equal 
volume of this reagent, look for any cloud or precipitate, and 
then heat to boiling. The true albumin cloud will remain per- 
manent, while that due to peptones or alkaloids accidentally 
present will be dissolved. Picric acid does not precipitate 
mucin, and is therefore a valuable confirmation test. 
(d) Bbdekeds method.—Take a drachm of the urine, acidulate it with 
acetic acid, and add some potassium ferrocyanide drop by drop 
till a clear excess has been added. If during the addition a 
precipitate forms, albumin is to be suspected. Mere traces 
require some time to cause the cloud. 
(e) To estimate the Albumin.—This may be done empirically by means 
of an albuminimetre, which can be purchased (with full instruc- 
tions for use) at apparatus depots. The action depends on 
observing the height of the albumin precipitate in a specially 
constructed graduated cylinder after standing for a given time. 
The precipitant is picric acid. In the absence of such a 
convenient appliance we may take a weighed quantity of the 
urine, and allow it to drop into boiling water acidulated with 
acetic acid. Collect the precipitate on a tared filter, wash with 
boiling w;ater, dry at 2120, weigh, and deduct the weight of 
the filter, when the balance=albumin in the weight of urine 
operated upon. 
5. Test for grape sugar, as follows ; 
(a) Moore's with acetic acid, boil, and filter out any 
albumin if necessary. Then mix the filtrate with equal parts 
of liquor potassce and heat to boiling, when ordinary urine will 
turn brownish-red, but saccharine urine will become dark brown 
or black. 
(b) Boettgers test (modified by Nylander).— Dissolve 2-5 grammes of 
pure bismuth oxynitrate (free especially from silver) and 4 
grammes of Rochelle salt in 100 grammes of 8 per cent, solution 
of sodium hydrate, and preserve for use. To use this reagent 
1 c.c. of urine is added to 10 c.c. and the whole boiled gently 
for some time, when if even only traces of sugar be present the 
mixture becomes black. 
(c) Fehling’s test.-—Render the urine alkaline with potassium hydrate, 
and filter to remove any phosphates, etc., which may precipitate, 
Boil the filtrate with Fehling’s solution of copper (see page 119). 
and if a red precipitate should form, sugar is present. 
(d) To estimate the sugar.—This is best done by taking 10 grammes of the 
urine and diluting it with water to 100 c.c. Place this solution 
into a burette, and run it gradually into 10 c.c. of Pavy’s 
solution, kept boiling in a flask as directed under the Volu- 
metric Analysis of Sugar, page 119. The number of c.c. of 186 
ANALYSIS OF URINE, ETC. 
urine used will contain 'OO5 gramme of grape sugar, and 
then 100 X °°s = sugar in the 10 grammes of urine taken, 
c.c. used 
6. Test for bile, as follows : 
(a) Oliver’s test.—Dissolve 2 grammes of flesh peptone, ‘25 gramme 
of salicylic acid, and 2 c.c. of 33 per cent, acetic acid, in 
enough water to yield 200 c.c. of product. The solution 
should be rendered perfectly brilliant by passing it through 
frozen filtering paper. The urine, which should be very clear, 
is diluted to a specific gravity of 1 -008. One cubic centimetre 
of this is added to 3 c.c. of Oliver’s reagent. An opalescence 
at once appears, which will be found to be more or less distinct 
according to the quantity of bile salts present. Keller’s contact- 
method can be advantageously employed for applying the test. 
(b) Gmelin's test for bile pigments.—Place a drachm of nitric acid in a 
test-tube and cautiously pour upon it an equal volume of the 
urine. In the presence of bile a play of colors from green to 
violet, blue, and red will be observed where the liquids touch. 
(c) Pettenkofer’s test for biliary acids.—Mix equal parts of urine and 
sulphuric acid, add one drop of saturated syrup, and apply a 
gentle heat. If biliary acids be present, the color will change 
from cherry-red to deep purple. 
Note.—Bilious urine is usually of a brownish-green color. 
7- Test for urea, as follows : 
(a) Separate any albumin (as directed in Moore’s test) if necessary, 
and evaporate an ounce of the urine to a syrupy consistence on 
the water bath. When cold add nitric acid, drop by drop, till 
crystals of nitrate of urea cease to deposit. 
(b) Estimation of iirea.—This is performed by the hypobromite pro- 
cess already given at page 124. 
8. Test for uric acid by mixing one ounce of the urine with one drachm 
of hydrochloric acid in a beaker, and set aside for some hours. The uric acid 
will be deposited in reddish-brown crystals, which may, if desired, be weighed 
and proved by the murexid test. 
This method is based on the known fact that argentic urate, unlike most 
other salts of silver, is insoluble in ammonia, but dissolves in nitric acid. 
The solutions required are:—l. “ ammonium-thiocyanate”; dissolve 
about 8 grammes of ammonium-thiocyanate in a litre of water, and check with 
argentic-nitrate solution ; dilute it for use with nine volumes of water. 
2. Dissolve 5 grammes of argentic nitrate in 100 c.c. of distilled water, 
and add ammonia until the solution becomes clear. 3. Dilute 70 per cent, 
nitric acid with two volumes of distilled water, boil, to destroy the lower 
oxides o nitrogen, and preserve from the action of light. 4. A saturated 
solution of ferric alum. 5. Strong solution of ammonia. The following is a 
descript on of the process :—Place 25 c.c. of urine in a beaker with 1 gramme 
of sodium bicarbonate. Add 2 or 3 c.c. of strong ammonia, and then 
1 or 2 c.c. (or an excess) of the arnmoniated silver solution. A special 
procedure is necessary in order to collect the precipitate, as follows :—Fill a ANALYSIS OF URINE. 
187 
glass funnel to about one-third with broken glass, and cover this with a 
bed of good asbestos to about a quarter of an inch deep. This is best done 
By shaking the latter in a flask with water until the fibres are thoroughly 
separated, and then pouring the emulsion so prepared in separate portions on 
to the broken glass. On account of the nature of the precipitate and of the 
filter, it is necessary to use a Bunsen water pump in order to suck the liquid 
through. Having thus collected the precipitate, wash it with distilled water 
until the filtrate ceases to become opalescent with a solution of NaCl. Now 
dissolve the precipitate by washing it through the filter into a beaker, with 
a few cubic centimetres of the special nitric acid. Estimate the silver by 
Volhard’s method, thus; Add to the liquid in the beaker a few drops of the 
ferric alum solution to act as an indicator, and from a burette carefully drop 
in T-i-0 ammonium thiocyanate solution until a permanent red color appears. 
