ACETIC ACID AND VINEGAR, 
AMMONIA, AND ALUM. announcement. 
TECHNOLOGICAL HANDBOOKS. 
This series has been designed to meet the wants of those 
who, on account of the high price of an encyclopaedia, are 
unwilling to purchase when they wish to consult but a 
small portion of it, and of others who seek for fuller infor- 
mation than can be found in works of such scope. It is 
hoped that these Handbooks may be of use both to the 
expert and the beginner. 
Each book is complete in itself, embracing information 
on several collateral subjects, illustrations being introduced 
whenever they are found of advantage in explaining the 
text. 
Three volumes have appeared binder the editorship of 
Mr. John Gardner, F.I.C., F.C.S., wjm has had large 
experience in work of this kind, having leen interested in 
the preparation of recent editions pf 11 Copley's Cyclopaedia 
of Practical Receipts." VV 
Mr. Gardner, finding that, owing to other engagements, 
he is unable to continue this work, the co-operation as 
editor has been secured of Mr. James Cameron, F.I.C., 
Analyst in the Laboratory, Somerset House. 
The Fourth Volume, treating of Oils, Varnishes, &c., 
will appear under Mr. Cameron's auspices. 
ALREADY PUBLISHED. 
Brewing, Distilling, and Wine Manufacture. 
Bleaching, Dyeing, and Calico-printing. 
Acetic Acid and Vinegar, Ammonia, and Alum. ACETIC ACID AND VINEGAR, 
AMMONIA, 
AND 
ALUM. 
PHILADELPHIA: 
P. BLAKISTON, SON & Co., 
1012 WALNUT STREET. 
1885. EDITOR'S PREFACE. 
In the compilation of the present, as in the preceding 
volumes of the series, it has been the aim of the Editor 
to combine conciseness with practical utility. He hopes 
his endeavours may have been successful. 
The Editor takes this opportunity of thanking his 
friends, Mr. James Taylor and Mr. John Linford, for 
many valuable suggestions ; as well as for having given 
the sheets the benefit of their revision. 
John Gardner, F.I.C., F.C.S. BIBLIOGRAPHY. 
"Chemistry, Theoretical, Analytical and Practical" (Mackenzie, 
London and Edinburgh). 
Bussauce on " Vinegar Making." 
Gmelin's " Chemistry." 
Spon's " Encyclopaedia of the Industrial Arts." 
Bee's " Dictionary of Arts, Manufactures and Mines. 
Wagnee's "Chemical Technology." 
Watts' " Dictionary of Chemistry." CONTENTS. 
CHAP. PAGE 
I. Acetic Acid and Vinegar x 
II. Ammonia . . . . , . .92 
III. Alum and Alum-making .... 147 ACETIC ACID AND VINEGAR, 
ALUM AND AMMONIA. 
CHAPTER I. 
ACETIC ACID. 
Acetic Acid, HC2HsO2 or C2H4O2.* Syn. Acid of 
Vinegar, Normal Acetic Acid, Real Acetic Acid, 
Hydrated Acetic Acid, Absolute Acetic Acid. 
Acetic Acid is the sour principle of vinegar. 
Mention of vinegar occurs both in " Numbers " and 
11 Proverbs." Hippocrates employed it in medicine, and 
the alchemists obtained acetic acid in a concentrated form 
by distilling verdigris. Lowitz was the first to procure 
pure hydrated or normal acetic acid; and Dr. John Davy 
first pointed out that acetic acid was produced when spongy 
platinum was brought into contact with the vapour of 
alcohol. 
Commercial acetic acid is met with under the forms cf 
the pure glacial and dilute acids of the chemist and 
* Gebhardt regarded acetic acid as the hydrated oxide of an un- 
isolated radicle, which he named acetyl. To acetyl he assigned the 
formula, C2H8O. That for acetic acid would therefore be : 
CA2|o = C2H4O2. 2 
ACETIC ACID AND VINEGAR, ETC. 
pharmacist, and of vinegar, of which there are many 
varieties. 
Its sources are-Fermented liquors; the vinegars of 
commerce; alcoholic liquors; wood, from which it is 
obtained, as pyroligneous acid, by distillation ; the com- 
mercial acetates of soda, potassa, lime, lead, copper, &c. 
The acetic acid of the chemist and of commerce is almost 
wholly obtained from the acetates, either by the action of a 
strong acid, which seizes on the base, setting the acid free ; 
or by dry distillation, in which the high degree of heat 
employed separates the acetic acid from the base in the form 
of vapour. It is also obtained by the oxidation of alcohol. 
Acetic acid is produced either by the partial dehydrogena- 
tion and subsequent oxidation of bodies containing its 
elements, or by their destructive distillation. The first is 
effected-by their exposure, in a finely divided state, to the 
action of air or atmospheric oxygen, as in the quick process 
of making vinegar ; or-by submitting them, in combina- 
tion with ferments, to contact with a free supply of atmo- 
spheric air, as in the old field process of making vinegar; 
or--by exposure to the direct action of chemical or 
mechanical oxidizing agents, as condensed air (platinum- 
black process), chromic and nitric acid, &c.; in which latter 
case pure acetic acid is obtained. In general it is alcohol 
more or less dilute, particularly as it exists in fermented 
liquors, which is thus converted into acetic acid. In the 
second process-viz., by destructive distillation-wood is the 
substance usually employed, and heat is the agent which 
develops the acid. 
The conversion of alcohol into acetic acid * is not immediate 
* 130J lbs. of hydrated acetic acid contain . 110'92 lbs. of an- 
hydrous acetic acid ; from which datum, it may be said, theoretically, 
that 100 lbs. of absolute alcohol will yield 111 lbs, of anhydrous ACETIC ACID. 
3 
and direct. The atmospheric oxygen first oxidizes two 
atoms of its hydrogen, aldehyd and water being formed; 
and this aldehyd, uniting with one atom of oxygen, produces 
one molecule of acetic acid. The changes are represented 
in the following equations :- 
Alcohol. Oxygen. Aldehyd. Water. 
I. c2h6o + 0 = c2h4o + h2o 
Aldehyd. Oxygen. Acetic Acid. 
2. c2h4o + 0 = hc2h3o2 
After the first formation of aldehyd, the two processes, 
unless artificially checked, go on simultaneously, as long as 
any undecomposed alcohol is present. 
The conversion of alcohol into acetic acid, although 
greatly accelerated by the presence of yeast or of other 
ferments,* is rather a case of slow combustion than of fer- 
mentation. Acetification effects combination, as shown by 
the foregoing equations; whereas fermentation resolves 
complex bodies into simpler ones, as when sugar is con- 
verted into alcohol and carbonic anhydride. Moreover, the 
presence of ferments is not essential to the change, since 
pure alcohol becomes acidified when exposed to the oxidiz- 
ing agents already named. 
Another remarkable distinction between acetification and 
acetic acid. One pound of monohydrated acetic acid is generated 
from 077 lb. of absolute alcohol, and 1 lb. of anhydrous acetic acid 
from 0'9 lb. of absolute alcohol. These results, however, are higher 
than those obtained in practice, when there is always more or less 
loss arising from evaporation of the alcohol. 
* Pasteur refers acetification of alcoholic solutions by the pro- 
cesses of fermentation to the presence of a fungus, which he calls 
the mycoderma aceti-the mycoderma vini of Mulder, or vinegar 
plant. Pasteur thinks this organism acts, like platinum black, by 
absorbing oxygen from the air, and imparting it in the nascent condi- 
tion to the alcohol. His method of manufacturing vinegar by means 
of this mycoderm is described further on. 4 
ACETIC ACID AND VINEGAR, ETC. 
fermentation is, that the former requires the continuous 
presence of atmospheric oxygen, whilst the vinous fer- 
mentation, after being once established, proceeds perfectly 
without it. 
During the oxidation of the alcohol of vegetable solutions, 
some of the other organic matters present also suffer change. 
A white gelatinous mass known as Mollier of Vinegar is 
commonly deposited, but this is a secondary result of the 
process, and not, as formerly supposed, one essential to it. 
In ordinary cases acetification occurs only at or near the 
surface of the liquid; which accounts for the length of 
time required for the operation under the old process of 
fielding, and the shorter time in which it is accomplished 
under Ham's process. 
Acetification proceeds favourably at temperatures ranging 
from 6o°Fahr. (15'5° Cent.) to 900 Fahr. (32'2° Cent.), and, 
according to Liebig, most rapidly at 950 Fahr. (350 Cent.). 
In the quick process of vinegar-making, a temperature of 900 
(32'2° Cent.) to 920 Fahr. (33'3° Cent.) is generally aimed 
at; but it often rises to ioo° (37'7° Cent.), or even to 1050 
Fahr. (40-5° Cent.). As the temperature falls, acetification 
proceeds more slowly, and at 46° (770 Cent.) to 500 Fahr. 
(io° Cent.) it ceases altogether. 
The following are processes for obtaining acetic acid :- 
I. From the acetates* in the moist way. 
a. From acetate of soda. 
1. Commercial acetate of soda (i.e., the " pure acetate " of 
the pyroligneous acid works), in crystals, is put into the 
body of a stout copper still, and a deep cavity being made 
in the centre of the mass, about 35 per cent, of sulphuric 
* When sulphuric acid is used for decomposing the acetates, it 
must be free from nitrous acid. ACETIC ACID. 
5 
acid of a sp. gr. of not less than 1'84 is poured in; the 
walls of the cavity are then thrown in upon the acid, and 
the whole briskly agitated, for a very short time, with a 
large wooden spatula; the head of the still is next luted on, 
and the distillation conducted at a gentle heat, the receiver 
being changed as soon as the distillate begins to acquire a 
slight empyreumatic odour. The product, when the pro 
cess is well managed, is an almost colourless acid of the sp. 
gr. of fully 1'05, containing about 40 per cent, of glacial 
acid, or between 34 and 35 per cent, of anhydrous acid 
(acetic anhydride, C4HcO3). Any trace of colour or 
empyreuma is removed by agitation with some well-washed 
and recently ignited vegetable charcoal, or with a very 
small quantity of recently ignited purified animal charcoal, 
and subsequently passing it through a prepared calico bag- 
filter ; or by allowing it to stand, for about a fortnight, in 
barrels containing some beech-wood chips; after which it is 
ready for sale, either as the ordinary acetic acid or pure 
pyroligneous acid of commerce; or on dilution with 5 times 
its weight of water, and after the addition of a little burnt 
sugar and acetic ether, as vinegar. 
2. The acid of sp. gr. 1-05 obtained as above is distilled 
with fused chloride of calcium, the distillate being run into 
a refrigerator; the crystals that form are drained at a 
temperature below 400 or 450 Fahr. (4'4°-7'2° Cent.), and 
after removal to a warmer temperature, where they liquefy, 
and agitation with a little peroxide of lead, are submitted to 
a second distillation, as before; and this is repeated until 
the whole of the acid crystallizes at 550 Fahr. (12'7° Cent.). 
The product is the glacial acetic acid of commerce. 
3. (Mollerat's process-without distillation.)-Pure 
commercial acetate of soda, in coarse powder, is placed in a 
hard glazed stoneware or glass pan or receiver set in a cool 
situation, and 35 or 36 per cent, of concentrated sulphuric 6 
ACETIC ACID AND VINEGAR, ETC. 
acid, of the sp. gr. 1'843, added in such a manner that the 
acid may flow under the powder, and little heat be generated 
by the operation; the whole being covered up, is then 
allowed to remain in contact for some hours, when 
crystalline grains of sulphate of soda are found covering 
the bottom and sides of the vessel, and hydrated acetic acid, 
partly liquid and partly in crystals, the upper portion. 
The temperature being now slightly raised to a point just 
sufficient to cause the liquefaction of the crystals of acetic 
acid (z.e.,to from 62° to 65° Fahr.) (16'6°-18-3° Cent.), the 
fluid is poured off, and a very small quantity of pure acetate 
of lime added to it gradually, until it ceases to yield any 
trace of free sulphuric acid on evaporation. After sufficient 
repose it is carefully decanted for use. An excellent com- 
mercial strong acetic acid is thus obtained, without distilla- 
tion, owing to the insolubility of sulphate of soda in acetic 
acid; and from which glacial acid may be procured by 
refrigeration. If, however, the process be badly managed, 
or the proportions of the ingredients be not carefully 
observed, the product will be contaminated with either a 
little sulphuric acid or saline matter. It is also important 
to the success of this process that it be performed in a cool 
apartment, and in well-cooled vessels. Perfectly-pure acetic 
acid may easily be obtained by rectification from this 
acid. 
4. (Liebig's process.)-Pure acetate of soda, thoroughly 
dried at 2120 to 248° Fahr. (ioo° to 1200 Cent.), and finely 
powdered, 3 parts, is placed in a capacious retort, and pure 
concentrated sulphuric acid, 97 parts, poured over it 
through the tubulure. One-eighth of the acetic acid passes 
over by the heat developed by the reaction of the ingredients. 
The heat of a sand-bath is next applied and continued 
until the contents of the retort become quite liquid. The 
distillate, carefully rectified, yields two parts of pure acid, ACETIC ACID. 
7 
containing only 20 per cent of water. On exposing the 
latter portion which comes over in a closed vessel to a 
temperature below 400 Fahr., crystals of hydrated acetic 
acid are deposited. The weaker or liquid portion being 
poured off, the crystals are again melted and re-crystallized 
by cooling. The crystals of the last operation, separated 
Fig. i. 
a is a flask containing the sodic acetate. The cork is perforated by two tubes, 
through one of which the sulphuric acid is introduced, whilst through the other the 
acetic vapours as they are evolved pass into the receiver e, through the condenser c, 
which is kept cooled by means of a stream of water flowing from the vessel d. b 
contains the gas-lamp for heating the mixture of sodic acetate and sulphuric acid. 
b is a jug placed to catch the heated water as it flows from the condenser, g is 
the support for the condenser. 
from the liquid, and carefully drained in a cool and closed 
vessel, are perfectly pure glacial acetic acid. 
The above is an excellent process for obtaining a 
chemically pure acid. The excess of sulphuric acid left 
from the process may be recovered by distillation ; or the 8 
ACETIC ACID AND VINEGAR, ETC. 
whole residuum may be employed in a second distillation 
with fresh acetate. 
Although a retort is recommended by Liebig for the dis- 
tillation, and is usually adopted, on the small scale, for the 
purpose, a flask closed by a cork perforated by two tubes, as 
shown in the engraving on the previous page, will be found 
more convenient and safe, as the product is then less likely to 
be contaminated by the " spurting " of the ingredients over 
the brim of the vessel. The heat of a diffused gas-flame may 
also be often advantageously substituted for a sand-bath. 
b. From acetate of potash. 
i. Acetate of potash, fused and powdered, is placed in a 
still, or other suitable vessel, and 50 per cent, of the 
strongest sulphuric acid of fully 1'840 sp. gr. being added, 
the mixture is distilled to dryness as before. 
The product is 50 to 51 per cent, of the weight of the 
acetate employed, with a sp. gr. of about 1'0735 to 1'0740, 
containing about 66 per cent, of acetic anhydride, or about 
75 per cent, of normal acetic acid. By rectification from a 
little dried acetate of lead, a perfectly pure acid of almost 
any strength may be obtained. The ingredients are in 
nearly equivalent proportions. 
2. According to Melsens, pure glacial acetic acid is 
most advantageously obtained by distilling pure and 
dry acetate of potash with an excess of strong and 
moderately pure acetic acid, rejecting that which first 
passes over. 
The potassium acetate is mixed with a quantity of pure 
acetic acid of 70-8° Baume, sufficient to form the acid salt, 
which is then heated in a suitable vessel. Dilute acid at 
first comes over, but as the temperature increases, the acid 
salt is decomposed, and a distillate is obtained which 
solidifies on coolins'. The residue is again treated with 
acetic acid, and a further quantity of acid salt is thus ACETIC ACID. 
9 
obtained. By rectifying the distillate over freshly fused 
potassium acetate, pure glacial acid is obtained. 
c. From acetate of lead. 
i. (Ure.)-Take of dried acetate of lead 4 parts ; strongest 
oil of vitriol, 1 part. Distil slowly to dryness. Nearly 
equal to the last. 
2. (Liebig.)-Acetate of lead, 3 parts; sulphuric acid, 8 
parts; as before. 
3. (Dolfus. Concentrated acetic acid.)-Take of dried 
acetate of lead, 12 oz.; sulphuric acid, 6 oz.; distil, 7 oz. 
d. From acetate of lime. 
1. (Christl.)--Raw acetate or pyrolignite of lime (pre- 
pared by Volckel's process),* 100 parts, is mixed with 
hydrochloric acid (200 Baume, or sp. gr. 1'1515), 120 
parts; and, after 12 hours, distilled in a copper vessel 
with a gradually applied heat. The product is 100 parts 
or lbs. of acetic acid of 8° Baume (sp. gr. 1'0556), con- 
taining about 45 per cent, of hydrated acid only slightly 
* Volckel's process is as follows :-The crude pyroligneous acid 
(that is, not previously distilled) is first saturated with lime, whereby 
part of the resinous matters are carried down with the excess of 
lime, and part remains in the supernatant liquid. This being either 
filtered or cleared by being kept at rest, is next evaporated in an iron 
pot to one-half its bulk. Hydrochloric acid is then added, in propor- 
tions (varying with the strength and quality of the pyroligneous 
acid) of from 80 to 50 parts of the latter to 1 part by weight of 
hydrochloric acid, or until the liquid acquires a faintly acid reaction. 
The hydrochloric acid liberates the resin, the creosote, and the 
volatile oils. The first rises to the surface, and is removed by 
skimming, while the creosote and oils are dissipated during the 
evaporation of the liquid. The solution of acetate of lime is then 
evaporated to dryness, the drying being conducted at a high tem- 
perature, to effectually remove the adhering empyreumatic matters, 
the presence of which would impart a very objectionable smell to 
the acid obtained from it. 10 
ACETIC ACID AND VINEGAR, ETC. 
coloured and empyreumatic, fit for various manufacturing 
purposes,* such as for making acetate of lead. The advantages 
of employing hydrochloric acid are the freedom of the pro- 
duct from contamination with sulphuric or sulphurous acid, 
besides which the deposition of a hard crust of sulphate of 
lime on the bottom of the retort is avoided. 
It will be found that pyrolignite of lime generally con- 
tains 60 to 70 per cent, of neutral acetate; a proportionate 
quantity must therefore be employed, according to the 
amount contained in the sample. When the proper propor- 
tions are used the distillate gives a scarcely perceptible tur- 
bid cloud when tested with nitrate of silver. If the hydro- 
chloric acid used has the sp.gr. 1-16, a smaller quantity 
being employed the product will have the sp. gr. of 1'058 
to i'061, and will then contain from 48 to 51 per cent, of 
the hydrated acetic acid, or 41 or 42 per cent, of acetic 
anhydride. The resin sometimes found floating upon the 
surface of the mixed ingredients should be carefully re- 
moved, by skimming, before distillation. 
As acid of the above strength is rarely required, and as 
the distillation is more easily conducted when the ingredients 
are less concentrated, a little water may be conveniently 
added either before or towards the end of the distillation. 
Hence the following proportions have been recommended :- 
2. (Volckel.)-Acetate of lime (as last), 100 parts; hydro- 
chloric acid (sp. gr. i'i6), 90 to 95 parts; water, 25 parts; 
mix, and proceed as before. The product will be 96 to 98 
parts of an excellent acid, well adapted to trading purposes, 
having a sp. gr. about 1'050 and containing nearly 40 per 
cent, of hydrated acetic acid. It has been correctly remarked 
* There is frequently a great difference in the specific gravity of 
the crude pyroligneous acid obtained from acetate of lime and hydro- 
chloric or sulphuric acid. ACETIC ACID. 