The number of c.c. used multiplied by o'ooi6B, gives the amount of uric acid 
in the 25 c.c. of urine. One milligramme maybe added to this amount as an 
allowance for average loss, and the whole multiplied by 4 gives the percentage 
of uric acid in the urine. The sodium bicarbonate is added in the early part 
of the process, to prevent decomposition of the argentic urate, which would 
otherwise occur. 
9. Test for phosphates, as follows : 
(a) Add to one ounce of the urine a slight excess of ammonium 
hydrate, and boil. Ca3(P04)2 and MgNH4P04 will both be 
precipitated, and the precipitate, if more than a distinct cloud, 
should be filtered out, dissolved in HCI, and analysed by the 
ordinary process already given for phosphates. 
{h) After filtering out the earthy phosphates as above, alkaline phos- 
phates may be tested for by adding magnesia mixture to the 
filtrate and getting the usual precipitate of MgNH4P04 after 
standing some hours in a cold place. 
(c) Estimation of Phosphates.—This is done by the volumetric process 
with uranic nitrate, already described at page 120. 
10, Test for sulphates, as follows 
Acidulate a weighed quantity of the urine with HCI, warm, and add 
excess of BaGl* If the precipitate appear too copious, estimate 
as usual. 
11. Test for chlorides, as follows : 
Acidulate a little of the urine with HNOs and add excess of argentic 
nitrate. If the precipitate thus produced looks very large, a 
weighed quantity of the urine should be taken, and the chlorides 
estimated by Volhard’s method (see page 113). 
12. Blood is best seen under the microscope; but urine containing it has 
always a very characteristic smoky appearance. A test for blood is to add 
tincture of guaiacum and ethereal solution of hydrogen peroxide, which pro- 
duce a sapphire blue; but such color of itself should not be taken as positive 
proof without the blood discs being also visible under the microscope. 188 
ANALYSIS OF URINARY CALCULI. 
DIVISION 111. ANALYSIS OF URINARY CALCULI. 
The following table will show at a glance the compositions and methods of 
proving the various calculi. 
1. Calculi, fragments of which, heated to redness on platinum, 
entirely burn away. 
Name. 
Physical Characters. 
Chemical Characters. 
Uric acid, C5N4H403 
Brownish-red; smooth 
or tuberculated ; 
concentric laminae 
(common) 
Insoluble in water ; soluble in KHO 
by heat, but evolves no NH3; dis- 
solves with effervescence in HN03, 
and the residue on evaporating the 
solution is red and gives the murexid 
test. 
Ammonium urate 
Clay-colored; usually 
smooth, and rarely 
with fine concentric 
laminae (uncommon) 
Soluble in hot water; soluble in 
heated KHO, evolving NH3. Be- 
haves with HN03 like uric acid. 
Insoluble in H„0, alcohol, and ether. 
Cystine, C3H7NS02 
Brownish -yellow, 
semi-transparent and 
crystalline (very 
uncommon) 
Soluble in N H4HO, and depositing, 
when allowed to evaporate spon- 
taneously, hexagonal plates. When 
heated, gives off odour of CSj. 
Soluble in KHO; soluble in HN03 
Xanthin, C5H4N402 
Pale polished brown 
surface (very un- 
common) 
zvithout effervescence, and the solu- 
tion leaves on evaporation a deep 
yellow residue. 
2. Calculi, fragments of which, heated to redness on platinum, 
do not burn away. 
Name. 
Physical Characters. 
Chemical Characters. 
Calcium oxalate, 
Deep brown, hard and 
Insoluble in acetic acid, but soluble 
mulberry calculus, 
rough ; thick layers 
without effervescence in HC1 ; 
CaC204 
(common) 
heated to redness, it is converted 
into CaC03 which dissolves with 
effervescence in acetic acid, and the 
solution gives a white precipitate 
with (NH4)2C204. Heated strongly 
before the blowpipe, CaO remains, 
which, when moistened, is alkaline 
to test-paper. 
Tricalcium phosphate, 
Pale brown, with regu- 
Infusible before the blowpipe, and 
bone-earth calculus, 
lar laminse (uncom- 
residue, when moistened, is not al- 
Ca„P04 
mon) 
kaline. Soluble in PIC1, and the 
solution gives a gelatinous precipi- 
tate with excess of NHjPIO. 
Magnesium ammo- 
White, brittle, crys- 
Fusible with difficulty before the 
nium phosphate, 
talline, with an un- 
blowpipe, evolving NH3, and re- 
triple phosphate cal- 
even and not usually 
sidue not alkaline. Soluble in HC1, 
cuius, MgNH4P04 
laminated surface 
and solution gives white crystalline 
(uncommon) 
precipitate with NH4HO. 
Mixed phosphates of 
White, and rarely 
Readily fusible before the blowpipe. 
Ca, Mg, and NH„ 
laminated 
Soluble in acetic acid, and solution 
fusible calculus 
gives a white precipitate with 
(NH4)„C.,04, and the filtrate from 
that precipitate gives a white pre- 
cipitate with excess of NH4HO. CHAPTER XII. 
THE ANALYSIS OF GASES, POLARISATION, AND 
SPECTRUM ANALYSIS. 
DIVISION I. THE ANALYSIS OF GASES. 
This operation is conducted by measuring a volume of the mixed gas under 
definite conditions of temperature and pressure, then exposing it to the action 
of some substance having the power of absorbing some one constituent of the 
mixture and again measuring the gas left. By seeing that the inside of the 
measuring tube is always kept moist the question of tension of aqueous vapor 
is equalised all through the experiment, and as many absorbents as may be 
necessary are employed in turn. Many of the gas-measuring appliances are 
large, costly, and require to be kept in special rooms devoted to the 
purpose. Quite recently, however, an American chemist, Mr. Keiser, has 
devised a gas-measuring apparatus which is likely, in the author’s opinion, to 
supersede all others for absorption analyses, because it is compact in form, 
may be easily carried about and used at any place, and yet is capable of 
measuring gas volumes with great accuracy. Long graduated glass tubes and 
graduated vessels of all kinds are discarded, and an instrument is constructed 
upon the principle of determining the volume of a gas from the weight of 
mercury which it displaces at a known temperature and pressure. From the 
weight of mercury displaced the volume of the gas can be determined with 
much greater accuracy than by a direct reading on a graduated glass 
eudiometer. 
The accompanying cut shows the construction of the measuring apparatus 
and the absorption pipette, ais the measuring apparatus, bis the absorption 
pipette; a and b are glass bulbs of about 150 c.c. capacity. They are 
connected at the bottom by a glass tube of 1 m.m. bore, carrying the three-way 
stopcock d. The construction of the key of the stopcock is shown in the 
margin. One hole is drilled straight through the key, and by means of 
this the vessels a and b may be made to communicate. Another opening 
is drilled at right angles to the first, which communicates with an opening 
extending through the handle, but does not communicate with the first 
opening. By means -of this, mercury contained in either a or b may be 
allowed to flow out through the handle d into a cup placed beneath. The 
bulb bis contracted at the top to an opening 20 m.m. in diameter. This is 
closed by a rubber stopper carrying a bent glass tube, to which is attached the 
rubber pump e. To a second glass tube passing through the stopper a short 
piece of rubber tubing with a pinchcock is attached. By means of the pump e 
air may be forced into or withdrawn from b, as one or the other end of the 
pump is attached to the glass tube. The bulb a terminates at the top in a 
narrow glass tube, to which is fused the three-way stopcock c. The construe- 190 
ANALYSIS OF GASES, POLARISATION, ETC. 
tion of the key of this stopcock is also shown in the cut. By means of it the 
vessel a may be allowed to communicate with the outside air, or with the tube 
passing to the absorption pipette, or with the gauge g. The gauge gis a glass 
tube having a bore 1 m.m. in diameter, and bent as shown in the figure. By 
pouring a few drops of water into the open end of this tube a column of water 
several centimetres high in both limbs of the tube is obtained. This serves 
as a manometer, and enables the operator to know when the pressure of the 
gas equals the atmospheric pressure. To secure a uniform temperature, the 
bulbs a and b are surrounded by water contained in a glass vessel. This 
vessel for holding water is merely an inverted bottle of clear glass from which 
the bottom has been removed. The handle of the stopcock d passes through 
a rubber stopper in the neck of the bottle. A thermometer graduated to io' 
is placed in the water near the bulb a. The whole apparatus is supported upon 
a vertical wooden stand. 
The absorption pipette b consists of two nearly spherical glass bulbs of 
about 300 c.c. capacity. They communicate at the bottom by means of a 
glass tube, 3 m.m. inside diameter, cis a two-way stopcock. The holes in 
the key are drilled at right angles, so that the tube which connects with the 
Fig. 46. 
measuring apparatus may be put in communication either with the funnel or 
with the absorption bulb. The funnel is of service in removing air from the 
tube which connects the measuring apparatus with the absorption pipette. By 
pouring mercury or water into the funnel and turning the stopcocks d and c in 
the proper directions all the air is readily removed, fis a rubber pump used 
in transferring gas from bto a. The lower part of the pipette contains 
mercury, which protects the reagent from the action of the air. 
To measure the volume of a gas, the vessel a is filled completely with pure 
mercury. This is easily accomplished by pouring the mercury into b, and then, 
after turning c until a communicates with the outside air, forcing it into a by 
means of the pump e. Any excess of mercury in bis then allowed to flow out 
through the stopcock d. When a and b are now placed into communication 
the mercury will flow from a to b, and gas will be drawn in through the stop- 
cock c. The volume of mercury which flows into bis equal to the volume of 
gas drawn into a. When the mercury no longer rises in b and it is desired to 
draw in still more gas into a, then it is only necessary to exhaust the air in b 
by means of the pump e. After the desired quantity of gas has been drawn 
into a the stopcock cis closed. After standing a few minutes the tempera- ANALYSIS OF GASES. 
191 
ture of the gas becomes the same as that of the water surrounding a. The 
pressure of the gas is then made approximately equal to atmospheric pressure 
by allowing the mercury to flow out of b into a weighed beaker placed beneath 
the stopcock d until it stands at nearly the same level in both a and b. 
Communication is now established between a and g, and by means of the 
pump e the pressure can be adjusted with the utmost delicacy until it is 
exactly equal to atmospheric pressure. The stopcock d is then closed, and 
the remainder of the mercury in bis allowed to flow out into the beaker. The 
weight of the mercury displaced by the gas divided by the specific gravity of 
mercury at the observed temperature gives the volume of the gas in cubic 
centimetres. 
If it is desired to remove any constituent of the gas by absorption, a pipette, 
b, containing the appropriate reagent, is attached to the measuring apparatus. 
All the air in the connecting tube is expelled by pouring mercury into the 
funnel and turning the stopcocks c' and c so that the mercury flows out through 
c. A little more than enough mercury to expel the gas in the vessel a is 
poured into b. The small quantity of air which is confined in the tube con- 
necting b with the stopcock is removed by allowing a few drops of mercury to 
run out through b. Then a and b are placed in communication. The stop- 
cocks c and c are turned so that the gas may pass into the pipette, the 
mercury which filled the connecting tube passes into the absorbing reagent, 
and unites with that which is already at the bottom of the pipette. The 
transfer is facilitated by the pump e. After absorption the residual volume is 
measured in the same way that the original volume was measured, ais com- 
pletely filled with mercury from the upper to the lower stopcock, and all the 
mercury in bis allowed to run out; the gas is then drawn back into the 
measuring apparatus, the last portion remaining in the connecting tube being 
displaced by means of mercury from the funnel. The volume is then deter- 
mined as before. 
The calculation of the results of an analysis is very simple. If the tempera- 
ture and pressure remain the same during an analysis, as is frequently the 
case, then the weights of mercury obtained are in direct proportion to the 
gas volumes, and the percentage composition is at once obtained by a simple 
proportion. 
If the temperature and pressure are different when the measurements are 
made, it is necessary to reduce the volumes to o° and 760 m.m. The 
following formula is then used : 
r_ w (H—h) 
D (i + '00367 x t) 760’ 
in which 
W = weight of mercury obtained (in grammes), 
D specific gravity of mercury at t°, 
t temperature at which the gas is measured, 
H height of the barometer, 
h = tension of aqueous vapor, 
V reduced gas volume (in cubic centimetres). 
In all the measurements made with the apparatus the gas is saturated 
with aqueous vapor, because it comes in contact with the water in the 
manometer g. 
The chief absorbents employed in gas analysis are as follows : 
A. Strong solution of potassium hydrate absorbs HCI, HBr,+ HI., 
C02, S02, and H2S. 
B. Crystallised sodium phosphate absorbs HCI, HBr, and HI. 192 
ANALYSIS OF GASES, POLARISATION, ETC. 