11 
that the acetic acid produced with hydrochloric acid is always 
of better quality than that produced with sulphuric acid, be- 
ing not only less coloured but also entirely free from sulphur- 
ous acid. If necessary it may be rectified by redistilling with 
carbonate of soda, and any remains of empyreuma may be 
removed by distillation with i or 2 per cent, of bichromate 
of potash. The distillation uniformly proceeds with ease 
and regularity, and the whole of the acetic acid passes over 
between 2120 and 248° Fahr. (xoo°-1200 Cent.), by which 
the danger of contamination with other products, resulting 
from a high degree of heat, is obviated. 
3. An acetic acid sufficiently strong and pure for many 
ordinary purposes may be obtained without distillation, by 
pouring strong sulphuric acid, 60 parts, diluted with water, 
5 parts, on well-dried acetate of lime, 100 parts; digesting, 
with occasional agitation in a close vessel, decanting the 
clear liquid, and straining the remainder. 
4. In 1868, H. B. Condy took out a patent for the prepa- 
ration of acetic acid from the double salt of chloride of 
calcium and acetate of lime (the aceto-chloride of calcium) 
and hydrochloric or sulphuric acid. 
The aceto-chloride of calcium is first prepared either from 
the commercial, or, as it is technically called, the il distilled," 
acetate, * or from the brown acetate of lime. If brown 
* As the commercial acetate of lime contains more or less im- 
purities, these are in great measure got rid of by roasting it for forty- 
eight hours in a large iron retort. The retort used for this purpose 
is usually about 6 feet long and 34 feet in diameter, and furnished 
with an iron grating placed near the bottom, but with as few points 
of contact with the sides as possible. The acetate of lime is placed 
in sheet-iron trays, arranged on the grating one above the other, 
until they fill the retort, the trays being kept apart by iron rods, 
and as much as possible kept from touching the retort. The retort 
being then closed, a moderate heat is applied to it from a fire under- 
neath, which is kept up until the water and volatile contamina- 12 
ACETIC ACID AND VINEGAR, ETC. 
distilled acetate, one part of the salt is dissolved in 5^ parts 
of boiling water, and to this solution, after it has been filtered 
or allowed to become clear by rest, dry chloride of calcium, 
in the proportion of y^ths of the weight of acetate of lime 
used, is dissolved by the aid of heat and agitation. The liquid 
is then cautiously reduced by heat until it has a specific 
gravity of 30° Baume. The aceto-chloride crystallizes out 
as the liquid becomes cold. The mother liquor is then 
drawn off, and evaporated down until it reaches 310 Baume, 
when it is again drawn off and left to crystallize. These 
processes are repeated until three other crystallizations have 
been obtained. For the third crystallization, the liquid 
which is drawn off boils at about 300 Baume, for the fourth 
at about 330, and for the fifth at about 36° Baume. An 
inferior acid is obtained from the final mother liquor by 
distillation with sulphuric or hydrochloric acid. The five 
batches of crystals, after being washed and drained, are next 
dissolvedin twice their weight of water, and to the solution, 
after being filtered through animal charcoal, is added 1 o per 
cent, of chloride of calcium. 
The liquid is then evaporated till it reaches 2 9° Baume, 
when pure white crystals are formed. By evaporating down 
the respective mother liquors from this last salt, the first at 
300 Baume, the second at 310, and the third at 320 Baume, 
three other crops of crystals may be procured. The results 
tions of the acetate are expelled, which may be known by the exit- 
pipe becoming cool. 
When the aceto-chloride has been prepared from acetate of lime 
obtained from crude pyroligneous acid, it is roasted in the same 
manner before being redissolved and recrystallized. Sometimes, 
instead of being roasted, the aceto-chloride when in solution, or the 
acetate of lime alone, is filtered through animal charcoal; or the 
commercial acetate may be used without roasting for making the 
aceto-chloride, and this may be roasted. ACETIC ACID. 
13 
are not so satisfactory or economical when the brown acetate 
of lime is employed in making the aceto-chloride. In this 
case it is requisite to use 20 per cent, more of the brown 
acetate than of " distilled " acetate for a given weight of 
chloride of calcium. The uncertain strength of the brown 
acetate renders it necessary to test the solution of aceto- 
chloride after it is evaporated down to 300 Baume, to 
ascertain whether or no it yields a good crop of crystals. 
If it do not, the evaporation must be continued until it 
does. 
Crude pyroligneous acid is sometimes used for preparing 
the aceto-chloride. The acid is first neutralized with lime, 
and the strength of the resulting solution ascertained by 
evaporating a small portion to dryness, weighing, and then 
apportioning the chloride of calcium according to the above 
ratio, and proceeding as before stated, with the exception 
that, for the first crop of crystals, the solution must be 
brought to 320 Baume. In most cases the mother liquors 
are evaporated to half their bulk before they yield an ad- 
ditional crop of crystals. To obtain acetic acid from the 
aceto-chloride, it is distilled either with sulphuric or hydro- 
chloric acid. 
When sulphuric acid is used, 24 parts of sp. gr. 1'840, 
diluted with twice its volume of water, and 112 parts of the 
aceto-chloride, are taken. With hydrochloric acid the pro- 
portions are 100 parts of aceto-chloride and 50 parts of acid 
diluted with water. 
As before stated, the acetic acid is obtained from the 
purified aceto-chloride of lime by distilling this with sul- 
phuric, hydrochloric, and, we may add, with any other acid 
having a greater affinity for the lime than the acetic. To 
free the resulting acid from hydrochloric acid it is redis- 
tilled with an alkali or with acetate of soda ; 1 lb. of either 
to every 10 gallons of acid. 14 
ACETIC ACID AND VINEGAR, ETC. 
Whichever the acid used, it will be found that the process 
of distillation goes on most satisfactorily if the mixture in 
the retort is largely diluted with water. 
5. (Kuhlmann's Process).-When crude pyroligneous acid 
is saturated by natural carbonate of baryta, or sulphide of 
barium, an acetate is obtained which it is necessary to roast 
with moderation in order not to decompose it; but, however, 
raising the temperature sufficiently high to drive off the 
tarry matter. It is important in every case, during this 
calcination, not to exceed an incipient red heat. The opera- 
tion may be repeated several times. 
The acetate of baryta thus obtained is decomposed by one 
equivalent of sulphuric acid; the decomposition is complete 
only when the solution is not too concentrated. 
The result is sulphate of baryta and weak acetic acid, 
which however has sufficient density to be directly used in 
some manufactures. Thus it can be immediately employed 
in the fabrication of white lead, acetate of lead and other 
acetates. 
When to produce the decomposition of the acetate of 
baryta by sulphuric acid, too much of the concentrated solu- 
tion of acetate is used, the sulphate of baryta does not 
separate in its ordinary form ; but then contains acetic acid, 
and presents a gelatinous, half transparent appearance, 
which it is difficult to destroy. 
To obtain a purer acid, the acetate of baryta can be 
transformed into acetate of soda by the addition of sulphate 
of soda. 
It is scarcely necessary to say that when a more concen- 
trated acid is required, it is sufficient to distil the acetate of 
baryta with sulphuric acid. 
The acetate of baryta is prepared by mixing finely pow- 
dered natural carbonate of baryta with pyroligneous acid, 
until all foaming ceases, and the resulting slightly acid ACETIC ACID. 
15 
solution is neutralized by sulphide or carbonate of baryta. 
After settling, the clear liquid is evaporated in a flat dish. 
The crystals as they form are removed, and deposited on an 
inclined surface, where they remain to drain. When 
drained the crystals are calcined in a large dish about three 
inches deep, and having a surface of 9 to io square feet, set 
in masonry in such a manner, as to be uniformly heated at 
the bottom without becoming red. 
The crystals are spread in the dish to the depth of about 
2 inches, and constantly stirred without being allowed to 
stick to the bottom. They are, lastly, heated until empyreu- 
matic vapours cease to be given off, and a sample when dis- 
solved in water gives a. colourless solution. The crystals 
effloresce to a homogeneous powder, which must be removed 
from the fire into another dish, and constantly stirred till 
quite cold. In order to prevent a too great pulverization 
during the calcination, there may be mixed with the crystals 
some acetate of soda, which by melting renders the acetate 
of baryta damp. The calcined mass is dissolved in water, 
and the white acetate of baryta obtained by evaporation 
can be used to prepare acetic acid and acetates. It is 
claimed for the acetic acid and acetates prepared by the 
above process that they are of very pure quality. 
II. From the acetates by dry distillation with a sulphate. 
a. From acetate of lead. 
1. Dried acetate of lead, 5 parts, and sulphate of iron, 
gently calcined, 2 parts, are separately powdered, and, after 
thorough mixture, carefully distilled, by the heat of a sand- 
bath, into a well-cooled receiver. This is an economical 
process for a strong acid, but is now seldom adopted. 
2. (Bardollier's strong acetous acid.)-Dried acetate of 
lead, 10 ozs.; calcined green vitriol, 12 ozs.; as the last. 
6. From the acetates of copper. 
By substituting acetate or diacetate of copper, in equiva- 16 
ACETIC ACID AND VINEGAR, ETC. 
lent proportions, or, better still, with excess of the sulphate. 
Seldom used. 
c. From acetate of potash; as the last. 
Fig. 2. 
A, Furnace. 
B B B B, Glass receivers. 
C, Stoneware retort. 
B, Bottle containing vinegar 
B B B B, Basins containing water. 
B B B B, Supports for basins. 
G, Welter safety-tube. 
7Z, Supply-pipe of cold water. 
1111, Cocks to supply water to the 
basins. 
J, Water main. 
L, Adapter connecting' retort and 
globes. 
III. From the acetates per se. 
a. From acetate of copper. 
Aromatic Vinegar; Spirit of Verdigris; Spiritus 
Veneris; Esprit de Venus, Fr.; Acidum Aceticum, Ph. 
L. 1787.-Dry carefully, crystallized verdigris (diacetate of 
copper) by a very gentle heat, and introduce it into a large 
stoneware retort (such as shown in the engraving), the bottom 
of which has been previously coated with a mixture of clay 
and horse-dung, to render it more capable of standing the 
fire. Next place it in a suitable furnace, and connect it, by 
an adapter, with three or four double tubulated globes 
(B, B, B, B,), the last of which must be furnished with a 
vertical tubulure, to which a double Welter's safety-tube 
should be adapted; the other end being immersed in a 
basin half-filled with distilled vinegar or water, while the 
funnel portion communicates with the atmosphere. The 
joinings are then to be coated with a paste composed of pipe- 
clay and linseed oil, and covered with glue-paper. Now ACETIC ACID. 
17 
place each globe in a basin of water, kept cool by a stream 
constantly passing through it; and cover the upper portion 
with cloths kept continually wet with cold water. After 
fifteen or twenty hours, fire may be applied, and must be so 
regulated that the drops follow each other with considerable 
rapidity from the end of the adapter, whilst the bubbles of 
air cause no inconvenience at the other end of the apparatus. 
If otherwise, the fire must be damped a little. The operation 
should be continued, and the fire gradually increased, until 
vapour ceases to come over, known by the globes gradually 
cooling, notwithstanding the heat of the furnace. The 
operation being concluded, the whole may be allowed to 
cool, and the acid collected preparatory to rectification. 
This may be effected in a similarly arranged apparatus, 
except that it must be wholly of glass; and the retort 
should not be much more than half filled. The operation 
must now be very carefully conducted, and discontinued 
before barely the whole of the acid has distilled over, as 
the last portion is apt to injure the flavour and colour of 
the rest. The first portions which come over are very 
weak, and should be kept separate until the sp. gr. reaches 
to about 1'072, when the receiver should be changed, anti 
the product collected in separate portions, as noticed 
below. 
Good diacetate of copper yields, by careful management, 
at a temperature of 4000 to 560° Fahr. (2O4'4c-293° Cent.), 
fully one-half its weight of a greenish-coloured acid, of the 
sp. gr. of about i'o6t, containing above 50 per cent, of 
hydrated acetic acid, or 40 per cent, of acetic anhydride. 
20 lbs. of the ordinary acetate yields 9^ lbs. of this rough 
acid, leaving a residuum of about 6^ lbs. of metallic copper 
mixed with a little charcoal in the retort; the remainder 
(nearly j%ths of the acid in the acetate) being decomposed 
by the heat, and lost. This 94 lbs. of crude acid yields 18 
ACETIC ACID AND VINEGAR, ETC. 
by rectification, and dividing the products, - lb. of acid of 
the sp. gr. 1'023 j 3 ^)S- the sp. gr. 1'042 ; and 6 lbs. of 
the sp. gr. 1'065 1 exclusive of a little acetone which comes 
over with it. In the first distillation, the strongest acid is 
found in the third receiver, and the weakest in the first. 
The acid obtained in this way, is always accompanied with a 
little fragrant pyro-acetic spirit, which renders it preferable 
for aromatic vinegar* and perfumery. It dissolves camphor, 
resins, and essential oils with facility. This is one of the 
oldest methods of obtaining glacial acetic acid, and the pro- 
duct is still preferred for some purposes. It is the "radical 
vinegar" of the alchemists, and it is that which is said to be 
preferred by the perfumers. Well-dried acetate of lead, or 
of iron, as well as several other acetates, may be substituted 
for acetate of copper in the above process, but are less 
economical and convenient. In all cases great care must 
be taken to avoid over-firing, as thereby the quantity 
obtained is lessened, and the quality injured. The residuum 
of the distillation is pyrophoric, and frequently inflames 
spontaneously on exposure to the air. Due caution must 
be therefore observed regarding it. Until of late years, the 
above method of procuring acetic acid was that almost uni- 
versally employed. 
IV. From wood by destructive distillation. Pyroligneous 
Acid. Syn. Vinegar of Wood. Crude Acetic Acid.- 
Impure acetic acid, obtained by the destructive distillation 
of wood in close iron retorts. The acid comes over along 
with tar, creasote, wood spirit, and other liquid and gaseous 
matters, charcoal being left behind. In this state it con- 
* The following formula from the Paris Codex yields a fragrant 
and refreshing aromatic vinegar :-Camphor, 2 ozs. ; oil of lavender, 
10 grains; oil of cinnamon, 20 grains ; oil of cloves, 30 grains ; 
concentrated acetic acid, 1 pint; macerate for seven days. ACETIC ACID. 
19 
tains much empyreumatic matter in solution ; but by sepa- 
ration from the tar, saturation with slaked lime or chalk, 
defecation and evaporation, an impure acetate or pyrolignite 
of lime is obtained, which, after being gently heated to 
-destroy part of its empyreumatic matter, without injuring 
its acetic acid, is either used as the direct source of the 
acid or is again dissolved and defecated, and then precipi- 
tated by a solution of sulphate of soda, when a solution of 
acetate of soda and a precipitate of sulphate of lime are 
formed by double decomposition. The solution is next 
evaporated to dryness, the dry mass (pyrolignite of soda) 
dissolved in water, and the new solution filtered and re- 
crystallized. The crystals of acetate of soda obtained by 
the last process yield nearly pure acetic acid by distillation 
with sulphuric or hydrochloric acid. Pyroligneous acid is 
largely manufactured in this country, France, Germany, and 
Belgium. 
Some years ago, Halliday, of Salford, patented an inge- 
nious method for the manufacture of pyroligneous acid from 
sawdust, spent bark from tan-yards, and dye-woods, the 
colour of which had been removed. Previous experimenters 
in this direction had hitherto failed, from their inability to 
prevent the deposition on the sides of the retort of a coating 
■of solid carbon, which, acting the part of a non-conductor, 
rendered the interior of the mass inaccessible to the external 
heat. Mr. Halliday overcame this difficulty by introducing 
the sawdust or other materials into a hopper fitted with a 
vertical revolving screw, which carried them into a horizontal 
cylindrical retort heated by a furnace. This retort was 
furnished with a movable worm, by which contrivance the 
whole of the material became perfectly carbonized, its vola- 
tile products being conveyed through an ascending pipe 
into a proper condenser, whilst the charcoal is discharged 
through a descending pipe into a cistern of water. 20 
ACETIC ACID AND VINEGAR, ETC. 
Halliday and Hadfield assert that the coniferous 
woods, which in ordinary retorts afford but a poor yield of 
Fig. 3. 
A. Hopper, b. Vertical screw, c. Retort, d. Movable worm. c. Ascending pipe. 
e. Descending pipe. ACETIC ACID. 
21 
pyroligneous acid, yield a very considerable amount, when 
employed in the form of sawdust in this apparatus. 
The sawdust of spent dye-wood, so treated, gave an 
amount of acid equal to that of ordinary woods. 
Eight of Halliday's retorts, 14 inches in diameter, will, it 
is stated, produce in 24 hours the same amount of acid as 
16 ordinary retorts, 3 feet in diameter, worked during the 
same time. 
Eight of Halliday's retorts worked for many weeks, and 
converting into charcoal 22 tons of sawdust per week, gave 
an average product of :- 
Pyroligneous acid, io° Tw. = 1'05 sp. gr. ... 2,484 gallons. 
Tar 240 ,, 
Erom 1 ton of oak, carbonized in ordinary cylinders, was 
obtained 
Pyroligneous acid, 6° Tw. = 1'03 sp. gr. ... 1,277 lbs. 
Charcoal ... ... ... ... ... ... 600 ,, 
Bower's apparatus is a modification of the above, and 
consists of a rectangular retort, placed at an angle of about 
2 50, and heated along its entire length by outside flues. 
Like Halliday's, it is adapted to the distillation of sawdust, 
spent dye-woods, tan, &c.; which before being introduced 
into the retorts are dried by being propelled along a drying 
floor, by scrapers fixed on a revolving chain which is 
worked by drums turned by steam. 
After the dried wood leaves the drying floor, it is raised 
by machinery and made to fall into the retort through a 
hopper, so constructed, as to prevent the escape of the 
products of distillation. When in the retort, the woody 
substances are kept in movement by an arrangement of 
chains, scrapers, and drums similar to that employed in the 
drying bed; and by the time they reach the end of the 
retort furthest from the hopper they have become charcoal, 22 
ACETIC ACID AND VINEGAR, ETC. 
and as such are discharged into a receptacle full of water. 
At the top of the retort are two pipes, through which the 
volatile products of distillation are carried off, and are con- 
densed in the ordinary manner. Bower's apparatus effects 
Fig. 4. 
d. Hopper, e. Receptacle containing water, into which the charcoal falls. 
F. Scraper for removing charcoal. g&. Pipes for carrying off products of distil- 
lation. 
a considerable saving in steam power, provided the drying 
floor and the furnace are so arranged that the waste heat 
of the latter can be utilized for the former. The apparatus, 
owing to the slow movement of the machinery, suffers but 
little from wear and tear. 
The drawbacks to the use of this and the previous 
apparatus are said to be the very inferior character of the 
charcoal, and the presence in the resulting acid of a large 
excess of resinous and oily substances, which are difficult 
of removal. The charcoal having to be dried, this involves 
another item of expense for fuel. The large demand for 
sawdust and its consequent high price, militate against 
its utilization for this purpose. ACETIC ACID. 
23 
Solomon and Azulay's patent consists in passing super- 
heated steam into a mass of sawdust, in such a manner 
that the sawdust becomes entirely and effectively carbonized. 
The volatile products largely diluted with steam when they 
leave the retorts, are made to traverse a coil of metal pipe 
placed in a pan of the distillates, which being thereby 
heated, the pyroligneous acid and other volatile products 
become volatilized, and pass into the adjoining condenser. 
By another process, which has formed the subject of 
several patents, acetic acid, associated with wood naphtha, 
resin, and other products, is obtained from woody fibre, 
before this is used for paper-making. Under these circum- 
stances, the wood is not of course, carbonized. By Fry's 
process, patented in 1869, the wood, after being cut into 
small pieces of from half an inch to an inch and a half long, 
and from §th to | inch thick, is placed in cages made of 
copper wire or perforated zinc. The cages are next put 
into a cylindrical, jacketted iron boiler, and are of such 
dimensions as to exactly fill the boiler. The boiler being- 
then filled with cold water, steam is admitted into the 
jacket from a second boiler connected with the first by a 
pipe, so that the steam can be regulated at pleasure. By 
this means the pieces of wood are heated to about 3300 F. 
(165° Cent.), at which temperature, according to the 
description and size of wood, they are kept for 3, 4, or 5 
hours, after which time the water surrounding them being- 
removed from the boiler under proper precautions, is placed 
in a still, and the acetic acid separated from the other sub- 
stances by fractional distillation. It is then neutralized 
with an alkali, carefully evaporated to dryness, and separated 
from the base by the usual treatment with sulphuric or 
hydrochloric acid. The difficulty of separating the acetic 
acid from the wood naphtha, resin, &c., has been a serious 
barrier to the successful working of this process. 24 
ACETIC ACID AND VINEGAR, ETC. 
In 1873, Steedman patented a process for the purification 
of pyroligneous acid by passing it through paraffin, fat, or 
some hydrocarbon which possessed the power of absorbing 
and removing its impurities. The acetic acid in the state of 
vapour is conducted by a pipe into a rectangular copper 
vessel, 5 feet long, 1 foot wide, and about 3 feet deep. 
This vessel is filled with the liquefied hydrocarbon kept at a 
little higher temperature than the acetic acid, whereby the 
condensation and consequent loss of the latter is prevented. 
The interior of the vessel is so contrived as to cause the 
acid vapours as they issue from the distilling apparatus, to 
traverse it on their way to the condensing apparatus, and 
thus to be brought into contact with as large a body of the 
paraffin or other hydrocarbon as possible. The paraffin or 
other depurator in the copper vessel, is heated either by a 
coil of steam pipe or by a steam jacket, and is removed 
when saturated with the impurities. 
By Stoltze's method the crude acetic acid is partially 
purified by distillation. He thus obtains 10 per cent, of a 
liquid which he uses for the production of wood naphtha, 
and 80 per cent, of impure acetic acid, the empyreumatic 
contaminations of which he destroys either by chlorine or 
ozone. 
Wood distillation is conducted in various ways. In 
some works cast or wrought iron retorts * are used, and in 
others large square sheet iron ovens. These ovens are set 
in brickwork, so as to allow the flames from the naked fire 
underneath to play spirally around them ; whilst the smoke 
* Cylindrical retorts or ovens should not be made of cast iron. 
It is a disputed point among pyroligneous acid-makers whether 
wrought or cast iron is the better adapted for the distillation of wood. 
The advantage of using wrought is its much less tendency to crack, 
a quality which admits of the retorts being made thinner, and, there- 
fore, causes them to be more quickly and economically heated. On ACETIC ACID. 
25 
is carried off by flues into the chimney. A vertical retort, 
fitted at the upper part with a tube 0 as shown at A in the 
accompanying figure is used in France. 
Fig. 5. 
When A is charged with wood, the lid is tightly screwed 
on, so that the retort is made air-tight, and it is then raised 
by means of the crane D, and placed in the furnace B, which 
is afterwards closed by a lid E constructed of fire-brick. The 
products of the distillation are carried into the pipe f, 
the other hand, retorts made of wrought iron, when overheated 
soon get out of shape, and occasionally leak at the joints. Owing 
to the liability of the acid vapours to condense, and consequently to 
act upon wrought iron, the exit pipes and doors of such retorts 
are always constructed of cast iron. The advantage of this latter is 
that the retorts being in one piece, the great inconvenience of leak- 
age is avoided. 26 
ACETIC ACID AND VINEGAR, ETC. 
(Fig. 6) which passes through a series of iron condensers 
c c c, as shown in the engraving. 
These condensers, which are supported on a framework d, 
are kept continually supplied with cold water* by the pipe f \ 
whilst the heated water passes off by the pipe 7c. Acetic 
acid, wood spirit, and tar become condensed, and flow through 
the pipe 6 into the vessel g, when the tar becomes separated 
Fig 6. 
and remains, whilst the vinegar and wood spirit run through 
the pipe m into the receptacle h. The pipe i is for carrying 
off the uncondensable gases which result from the distilla- 
tion, into the fire, where they are consumed, and thereby 
effect a considerable saving of fuel. This description of 
apparatus is employed, when the yield of acid is the first 
consideration. 
* In some works the volatile products are condensed by means of 
cold air. This method, however, is very rarely adopted. ACETIC ACID. 
27 
A similar condensing apparatus is employed when the 
distillation is carried out in ovens. 
A rude form of distillation is carried on in some parts of 
France and Germany, where brushw'ood and heather are 
abundant. The wood is packed in a wrought iron retort 
resembling an inverted cone, and is set fire to, care being 
taken to admit no more air than is needed to effect car- 
bonization. To the apex of the cone is attached a pipe 
through which the products of combustion pass into the 
condensers. 
Schwartz's carbonizer, which is largely used in France 
and Belgium, where the charcoal is the principal product 
required, consists of a fire-brick furnace, with a fireplace at 
the bottom having direct communication with the chamber 
or space containing the wood intended for distillation. In 
some cases the walls of the furnace are hollow, and filled 
with a mixture of sand and aluminous schist. When the 
fire is well alight , the flames play around the blocks of wood, 
causing them to become speedily carbonized, whilst the pro- 
ducts of distillation are correspondingly rapidly liberated. 
These last are carried through exit pipes, in their passage 
through which they part with their tar, whilst the acetic 
acid and oily matters together with the smoke, pass into 
wooden condensers, where the acid and oily substances re- 
main, whilst the smoke escapes by the chimney. 
When the carbonization is finished, as indicated by the 
colour of the smoke, from black to light blue, the chimneys 
and all the apertures are carefully closed, and when the 
furnace has cooled down, water is thrown upon the charcoal, 
the air being meanwhile excluded, until the charcoal ceases 
to show signs of ignition. Schwartz's apparatus is so con- 
trived as to admit only just sufficient air to carbonize the 
charcoal. It also possesses the advantage of enabling small 
wood to be utilized in the manufacture of the acid. " The 28 
ACETIC ACID AND VINEGAR, ETC. 
cost of this furnace is about ^120, the capacity being about 
6,000 cubic feet." * This apparatus gives the best charcoal. 
Reichenbach's carbonizer is a large square oven, the 
interior walls of which are of fire-brick. Running longitu- 
dinally through the oven from end to end and doubling back, 
Fig. 7, 
are large tubes, around which the wood is placed. These 
tubes are from i to 2 feet in diameter, a,nd are heated by 
means of a fire lighted inside them at their exterior orifice. 
When they become red-hot, the wood is carbonized, and the 
products of distillation run off, through openings in the 
bottom of the oven, into covered channels, where they de- 
posit the tar, whilst the acetic acid in the state of vapour 
passes into a condensing apparatus. This and Schwartz's 
carbonizer are frequently made of a capacity of 5,000 or 
6,000 cubic feet. 
The English pyroligneous acid-makers usually employ 
* "Chemistry, Theoretical, Practical, and Analytical." Mac- 
kenzie, London and Edinburgh. ACETIC ACID. 
29 
cylindrical iron retorts built into brickwork. Eight such 
retorts constitute a good-sized work. Over the range of 
Fig. 8. 
abc. Cylinders, n. Fire, e, e. Flues, n. Drying house. 
ovens is the drying house, on the floor of which the 
acetate of lime is dried. The retorts vary in length in 
different works, usually from 4 to 9 or 10 feet, and in 
breadth from 2 g to 4 feet,* which experience, has shown to 
be a maximum diameter. The smaller the diameter the 
* Satisfactory results have been obtained by cylinders having the 
following dimensions:-No. I, 7 feet long, 5 feet in diameter, 5 feet 
deep, and 5 feet broad (this was of wrought iron). No. 2, 10 feet 
long, 34 feet in diameter, 34 feet deep, and 3I feet broad (this was 
of cast iron). No. 3, 10 feet long, 3T\th feet in diameter, Sruth 
feet deep, 3^11 feet broad (this was also of cast iron). No. 4, 94 
feet long, 2J feet in diameter, 5 feet deep, and 3| feet broad (this 
was of rectangular shape, and of cast iron). Experience has shown 
that it is advantageous to let the end of the retort to which the pipe 
is attached, stand in about 5 inches, and to surround the exit pipe 
with a 44-inch brick wall. 30 
ACETIC ACID AND VINEGAR, ETC. 
more rapid the distillation. They are arranged horizontally, 
sometimes in sets of twos or threes or fives, with flues 
Fig. 9. 
Iron door of retort closed. 
around each, and are heated by a fire underneath, which is 
not in direct contact with them. Very frequently each 
retort is heated by a separate fire, an arrangement which 
permits of the repair of a cylinder if needful. Rectangular 
retorts are heated by a separate furnace. The wood cut up 
into suitable lengths is packed into the retorts as closely as 
possible, so as to economize space. The average charge of 
each cylinder is about 24 cwt. of dry wood. One end of the 
retort is closed, sometimes by a massive iron door, which 
swings on stout hinges; and at others by an iron plate 
fastened by strong iron screws, or by cross bars, all being 
covered externally with a luting of clay or loam. To the 
other and further end of each retort is attached an iron pipe, 
which conducts the products of distillation into the con- 
densers, which are metal pipes surrounded by cold water. ACETIC ACID. 
31 
Here the vaporized tar, pyroligneous acid, naphtha, &c., 
assume the liquid form, and in this state reach the tar 
settlers. These are large tanks, about 20 feet in length, 
5 feet in breadth, and 5 feet in width, constructed of strong 
3-inch deal boards, bound together with iron rods. 
The tar which falls to the bottom, is removed from the 
settlers by stop-cocks, to the tar still; whilst the super- 
natant fluid in which is contained the pyroligneous acid, 
naphtha, &c., undergoes different treatment according to the 
nature of the particular product required. If, for instance, 
pyroligneous acid, or white or grey acetate of lime be 
desired, the naphtha is first distilled off at a gentle heat, 
leaving the acid in the retort, this being obtained and in 
great measure deprived of its impurities by after distillation. 
When the object is to procure the brown acetate, the 
fluid is pumped into the neutralizer in which it is mixed 
with lime, the naphtha being afterwards removed by distilla- 
tion. 
There are many varieties of condensers. A very useful 
form of one is connected with the exit pipes of the retorts 
in such a manner as to admit of these being easily detached 
when necessary. Each exit pipe has a separate condenser, 
although in some works two retorts have only one con- 
denser, which arrangement is found to work less satisfac- 
torily than when one retort is used. The condensers, which 
consist of one large pipe of about 10 inches in diameter, 
in connection with two pipes of half that diameter, 
and are so curved as to expose a large amount of surface, 
are placed in a large cistern fixed at the back of the retorts, 
and corresponding in length with the line of furnaces which 
heat the retorts. The water supply is so managed as to 
ensure its being in constant movement. The smaller con- 
densers dip considerably so as to prevent the tar accumulat- 
ing in them, and stopping them up. The incondensable 32 
ACETIC ACID AND VINEGAR, ETC. 
gases, consisting of carbonic acid, and oxide, marsh and 
olefiant gases, are carried off by a pipe, whence they are 
conveyed to the furnace and there burnt. Should the least 
quantity of the volatile liquids generated during distillation#1 
Fig. io. 
Condensing Cistern, 4-7 x 75 
have escaped condensation, tins may be known by placing 
the palm of the hand in the stream of out-coming gas, when 
moisture will be deposited upon the hand. When no more 
liquid issues from the condensers, and the exit pipes from 
the retorts become cool, the distillation is known to be 
completed. 
In the Forest of Dean and elsewhere, instead of cylindrical 
retorts, large square ovens of wrought iron are in use. The 
charge of wood (usually consisting of about half a cord) is 
placed in a waggon made of sheet iron, which is run by 
means of a tramway into the oven, and removed in the same 
manner when the carbonization is over. The wood is so ACETIC ACID. 
33 
piled above the top of the waggon as to enable it to enter 
the oven. Each oven is about 8 feet long, by 5 high, and 
5. wide, and holds two waggons. The oven doors are fastened 
and luted in the usual manner. These square ovens are 
g enerally found to answer best for the distillation of small 
timber, which is mostly used in the Welsh works; whereas 
for the larger and heavier kinds the cylinder is preferable. 
Fig. ii. 
Chests made of wrought iron are sometimes employed, 
and are said to act satisfactorily. The heat is conveyed 
into the interior by an iron pipe, 6 inches in diameter, 
carried through the centre of the chest. 
At some of the South Wales works they use large 
cylindrical carbonizers, divided in the interior into six com- 
partments, into each of which a large sheet iron vessel, 
4 feet high, and 2 feet wide, for holding the wood, fits. The 
carbonizer has but one opening at the top, through which 
the vessels containing the wood are lowered in succession 
by a crane, each being removed into the interior, to 
make way for the next, by a movable framework at the 
bottom of the carbonizer. When full, the opening is bolted 34 
ACETIC ACID AND VINEGAR, ETC. 
and luted. This apparatus, which is placed in brick- 
work, is directly over the fire which heats it. The wear 
and tear to which it is subjected is very great. 
The charcoal is sometimes removed at one operation, and 
in an unbroken condition, from the cylindrical retorts, by 
dragging through them from end to end, by means of an 
iron chain or rod, an iron plate, which fits into the interior 
of the retort. By this means the charcoal, in as whole a 
condition as possible, is drawn out. 
From the retorts, the charcoal falls into deep iron 
waggons, fitted with sheet iron covers, which as soon as the 
waggons are filled, are immediately luted down with clay, 
so as to exclude the air, and prevent the combustion of the 
charcoal. 
In some works the charcoal is raked into a large iron 
barrow, when it is wheeled without loss of time to the 
manhole or trap-door of a capacious underground tank or 
vault, into which the contents of the barrow are emptied. 
Water being then thrown upon the charcoal to extinguish 
it, the manhole is closed, and afterwards covered with a 
strong luting. 
The yield of acid, charcoal, tar, and the other useful 
products, varies with different woods,* and is largely de- 
pendent upon their state of dryness or the reverse. Wood 
which has been felled about six months, gives about one- 
fifth its weight of charcoal. " A cord of such wood," says 
Mr. Randall, "yields from 120 to 130 gallons of liquor, 
consisting of pyroligneous acid, water, and tar." The yield 
is also largely influenced by the temperature at which the 
* Payen states that the larger the amount of incrusting matter, 
and the smaller that of the cellulose a wood contains, the greater 
will be its yield in acid. According to this chemist the hard woods 
give from 4 to 5 per cent, of hydrated acid, and soft woods only about 
3| per cent. ACETIC ACID. 
35 
distillation is conducted. The retorts should be gently- 
heated at the commencement to drive off the moisture con- 
tained in the wood, and the heat cautiously increased, so 
that only just as the operation is being finished, should a 
commencing red heat be reached. 
The length of time for distilling wood in metallic retorts 
varies from eight to forty-eight hours; but on an average 
twelve hours for small retorts, and twenty-four hours for 
large ones is sufficient, and includes the time for charging 
the retorts, the distillation proper, and the extraction of 
the charcoal. 
It has been conclusively shown that the largest amount 
of charcoal is obtained at a low temperature, and of acid 
also, when the distillation is performed at a low temperature 
in large ovens. On the contrary, when the distiller desires 
naphtha as his chief product, he must work with small 
retorts, and heat them very highly. 
The following tables by Stoltze show the relative amount 
and strength of products yielded by various woods :- 
One pound of Wood. 
Weight of 
Acid. 
o 
° ? 6 'o 
Weight of 
Charcoal. 
Carbonate 
Potassa ne 
tralized by 
6 
CD 
C 
c 
ozs. 
grs. 
ozs. 
White birch . . . 
Betula alba 
Red beech . . . 
Fagus Sylvatica 
7 
54 
Q-2- 
Large-leaved linden 
'J ilia plataphylla 
bi 
52 
Oak 
Quercus robur 
50 
4k 
Common ash . . 
Fraxinus excelsior 
71 
44 
31 
Horse chestnut. . 
TEsculus hippoeastanum . . . 
7t 
41 
31 
Lombardy poplar . 
Populus dilatata 
7t 
40 
31 
White poplar . . 
Populus alba 
7k 
39 
31 
Bird cherry . . . 
Prunus padus 
7 
37 
Basket willow . . 
Salix . 
7k 
35 
31 
Buckthorn . . . 
Rhamnus 
71 
34 
31 
Logwood .... 
Haematoxylon campeehianum . 
7i 
35 
2 
Alder 
Alnus 
7k 
3° 
31 
Juniper .... 
Juniperis communis .... 
71 
29 
White fir ... . 
Pinus abies 
61 
29 
3k 
Common pine . . 
Pinus sylvestris 
6f 
28 
„ 1 
Common savine . 
Juniperus sabina 
7 
27 
Red fir 
Abies pectinata 
25 
31 36 
ACETIC ACID AND VINEGAR, ETC. 
Beech 
Walnut 
Birch, cut three years . . 
Oak 
J Ash 
Apple 
Witch-elm 
Maple 
336 lbs. of Wood. 
c § g-=rc-S:g 3 
s 5.S? g 0 -0 p- 
«=? . 3 V 
g.3. . . 
■ g § • • • 
g 3. 
। 84 lbs. of Wood. 
23a 
21J 
18 
24 
20 
20 
23 
20 
20 
28 
Charcoal. 
3i'33 
28'66 
24'00 
32'00 
26'64 
26'64 
30'68 
26'64 
26'64 
37'33 
Charcoal per 
cwt. of Wood. 
84 
72 
70 
91 
9° 
70 
70 
77 
Charcoal. 
45 
451 
49 
46 
47 
46 
48 
48 
27 
39 
Acid Liquor. 
28'00 
24'00 
23'33 
30'33 
30-00 
23'33 
23'33 
25-66 
Charcoal per cwt. of 
Wood. 
1'046 
1'036 
1'029 
1-039 
i'°34 
1'030 
1'035 
1'030 
1'040 
1'038 
Specific Gravity 
cf Acid Liquor. 
: 180 
. 150 
120 
190 
190 
200 
180 
i45 
Acid Liquor. 
0^00000000 
CO 0 tn oc 4- CO 
tn. O Ol CCtn.-<I O DiUi 0 
Specific Gravity 
of Acid Liquor 
saturated with 
Lime. 
1.029 
1'018 
1'031 
1'022 
I '024 
I '017 
I'OlS 
i -oi8 
Specific Gravity of Acid 
Liquor. 
70 
83 
29 
115 
90 
75 
92 
7° 
140 
115 
Measures of Soda 
to neutralize 
Acid Liquors. 
tcH 
Grains of Bicarbonate 
of Potash neutralized 
by one ounce. 
i5 
i7? 
17 
14 
17 
18 
13 
16 
37 
14 
Incondensable 
Products. 