C. 1 vol. of 25% solution of pyrogallic acid -f 6 vols. 60% solution 
of KHO absorbs 02 (after removal of any gas absorbed by 
KHO alone). 
D. Concentrated solution of cuprous chloride in dilute hydrochloric 
acid absorbs CO (after removal of C02 and 02 with alkaline 
pyrogallate). 
E. A solution of sulphuric anhydride in strong sulphuric acid, or 
solution of bromine, absorbs C 2H4, and the other gaseous 
hydrocarbons of the series CnH2n, and of CnH2n_2. 
F. Absolute alcohol absorbs certain of the paraffins, except marsh gas. 
G. Adding an excess of pure oxygen, and then absorbing with alkaline 
pyrogallate will remove NO together with the excess of oxygen 
used. 
H. Hydrogen and nitrogen are left to be estimated by difference. 
They may be separated by passing the mixture into an eudio- 
meter and adding excess of pure oxygen, measuring the total 
volume, and passing an electric spark. The hydrogen then 
forms water, and the gas being remeasured, f of the total loss 
in volume represents the H2 present. The excess of 02 having 
then been removed by alkaline pyrogallate, the remainder is N2. 
Full details of the analysis of gases, beyond the scope of the present work, 
will be found in Sutton’s “ Volumetric Analysis.” 
DIVISION 11. ANALYSIS BY CIRCULAR POLARISATION. 
THE SACCHARIMETER. 
Crystals which do not belong to the regular system (notably calc-spar) 
possess the power of double refraction. That is to say, when a ray of light 
falls upon them, it is divided into two rays, one of which follows the ordinary 
rule of refraction, while the other takes a totally different course ; and the two 
rays are called respectively the “ ordinary ” and the “ extraordinary ” ray. 
The most convenient polarising medium is what is called a “ Nicol’s prism.” 
It is composed of a crystal of calc-spar cut into two portions in the direction 
of its axis, and the two parts thus obtained cemented together with Canada 
balsam. When a beam of light enters the prism, it is doubly refracted by the 
first portion of the crystal, and the extraordinary ray only passes through the 
second portion to the eye of the observer; while the ordinary ray is com- 
pletely reflected away by the layer of Canada balsam, and so lost to view. 
When this extraordinary ray is examined it is found to possess peculiar 
properties, such as showing color in transparent bodies which are usually 
colorless. This is accounted for by believing that it has become polarised 
—i.e., that all its vibrations have been reduced to the same plane. If the 
polarised light thus obtained be examined by means of another Nicol’s prism, 
it will be found that when the two prisms are placed with the principal 
sections parallel to each other, the ray will pass freely ; but if the second 
prism, called the analyser, be then turned round so that its chief section is 
at right angles to that of the first, the polarised ray will in turn be entirely 
reflected from the layer of balsam, and no light will now reach the observer’s 
eye. This holds good so long as nothing intervenes between the two prisms; 
but it has been found that certain bodies, such as quartz, possess the power, 
when interposed between the prisms, of giving a color instead of darkness, 
owing to their possessing the power of twisting the polarised ray from its ANALYSIS BY CIRCULAR POLARISATION, ETC. 
193 
original plane. Such substances are said to possess the power of circular 
polarisation, either in a “right-handed” or “left-handed ” direction, accord- 
ing as it is necessary to turn the prism either to the right or left from its 
proper position to once more produce complete passage of the colorless 
polarised ray. The direction of the rotation is indicated by the use of 
arrows, thus: Cane sugar, grape sugar, dextrin, maltose, creasote, 
camphor, tartaric acid, cinchonine, castor oil, croton oil and oil of lemons 
rotate the plane of the polarised ray to the right; while fruit, or invert-sugar, 
quinine, cinchonidine, turpentine, and many essential oils, morphine, etc., 
have a left-handed rotation. 
There are two varieties of quartz, known as right-handed and left-handed, 
one of which rotates the plane of polarisation to the right and the other to 
the left. If a plate of quartz 1 millimetre thick be placed between the two 
“ Nicols,” the ray of polarised light is rotated, and instead of being colorless, 
is colored, changing to all the colors of the spectrum as the analyser is turned, 
until it once more becomes colorless, and the amount that the analyser has to 
be turned (registered by a pointer on the degrees of the circle) is the index of 
rotary polarisation possessed by the quartz either in a right- or left-handed 
direction. If the turning of the analyser be now continued, color will again 
show itself, but this time it will be the color complementary to that at first 
produced. Thus, if we start with a plate of quartz showing red between the 
uncrossed prisms, and rotate, we shall find that when we have turned through 
an angle of 45°, we get no color, but after that we begin to get the com- 
plementary color green, which becomes most intense at the right angle of 90°, 
when the prisms are crossed. The polariscope as used for analysis is therefore 
essentially (a) a Nicol’s prism acting as a polariser, (b) :a plate of quartz 
usually divided down the centre, the one side being right-handed and the 
other left, (c) a tube to contain the solution, (d) another “Nicol” capable of 
being rotated, and having a pointer acting on degrees of the circle on a scale, 
[e) a telescope to focus the line between the two sides of the quartz. When 
the pointer is placed at zero, the tube filled with water and the line focussed, 
no color is seen on either side of it, but if a solution say of sugar be intro- 
duced, then color appears on one side of the line according to the nature of 
the sugar, and then the distance through which the pointer has to be moved 
round the graduated circle to get both sides of the quartz colorless is the 
degree of rotary polarisation. In practice monochromatic light from a sodium 
flame is employed, and this, destroying all color, causes a dark shadow instead 
of a color to appear when the instrument is used, so enabling color-blind 
persons to employ it without difficulty. To use the instrument we make a 
solution of the body to be examined of a definite percentage strength by dis- 
solving a certain number of grammes in 100 c.c. of a solvent. We then fill 
the tube, observe the degree of rotation produced, and from that we calculate 
the absolute angle of rotation for the sodium light (always expressed as [a]) as 
follows:— 
Let <z=the observed angle, c the strength in grammes per xoo c.c., and I the length of 
the tube used in decimetres ; then— 
iooa 
= 7x7 
If the absolute angle thus found coincides with that obtained from the same substance 
in a state of purity, then the article under examination is pure, but if not, then a simple per- 
centage calculation gives the impurity. 
Thus the [a]D of pure cane sugar == . A sample examined as above gave an [d] d = . 
Then : x 100 = per cent, of real sugar present in the sample. ANALYSIS ON GASES, POLARISATION, ETC. 
DIVISION 111. SPECTRUM ANALYSIS. 