25 
144 
13 
24 
22 
18 
l6 
20 
Dry Acetate of Lime 
produced. 
i'86 
2'26 
o'77 
3-06 
2'40 
2'00 
2-45 
1'86 
3'73 
3-06 
Beal Acid. 
In this country pyroligneous acid and its accompanying 
products are chiefly obtained from the lesser branches of 
large trees, known as " lop," or from the timber of smaller 
ones called " coppice wood," the coppice being a plantation 
consisting of trees of various kinds, mostly alder, ash, 
hazel, maple, birch, and oak. The trees are in the best 
condition for felling when they are about sixteen or eighteen 
years old, although they are frequently cut when only of 
six years' growth. Beech is the only tree of large size used ACETIC ACID. 
37 
in England. The timber is first sawn into blocks the 
length of the retorts. These blocks are afterwards divided 
into smaller ones, by blasting with gunpowder. Thorn, 
apple, holly, and yew are also occasionally employed. 
Of the above woods yielding the purest acid, is birch; 
then follow thorn and applewoods. 
The "lop," or small branches of oak trees, and oak 
saplings afford an excellent charcoal, as well as a good yield 
of tar, naphtha, and acid, in which particular, beech is 
nearly as valuable, beside being the source of the best 
creasote. 
The Coniferce furnish the worst quality of acid, and in 
the smallest quantity, although by cautious distillation and 
complete' carbonization the quantity may be increased. 
These trees, however, afford good quantities of tar and 
naphtha. 
Sound roots are sometimes distilled with good results, 
but because of the trouble and expense of breaking them 
up, they are sometimes put into the ovens intact, and heated 
for forty-eight hours. Gunpowder is employed when neces- 
sary to divide them. Large pieces of wood are preferred 
by the wood-distiller, provided their complete carbonization 
can be effected in twenty-four hours. 
Rotten wood of all kinds, or wood affected with dry-rot, is 
very unprofitable, and should never be used. Timber derived 
from trees of slow growth, and flourishing on dry soils, 
affords, as might be expected, the best acid. Branches less 
than three inches in diameter are seldom distilled, as the 
resulting charcoal is too small, and their yield in acid is 
inferior. 
Different woods contain very varying proportions of 
water, as will be seen in the following table, compiled by 
Schubler and Hartig, whose experiments were conducted 
with freshly cut wood :- 38 
ACETIC ACID AND VINEGAR, ETC. 
Hornbeam contains. . . . 18'6 per cent, of water. 
Willow ,, .... 26'0 ,, ,, 
Sycamore ,, .... 27'0 ,, ,, 
Mountain Ash ,, .... 28'3 ,, ,, 
Ash ,, .... 287 ,, ,, 
Birch ,, .... 30'8 ,, ,, 
Oak ,, .... 347 ,, ,, 
White Fir ,, .... 37-1 ,, ,, 
HorseChestnut,, .... 38'2 ,, ,, 
Pine ,, .... 397 ,, 
Red Beech ,, .... 397 ,, ,, 
Alder „ .... 41'6 ,, ,, 
Elm ,, .... 44'5 ,, ,, 
Red Fir ,, .... 45'2 ,, ,, 
Lime ,, .... 47'1 ,, ,, 
Italian Poplar „ .... 48'2 ,, ,, 
Larch ,, .... 48'6 ,, ,, 
White Poplar ,, .... 50'6 ,, ,, 
It will be evident the larger the amount of water a wood 
contains, the greater will be the waste of fuel expended in 
distilling it, and the less concentrated the various products 
derived from it. The shoots and twigs of trees contain more 
water than the stems, and as during the season of the rising 
of the sap, the water is in excess, it is unadvisable to fell the 
tree at this particular time. It has been estimated that wood 
arranged in stacks or exposed to the air, loses in moisture 
about a third of its weight. Before the cut wood is fit for 
distillation it must be stripped of its bark, an operation 
which is termed " peeling," the removed bark being kept in 
the coppice until required for use. The bark is sold to the 
tanner, and generally realizes a sufficient sum to pay for 
cutting and peeling the wood. The cost for cutting this up 
and conveying it to the ovens, averages about ys. per ton. 
An acre of coppice yields on an average 15 tons of timber, 
and this, taking the wet and dry seasons together, gives 
about 2 tons of bark. 
The following were the quantities of crude and acid liquors ACETIC ACID. 
39 
obtained in a well-arranged English works by the distilla- 
tion of :- 
174 cords which produced 23'923 gallons of about 10 lbs. each. 
160 ,, ,, 27720 ,, ,, ,, 
252 „ „ 3O'424 „ „ „ 
318 ,, „ 40-584 „ 
330 „ ,, 55'9oo „ 
400 „ ,, 50700 ,, „ 
M. Mollerat obtained at his works at Knits from 1,000 
steres of wood, equal to 5,120 cwts., as follows :- 
Charcoal ......... 1280 cwts. 
Pyroligneous Acid 850 ,, 
Acetic Acid 54 „ 
Acetate of Lead 152 ,, 
In this country the chief seats of the acetic acid industry 
are in Yorkshire, Lancashire, and South Wales. There are 
a few works around London, and also in Somersetshire and 
Gloucestershire. Large quantities are also manufactured 
in France, Germany, Belgium, Russia, Sweden and America. 
V. From Alcohol. Alcohol Vinegar, German Ace- 
tic Acid. In a bell-glass, or an oblong glass case, perforated 
shelves are arranged, 12 inches apart, one above another, 
on which are placed a number of small flat dishes of porce- 
lain, earthenware, or wood (J). These dishes are filled with 
spirit of wine or dilute alcohol; and over each is suspended 
a watch-glass or capsule containing a portion of platinum 
black; the whole being arranged so that the platinum black 
and the surface of the alcohol are not more than ij to 2 
inches apart. Strips of porous paper are next so hung in 
the case that their bottom edges are immersed in the spirit, 
to promote evaporation; and, lastly, the apparatus, loosely 
covered, is set in a light place, preferably the sunshine, 
when convenient, at a temperature of from 700 to 900 Fahr. 
(21'1°-32-2° Cent.). In a short time the temperature of 40 
ACETIC ACID AND VINEGAR, ETC. 
the platinum rises, and the formation of acetic acid begins; 
and the condensed vapour trickles down the sides of the 
Fig. 12. 
glass and collects at the bottom of the case, whence it is 
drawn off once or twice a day into the jug (Zi). The pro- 
duct of a case of twelve cubic feet content, with 7 or 8 
oz. of platinum in powder, is capable of producing daily, 
if well managed, nearly 1-31 lb. of hydrated acetic acid 
from 1 lb. of absolute alcohol ; 25 lbs. of platinum in 
powder and 300 lbs. of alcohol, will, in a case of propor- 
tionate capacity, in like manner, furnish a daily supply of 
nearly 350 lbs. of pure acid, and of other strengths in pro- 
portion. Theoretically, the product should be 130 parts of 
hydrated acid for every 100 parts of alcohol consumed; but ACETIC ACID. 
41 
this is never quite obtained in practice, owing to a small 
portion of the alcohol mixing with the newly formed acid, 
and escaping decomposition ; and from another small portion 
of both the alcohol and of the newly formed aldehyd being 
carried off by the air that permeates the apparatus. The 
platinum-powder does not waste, and the most inferior 
spirit may generally be employed. 
In this process, the alcohol, as in other cases of acetifica- 
tion, is first converted into aldehyd ; and this, as rapidly as 
formed, absorbs oxygen and passes into hydrated acetic acid. 
The simultaneous formation of aldehyd during the oxygena- 
tion of that already formed, may be detected by its odour. 
During the mutual action of the platinum-black and the 
vapour of alcohol, the temperature increases, and continues 
to do so until all the oxygen contained in the air enclosed 
in the case is consumed, when the acetification stops. On 
opening the case for a short time, to admit a fresh supply of 
air, the operation recommences, thus showing its depend- 
ence on the oxygen of the atmosphere. For this transmu- 
tation, 100 grains of alcohol require 70 grains (equal to 
200 cubic inches) of oxygen, or about 1,000 cubic inches of 
atmospheric air. To render the process continuous and 
rapid, a fresh supply of air must, therefore, be constantly 
provided. This may be effected by either having a loosely 
covered opening at the top of the case, and several much 
smaller ones near its lower part; or, preferably, by means of 
two small glass tubes passing through the lid or cover, one 
of which (e) terminates just below the point of insertion, 
whilst the other (6) divides into branches which reach to 
within a short distance from the bottom, as shown in the 
engraving. In this way a very slow current of fresh air 
will always be kept up in the apparatus. 
In practice we find, that by loosely spreading the platinum 
black on pieces of platinum-gauze, and supporting these on 42 
ACETIC ACID AND VINEGAR, ETC. 
small tripods or bars of glass, porcelain, or wood, the 
watch-glasses and their troublesome suspension may be dis- 
pensed with, as well as the strip of porous paper, provided 
a temperature of not less than 900 Fahr. (32*2° Cent.) 
be maintained in the case or acetifier, which may easily be 
done by the application of artificial heat in the absence of 
sunshine. On the large scale, a case of wood with a glass 
roof, or even a well-seasoned cask or vat may be employed, 
in which case the temperature of the apparatus must be 
kept up either by means of steam-pipes or flues, or by the 
supply of warm air. On the small scale, a hand bell- 
glass, placed on a dish, with a single watch-glass or piece of 
platinum-gauze, and a single capsule con- 
taining alcohol, may be used, provided 
the bell-glass be supported on three very 
small wedges, to admit of a supply of 
air. A modification of this is sometimes 
employed, in which the alcohol is 
supplied, in drops, to the platinum black 
in c by means of a long, tubular funnel 
(cZ), passing through the mouth of the 
bell-glass (a), and having its lower ex- 
tremity drawn to a very fine point, as 
shown in the engraving; b is the 
dish into which the bell-glass fits, f is an orifice 
serving for the circulation of the air. To ensure success, 
the platinum-black should be either freshly prepared, or 
recently washed and very gently heated, before placing it in 
the acetifier. Spongy platinum does not answer well for 
this process. Previous to its being poured into the bell- 
glass the alcohol should be heated to about 900 Fahr. 
(32° Cent.) 
By this second method perfectly pure acetic acid of con- 
siderable strength may be produced from even impure 
Fig. 13. ACETIC ACID. 
43 
alcohol; but it is impossible in this way to obtain a con- 
centrated acid without a subsequent operation, because the 
action of platinum black on absolute alcohol, or even on 
strong alcohol, is so violent that the platinum soon begins 
to glow, and inflammation ensues. The obstacles to the adop- 
tion of this process in Britain are the high price of alcohol 
as well as the great loss occasioned by its becoming converted 
into, and volatilized as aldehyd; and the large quantity of 
platinum required to work the process on a large scale. 
VI. Miscellaneous Formulae :- 
i. An excellent acetic acid of considerable strength may 
be made by soaking freshly burnt and perfectly dry char- 
coal in common vinegar, and then subjecting it to distilla- 
tion. The water comes over first, and on increasing the 
heat, the acid follows. Vinegar-bottoms and waste vinegar 
may be used. 
2. By exposing vinegar or dilute acetic acid to the air in 
very cold weather, or to freezing mixtures, the water sepa- 
rates in the form of ice, and the strong acetic acid may be 
obtained by draining it into suitable glass vessels, observing 
to do so at a temperature sufficiently low to keep the water 
solid. This method is said to answer well in cold climates, 
but it entails a considerable loss of acid. 
3. Liebig. Acetic acid containing 20 per cent, of water 
may be deprived of a good deal of its superfluous water by 
standing over dry sulphate of soda. It may then be used 
either with or without distillation. 
4. Acetic acid of ordinary strength may be concentrated 
to any degree, by rectification once, or oftener, from dry 
acetate of potash or soda, rejecting the first and last por- 
tions. The same acetate may be used repeatedly. The 
temperature need not exceed 4000 (2040 Cent.), and must 
not rise above 5700 Fahr. (2990 Cent.). 
The acetic acid of the British Pharmacopoeia consists of 44 
ACETIC ACID AND VINEGAR, ETC. 
water mixed with 33 per cent, of hydrated acetic acid. 
It is prepared by distilling acetate of soda with sulphuric 
acid. It is a colourless sour liquid ; its sp. gr. being 1'044. 
As acetic acid acts readily upon the lead and copper of the 
vessels in which it is prepared, the dilute acid employed by 
the pharmacist and the concentrated from which it is 
obtained, should always be examined for lead and copper. 
5. Stein says very strong acetic acid may be obtained from 
vinegar by distilling 100 parts of vinegar with 30 of salt. 
6. The late Dr. Stenhouse, by fermenting different 
varieties of sea-weed in presence of lime, obtained acetate 
of lime in such quantities as to yield 1 -8 per cent, of absolute 
acetic acid for the sea-weed employed. 
8. The glacial acetic acid of the British Pharmacopoeia 
contains 84 percent, of acetic anhydride. Like the previous 
acid, it is obtained by distilling acetate of soda with sul- 
phuric acid. 
9. Vinegar obtained from brandy contains from 14 to 18 
per cent, of acetic acid. By treating the brandy vinegar 
with lime, straining and evaporating the solution and drying 
the salt, Volckel obtained it in a colourless condition. He 
distilled the dried acetate of lime so obtained, with hydro- 
chloric acid, in the proportion of 130 parts of acid to 100 of 
salt. 
The synthetic preparation of acetic acid has been accom- 
plished by Berthelot, Wanklyn, and Harnitzky. The first 
chemist obtained potassium acetate by heating acetylene 
dichloride with aqueous or alcoholic potash for some hours. 
Wanklyn procured sodium acetate by the direct union of 
carbonic anhydride and sodium methyl. Harnitzky formed 
acetic acid by causing carbonyl chloride mixed with marsh 
gas, to be passed into a heated retort. Hydrochloric acid 
was evolved and acetyl chloride formed, which, on the 
addition of water, yielded hydrochloric and acetic acids. ACETIC ACID. 
45 
The acetates yield by a comparatively inexpensive, and a 
not difficult operation, an acid sufficiently strong and pure 
for commercial purposes, without the necessity of rectifica- 
tion. In this process, shallow vessels of wood or of copper, 
formed without rivets or solder (unless it be silvei- solder) in 
those parts exposed to the action of the acid, are generally 
employed for the purpose of the distillation. A coil of 
drawn copper pipe, heated by steam having a pressure of 
30 to 40 lbs. to the inch, traverses the bottom of the 
apparatus, to impart the necessary heat. The refrigerator 
consists of well-cooled earthenware, Berlin ware, or glass 
vessels ; and the adapter pipe is also of the same materials. 
Another common form, which is even still more convenient, 
is a stout copper still, furnished with a cast-iron jacket to 
hold high-pressure steam, the usual refrigeratory being 
employed, and a stop-cock fixed to the lower part of the 
jacket for the removal of the condensed water. In a few 
instances the space between the still and jacket is filled 
with sand, oil, tallow, or fusible metal; in which case the 
apparatus is set in brickwork, and heated by a naked fire, a 
safety-tube for carrying off the gases that might be gener- 
ated when oil or tallow is employed, being attached to the 
apparatus. Stills of earthenware are also frequently em- 
ployed ; and even worms and condensers of silver, or silvered 
copper, are sometimes used, and with advantage. If a 
leaden worm is used the product is always contaminated 
with a little of that metal. When a lute is required, it is 
best made of linseed meal and water, with or without a 
little powdered plaster of Paris; but flat bands and short 
tubes of well-seasoned vulcanized india rubber are infinitely 
more convenient and efficacious. The acetate of soda and 
oil of vitriol being placed in the still, and rapidly, but 
thoroughly stirred together with a wooden spatula, the head 
is luted on, and the distillation soon afterwards commenced. 46 
ACETIC ACID AND VINEGAR, ETC. 
The heat must be very cautiously and gradually increased as 
the distillation proceeds; and when a steam-heat is not used, 
over-firing must be carefully avoided, particularly towards 
the close of the operation. A little acetic ether is added by 
some manufacturers to the product. In this way 4 lbs. of 
acid of the sp. gr. 1'050 is obtained for every 3 lbs. of 
acetate of soda employed. Should rectification be had 
recourse to, the addition of about 2 or 3 per cent, of 
bichromate of potash, peroxide of manganese, or red oxide 
of lead, will remove empyreuma, if present. The first of 
these substances is the most effective, the efficiency of the 
others being in the order in which they are printed; or 
very frequently the acid is digested with animal charcoal, 
or kept in a tub containing beechwood shavings, for eight or 
ten days. In distilling the weaker acids and vinegars, it 
is found useful to add from 25 to 30 per cent, of chloride 
of sodium, which, by raising the boiling point of the liquid, 
causes the acid to pass over more freely; but this addition 
proves disadvantageous when any sulphuric acid is present, 
in which case sulphate of soda may be employed instead. 
If this addition be not made, the whole of the acid cannot 
be obtained without distillation to dryness, and the con- 
sequent generation of empyreuma. 
On the small scale, glass retorts are usually directed to 
be used, but glass alembics or flasks are more convenient 
and safe, as already noticed. In the preparation of the 
pure acid, care should be taken that the acetate of soda does 
not contain common salt, as the carbonate of soda prepared 
by calcination, and frequently used to form the acetate, is 
generally contaminated with it, and yields up its hydro- 
chloric acid or chlorine during the process of distillation, 
thus vitiating the product. In all the methods given, the 
product becomes more concentrated in proportion to the 
dryness of the acetate and the strength of the oil of vitriol ACETIC ACID. 
47 
or hydrochloric acid employed. By using the one dry, and 
the other concentrated, glacial acid may always be obtained 
by collecting separately the last two-fifths that come over, 
and submitting this to refrigeration. 
A process for the preparation of the acetates-the source 
of acetic acid-was some years back devised by Pauer. By 
this method, the use of retorts, as well as the operation of 
distillation, and many of the steps usually followed in 
making this acid,' were got rid of. One of the processes 
by which wood charcoal is obtained, consists, as is well 
known, in surrounding with earth, rough logs or piles of 
wood, placed upon a layer of brushwood, and erected into 
a mound or stack. At the base of, as well as at different 
heights about the stack, holes are made, the first for the 
admission of air after the brushwood has been set light to, 
the second for the escape of the various products generated 
by the combustion of the wood. Into the latter orifices 
Pauer placed small tubes, which, penetrating into the stack, 
collected the evolved products and carried them off into 
casks placed outside. The casks which act as receivers are 
more or less filled either with lime, potash, soda, magnesia, 
or their carbonates. The pyroligneous acid and other 
volatile bodies which are given off by the wood, are carried 
by pipes to the bottom of the cask, when the acid ascend- 
ing through the contents, becomes fixed by them, whilst 
the other products escape at the top of the cask. 
By Pauer's process, owing to the high temperature in the 
interior of the cask, there is a considerable diminution in 
the yield of tar, whereby the after-purification of the acid 
is said to be facilitated; but the process has been found an 
unsatisfactory and uncertain one. 
Acetic acid on the large scale is made from the acetates 
of lime and soda, which are prepared as follows :- 
The crude pyroligneous acid, after separation of the 48 
ACETIC ACID AND VINEGAR, ETC. 
naphtha, is run off into tanks, where, after depositing part 
of its impurities, it is pumped into a large pan. Hydrate, 
or caustic lime, made into a stiff paste with water, is then 
added, slightly in excess, and the mixture boiled. 
It is then drawn off into another vessel, where it is kept 
at rest for ten or twelve hours, and then conveyed to the 
evaporating pan. 
Sometimes the crude acid is distilled previous to being 
neutralized with lime,* in which case the lime is added to 
the distillate, the mixture allowed to settle, and, when clear, 
run into the evaporating pan. The evaporating pans are 
sometimes constructed of wood, and lined with lead. Some- 
times the contents are heated by steam passing through a coil 
of iron pipe, and at others, in shallow sheet-iron pans over 
the naked fire. During evaporation the liquid is frequently 
stirred with a wooden spatula, and kept constantly skimmed. 
The crystals of acetate of lime which in time form upon 
the surface of the evaporating fluid, are scooped or ladled 
into baskets suspended over the pan, whereby the drainings 
are prevented from cooling. 
Acetate of soda is obtained as follows :-A solution of 
grey acetate of lime in water having a sp. gr. i-2oo 
is first prepared and filtered. To the filtered liquid, 
sulphate of soda in powder is added, in the proportion 
of four parts to one part of acetate of lime employed, 
* The resulting acetate is then called grey acetate of lime ; if, on 
the contrary, the crude and undistilled acid has been used, the pro- 
duct is called brown or blade acetate of lime. Previous to its being 
used for the production of acetate of soda, the brown acetate is 
dried in a furnace, or on heated iron plates at a temperature of 450° 
Pahr. (2320 Cent.). This chars and removes resinous and other 
impurities. Acid-makers give the preference to brown over- the grey 
acetate, for this reason :-the crude acid being saturated with lime 
before distillation, the excess of lime carries down and removes some 
of the impurities. ACETIC ACID. 
49 
and the whole thoroughly mixed by vigorous stirring. 
When the excess of sulphate of soda and the sulphate 
of lime* have subsided the solution of acetate of soda 
is drawn off and evaporated down till it acquires the 
sp. gr. of 1'300, any impurities floating on the surface 
being carefully removed. The crystals of acetate of soda 
which soon form in the liquid are removed in the same 
manner as the acetate of lime. The different mother 
liquors are successively evaporated down till they have a 
specific gravity of 1'300 (care being taken to remove the 
tarry matters), and until they cease to give crystals of 
acetate of soda.f 
The different crops of crystals are mixed and dissolved 
in water, and the solution concentrated by evaporation until 
it has the density of 1'500, and, after remaining at rest 
for ten hours, the resinous bodies are removed, and the 
acetate of soda again crystallized, the mother liquor being 
treated as above described. 
Acetate of soda may be safely dried at a temperature 
of 400° to 4500 Fahr. (2040-232° Cent.), provided care be 
taken to avoid ignition from contact with sparks. A less 
heat is, however, quite sufficient to drive off the whole of its 
water of crystallization. It is known to be dry by its 
assuming the appearance of a smooth, oily liquid whilst hot, 
and by the subsidence of frothing. 
The drying is generally conducted in an iron pot, the 
* These are washed with the water till the liquid is nearly taste- 
less, the washings being used in decomposing fresh acetate of lime. 
+ By evaporating the mother liquors to dryness, and calcining the 
residue at a red heat, carbonate of soda results. This may be ex- 
tracted by treating the ignited residue with water. If the residue 
be, in the first place, roasted at a temperature of 450° Fahr. (204° Cent.) 
acetate of soda remains, and this may be removed by treatment 
with water. 50 
ACETIC ACID AND VINEGAR, ETC. 
contents of which must be stirred during the whole time. 
If whilst being heated it emits white fumes, the acetate is 
suffering decomposition, and directly this occurs, the pot 
must be cooled by raking out the fire. The same applies to 
the other acetates. 
Crystallized acetate of soda loses about fths of its weight 
by thorough drying. 
Properties, Tests, Uses, &c., of Acetic Acid. Pure 
normal, or hydrated acetic acid is a thin colourless liquid 
above 62° Fahr. (16'4° Cent.); at 500 to 55° Fahr. (io° to 
i2'7o° Cent.) it crystallizes in large, brilliant, colourless, 
transparent needles and plates, and even at 6o° Fahr. (15'5° 
Cent.) if a crystal of acid be dropped in. In the glacial con- 
dition, litmus is not reddened by it, water being necessary 
to produce the acid reaction. The specific gravity of the 
liquid acid, according to Mollerat, is 1'063 1 and, according 
to Mohr, 1'0635 59° Pahr. (15° Cent.) ; that of the crys- 
tallized at 55° Fahr. (12-7° Cent.) being 1'135. Its odour is 
intensely pungent when concentrated; but grateful, fra- 
grant, and refreshing when diffused. It has an intensely 
sour and acrid taste, but on sufficient dilution with water it 
is agreeable and refreshing to the palate. Its vapour is 
volatile and extremely inflammable. Acetic acid dissolves 
camphor, resins, gum resins, volatile oils, gelatin, gliadin, 
various albuminous substances, and fibrin. It coagulates 
casein, but not liquid albumen, as exemplified in the serum 
of the blood and white of egg. It is miscible in all propor- 
tions with water, alcohol, and ether. According to Kopp, 
it boils at 242'6° Fahr. (117° Cent.) and is partially decom- 
posed at a red heat, the products of combustion being carbon, 
acetone, naphthalin, benzol, and some combustible gaseous 
compounds. In its concentrated state it chars organic 
bodies when poured on them, and is consequently a corrosive 
and acrid poison if taken internally, and acts as a powerful ACETIC ACID. 
51 
caustic if applied to the skin. With chlorine, acetic acid forms 
chloracetic (C3H3C1O2) and trichloracetic acid (C3HC18O3) ; 
and with bromine, bromacetic acid (C2H3BrO2) and di- 
bromacetic acid (C2H2Br2O2). 
Acetic acid may be readily recognized by its odour and 
volatility. When perchloride of iron is added to an aqueous 
solution, and the acid then nearly saturated with a solution 
of ammonia, the fluid acquires a deep, dark, red colour; 
when a solution of mercurous nitrate is added to acetic 
acid, mercurous acetate is precipitated in white scales, which 
become partially resolved into metallic mercury by heat. 
The mercurous acetate dissolves in excess of the precipitant. 
Terchloride of gold mixed with excess of potash is reduced 
to metallic gold when treated with acetic acid. 
Pure acetic acid is completely vaporized by heat, and 
should give no precipitate upon the addition of nitrate of 
silver, chloride of barium, or sulphuretted hydrogen. It is 
sometimes contaminated with sulphurous acid, which may be 
recognized by putting a fluid drachm of the suspected acid, 
mixed with an ounce of distilled water and half a drachm 
•of pure hydrochloric acid, with a few pieces of granulated 
zinc, into a flask. If, when the gas begins to be disengaged, 
a slip of white blotting-paper, moistened with a solution of 
subacetate of lead, be placed in the upper part of the flask 
above the liquid for about five minutes, and no discoloura- 
tion of the paper takes place, no sulphurous acid is present. 
Acetic acid which has been obtained from acetate of lime 
is very likely to contain sulphuric or hydrochloric acid. 
Besides which, these latter are often added by the maker, 
under the erroneous impression that they assist to preserve 
the acetic acid. 
Besides the above, another convenient qualitative test 
for sulphuric or hydrochloric acid, consists in boiling for a 
few minutes a small quantity of the previously diluted 52 
ACETIC ACID AND VINEGAR, ETC. 
acetic acid, with a little potato starch. When cold, a few 
drops of solution of iodide of potassium are added to the 
mixture, when, if either sulphuric or hydrochloric acid are 
present, no change of colour takes place ; if they be absent 
the liquid changes to a blue colour. Acetic acid is not 
affected by nitric acid. 
Acetic acid is largely employed by the varnish and paint- 
maker, the chemist, the pharmaceutist, and perfumer, and 
by the calico printer, in the form of acetates. It is also in 
great demand in the preparation of caoutchouc; and, as 
pyroligneous acid, is extensively used in the preservation of 
wood and of flesh. Concentrated and diluted, it is employed 
in medicine as an antiseptic, stimulant, alterative, refrig- 
erant, and escharotic. Aromatic vinegar is acetic acid in 
which are dissolved certain fragrant essential oils, or in 
which have been macerated, various sweet-smelling flowers 
and herbs. 
For the estimation of acetic acid see Acetimetry, page 82. 
Acetates. In general these may all be formed by direct 
solution of the carbonate, hydrate, or oxide of the metal 
whose acetate it is desired to form, in dilute acetic acid; or 
from a solution of an acetate and another salt of the metal 
by double decomposition. In either case, the resulting 
solution must be carefully evaporated by a gentle heat and, 
when possible, crystallized. All the neutral acetates, except 
those of molybdenum, tungsten, mercury, and silver, are 
more or less soluble in water, several so much so, as to be 
uncrystallizable; many dissolve in alcohol; they all suffer 
decomposition at a dull red heat; at a full red heat, those 
of potassium, sodium, barium, strontium, calcium, and mag- 
nesium are converted into carbonates, whilst the other 
metallic acetates leave behind the pure metal, or its oxide. 
The acetates are known:-By evolving, on the addition of 
concentrated sulphuric acid, fumes of acetic acid, recog- ACETIC ACID. 
53 
nizable by its odour, and giving off the vapour of acetic 
ether when heated with a mixture of about equal parts of 
concentrated sulphuric acid and alcohol. 
We append a list of the technically most important 
Acetates:- 
Acetates of Alumina. Pure hydrate of aluminium is 
digested to saturation in strong acetic acid in the cold ; and 
the resulting solution, after being filtered or decanted, 
is either evaporated by a very gentle heat to a gelatinous 
semi-solid consistence, which is its usual form, or is preserved 
in the liquid state. By spontaneous evaporation it may be 
obtained in long transparent crystals. 
Reel liquor.-i. From alum in powder, 4 parts ; warm 
water, q. s. to dissolve; acetate of lead in powder, 3 parts. 
The solution is effected by lengthened agitation in a tub or 
other wooden vessel, and the clear liquid, after repose for a 
sufficient time, is decanted or drawn off from the sediment. 
2. Alum, 2 parts, dissolved in a sufficient quantity of warm 
water; solution of pyrolignite of lime, at 200 Baume, 3 
parts. As before, but allowing a longer time for the subsi- 
dence of the precipitate, and taking more care in the decan- 
tation than when acetate of lead is employed. 
3. Acetate of lead in fine powder, 100 lbs.; to be added to 
100 lbs. of alum previously dissolved in 50 gallons of boil- 
ing water. 
4. 100 lbs. alum; 5 lbs. of soda crystals ; 50 lbs. of acetate 
of lead, and 50 gallons of water. 
10 lbs. alum ; soda crystals, 1 lb.; acetate of lead, 7^ lbs.; 
and 2^ gallons of water. 
5. (Grace Calvert). 453 lbs. of ammonia alum (or 383 
lbs. of sulphate of alumina), 1132 lbs. of water; and 379 
lbs. of acetate of lead. 
In the manufacture of red liquor, it should be remem- 
bered that acetate, or pyrolignite of lime, is less certain in 54 
ACETIC ACID AND VINEGAR, ETC. 
its action than lead acetate; besides which the resulting 
sulphate of lime is more troublesome to deal with than sul- 
phate of lead. Ammonia alum is more variable in composi- 
tion than potash alum. 
Red liquor is extensively employed by the dyer and 
calico-printer. 
Acetate of Ammonia, NH4C2H3O„. Take of acetate of 
lime or of potash, and sal ammoniac, equal parts; mix, 
and distil at a gentle heat. The liquid in the receiver 
which is binacetate of ammonium forms a radiated crys- 
talline mass on cooling. Dry gaseous ammonia passed into 
this salt, melted by a gentle heat, transforms it into the in- 
odorous neutral acetate. 
It occurs in long, slender crystals, or in a crystalline 
mass freely soluble in both alcohol and water, and deliques- 
cent in the air. Mindererus' spirit is an aqueous solution 
of this salt. 
Acetates of Copper. Acetate of Copper (neutral), 
Cu(C2H3O2)2, Syn. Normal Cupric Acetate, Acetate 
of Copper, Crystallized Verdigris, Distilled Ver- 
digris. This name is applied to the normal acetate of cop- 
per, which is prepared in the wine districts by dissolving 
ordinary verdigris, i part, in good distilled vinegar, 2 parts ; 
the operation being performed in a copper vessel by the aid 
of a gentle heat and agitation. The solution is afterwards 
slowly evaporated until a pellicle begins to form on the sur- 
face, when it is transferred into glazed earthenware pans, 
called oulas, in each of which are placed two or three cleft 
sticks, and it is then left in a warm apartment for fourteen 
or fifteen days to crystallize. 
It occurs in beautiful dark bluish-green prisms, which 
dissolve in 14 parts of cold and 5 parts of boiling water. 
It is often made by adding a solution of sulphate of cop- 
per, 12I lbs., to a solution of sugar of lead, 19 lbs., or q. s., ACETIC ACID. 
55 
and then filtering and evaporating the liquid, and crystal- 
lizing. 
Basic Acetates of Copper. Syn. Subacetates of 
Copper, Verdigris (Verte de Gris, Er.). This is a mix- 
ture of several basic acetates of copper, which have a green 
or blue colour. It is obtained in the wine districts of the 
South of Europe by the action of refuse grapes (from which 
the juice has been expressed) on thin sheets of copper. 
The verdigris of commerce should not contain more than 
4-or at the utmost-5 per cent of impurity, mostly in the 
form of insoluble substance. It is frequently sophisticated 
with chalk and sulphate of copper. It should dissolve almost 
entirely in diluted hydrochloric or sulphuric acid. 
The presence of sulphate of copper may be detected by 
treating the filtered solution of the suspected sample with 
chloride of barium. 
An inferior quality of verdigris is prepared from iiomage 
or apple marc in the cider districts of England. 
Sesquibasic Acetate of Copper is obtained by digesting 
powdered verdigris in tepid water, filtering, and leaving 
the soluble part to spontaneous evaporation. 
Tribasic Acetate of Copper is the green insoluble 
residue of the verdigris left after it has been treated with 
tepid water. It may be formed by digesting the neutral 
acetate of copper with the hydrated oxide. 
All the acetates of copper are used as pigments, and also 
in dyeing, calico-printing and in medicine. 
The distilled verdigris is often employed as a source of 
aromatic vinegar. 
Annexed is the composition of three kinds of verdigris 
compared with Berzelius' centesimal analysis of the 
tribasic acetate of copper :- 56 
ACETIC ACID AND VINEGAR, ETC. 
Bibasic 
Acetate. 
French 
Verdigris. 
English 
Crystallized 
Verdigris. 
English 
Compressed 
Verdigris. 
Anhydrous Acetic Acid 
27'45 • 
.. 29-30 . 
.. 28-30 .. 
. 29'62 
Oxide of Copper . . . 
43'24 • 
•• 43'5° • 
43'25 •• 
• 44'25 
Water 
29'21 . 
.. 25'20 . 
.. 28'45 •• 
■ 25-51 
Impurities 
OO'IO . 
.. 2'00 . 
- .. 
. 0'62 
100'00 
100'00 
100'00 
100'00 
Acetates of Iron. Ferrous Acetate, Fe(C2H3O3)2. 
i. From freshly precipitated ferrous carbonate dissolved in 
dilute acetic acid. ?. By adding a solution of calcium 
acetate to another of ferrous sulphate, and evaporating the 
filtered liquid out of contact with the air. It occurs in 
small, colourless, or pale-greenish needles or prisms, very 
soluble and prone to oxidation. 
In the arts, ferrous acetate is obtained by covering old 
iron, as free as possible from rust, with distilled pyroligneous 
acid in iron or wooden tanks, and keeping the whole at a 
heat of about 1500 Fahr. (66° Cent.) for several days, until 
the solution has a specific gravity of ropto rio at the 
temperature of 69° Fahr. (15-5° Cent.) 
Ferric Acetate.-The pure acetate may be prepared by 
dissolving recently prepared hydrate of sesquioxide of iron in 
acetic acid, or by the double decomposition of ferric sulphate 
and acetate of baryta or lead. 
Iron Liquor. Syn. Pyrolignite of Iron, Dyers' 
Acetate of Iron, Black Liquor, Tar Iron.-This 
article, which is extensively used in dyeing, is a crude mixed 
acetate of the protoxide and sesquioxide of iron. 
It is usually prepared by one or the other of the follow- 
ing methods:- 
1. Old scraps of iron, such as hoops, worn-out tin-plate, 
&c., are left in a cask of pyroligneous acid of the sp. gr. 
of 1'035, a temperature of about 66° Fahr., occasional 
agitation being had recourse to, until a sufficiently strong ACETIC ACID. 
57 
solution is obtained. By keeping the acid moderately warm 
at the above temperature, in a few days it will become 
saturated with the iron. With cold acid on a large scale, 
forty days or more are required to complete the process. 
2. A solution of pyrolignite or crude acetate of lime is 
added to another of green copperas as long as a precipitate 
is formed; after repose the clear liquor is decanted. 
Acetate of Lead, Pb (C2H3O2)„, 3H2O. Syn. Diacetate 
of Lead, Sugar of Lead.--This is the most important of 
the lead acetates, and is extensively employed in dyeing, 
and calico-printing, in the manufacture of acetate of 
alumina and chrome yellow, as well as in making sulphide 
of lead, which is in great demand by the manufacturers of 
india-rubber articles. 
Acetate of lead is also employed in medicine, and 
possesses astringent, styptic and haemostatic properties. 
It is met with in commerce under the three forms of 
white, grey and brown acetate, the white being the purest. 
It is mostly ■ prepared by dissolving litharge in acetic acid, 
and sometimes by exposing thin sheets of lead in closed 
chambers to the action of air and acetic vapours. 
i. The British pharmacopoeia gives the following 
formula for the preparation of a pure white acetate :- 
Litharge in fine powder, 24 parts ; distilled water, 20 parts ; 
acetic acid, 40 parts. Mix the acetic acid and the water, 
add the litharge, and dissolve by the acid of a gentle 
heat, filter, evaporate until a pellicle forms, and crystallize. 
Drain and dry the crystals. 
2. Another method employed by manufacturers, is as 
follows:-230 parts of acetic acid of sp. gr. 1'0843 are 
gently heated in a copper boiler rendered electro-negative 
by means of a large flat piece of lead soldered within it, 
and 130 parts of pure litharge in fine powder is sprinkled 
in; the heat is then continued with constant stirring, 58 
ACETIC ACID AND VINEGAR, ETC. 
until the acid is saturated, when the mother waters of 
a former process, if any, are added, and the whole is 
heated to the boiling point, and allowed to settle until cold. 
The clear portion is now decanted, and evaporated in a 
similar vessel until the liquor has the sp. gr. 1*266 or 
1*267, when it is run into salt-glazed stoneware vessels 
(the edges of which have been well smeared with candle 
grease) and allowed to crystallize. The product is 360 to 
380 parts of crystallized sugar of lead. It is found ad- 
vantageous to preserve a very slight excess of acid during 
the boiling and crystallization, to prevent the formation of 
any basic acetate, the presence of which impedes the for- 
mation of regular crystals. 
Sometimes, instead of using the mother waters of a 
former process, water in proportion to about half the 
acid taken, is added to the lead solution, whereby the 
impurities are brought to the surface, and skimmed off. 
The mixture is then carefully and slowly evaporated until 
it acquires a density of about 1*500, the proper degree of 
condensation being reached when a sample of the liquid 
placed in a small shallow vessel affords a compact mass of 
crystals upon cooling. When this occurs, the liquid is 
siphoned into the crystallizing pans, and when the crystals 
which form are sufficiently solid, they are removed in a mass 
to the drying house, and drained, by being placed on a sloping- 
bench, the drainings being collected in a cistern, and used in 
subsequent operations. 