When a ray of sunlight is allowed to pass through a prism, it is deflected 
and dispersed into a number of rays differing in their degree of refrangibility. 
When these rays, as they pass from the prism, are caused to fall upon a white 
surface, they are observed to have a marked difference in color. The image 
so produced is called a spectrum; and when sunlight is thus treated it is 
found to give a spectrum consisting of the following colors : viz., violet, indigo, 
blue, green, yellow, orange, and red. The violet end of the spectrum, owing 
to its greater refrangibility, is always the nearer to the base or broad end of the 
prism. By this means of separating the rays of light we are able to ascertain 
the peculiar properties of each of the colors which go to compose it, and we 
find that the chemical activity of light resides chiefly in the most highly re- 
frangible rays just outside the violet end of the visible spectrum, which are 
called the actinic rays ; while, on the other hand, the heat transmitted by the 
sun is most felt at the opposite or red end of the spectrum. 
Further research demonstrated that if we substituted the light emitted from 
various bodies in a state of incandescence to the action of a prism, the image 
or spectrum produced varied in each case, and was, moreover, almost cha- 
racteristic of the particular bodies employed. This discovery led to the 
invention of the spectroscope, which, in its simplest form, consists of a 
metallic diaphragm with a narrow slit, through which a ray of light from the 
burning body is allowed to pass and is condensed by a lens upon a prism of 
glass, or, better still, a triangular bottle of thin glass filled with disulphide of 
carbon. At the opposite side of the prism is a short telescope, so arranged 
that an observer, looking through it, sees the spectrum or image produced 
by the light after passing through the prism. This telescope works upon a 
graduated scale, by which its position for viewing any particular line observed 
can be noted. 
When ordinary solar light is examined through the spectroscope, a number 
of dark lines are found crossing the image at certain fixed points. They are 
called “ Frauenhofer’s lines,” and their position is characteristic of sunlight. 
It has been proved that such lines are only formed when the source of light 
contains volatile substances, as we find that the light emitted by a non-volatile 
heated body gives a continuous image devoid of lines. If, for example, a 
platinum wire be heated to a high temperature in a Bunsen burner, and the 
light thus produced be examined, no lines will be visible ; but if the wire be 
now tipped with a fragment of sodium chloride, and once more ignited, a 
bright line will suddenly appear in the yellow of the spectrum, and in so 
dazzling a manner as to render the whole of the rest of the image almost 
invisible. In carrying out this system of analysis, therefore, it is only necessary 
to procure a perfectly clean piece of platinum wire, with one end bent into 
the form of a loop, and place a Bunsen gas burner in such a position that the 
rays from anything heated in it will pass into the spectroscope. The wire is 
then to be moistened with a little hydrochloric acid, and having been dipped 
in the substance to be examined, is to be held in the hottest portion of the 
Bunsen flame, and its spectrum simultaneously observed through the spectro- 
scope, noting carefully the color, number, and position on the scale of the 
bright lines produced. When thus examined, we find that potassium exhibits 
one bright line in the red, and one in the blue; lithium, one bright line in the 
yellow, and one more brilliant in the red; strontium, one blue, one orange, 
and six red lines; barium, a number of lines chiefly green and yellow; cal- 
cium, three distinct bright yellow lines, one within green, and some broad but MELTING POINTS. 
195 
indistinct ones in the orange and red ; and lastly, sodium the single bright 
yellow line already mentioned. 
The student must commence with the examination of pure salts, carefully 
noting for reference the position of the index of the telescope on the scale 
where each characteristic line is found. When it is desired to examine any 
mixture the telescope index is brought to the required position and the sub- 
stance is examined : if the proper line is seen, then the element searched for 
is present; if not, it is absent. If we examine ordinary light which has been 
made to pass through solutions of various colored bodies, we obtain dark 
bands analogous to the lines of Frauenhofer. These are called absorption 
spectra, and are very useful in the detection of soluble coloring matters. A 
solution of blood, for example, shows characteristic bands in the green of the 
spectrum. All this is a matter of special study, and to go farther into it would 
be beyond the scope of this volume. 
The accurate taking of the melting point is an important factor in testing 
the purity of many solid organic bodies, notably of fats and waxes. Many 
methods have been from time to time proposed, but the following will be 
found to be sufficiently good for all ordinary purposes, and is, moreover, 
the method officially adopted in the Pharmacopoeia. 
A piece of narrow glass tube is softened in the gas flame and drawn out, so 
as to give it a long thin end with a capillary bore. The fat or wax is melted, 
and a little of it is sucked up into this capillary tube and allowed to solidify 
therein. The tube is then tied to a delicate thermometer so that its capillary 
end (having the semi-opaque column of solidified fat inside) just rests against 
the bulb of the thermometer. Both are now supported perpendicularly in a 
beaker of water, and heat is gently applied to the same. The rise of the 
thermometer and the appearance of the tube of fat being both observed, the 
height of the former, at the moment when the column of fat becomes trans- 
parent, is noted as the melting point required. It is always useful to repeat 
the process three times and to take the average as the true melting point. 
Students desiring to go more deeply into this subject are referred to Allen’s 
“Commercial Organic Analysis.” 
DIVISION IV. MELTING POINTS. INDEX. 
A. 
Acetates, 51. 
Acetic, acid, 51* 
Acids, Acetic, 51. 
Antimonic, 50. 
Arsenic, 48. 
Arsenious, 48, 115. 
Benzoic, 56. 
Boric, 39. 
Carbolic, 55, 57. 
Carbonic, 38. 
Chromic, 49. 
Citric, 54. 
Cyanic. 43. 
Cyanuric, 43. 
Formic, 50. 
Fulminic, 44. 
Gallic, 57. 
Hydriodic, 32. 
Hydrobromic, 30. 
Hydrochloric, 29. 
Hydrofluosilicic, 40. 
Hydrosulphuric, 34. 
Lactic, 52. 
Malic, 53, 55. 
Meconic, 55. 
Metaphosphoric, 46. 
Nitric, 41, 123. 
Nitrous, 40. 
Oleic, 52, 180. 
Orthophosphoric, 47. 
Oxalic, 52, 146. 
Pyrophosphoric, 45. 
Salicylic, 56, 126. 
Silicic, 39, 146. 
Stannic, 50. 
Stearic, 52. 
Succinic, 53. 
Sulphuric, 37. 
Sulphurous, 36, 115. 
Tannic, 57. 
Tartaric, 53, 146. 
Uric, 182. 
Valerianic, 51- 
Acidulous radicals, Detection 
of, 29, 75. 