"When dry, the crystals are carefully scraped, broken up, 
and put into casks, when they are ready for sale. 
Crystallizing vessels of copper are often used as well as 
stoneware ones, over which they possess the advantage of 
not being breakable. 
The temperature of the drying room should be about 900 
Fahr. (320 Cent.), and the fire-place or stove for heating it ACETIC ACID. 
59 
should be outside the room, since dry wood, matting, and 
other materials used in the drying, are readily combustible 
when they become impregnated with acetate of lead. 
3. When prepared by the action of the vapour of acetic 
acid and atmospheric air upon metallic lead, a mixture of 
carbonate and acetate forms upon the surface. This coating, 
when sufficiently thick, is scraped off and dissolved in a 
slight excess of acetic acid. The solution is then evaporated 
down till of the sp. gr. of 2'30. If small, needle-shaped 
crystals are required, the solution is rapidly cooled. 
When the evaporation is slowly conducted, truncated 
flattened prisms are obtained. 
The above is a more expensive method than the previous 
one, and in consequence, is but seldom had recourse to. 
The crystals of pure acetate of lead are slightly efflores- 
cent in dry air; they are soluble in 8 parts of alcohol and 
in about parts of cold water. The aqueous solution has 
a sweet astringent taste, and feebly reddens litmus, but 
turns the juice of violets green; when gently heated 
it melts in its water of crystallization; by continuing the 
heat the whole of the water is expelled, and the anhydrous 
acetate obtained. At a higher temperature the salt suffers 
decomposition, and acetic acid, carbonic acid, and acetone 
are given off. Commercial acetate of lead is in general a 
confused crystalline mass, somewhat resembling broken lump 
sugar. It is powerfully poisonous. 
Grey acetate of lead is obtained from the dirty mother- 
liquors which are left after the preparation of the white. 
Blocks of crystals which have become soiled are also used in 
its manufacture. It is very impure, and nearly or wholly 
destitute of crystalline form. 
In making brown-acetate, or sugar of lead, distilled pyro- 
ligneous acid placed in a large tub is first saturated with 
litharge. From the tub, the thick mixture, after being well 60 
ACETIC ACID AND VINEGAR, ETC. 
stirred, is ladled into a large cask and allowed to settle, after 
which the clear liquid is siphoned or run off into a pan of 
wrought or cast iron, 6 feet by 4 and having a depth of about 
12 inches, heated at the bottom, and in which, after being 
brought to the boiling point, it is left to settle. The fluid is 
next conveyed into a hemispherical pan of about 500 gallons 
capacity, where it is evaporated down until it about reaches 
the point of crystallization. About three times its bulk of 
water is then added to it, with constant stirring, the solution 
meantime being kept boiling, whilst the impurities which rise 
to the surface are removed by skimming. If the solution is 
too highly coloured, this must be remedied by the addition of 
more water. The requisite quantity of water having been 
added, the solution is again evaporated until it is of such a 
strength that it will crystallize. It is then transferred into 
wrought iron crystallizing pans of about 4 feet long by 3 
wide and 6 inches deep. After the crystals are " set," they 
are removed from the pans by inverting the latter, drained, 
dried, and broken up for sale. 
A more satisfactory product than the above, is said to be 
obtained, if the liquid before dilution and evaporation, is first 
brought to the point of ebullition, and then allowed to settle. 
The following analyses represent good commercial samples 
of neutral acetate or sugar of lead :*- 
White. 
Brown. 
Acetic Acid 
27'6 . 
.. 21'8 
Oxide of Lead 
58-4 • 
59'9 
Water 
14'0 . 
•• 15'5 
Carbonate of Lead and Insoluble Matter . 
- 
.. 2'8 
100'0 
100'0 
Basic Acetates of Lead.-There are several of these 
salts. They are mostly procured by dissolving powdered 
* Spoil's " Cyclopaedia of the Industrial Arts." E. & F. N. Spon, 
Charing Cross. ACETIC ACID. 
61 
litharge in hot solutions of the neutral acetate. Some of these 
basic acetates contain as much as six times the normal quan- 
tity of oxide of lead. They are employed in dyeing and 
calico-printing. 
Tribasic Acetate of Lead, Pb (C2H3O2)22PbO,H3O. 
Syn. Triplumbic Diacetate, Subacetate of Lead, Goul- 
ard's Extract of Lead.-Made by digesting 7 parts of 
litharge in fine powder, and 6 parts of neutral acetate of lead 
in 30 parts of water, at a moderate temperature. This is the 
salt employed in the manufacture of carbonate of lead, or 
white lead, by the Clichy method, which consists in passing 
carbonic acid into a solution of tribasic acetate of lead, which 
thereby becomes converted into carbonate and neutral ace- 
tate. Tribasic lead acetate occurs in large needles. It has 
a strongly alkaline reaction, is very soluble in water, and 
insoluble in alcohol. 
Goulard wrater is an aqueous solution of hexabasic acetate 
of lead. 
Acetate of Manganese, Mn(C2H„O2)2. 1. May be pre- 
pared by neutralizing concentrated acetic acid with man- 
ganous carbonate, and evaporating the solution, so that crys- 
tals may form. The crystals when pure are of a pale red 
colour, permanent in the air; soluble in alcohol, and in 
3^ parts of water. 
2. The best commercial acetate, employed in dyeing and 
calico-printing, is made by mixing in their equivalent pro- 
portions manganous sulphate and crystallized lead acetate, 
both previously dissolved in water. 
Acetate of Tin. Obtained by dissolving metallic tin in 
acetic acid. It is a very unstable compound. The commer- 
cial acetate, used in dyeing and calico-printing, may be pre- 
pared by mixing 103 parts of chloride of tin with 190 of 
brown lead acetate, well stirring the mixture, allowing it to 
settle, and drawing off the supernatant acetate of tin. 62 
ACETIC ACID AND VINEGAR, ETC. 
Acetate of Zinc. The following is the formula of the 
British pharmacopoeia for the preparation of this salt - 
Add 2 oz. carbonate of zinc in successive portions to 3 fluid 
ounces of acetic acid, previously mixed with 6 fluid ounces of 
distilled water, in a;flask; heat gently j add by degrees 2 fluid 
ounces more of acid, or q. s., till the carbonate is dissolved; 
boil for a few minutes, filter whilst hot, and set it aside for 
two days to crystallize. Place the crystals in a funnel to 
drain, then spread them on filtering paper on a porous tile, 
and dry them by exposure to the air at an ordinary tem- 
perature. 
The acid used by the calico-printer is made by dissolving 
4 parts of sulphate of zinc and 7 J parts of acetate of lead, 
each in 3 parts of hot water, mixing the solutions, allow- 
ing the sulphate of lead to precipitate, and decanting or 
siphoning off the clear acetate. 
Anhydrous Acetic Acid. Syn. Acetic Anhydride. 
Acetic acid deprived of the elements of water, thus 
2 C2H4O-H2O = C4HcO3 
It may be prepared by distilling 3 parts of phosphoryl 
chloride with 6| parts of anhydrous acetate of soda, pouring 
back the distillate upon the residue, and redistilling until 
the odour of the chloride has disappeared, and, lastly, recti- 
fying the liquid. Acetic anhydride is a colourless mobile 
liquid, of high refracting power, and possessing a very pun- 
gent smell, like that of a mixture of acetic acid and hawthorn 
blossom. VINEGAR. 
Vinegar is dilute acetic acid, more or less contaminated 
with gum, sugar, and vegetable matter. 
i. English vinegar was formerly almost wholly obtained 
from malt and unmalted grain; but of late years, besides 
these, artificial glucoses, cane sugar, and molasses have been 
largely used in its manufacture. The explanation of the 
fact that a mixture of malted and unmalted grain gives rise 
to a vinegar superior in keeping properties, and therefore of 
better quality than that made from unmalted alone, is as 
follows:- 
In malted grain, the diastase which converts the starch 
into sugar, is in considerable excess of the quantity required 
for that purpose, and is left to set up putrefactive changes 
in the resulting vinegar. By the addition, however, to the 
malted, of unmalted grain in quantities which must have 
been previously determined by calculation, the superfluous, 
and as such detrimental, diastase is removed, since it is ex- 
pended in converting the starch of the unmalted variety into 
sugar. The umnalted grain usually employed, is either 
barley, oats, maize, or rice. 
In the manufacture of malt, or grain vinegar, the malt, 
or grain, or both, as the case may be, previously thoroughly 
kiln-dried, is first crushed (grinding being particularly 
avoided) by being made to pass between cast-iron rollers. 
From the crushing apparatus it is carried by machinery to 
hoppers, whence it is transferred to the mash tun, and mixed 
with water * at a temperature of about 1700 Fahr. (76'6° 
Cent.). 
* In. the manufacture of vinegar the purest water should be used ; 
hence it is essential the water should be free from organic matter of 64 
ACETIC ACID AND VINEGAR, ETC. 
In this vessel the mixture of malted and unmalted grain 
and water is kept in a state of agitation by means of revolv- 
ing forks, which are carried around the tun whilst they are 
revolving. After being sufficiently stirred, the wort, as the 
liquid is now called, is left to settle, after which it is pumped 
into boilers, where it is kept in brisk ebullition for some 
time. The grain remaining in the mash tun is then sub- 
jected to a second treatment with water, at the same tem- 
perature as that employed for the first maceration, to exhaust 
it of its saccharine constituent, the water in this case being 
supplied to it, and regulated by means of a revolving pipe 
fixed in the mash tun, and called a sparge. 
When the boiling is finished, the wort cooled by being 
passed through a refrigerator, is carried to the fermenting 
tuns. Here large quantities of yeast at frequent intervals 
are added to it, and the fermentation which ensues, under 
proper conditions as to temperature, &c.,* is continued until 
the glucose is converted into alcohol and carbonic acid. 
From the fermenting tuns the liquid is pumped into the 
every kind, since this latter is a fruitful source of putrescence. 
Muddy water, even if the mud be free from organic impurity, should 
always be discarded. This may, however, become clear by being left 
to settle. 
The presence in the water of the carbonates of lime, magnesia, 
and iron, acts also prejudicially. 
Dussauce recommends those vinegar-makers who are compelled to 
use water which contains any of the above impurities, to first boil 
it, to drive off the carbonic acid, when the lime and magnesia salts 
will fall to the bottom; and then to filter it through alternate layers 
of gravel and charcoal, whereby suspended matters and organic com- 
pounds will be separated. 
A temperature of 68° to 86° Cent, is the best suited for the conver- 
sion of the alcohol into acetic acid. 
* Pasteur has shown that fermentation is always brisker in the 
presence of light. VINEGAR. 
65 
fining vats, where it remains for some days, at the end of 
which time it has become clear, owing to the deposition of 
the exhausted yeast and other matters. 
Fig. 14. 
a, Coil of block-tin piping for passage of steam for heating ; J, intake of 
pump to feed sparges ; c, pump; d, surface of the liquid in course of manu- 
facture, above which is a space for dripping; f, escape-pipe at bottom of 
steam coil; g, sparges for distributing finely divided wash over the birch bed; 
h, support for pump. 
From the fining vats' it passes to the acetifiers (which 
are immense vessels having a capacity of from 8,000 to 10,000 
gallons) where its alcohol is converted by oxidation into 
vinegar. The acetifier is heated by means of steam passed 
through a coil of metal tubing which runs at the bottom. 
The wash or alcoholic liquor from the fining vats is pumped 66 
ACETIC ACID AND VINEGAR, ETC. 
to the top of the acetifier into a horizontal pipe perforated 
with very small holes, from which it falls in a finely divided 
state upon a layer of bundles of birch wood about 4 feet 
deep, after percolating which it falls in a small shower of 
spray into the lower part of the acetifier. 
It will be seen that by the above arrangement the 
alcoholic liquid, in consequence of its state of minute 
subdivision, is made to expose as large a surface as pos- 
sible to the action of the atmospheric oxygen; in short, 
this is an essential condition for the successful issue of the 
process. 
By means of a screw tap which regulates the admission of 
steam into the metal coil, or worm, the wash may be kept at 
the desired temperature. At the commencement of the pro- 
cess a suitable temperature is about no° Fahr. (430 Cent.), 
which is gradually lowered with the progress of the aceti- 
fication to roo° Fahr. (38° Cent.). 
As to the birch, it must be entirely freed from juice, colour 
and smell. These are best got rid of by boiling. Wood 
with the sap in it, ought not to be used. 
At the end of about two months, the vinegar is removed 
from the acetifiers into other vessels, called " refining " or, 
" rape " vessels, containing prepared wood shavings, or, 
preferably, when they can be obtained, the stalks and 
skins of raisins, occurring as refuse in the manufacture of 
British wines. The vinegar being subjected to several 
filtrations through one or the other of these substances, 
becomes what is termed " cleansed," and assumes a bright 
appearance; and, after being coloured * and flavoured, is fit 
for sale. 
* The colouring may be effected either by admixture of a light 
with a dark vinegar, or by the addition of a small quantity of caramel. 
In America, burnt onion, chicory, and coffee are used. The desired VINEGAR. 
67 
In vinegar-making it should be borne in mind that the 
greater the proportion of alcohol in the wash the stronger 
of course, will be the vinegar; the larger the amount of 
ferment the quicker the acetification, and the greater the 
surface of contact with the air the more rapid the 
operation. 
The vinegar-makei must use discretion and judgment, how- 
ever, in availing himself of the knowledge conveyed by these 
facts, and should remember-that the process of acetifi- 
cation is retarded by the presence of too much alcohol, and 
that a loss of the latter from evaporation and conversion 
into aldehyd is incurred; also that too much ferment im- 
pairs the flavour and keeping qualitiesf of the vinegar, and 
gives i'ise to the production of those organisms known as 
vinegar eels ; and, lastly, that when there is an excess of air, 
particularly combined with too elevated a temperature, not 
only will there be a loss of alcohol from evaporation, but that 
the ethers, to which vinegar owes its pleasant smell and 
flavour, will escape also. 
In some works the acetification is carried out in a 
series of casks or barrels. The malt wort, after treatment 
with yeast for 36 hours, is run into casks or barrels placed 
on their sides in a chamber the temperature of which 
ranges from 700 to 770 F. (210 to 240 C.). In 
addition to the bung-hole, each cask has a hole bored in 
the front and another at the end, near its upper edge. 
By this arrangement, when the orifices * are kept open, a 
colouration may be gained by using brown malt in the manufacture of 
the vinegar. Highly coloured vinegars in France and Spain are de- 
colourized by mixing with them 4 or 5 per cent, of hot milk. The 
casein coagulates and carries down the greater part of the colouring 
matter. 
+ A small quantity of alcohol, added to a vinegar that does not 
keep well, will often be found to preserve it. 68 
ACETIC ACID AND VINEGAR, ETC. 
constant current of air circulates over the top of the 
liquid, and effects its acetification. This is known as the 
stoving process. 
Another method of vinegar-making, occupying a much 
longer time than the above, and known as fielding, 
instead of being carried on within doors, is effected in the 
open air. Both plans are, however, often adopted in the 
same works. In the fielding process the casks, resting 
upon massive supports, which are arranged in parallel 
rows, with a narrow pathway between every two rows, 
are filled by means of a large hose which conveys the 
wash from the brew-house. 
The bung-holes are kept open in fine weather, but- are 
lightly covered with a slate or tile when it rains. The 
casks are only two-thirds filled, the better to ensure their 
acetification, and when this is judged to be satisfactorily 
accomplished, their contents are siphoned off into a sluice 
which conveys them into the storeroom. Here the 
vinegar is refined and cleared by being filtered through a 
layer of grape stalks and skins, or raisins, or, failing these 
not being obtainable, of wood shavings, spent tan or straw, as 
before stated. This operation is performed in large casks 
with false bottoms called 11 rapes." 
Vinegar by the fielding process cannot be manufactured 
in less than three months. Both the above varieties of 
malt vinegar are used for pickling purposes. 
The following proportions of ingredients may be taken for 
making malt vinegars :- 
Malt and barley, both crushed, of each 15 quarters, 
mashed three times, 183 barrels or 6,588 gallons of water, at 
the usual temperature, being used in the three mashings. 
For the total wort from the three mashings, 50 gallons of 
thick barm are required. VINEGAR. 
69 
The above 30 quarters of grist should produce 150 barrels. 
Sour ale or beer does not yield good vinegar, but a pro- 
duct very liable to undergo putrid fermentation, a very 
disagreeable smell being imparted to the vinegar in conse- 
quence. Besides, such vinegar very often loses its acidity 
when kept. 
The general properties of malt vinegar are well known. 
Its pleasant and refreshing odour is chiefly derived from 
acetic acid and acetic ether. 
Its strength is distinguished by makers as Nos. 18, 20, 
22, and 24, from the fact that 1 fluid ounce of each variety 
requires as many grains of dry carbonate of soda to 
neutralize it. The last, which is called " proof vinegar," is 
the strongest, and usually contains about 5 per cent, of 
hydrated acetic acid. Its density varies according to the 
quantity of foreign matter which it contains, but averages 
about 1'0085. Until of late years, the vinegar maker was 
allowed to add Twcr^h of its weight of sulphuric acid, 
under the erroneous impression that it acted as a preservative. 
Such addition now constitutes a legal offence under the 
" Food and Drug Adulteration Act." 
It may be well to mention that-with the exception of 
those made of silver, perfectly clean copper and enamelled 
iron-metallic vessels are very unsuitable for keeping 
vinegar in. 
Leaden vessels are readily attacked and acted on by it. 
Common pottery, which is almost always glazed with oxide 
of lead, should, for the same reason, never be used. Salt 
glazed stoneware is, however, perfectly safe. 
(1) Paper written on or smeared with pure vinegar is 
not charred when strongly warmed before the fire; if it 
is, the sample examined contains fully 2 per cent, of oil of 
vitriol. 70 
ACETIC ACID AND VINEGAR, ETC. 
(2) If a solution consisting of 1 part sugar in 30 times its 
weight of water, in a small capsule or china cup, be heated 
to a temperature of about 2000 Fahr., it should not be 
materially discoloured when a drop of pure vinegar is 
poured on to it; but a spot of an intensely brown or black 
colour is formed if the sample contains only Par^ 
of sulphuric acid; if it contains only -f^-^th part, the 
spot is olive green; and if a less quantity, then only of a 
pale green colour. 
(3) The heavy white precipitate given with chloride of 
barium shows the presence of sulphuric acid; each grain, 
after being dried, and gently ignited, represents '344 grs. of 
dry sulphuric acid.* 
(4) If a solution of nitrate of silver gives a cloudy white 
* Allowance should, always he made for the presence in vinegar of 
soluble neutral sulphates, derived, in the first place, from the malt 
used for the preparation of the wash, or, when the vinegar is pre- 
pared from wine, from the grapes. These sulphates may be deter- 
mined as follows 8 or io ozs. of the vinegar, in a platinum or 
porcelain basin, is evaporated over a water-bath to i oz., and then, 
when the liquid becomes cool, 5 or 6 ozs. of strong alcohol are 
added to it. This precipitates the natural neutral sulphates, 
which are removed by filtration. The filtrate, with the washings of 
the precipitate (it must be washed with dilute alcohol), is then 
placed over a water-bath until the greater part of the alcohol 
is driven off, what remains being diluted with 10 or 12 times its 
bulk of distilled water, and the free sulphuric acid in it, determined 
by means of a standard solution of chloride of barium. For 
determining free acetic acid in presence of free sulphuric acid Hilger 
carefully neutralizes 20 c.c. of the vinegar with standard potash 
(1 c.c. = o-o6o acetic acid). The number of potash c.c. used, is at 
present only noticed, as a direct calculation of free acetic acid cannot 
possibly be made. The sulphuric acid is next determined as sulphate 
of barium, and the acid formed, calculated on the potash. The 
quantity of potash belonging to sulphuric acid is now deducted 
from the original quantity used for neutralization, and the remainder 
calculated as belonging to free acetic acid. VINEGAR. 
71 
precipitate, hydrochloric acid is present. Previous to apply- 
ing this test, the vinegar must be distilled in a glass retort, 
and the nitrate of silver solution added to the distillate. 
(5) If, after the addition of 2 or 3 grs. of carbonate of 
potash, and evaporation of the sample to dryness, the 
residuum deflagrates when ignited, the sample under 
examination contains nitric acid. Or, if a portion of the 
vinegar be evaporated, and the residue boiled with hydro- 
chloric acid and copper turnings, the characteristic red 
fumes of nitrous acid will be generated if nitric acid be 
present in the vinegar. 
(6) If the vinegar be blackened by sulphuretted hydrogen 
or hydrosulphide of ammonium, it contains either lead or 
copper; if the precipitate be yellow, tin is present. If it 
gives a yellow precipitate with iodide of potassium or chro- 
mate of potash, the metal is lead. If ferrocyanide of 
potassium gives a bronze-brown coloured precipitate, or a 
little olive oil, when agitated with some of the vinegar, be 
turned green, the metal is copper. Zinc is present if, on 
the addition of ammonia, a white precipitate is formed. 
(7) If a small sample, gently evaporated to dryness, leaves 
more than 1 per cent, of residuum, and this has a sweet 
taste, it is undecomposed sugar. The presence of acrid 
substances, as capsicum, chillies, grains of paradise, mustard 
seed, pellitory of Spain, pepper, &c., may be detected by 
neutralizing the acidity of the vinegar with carbonate of 
soda, when the acrid taste of the adulterant will be readily 
perceived. 
2. Wine Vinegar. Syn. French Vinegar, Orleans 
Vinegar.-This is prepared in wine countries from sour 
wine, that which is full flavoured and clear, producing 
the best vinegar. Sometimes the wines are worked up with 
wine lees. In Orleansj the principal seat of the manufacture 72 
ACETIC ACID AND VINEGAR, ETC. 
of this variety of vinegar, the factories have a southern 
aspect, and the apartments in which acetification is carried 
on, are found to favour the process best, if they are low- 
roofed. It is also very important they should be amply 
supplied with atmospheric air; and so constructed as to 
allow of unimpeded ventilation, an essential condition in all 
varieties of vinegar-making. The casks in which the process 
is conducted are called mothers, and vary in capacity from 
50 to 100 gallons, as little iron as possible being used in their 
construction. Every new cask is first one-third filled with 
strong boiling vinegar, to which the wine is added in 
instalments of 2^ gallons every eight days, by which time 
each charge of wine becomes acetified. This addition of 
wine is continued until each cask becomes more than half 
filled, when one-third of its contents is siphoned off into the 
store tuns, when the mothers are again recharged every 
eight days as before. It occasionally happens that in some 
of the mothers the charge does not become acetified in eight 
days. When this occurs, such mothers must be emptied, 
then filled to one-third of their capacity with hot strong 
vinegar, and then the charges of wine added as usual. 
The acetification is known to be completed, when a white 
thick foam is found adhering to a white rod bent at one 
end, which has been plunged into the mothers and with- 
drawn horizontally. Should the foam be of a reddish brown 
colour, more wine must be run into the mother, and the 
temperature raised, until the froth becomes white. 
The temperature that is found to answer best is one 
between 750 and 8o° Fahr. (240 and 26'6° Cent.).* When 
* Dussauce says that to cause the establishment of the acetic 
fermentation the wine must be exposed to a temperature between 
500 and 86° Fahr. (10° and 30° Cent.), and that the most favourable tem- 
perature is that between 68° and 86° (20° and 300 Cent.). Demachy VINEGAR. 
73 
weak wines are employed in the Orleans process, it often 
happens that the vinegar is ropy and wanting in trans- 
parency. When this is the case, it must undergo the 
fining process. 
Vinegar prepared from white wine by the above process 
is the most esteemed, being purer and of a more pleasant 
flavour than malt vinegar. It usually contains from 5 to 6 
per cent, of acetic acid. According to Soubeiran, ioo 
parts of good Orleans vinegar should require 10 parts of 
dry carbonate of potash for saturation. 
In some parts of France, Germany, and Holland, 
Boerhaave's process of vinegar-making is still largely 
practised. 
Two large casks or vats are raised on supports about ten 
or twelve inches high. These casks are open at the top, 
and are each fitted with a false perforated bottom, about a 
foot from the floor of the vat. Vine cuttings, willow twigs 
and the footstalks and skins of grapes are placed upon the 
perforated bottoms and pressed closely down. One of the 
casks is then filled, and the other half filled with wine. 
The contents of each vessel are then allowed to remain at a 
temperature of 75° Fahr. (23'90° Cent.) for twenty-four 
hours, at the end of which time the half-filled cask is filled 
up from the full one, and in this manner each cask is alter- 
nately filled and half-emptied every twenty-four hours. 
The process of acetification progresses most rapidly in the 
half-filled cask, and in this a decided elevation of temperature 
occurs after the first three or four days; but this rise of 
temperature is not allowed to exceed 80° Fahr. (26*7° Cent.). 
affirms that the alcoholic liquid, must reach a temperature of 
77° to 8i° Fahr. (25° to 27° Cent.), and that it must not exceed 88° Fahr. 
(31° Cent.). Opposed to Demachy's statement is the fact, that in 
the South of France vinegar is made in cellars the temperature of 
which is constantly at 50° Fahr. 74 
ACETIC ACID AND VINEGAR, ETC. 
The process requires from two to three weeks for com- 
pletion, according to the atmospheric temperature. The 
vinegar is, lastly, drawn into casks, when, after settling and 
becoming clear, it is ready for use. 
3. German or quick method of making vinegar; process 
of Ham. This method is based upon the fact that acetifi- 
cation is the mere oxidation of alcohol in contact with 
organic matter. Hence, by employing dilute alcohol, or 
liquors containing it, and by vastly enlarging the surface of 
the liquid exposed to the air at a proper temperature, and 
Fig. 15. 
replacing the air as rapidly as possible, we may reduce the 
period occupied in acetification, from weeks to as many 
hours. In practice this is effected by causing the dilute 
spirit, previously mixed with y^L-^th part of sugar or 
malt extract, or the fermented and clarified malt-wort, to VINEGAR. 
75 
slowly trickle clown through a mass of beech shavings,* 
through which strong and very pure vinegar has been pre- 
viously run, and contained in a vessel called a vinegar- 
generator, or graduation vessel, and known in Germany as 
essigbilder. The generator is an oaken tub, narrower at 
the bottom than at the top, furnished with a loose 
lid or cover, below which is a perforated shelf, a sort 
* Instead of beech shavings some makers employ charcoal, because 
of its superior power of rapidly oxidizing the alcohol and converting 
it into acetic acid. The charcoal must be previously freed from 
saline substances by soaking in hydrochloric acid, the acid being 
afterwards carefully washed out. 
Another formula, given in Tomlinson's " Cyclopaedia," for the 
vinegar mixture, and mode of conducting the operation, is as 
follows :-" The vinegar mixture consists of 20 quarts of alcohol, 
40 of vinegar, and 120 water ; or 154 quarts of alcohol, 20 vinegar, 
and 137 of water. The water is first heated to 100° or 1040 Fahr. 
(37'7°-400 Cent.), and then the vinegar and alcohol are added so 
that the temperature of the mixture may be about 86° or 900 Fahr. 
(30°-32'3° Cent.) before it is poured into the generator. 
" From 24 to 5 quarts of the mixture, according to the size of the 
generator, are poured upon the shavings every half hour. The cover is 
then put on, but the hole in the centre is left open. When all the 
mixture is filtered through, it is drawn off into the mixing vessel, 
and a few quarts of alcohol are added. It is passed a second time 
through the shavings, then drawn off and a second quantity of 
alcohol added; it is then sent through the shavings a third time. 
The supply of air to the casks should be abundant. With a vinegar 
room at 770 Fahr. (25° Cent.), and the mixture at 82° (27'1° Cent.), 
the interior of the casks will often be 98° or 100° Fahr. (36'6° to 37'7° 
Cent.); the internal temperature of the casks should not be less than 
95° (35° Cent.). In general it may be remarked that the higher the 
temperature, and the larger the quantity of air conveyed in the 
shortest time to the mixture, the more rapidly is the hydrogen of 
the alcohol oxidized and vinegar formed. The more alcohol there 
is in the mixture, the stronger will be the vinegar, but the quantity 
of alcohol in the mixture ought not to exceed 10 per cent. ; the 
temperature must not be below 72° (22'2° Cent.), nor above 113° 
Fahr. (450 Cent.)." 76 
ACETIC ACID AND VINEGAR, ETC. 
of colander, or false bottom having a number of small 
holes, which are loosely filled with packthread about six 
inches long, and prevented from falling through by a knot 
at the upper end. The shelf is also perforated with four 
open glass tubes, as air vents, each having its ends projecting 
above and below the shelf. This arrangement is repeated 
a second and a third time, or even oftener, according to the 
size of the vessel. The tube or graduator at its lower part 
is pierced with a horizontal row of eight equidistant round 
holes, to admit atmospheric air. One inch above the bottom 
is a syphon-formed discharge pipe, whose upper curvature 
stands one inch below the level of the air-holes in the side 
of the tub. The floors or partitions of the tub or generator 
being covered with birch twigs or beech chips to the depth 
of a few inches, the alcoholic liquor (first heated to between 
750 and 83° Fahr. (23'9° and 28'3° Cent.), is introduced at 
the upper part of the apparatus. The fluid immediately 
commences trickling slowly down through the holes by 
means of the packthreads, diffuses itself over the chips or 
twigs forming the respective strata, slowly collects at the 
bottom of the tub, and then runs off by the syphon-pipe. 
The air enters by the circumferential holes, circulates freely 
through the tub, and escapes by the glass tubes. As the 
acetification proceeds, the temperature of the liquid rises to 
ioo° oi- 1050 Fahr. (37-7° or 40-8° Cent.), and remains 
stationary at that point while the action goes on favourably. 
The alcoholic solution or wort requires to be passed three 
or four times through the cask before acetification is com- 
plete, which is, in general, effected in from twenty-four to 
thirty-six hours. The larger the graduator the more quickly 
will the process be completed. 
For the production of a superior vinegar by this process, 
it is necessary that the spirit employed be sufficiently pure, so 
as not to contaminate the product with its flavour or odour, VINEGAR. 
77 
and that the malt-wort should be fermented * and treated 
with all the care usually employed in the production of beer. 
The best English manufacturers who have adopted this pro- 
cess are in the habit of filtering or clarifying their fermented 
wash, and also of storing it away for several months before 
they subject it to acetification in the graduator. The most 
favorable temperature for the process is about 900 Fahr. 
(32'2° Cent.), and this should be preserved as much as 
possible by artificial means. A malt-wort of the sp. gr. 
1'072, or, in "technical language, weighing about 26 lbs. 
per barrel, afforded a vinegar containing 5'4 per cent, of 
pure acetic acid and a residuary extract of 10 lbs., for 36 
gallons. The former of these would indicate 35 lbs. of 
sugar, or 13'7 lbs. per barrel of gravity; whilst the latter 
shows 3'8 lbs. per barrel; the two united being only 
17'5 lbs., instead of 26, the original weight. The loss, 
therefore, has been 8'5 lbs., or from a sp. gr. of 1'072 to less 
than 1'050." Thus, about one-third of all the extractive 
matter of the malt is lost or dissipated during the processes 
of fermentation and acetification. According to Knapp, a 
mixture of about 80 gallons of water, 9 gallons of spirit of 
from 44 to 45 per cent. Tralles (18 or 20 u. p.), and 3 
gallons of vinegar containing 3-5 per cent, of real acid, 
forming together 92 gallons, yield, on an average, an almost 
equal quantity of vinegar, or about from 90 to 91 gallons of 
* Iii localities where yeast cannot be procured, wheaten flour and 
water, made into a thick paste will be found a very efficient substitute. 
The mixture should be lightly covered, and left in a warm situation 
to undergo spontaneous decomposition. At the end of six or seven 
days a vinous smell will be developed; and if some of the decom- 
posed flour, or leaven, previously mixed with a little tepid water, be 
now added to the wort, the temperature of which should range from 
90° to ioo° Fahr. (32° to 38° Cent.) alcoholic fermentation will be set 
up in a few hours. 78 
ACETIC ACID AND VINEGAR, ETC. 
the above-stated strength. When obtainable, good spring 
water should be used in this process, and, failing this, well 
filtered river-water. 
In the above process the great loss alluded to, arises from 
volatilization of the alcohol and aldehyd. Great care must 
therefore be taken to duly regulate the temperature, as well 
as the supply of air during acetification. When this loss, 
which is always considerable on the quick process, is owing 
to too high a temperature, it may be diminished by passing 
the heated air, as it escapes from the acetifier, through a 
porcelain or silvered copper worm or refrigerator, set in a 
chamber containing water of a temperature not higher than 
400 to 450 Fahr. (4'4°-7'2° Cent.), the connection being 
made at the lower end of the worm, whilst the upper end is 
open to the air. On the small scale, as in the platinum-black 
process, the loss may be almost entirely prevented, by 
causing the upper air-tube to pass through a vessel con- 
taining ice or a freezing mixture; or by uniting it with the 
lower end of a Liebig's condenser. When the loss arises 
from a deficient supply of atmospheric air, more holes must 
be bored in the graduator. 
The advantages of this process are the small capital 
required for working it, no large factory or expensive 
apparatus being required. 
The per contras are the loss of alcohol by ^evaporation 
and the necessity of operating upon clear liquids. The 
quick process is not well adapted for malt washes and highly 
coloured wines, which abound in gummy, nitrogenous, and 
colouring matters, since these impurities clog the pores of 
the shavings, and thereby render them useless. 
4. Vinegar by Means of the Vinegar Fungus.-In 
1862 a new method of making vinegar was devised by 
Pasteur. The vinegar fungus (the Mycoderma Aceti), 
which is the agent by means of which acetification is brought VINEGAR. 
79 
about, is first propagated and cultivated in a fluid composed of 
water, with 2 per cent, of alcohol, 1 per cent, of vinegar, and 
a small quantity of the phosphate of potash, magnesia and 
lime. The surface of the fluid soon becomes completely 
covered with the fungus, a part of the alcohol becoming at 
the same time acetified. When half the alcohol has become 
converted into acetic acid, small quantities of beer and wine 
are added to the fluid every day, and the process carried on 
until all the alcohol has become oxidized. The vinegar is 
then removed from the containing vessel, and the fungus 
employed in the manufacture of a second batch. Vinegar 
prepared by this process is said to possess the agreeable 
aroma of wine vinegar. The vessels in which the vinegar 
is made are of wood, and in the form of round or 
rectangular shallow tanks. The prepared liquid, contained 
in a vessel having an area of about 10^ square feet and a 
capacity of from 90 to 100 pints, yields about 9 to 10 pints 
of vinegar daily. The tanks are covered by means of lids, 
and air is admitted to their contents through holes bored 
at the ends of the vessel, whilst the alcohol is conveyed to 
the bottom of the fluid through perforated gutta-percha 
tubes, an arrangement which gets rid of the necessity of 
opening the lids. When alcohol alone is employed, Pasteur 
makes the addition to the fluid of about Kth of its 
weight of sulphate of ammonia and phosphate of potash and 
magnesia, as well as some vinegar. 
The above salts constitute the food of the fungus, and as 
they are contained in beer and wine, they are dispensed with 
when these fluids are employed instead of alcohol. 
A successful result can only be obtained by paying great 
attention to the healthy development and growth of the 
mycoderma at starting. 
5. Vinegar from Sugar Beet.-The roots of the sugar 
beet, thoroughly washed, deprived of shoots and tops, and 80 
ACETIC ACID AND VINEGAR, ETC. 
rasped into a pulp, are submitted to considerable pressure in 
strong cloth bags, until exhausted of juice. The expressed 
juice is then diluted with water until the mixture has a 
sp. gr. of 1'025. After being boiled for a short time, the 
liquid is then run into coolers, and when its temperature 
has fallen to 6o° Fahr. (450 Cent.), it is conveyed into proper 
receptacles and fermented with yeast, in the proportion of 
1 gallon of yeast to every 200 gallons of wort. When the 
fermentation is complete, the wash is mixed with an equal 
volume of vinegar, and exposed at a suitable temperature 
to the air, when acetification soon takes place. By Neale's 
and Duyck's process the wash is conveyed to a strong and 
large vat having a capacity of several thousand gallons, 
where it is mixed with an equal measure of vinegar. A 
little yeast being now added to the mixture, acetification is 
soon started. When this commences, air is injected into 
the liquid through a perforated nozzle or rose at the bottom 
of the vat. By this contrivance, the oxidation of the fluid 
is effected in a few days, the contents of the vat meanwhile 
being kept at a temperature of from 700 to 8o° Fahr. (210 
to 2 70 Cent.), maintained, if necessary, by means of a steam 
worm which runs through the bottom of the vat. 
6. Vinegar by Widemann's Process.-Wedemann's pro- 
cess consists in the rapid oxidation of alcohol by ozone, and 
the consequent conversion of the alcohol into acetic acid. 
Widemann found that by adding water to maize whisky, and 
passing ozonized air over it, the alcohol was completely 
converted into acetic acid in 8 minutes. Works for making 
vinegar upon this principle were established at White Plains 
in 1871 and 1872, which turned out in the first year 30 
barrels, and in the second, 90 barrels of pickling vinegar. 
7. Other varieties of vinegar of minor importance, chiefly 
domestic, and commonly worked as malt vinegar, are :- 
(1) Crystal Vinegar.-Pickling vinegar decolourized with VWEGAR. 
81 
freshly-burnt animal charcoal. 2. Cider Vinegar.-From 
cider worked as malt vinegar. 3. German Household 
Vinegar.-From soft water 7^ gallons, honey or brown 
sugar 2 lbs., cream of tartar 2 oz., corn spirit or whisky 
1 gallon. 4. Gooseberry Vinegar.-From bruised goose- 
berries and brown sugar of each i| lbs., water 1 gallon. 
Other fruits may be substituted for gooseberries. 5. Raisin 
Vinegar.-From the marc left from making raisin wine ; 
1 cwt. to every 12 or 15 gallons of water along with a little 
yeast. 6. Sugar Vinegar.-From brown sugar 4 lbs. to each 
gallon of water. 7. Whisky Vinegar.-From whisky 1 
pint, sugar 2 oz., yeast a dessert-spoonful. 
Culinary Vinegars. 
i. Black Pepper Vinegar, Caper Vinegar, Capsicum 
Vinegar, Celery Seed Vinegar, Chilli Vinegar, Cress 
Seed Vinegar, Garlic Vinegar, Ginger Vinegar, Horse- 
radish Vinegar, Onion Vinegar, Bed Rose Vinegar, 
Seville Orange Peel Vinegar, Shallot Vinegar, Truffle 
Vinegar, White Pepper Vinegar, with several others of 
a similar kind, are made by steeping about an ounce of the 
respective articles in a pint of good vinegar for fourteen 
days and straining. 