Gravimetric estimation of, 
141. 
Acidimetry, 112. 
Air, sanitary analysis, 163. 
Albuminoid ammonia, 158. 
Alcohol, estimation of in 
spirits, etc., 167. 
Table of percentages, 168. 
Alkaline carbonates, estima- 
tion, 109. 
hydrates, estimation, 108. 
Alkalies, Organic salts of, esti- 
mation, no. 
Alkaloids, table of reactions, 94. 
Detection, 89. 
Estimation, 121. 
Tests for, 94. 
Strength of extracts, 177. 
Alkaloidal strength of scale 
preparations, 179. 
Aluminium, 20. 
Estimation, 138. 
Ammonia, 125. 
Albuminoid, 158. 
Ammonium, 27. 
Estimation, 139. 
Analysis—• 
Bread, 167. 
Butter, 163. 
Colorimetric, 124. 
Colored sweets, 169. 
Drugs, 172. 
Food, 164. 
Gases, Keiser’s apparatus, 
189. 
Gravimetric, 132. 
Milk, 162. 
Mineral (of water), 147. 
Mustard, 169. 
Nitrometer, by the, 122. 
Pepper, x 66. 
Polariscopic, 192. 
Qualitative, I. 
Quantitative, 95. 
Sanitary, of water, 155. 
„ „ air, 163. 
Spectrum, 194. 
Starch, 169. 
Ultimate organic, 150. 
Urine, 184. 
Urinary calculi, 188. 
Vinegar, 171* 
Volumetric, 105. 
Analytical factors, use of, 131. 
Antimonic acid, 50. 
Antimony, 16. 
Estimation, 136. 
Apparatus, 106, 150. 
Arseniates, 48, 145. 
Arsenic, 15. 
Estimation. 136, 155. 
Arsenic acid, 48. 
Arsenious acid, 48. 
Estimation, 115. 
Arsenites, 48. 
Ash filters, 129. 
~ of organic bodies, 131. 
B, 
Barium, 24. 
Estimation, 134. 
Barks, cinchona analysis, 174. 
Benzoates, 56. 
Benzoic acid, 56. 
Bile (urine), 186. 
Bismuth, 14. 
Estimation, 134. 
Blood (urine). 187. 
Bread, analysis, 167. 
Borates, 39. 
Boric acid, 39. 
Bromates, 31. 
Bromides, 30. 
Estimation, 141. 
Separation, 42. 
Bromine, 30. 
Estimation, 116. 
Butter, analysis, 163. 
C. 
Cadmium, 15. 
Estimation, 134. 
Calcium, 25. 
Estimation, 138. 
Calculi, urinary, analysis, 188. 
Carbolates, 55. 
Carbolic acid, 55, 57. 
Carbon, 38. 
Estimation, 151. 
Carbonates, 38, 145. 
Alkaline, 109. 
Soluble, 123. 
Carbonic acid, 38. INDEX. 
Cerium, 20. 
Estimation, 138. 
Chemical processes, 1. 
Chlorates, 30. 
Chlorides, 29, 42. 
Estimation, 141, 187. 
With bromides, detection 
of, 31. 
With iodides, detection 
of, 32. 
Chlorine, 29. 
Estimation. 116, 155. 
Available, estimation. 116. 
Chromates, 49. 
Chromic acid, 49. 
Chromium, 21. 
Estimation, 138. 
Cinchona, analysis, 174. 
Circular polarisation, 192. 
Citrates, 54. 
Citric acid, 54. 
Clark’s process, 161. 
Cobalt, 23. 
Estimation, 136. 
Coefficients for analysis, 127. 
Colorimetric analysis. 124. 
Copper, 14. 
Standard solution, 119. 
Estimation, 134. 
Crystallisation, 5. 
Cyanates, 43. 
Cyanic acid, 43. 
Cyanides. 43, 141. 
Cyanogen. 43. 
Cyanuric acid, 43. 
D. 
Decantation. 3. 
Density, vapor, 102. 
Detection and separation of 
acidulous radicals. 29, 
75- 
Detection of alkaloids, 89. 
Bromine, hydrobromic 
acid and bromides, 30. 
Bromides in presence of 
iodides, 32. 
Chlorides in presence of 
bromides, 31. 
Chlorine, hydrochloric 
acid, and chlorides, 29. 
Cyanides in presence of 
ferro-and ferri-cyanides, 
45- 
lodate in an iodide, 33. 
Inorganic acids, 78. 
Metals. 10. 
Nitrite in presence of a 
nitrate, 41. 
Organic acids, 80. 
Phosphate in presence of 
calcium, barium, stron- 
tium, manganese, mag- 
nesium, 48. 
In presence of iron, 48. 
Soluble sulphide in pre- 
sence of sulphite and 
sulphate, 36. 
Diagrams, Smith’s. 182, 183. 
Drying precipitates, 129. 
Drugs, analysis, 169, 
~ Micro-chemical analysis, 
181. 
~ Resinous (strength of), 
178. 
Dumas’ process, 153. 
E. 
Electrolysis. 6. 
Ether, Nitrous (estimation), 
123. 
Ethylsulphates, 51. 
Estimation of— 
Alkaline hydrates. 108. 
„ carbonates, 109. 
Alkaloids, 121. 
Aluminium, 138. 
Ammonia (Nesslerising), 
125- 
Ammonium, 140. 
Antimony, 136. 
Arseniates, 145. 
Arsenic, 136, 155. 
Arsenious acid. 115. 
Ash filters, 129. 
~ of organic bodies, 
131- 
Barium, 138. 
Bismuth 134. 
Bromine, 116. 
Cadmium. 134. 
Calcium. 138. 
Carbonates, 145. 
Carbon dioxide, 163. 
Carbon and hydrogen. 151. 
Chlorine, 155. 
~ free, 116. 
~ available. n6. 
Chromium, 138. 
Cobalt, 136. 
Copper, 134. 
Fatty acids in soap, 180. 
Ferric and ferrous salts, 
117- 
Glycerine. 180. 
Gold, 135. 
Gravimetric (of metals), 
132. 
Hydrocyanic acid, 114. 
Hydrogen peroxide, 124. 
lodine, Free, 115- 
Iron, 137. 
Lead, no, X 32. 
Manganese. 137- 
Magnesium, 139. 
Mercury, 133. 
Moisture, 131. 
Nickel, 137. 
Nitric acid in Nitrates, 
123- 
Nitrogen, 152. 
Nitrous Ether, 123. 
Oleic acid, 180, 
Organic salts of alkalies, 
110. 
Oxalic acid, 146. 
Estimation of— 
Phenol, 175. 
Phosphates, 143. 
Phosphoric acid, 120. 
Phosphorus, 155. 
Platinum, 135. 
Potassium, 139. 
Salicylic acid, 126. 
Silicic acid, 146. 
Silver, 132. 
Sodium, 140. 
Soluble carbonates, 123. 
„ haloid salts, 113. 
Sugar and starch, 120. 
Sulphur, 155. 
Sulphurous acid, 115. 
Tartaric acid, 146. 
Thiosulphites. 115. 
Tin, 135. 
Urea in urine, 124. 
Zinc, 137. 
Evaporation, 5. 
Extraction, 2. 
Extracts, alkaloidal strength 
of, 177. 
F. 
Factors, analytical (use of).X3i. 
Fehling’s solution, 119. 
Ferricyanides, 45. 
Ferro- from ferri-cyanides, 
separation, 45. 
Ferrocyanides, 44. 
Ferric and ferrous salts, esti- 
mation, 117. 
Filters, preparation of, 128. 
ash, estimation, 129. 
Filtration, 3. 
Fluorides, 29. 
Food analysis, 164. 
Formic acid and formates, 50. 
Fulminic acid, 44. 
Fusion, 4. 
G. 
Gallic acid, 57. 
Gallic, tannic, and pyrogallic 
acid, 57. 
Gases, sp. gr., 101. 
Analysis of, 189. 
Gaseous impurities (testing 
for), 163. 
Glycerine, 176. 
Gold, 17. 
Estimation, 135. 
Gravimetric estimation. 132. 
Acidulous radical-. 141. 
Metals, 132. 
Gravity, specific, 97. 184. 
Group reagents, 10. 
Aluminium, 20. 
Ammonium, 27. 
Antimony, 16. 
Arsenic, 15. 
Barium, 24. 
Bismuth, 14. 
Cadmium, 15. 
Calcium, 25. INDEX. 
199 
Group reagents (contd.) 
Cerium, 20. 
Chromium, 21. 
Cobalt, 23. 
Copper, 14. 
Gold, 17. 
Iron, 18. 
Lead, 12. 
Lithium, 26. 
Manganese, 21. 
Magnesium, 26. 
Mercuricum, 13. 
Mercuriosum, 13. 
Nickel, 23. 
Platinum, 18. 
Potassium, 27. 
Silver, 11. 
Sodium, 27. 
Strontium, 25- 
Tin, 17. 
Zinc, 22. 
H. 
Haloid salts, 113. 
Hardness, Clark’s process, 161. 
Hydrates, 33. 
Alkaline, estimation, 108. 
Sodium, 112. 
Hydriodic acid, 32. 
Hydrobromic acid, 30. 
Hydrochloric acid, 29. 
Hydrocyanic acid, 43, 114. 
Hydrofluoric acid, 29. 
Hydrofluosilicic acid, 40. 
Hydrogen, estimation, 151. 
Peroxide, estimation, 124. 
Hydrosulphuric acid 34. 
Hypobromides, 31. 
Hypobromic acid, 30. 
Hypochlorites, 30. 
Hypochloric acid, 29. 
Hypophosphites, 36. 
Hyposulphites, 46. 
I. 
Igniting precipitates, 130. 
Indicator, 105. 
lodate with iodide, detection 
of. 33- 
lodates, 33. 
lodides, 32, 42. 
Estimation, 141. 
lodine, 32. 
Estimation, Ixs. 
Standard solution, 114. 
Iron, xB. 
Estimation, 137. 
K. 
Reiser’s apparatus, 189. 
Kjeldahl’s process, 154. 
L. 
Lactates, 52. 
Lactic acid, 52. 
Lead, 12. 
Estimation, no, 132. 
Liquids (sp. gr. of), 97. 
Lithium, 26. 
Lixiviation, 2. 
M. 
Magnesium, 26. 
Estimation, 139. 
Malates, 53, 55. 
Malic acid, 53. 
Manganates, 49. 
Manganese, 21. 
Estimation, 137. 
Manures, 161. 
Estimation of phosphates, 
_144- 
May er’s standard solution, 121. 
Measuring and weighing, 95. 
Meconates, 55. 
Meconic acid, 55. 
Melting points, 195. 
Mercuricum, 13. 
Mercurosum, 12. 
Mercury, estimation, 133. 
Metals, detection of, 10. 
Gravimetric estimation, 
132- 
In complex mixtures, 65. 
Present in a salt, 61. 
Separation into groups, 
10, 66. 
Tables for detection, 62. 
Metaphosphoric acid and salts, 
46. 
Method, Volhard’s, 113. 
Varrentrapp and Will, 
J53- 
Pavy's, 119. 
Methylated spirit, in tinctures, 
*77- 
Micro-chemical analysis, 181. 
Milk analysis, 164, 
Mineral analysis in water, 
147- 
Moisture, estimation, 131. 
Mustard analysis, 169. 
N. 
Nesslerising, 125. 
Nickel, 23. 
Estimation, 137. 
Nitrate, 40. 
Nitrate, argentic, 113. 
Nitrates, 41, 43, 157. 
Nitric acid, 41. 
Nitric acid estimation, 123. 
Nitrite with nitrate, detection 
of, 41. 
Nitrites, 40, 142. 
Nitrogen estimation, 152, 157. 
Nitrometer, use of, 105. 
Analysis by, 122. 
Nitrous acid, 40. 
Nitrous ether, estimation, 123. 
O. 
Official standards of strength, 
in. 
Oleates, 52. 
Oleic acid, 52. 
Opium analysis, 176. 
Organic analysis, ultimate, 150. 
Matter, 163. 
Orthophosphoric acid, 47. 
Oxalates, 52, 146. 
Oxalic acid, 52, 146. 
Standard solution, 108. 
Oxides, 34. 
Oxygen required to oxidise, 
160. 
P. 
Pavy’s method, 119. 
Pepper analysis, 169. 
Perchlorates, 30. 
Periodates, 33. 
Permanganates, 49. 
Peroxide hydrogen, 124. 
Phenol and Phenates, 55. 179. 
Phosphates, detection of, 46, 
48. 
Estimation, 143. 187. 
Phosphoric acid, 156. 
Estimation, 120. 
Phosphorous acid, 46. 
Phosphorus estimation, 155. 
Platinum, 18. 
Estimation, 135. 
Poisons in mixtures (testing 
for), 92. 
Polarisation, analysis by, 192. 
Potassium, 27. 
Estimation, 135. 
Bichromate, standard so- 
lution, 117. 
Preparation of sulphuretted 
hydrogen, 9. 
Preparation of filters, 128. 
Precipitates, drying, etc.,, 129. 
Precipitation, 2. 
Process, Clark’s, 160. 
Dumas’, 163. 
Kjeldahl’s, 154. 
Processes, chemical, 1. 
Special analytical, 84. 
Clark's for hardness, 161. 
Testing for poisons, 92, 
Pyrogallic acid, 57, 
Pyrology, 7. 
Pyrophosphoric acid and salts, 
46. 
Q- 
Qualitative analysis— 
Processes, 1. 
Detection of metals, 10. 
Detection and separation 
of Acidulous Radicals, 
29- 
Detection of unknown 
salts, 58. 
Detection of Alkaloids, 
and of “ Scale ” medici- 
nal preparations, 89. 
Quantitative analysis— 
Weighing and measuring, 
95- 
Specific gravity, 97. 200 
INDEX. 
Quantitative analysis(contd.)— 
Vapor density, 102. 
Standard solutions, 105. 
Separations, 146. 
Quinine sulphate (testing) 174. 
R. 
Radicals, acidulous, 29, 75, 
141- 
Reactions of the alkaloids 
(tables), 94 
Reagents, 10. 
Group 1., ii. 
Group 11. Div. A, 13. 
Group 11. Div. B, 15. 
Group 111. Div. A, 18. 
Group 111. Div. B, 21. 
Group IV., 24. 
Group V., 26. 
Resinous drugs (strength of), 
178. 
S. 
Saccharimeter, 192. 
Salicylic acid, 56. 
Estimation, 126. 
Salts, detection of unknown, 
5.8- 
Estimation of ferrous and 
ferric, 117. 
Estimation of soluble 
haloid, 113. 
Used in pharmacopoeia,64. 
Sanitary analysis of air, 163. 
Sanitary analysis of water, 156. 
Scale preparations, 89. 
Alkaloidal strength of, 
179- 
Separation Group metals, 
120—128. 
Arseniate from phosphate, 
49- 
Chlorates from chlorides, 
30- 
Chlorides, iodides, bro- 
mides from nitrates, 42. 
Cyanides from chlorides, 
44. 
Ferro- from ferri-cyanides, 
45- 
lodide from bromide and 
chloride, 33. 
Metals into groups, 66. 
Oxalates, tartrates, ci- 
trates, malates, 55. 
Quantitative, 146. 
Silica from all other acids, 
40. 
Sulphides, sulphites and 
sulphates, 38. 
Silica, 40. 
Silicates, 39. 
Silicic acid, 39, 146. 
Anhydride, separation of, 
40. 
Silver, n. 
Estimation, 132. 
Smith’s diagrams, 182, 183. 
Soap, fatty acids in, 180. 
Sodium, 23. 
Estimation, 139. 
Hydrate, standard solu- 
tion, 112. 
Soil, estimation of phosphates, 
144- 
Solutions, standard, 105. 
Separate, (treatment of), 
173- 
For testing acidulous 
radicals, 77. 
Solubility tables, 82. 
Specific gravity, 97. 
Practical application, 101. 
Liquids, 97. 
Of urine, 184. 
Solid bodies, 99. 
Gases, 101. 
Spectrum analysis, 194. 
Spirits, alcoholic strength, 167. 
Table for percentages, 
x6B. 
Standard solutions, 105. 
Argentic nitrate, 113. 
Barium chloride, 121. 
Copper, Fehling’s, 119. 
For alkaloids, Mayer's, 
121. 
lodine, 114. 
Oxalic acid, 108. 
Phosphate, 161. 
Potassium bichromate, 
117- 
Sodium hydrate, 112. 
Thiosulphate, 115. 
Standards of strength, in. 
Stannates, 50. 
Stannic acid, 50. 
Starch estimation, 169. 
Stearates, 52. 
Stearic acid, 52. 
Strength of extracts (alka- 
loidal), 177. 
Resinous drugs, 178. 
Standards of, in. 
Strontium. 25. 
Sublimation, 4. 
Succinates, 53. 
Succinic acid, 53. 
Sugar estimation, 120. 
In urine, 185. 
Sulphates, 36, 38. 
Estimation, 142, 187. 
Sulphides, 34, 36, 38. 
Estimation, 142. 
Sulphides, sulphites, and sul- 
phates, separation of, 38. 
Sulphites, 36, 38. 
Sulphocyanates, 44. 
Sulphovinates, 51, 
Sulphur, 34. 
Estimation, 155. 
Sulphuric acid, 37. 
Sulphurous acid, 36. 
Estimation, 115. 
Sulphuretted hydrogen, pre- 
paration of, 9. 
Sweets (colored), analysis, 169 
T. 
Tables— 
Coefficients for analysis, 
127. 
Degrees of thermometer, 
164. 
Detection of the metal in 
a simple salt, the metals 
as in pharmacopoeia, 64. 
Detection of the metal in 
a solution containing 
one base only, 62. 
Distinction between gallic, 
tannic, and pyrogallic 
acids, 57. 
General reaction of alka- 
loids, 94. 
Percentages of alcohol, 
168. 
Tannic acid, 57. 
Tartaric acid, 53, 146. 
Tartrates, 53. 
Testing for poisons, 92. 
Chief alkaloids, 94. 
Gaseous impurities, 163. 
Quinine sulphate, 178. 
Thiocyanates, 44. 
Thiosulphates, 36, 115. 
Tin, r7. 
Estimation, 135. 
Tinctures, methyl spirit in, 177. 
Toxicological analysis. 89. 
U. 
Ultimate organic analysis, 150. 
Urea, estimation, 124, 186. 
Uric acid, 186. 
Urinary calculi, analysis, 188. 
Urine, 124. 
Analysis, 184. 
V. 
Valerianates, 51. 
Valerianic acid, 51. 
Vaporisation, 5. 
Vapor, specific gravity, 101. 
Vapors, density of, 102. 
Varrentrapp and Will, 153. 
Vinegar analysis, 171. 
Sulphuric acid in, 171. 
Volhard’s method, 113. 
Volumetric analysis, 105. 
Coefficients for, 122. 
W. 
Washing precipitates, 129. 
Water, 33. 
Mineral analysis of, 147. 
Sanitary analysis of, 156. 
Weighing precipitates, 129. 
Will & Varrentrapp, 153. 
Wines, alcoholic strength, 167. 
Zinc, 22. 
Estimation, 137.