2. Basil Vinegar, Burnet Vinegar, Celery Vinegar, 
Cherville Vinegar, Elder Flower Vinegar, Green 
Mint Vinegar, Tarragon Vinegar, are prepared by adding 
to each pint of vinegar 2 to 3 oz. of the leaves, the whole 
being frequently shaken for fourteen days, then strained 
or filtered, and bottled. 
3. Camp Vinegar.--Take of sliced garlic, 8 oz.; cayenne 
pepper, soy and walnut ketchup, of each 4 oz.; thirty-six 
chopped anchovies; vinegar, 1 gallon; powdered cochineal, 
1 oz. Macerate for a month, strain, and bottle. 82 
ACETIC ACID AND VINEGAR, ETC. 
Currie Vinegar.--Good currie powder, J lb.; vinegar, 
i gallon. Infuse for a week. Used as a flavouring. 
Raspberry Vinegar.--Bruised ripe raspberries and 
white wine vinegar, of each 3 pints. Macerate for three 
days, press, strain, and to each pint add of white sugar, 1 lb. 
Boil, skim, cool, and bottle at once. 2 oz. of brandy to each 
pint is sometimes added. 
In a similar manner may be made, Cherry Vinegar, 
Strawberry Vinegar, and the vinegars of similar fruits. 
ACETIMETRY. 
The art or process of determining the quantity of pure 
acetic acid in vinegar or in any other liquid. The plans 
adopted for this purpose are :- 
a. From the saturating power of the acid, as in the 
common methods of acidimetry. This is the most satisfac- 
tory method of assay. 
i. The molecular weight of commercially pure bicarbonate 
of potash in crystals being 100, whilst that of absolute 
acetic acid is 60, it is evident that every io grains of the 
bicarbonate will exactly equal 6 grains of the acid. To 
apply this practically, we have only to exactly neutralize 
100 grains of the vinegar or solution under examination 
with the bicarbonate, observing the usual precautions, such 
as well boiling- the solution after the addition of the potash 
salt to di'ive off the carbonic acid, and using litmus or 
some other suitable indicator. Then as io is to 6 so is the 
number of grains used to the percentage strength required. 
In this, as in similar cases, it is convenient to form a 
test solution with the bicarbonate by dissolving it in 
sufficient distilled water to fill the 100 divisions of any 
simple form of acidimeter,* when the quantity of the 
* A very convenient form of acidimeter is Binks' (No. i). 
Gay-Lussac's burette (No. 3) consists of a graduated glass VINEGAR. 
83 
solution, and consequently of the salt used, may be read off 
at once from the graduated portion of the tube. Still 
cylinder, to which is attached, and having connection with it, a thin 
glass tube of nearly equal height, through which the test liquid is 
dropped. The quantity consumed is read off on the graduated and 
larger cylinder. 
Mohr's burette (No. 2), however, will be found more convenient 
than any of these instruments for acetimetrical operations. It 
consists of a cylindrical glass tube, open at top and bottom, "o'' 
No. 2. 
No. 4. 
No. 1. 
No. 3. 
being at the top and " 100 " at the bottom of the tube. To the 
bottom, which is slightly contracted, is attached a small piece of 
flexible india-rubber tubing, into which is inserted a little glass exit 
pipe, which is opened or closed by means of a nipper clip, by manipu- 84 
ACETIC ACID AND VINEGAR, ETC. 
greater accuracy may be obtained by dissolving the bicar- 
bonate in exactly 1,000 grains of distilled water contained 
in an alkalimeter previously very carefully weighed, in 
which case each grain of the test solution will indicate 
j^th of a grain or o'i per cent, of absolute acetic acid, 
whilst every 10 grains will be equal to 1 grain or 1 per- 
cent. 
2. The test solution may also be prepared from bicar- 
bonate of soda, or from the carbonates of soda or potash, care 
being taken that the quantity of salt dissolved be in propor- 
tion to its molecular weight. 
3. The hydrated alkalies, soda, potash, and ammonia are 
also used for the estimation of acetic acid. When soda is 
employed, a normal solution is first prepared by dissolving 
40 grains of pure and dry caustic soda in distilled water, 
and making the solution to 1,000 grain measures : 100 grain 
measures of this solution containing 4 grains of caustic- 
soda are equivalent to 6 grains of glacial acetic acid. To 
100 grain measures of the acid or vinegar to be tested, 
coloured with litmus, the soda solution is added from one of 
the graduated burettes or acetometers before described, until 
the mixture just turns blue. Then from the number of 
grain measures of the soda solution required, the percentage 
lating which the stream of liquid from the burette can be regulated 
at pleasure. 
Otto's acetometer (No. 4), which is in general use in Germany, is 
a glass tube about 14A inches high and *ths of an inch wide, closed at 
one end, and graduated into an upper and lower scale, the latter 
being for the measurement of the vinegar coloured by litmus, and 
the upper for measuring the test liquor. When used, a certain 
quantity of litmus is poured into the tube, and then vinegar up to 
the beginning of the second division ; afterwards the test liquor is 
added until the blue colour of the litmus is restored, the quantity 
used being indicated on by the upper scale. The test liquor is a 
solution of ammonia containing 1'369 per cent, of ammonia. VINEGAR. 
85 
of glacial acetic acid is arrived at by a very simple calcula- 
tion. 
Thus, suppose for the sample under examination 70 
measures of the solution of soda have been taken, then as :- 
6 x 70 
= 4'20 per cent, of absolute acid. 
100 
When potash is used as a test liquid the normal solution 
is made by adding 56 grains of pure and dry caustic potash 
to 1,000 grain measures of distilled water, and proceeding 
precisely as with soda. 
When ammonia is employed, the following process, 
recommended by Ube, will be found a convenient and 
expeditious one :-100 grains of the sample under examina- 
tion are slightly reddened with tincture of litmus, and 
ammonia of sp. gr. 0'992 is added drop by drop (from an 
acetometer holding 1,000 water-grain measures, divided 
into 100 divisions), until precise neutralization is effected, as 
indicated by the blue colour of the litmus being restored. 
The number of the divisions of the acetometer used, 
multiplied by 60, and the first two right-hand figures of the 
product cut off as decimals, gives a number which represents 
the exact quantity of absolute acetic acid in the sample. In 
practice it is found more convenient to keep the test 
ammonia ready tinged with litmus. 
The ammoniacal test liquor is very liable to become weaker 
by keeping. To ascertain if this be the case, two hydro- 
static beads are placed in the bottle containing it. When 
the solution is of the proper strength, one of the beads 
assumes a position very near the bottom of the bottle, and 
the other just under the surface of the liquid. Upon the 
evaporation of the ammonia and the consequent increase in 
the sp. gr. of the liquid, the beads rise in it, the lower one 
higher above the bottom and the other partially above the 86 
ACETIC ACID AND VINEGAR, ETC. 
surface. When this takes place, as much ammonia must be 
added as will restore the beads to their original position. 
The mode of estimating the percentage of acetic acid in 
beers, when finding their original gravities, is a slight 
modification of the above. 
A test-solution of ammonia is prepared of such a strength 
that a given bulk of it will exactly neutralize one per cent, 
of absolute acetic acid in an equal bulk of beer, so that if 
ioo fluid grains of the solution are sufficient to neutralize 
the acid in 1,000 fluid grains of beer, such beer contains 
y oth per cent, of acid. A solution of ammonia diluted with 
distilled water until it has the sp. gr. '9986 at 6o° Fahr. 
(15'5° Cent.) is of the exact strength required. 
An acetometer holding 1,000 grains, and graduated down- 
wards to 100 equal divisions, is filled to " 0" of the scale 
with the test ammonia • which is then added drop by drop 
to 1,000 measured grains of the beer until neutralization 
takes place. Every division of the acetometer (correspond- 
ing to ten fluid grains) so emptied, indicates -oi per cent, of 
acetic acid in the beer. The progress of the neutralization 
is tested from time to time with a slip of reddened litmus 
paper, which should be suffered to become faintly blue 
before ceasing to add the ammonia. By this method the 
exact percentage of absolute acetic acid in any sample may 
be accurately determined. The only precaution necessary is 
to be certain that the test ammonia has the required specific 
gravity, viz., '9986. 
The above methods will be found appropriate to acetic 
acid of all strengths, unadulterated with mineral acids. 
Ow'ing to the circumstance that the normal or neutral 
acetates exhibit a slight alkaline reaction, none of the above 
methods are strictly accurate. 
Otto has shown, however, that the error arising from 
this cause is a very insignificant one, and does not exceed o-i VINEGAR. 
87 
per cent, for an acid containing io per cent, of absolute 
acid. 
I). Mr. Greville Williams suggests the employment of 
lime saccharate for acetic acid testing :- 
A moderately strong solution of sugar being prepared with 
distilled water, lime is dissolved in this, and the strength of 
the mixture ascertained by titration with a standard solution 
of sulphuric acid. The lime saccharate is then diluted so 
that 5 burette divisions shall be equivalent to i grain of 
absolute acetic acid. The assay is made as follows : Fifty 
grains of the sample to be examined are diluted to about 
two ounces with water, and a few strips of litmus paper put 
into the solution, the test liquid being then carefully added, 
with constant stirring, until the blue colour of the liquid is 
restored. This is an accurate method, if carefully per- 
formed, and, even where much expedition is required, gives 
results within 0'25 per cent. 
c. From the specific gravity of the liquid after it has 
been neutralized with hydrate of lime:- 
Common hydrate of lime (freshly slaked lime), in powder, 
is added gradually to the sample under examination, until 
it is saturated, when the sp. gr. of the resulting clear solu- 
tion of acetate of lime is taken by Taylor's acetometer. 
This instrument is so adjusted and graduated as to float at 
the mark on the stem called " proof," in a solution contain- 
ing 5 per cent, of absolute acetic acid (No. 24 vinegar). 
For vinegars stronger than proof, small weights are provided, 
each of which indicates an additional 5 per cent. To ascer- 
tain the percentage of real acid, 5 per cent, must therefore 
be added to the acetometer number. Thus, without being 
loaded, the instrument, floating at the " proof mark," indi- 
cates a vinegar of 5 per cent.; with one weight, a vinegar 
of 10 per cent. ; with two weights, 15 per cent, and so on. 
According to this system of notation, each 5 per cent, is 88 
ACETIC ACID AND VINEGAR, ETC. 
called a "vinegar." An acid of io per cent, is said to con- 
tain two vinegars; one of 15 per cent., three vinegars, &c. 
It is also common to speak of the degrees of the acetometer 
as " proof " or " over-proof." Thus, No. 24 vinegar is said to 
be proof; one of 5 acetimeter degrees, 5 over-proof ; one of 1 o 
degrees, 10 over-proof, &c. For malt and wine vinegars, 
which contain gluten and mucilage, this method is not 
strictly accurate, as a portion of these substances escapes 
precipitation by the lime, and consequently alters the specific 
gravity. A small weight marked " M " is generally supplied 
with the acetometers for trying such vinegars. 
d. From the specific gravity. The specific gravity of the 
sample, carefully determined by an acetometer or any of the 
usual methods, is sought in the following tables, when the 
corresponding percentage content of acetic acid is at once 
seen. 
This method furnishes reliable results only with pure or 
nearly pure solutions, which do not contain much above 50 
per cent, of absolute acid, or which have a sp. gr. not higher 
than 1'062. It is also more to be depended on for weak 
solutions than strong ones. By carefully diluting a strong 
acid with an equal weight, or twice or thrice its weight of 
water, and allowing the mixture to again acquire its normal 
temperature, the sp. gr. may be taken as a guide in all cases 
in which great accuracy is not required. When such dilu- 
tion is made it only becomes necessary to multiply the indi- 
cation furnished in the Tables by 2, 3, or 4, as the case may 
be. As, however, authorities are not agreed as to the 
precise sp. gr. of the monohydrate or glacial acid, and of its 
solutions, extreme accuracy must not be expected by this 
method. VINEGAR. 
89 
1 able I.-Adapted to the Specific Gravities of Common Vinegar. 
By Messrs. J. and P. Taylor. 
SP- Sr- per cent. 
1-0085 contains of anhydrous or real acetic acid 5 
^o^o „ „ 10 
rO257 „ „ 15 
1'0320 „ ,, 20 
1'O47° „ „ 30 
*'0580 ,, ,, 40 
Iable II.-The following table refers to an acid composed of 95 per 
cent, of pure glacicd acetic acid (hydrated acetic acid) and 5 per cent, 
of water. It was the result of a series of determinations undertaken 
by Messrs. Mohr/or Oudemann's. 
Acetic Acid 
CaH4O2 
Per cent. 
Density. 
Acetic Acid 
C2H4O2 
Per cent. 
Density. 
J5° C. 
40° C. 
>5° c. 
400 C. 
I 
I '0007 
0*9936 
29 
I *0400 
I *0246 
2 
I *0022 
0*9948 
30 
1*0412 
1-0255 
3 
1*0037 
0*9960 
31 
I *0424 
I *0264 
4 
I *0052 
0*9972 
32 
I *0436 
I *0274 
5 
I *0067 
0*9984 
33 
I *0447 
I *0283 
6 
I *0083 
0*9996 
34 
i -0459 
I *0291 
7 
1 *0098 
I *0008 
35 
1 *0470 
I *0300 
8 
I*OII3 
I *0020 
36 
1*0481 
I *0308 
9 
1*0127 
I *0032 
37 
1 *0492 
1*0316 
IO 
I*OI42 
I *0044 
38 
1*0502 
I -0324 
11 
1*0157 
I *0056 
39 
1-0513 
1*0332 
12 
I*OI7I 
I *0067 
40 
1-0523 
1-0340 
13 
I*Ol85 
I *0079 
4i 
I-O533 
I *0348 
14 
I *0200 
I *0090 
42 
1 -0543 
I-O355 
i5 
1*0214 
I *OIOI 
43 
1-0552 
1*0363 
16 
1*0228 
I*0112 
44 
1*0562 
1 -0370 
17 
I *0242 
J *0123 
45 
1-0571 
I-O377 
18 
I *0256 
I-OI34 
46 
1 *0580 
1 0384 
i9 
I *0270 
1*0144 
47 
1*0589 
1-0391 
20 
I *0284 
i-oi55 
48 
1 -0598 
1 -0397 
21 
I*O298 
1*0166 
49 
1 *0607 
1 *0404 
22 
I*O3II 
1*0176 
50 
1*0615 
1 *0410 
23 
I*O324 
1*0187 
5i 
1 *0623 
1*0416 
24 
1'0337 
1*0197 
S2 
1*0631 
1 -0423 
25 
1*0350 
1 *0207 
53 . 
1 *0638 
1 *0429 
26 
1 -0363 
1*0217 
54 
1 *0646 
1'0434 
27 
1-0375 
1 *0227 
55 
1 *0653 
1 *0440 
28 
1*0388 
1 *0236 
56 
1 *0660 
1 -0445 90 
ACETIC ACID AND VINEGAR, ETC. 
Table II.-continued. 
Acetic Acid 
CaH4O2 
Per cent. 
Density. 
Acetic Acid 
C2H402 
Per cent. 
Density. 
150 C. 
400 C. 
15° C. 
400 C. 
57 
1 -0666 
I '0450 
79 
I '0748 
I -0499 
58 
1-0673 
1'0455 
80 
I -0748 
I -0497 
59 
1 '0679 
1 '0460 
81 
I -0747 
i -0495 
60 
1 '0685 
1 '0464 
82 
I '0746 
1 -0492 
61 
1'0691 
1 '0468 
83 
I -0744 
1 -0489 
62 
1 '0697 
1 '0472 
84 
I -0742 
1 -0485 
63 
1 '0702 
1 -0475 
85 
I -0739 
1 -0481 
64 
1 -0707 
1 -0479 
86 
I -0736 
1'0475 
65 
1 -0712 
1 -0482 
87 
I-O73I 
1 -0469 
66 
1-0717 
1 -0485 
88 
I '0726 
1 -0462 
67 
1 -0721 
1 '0488 
89 
I'0720 
1'0455 
68 
1-0725 
1 '0491 
90 
I-O7I3 
1 -0447 
69 
1 '0729 
1 -0493 
9i 
I-O7O5 
1 -0438 
70 
I-O733 
1 -0495 
92 
1 '0696 
1 -0428 
7i 
1 -0737 
1 -0497 
93 
i -o686 
1-0416 
72 
1 0740 
1 -0498 
94 
1 '0674 
1 -0403 
73 
1 -0742 
1 -0499 
95 
1 -0660 
1 -0388 
74 
1 -0744 
1 '0500 
96 
1 '0644 
1-0370 
75 
1 '0746 
1 '0501 
97 
1 -0625 
1-0350 
76 
1 -0747 
1-0501 
98 
1 -0604 
1 -0327 
77 
1 '0748 
1 -0501 
99 
1 '0580 
1 -0301 
78 
1 '0748 
1 -0500 
100 
I-O553 
1 -0273 
Before applying the above processes, account should be 
taken of any mineral acid which may be present in the 
sample, such being not unfrequently added to vinegar to 
impart artificial strength. The methods depending on the 
saturating power of the acid, will be, found appropriate to 
acetic acid of all strengths, when unadulterated with the 
mineral acids. The method based on the sp. gr. is also very 
convenient, and is sufficiently accurate for distilled vinegars 
and for pure acids of moderate strength, although neither 
this, nor the saturation by lime, give perfectly reliable 
results. 
It is found that the decimal fraction of the sp. gr. of pure 
or nearly pure vinegar, is doubled by its conversion into 
acetate of lime. Thus, 1-0085 in vinegar becomes 1'0170 VINEGAR. 
91 
when converted into a solution of acetate of lime. In malt 
vinegar, however, 0'005 may be deducted from the sp. gr. 
for mucilage and gluten. The quantity of foreign matter 
present in vinegar may therefore be approximatively 
ascertained, by deducting the decimal of the sp. gr. of the 
solution of acetate of lime from double that of the decimal 
part of the sp. gr. of the vinegar. Thus :-the sp. gr. 
of a sample of vinegar being 1'014, and after saturation 
with hydrate of calcium, 1'023, ^be sp. gr. of the pure 
vinegar would be 1'009, and that due to foreign 
matter '005. For- 
•028-*023= '005 
and- 
1'014-'005 = 1-009. CHAPTER II. 
AMMONIA. 
(NH3=i7.) Syn. Ammonia gas, Ammoniacal gas, Anhy- 
drous ammonia, Terhydride of nitrogen ; Volatile 
alkali, Priestly's alkaline air.-This compound derives 
its name from Jupiter Ammon, in consequence of its having 
been first procured from the salt obtained by the ignition 
of camel's dung, near a temple of that mythological deity in 
Libya. 
In the uncombined state ammonia exists in the juices 
of certain plants, and is freely developed during the 
decomposition' of azotised vegetable substances and the 
putrefaction of animal matter, very probably owing to the 
combination of the nascent hydrogen liberated during the 
process of decay, with the nitrogen of the atmosphere which 
in small quantity occurs in solution. Ammonia is also 
largely given off when nitrogenous substances, except 
when in the form of nitrates and cyanides, are heated 
with the hydrated alkalies. It is also produced when 
nitric acid becomes deoxidized by acting on certain metals, 
preferably zinc, iron, and tin. It is likewise formed when 
moist iron filings are exposed to the atmosphere and is found 
in tiie resulting oxide. When nitric oxide and hydrogen, in 
the proportion of two volumes of the former to five of the 
latter, are passed over gently heated spongy platinum, 
ammonia and water are generated; and when an excess of 
hydrogen is ignited in the atmosphere, the product is 
ammonium nitrate. AMMONIA. 
93 
Ammonia is likewise evolved during certain industrial 
processes, as in the preparation of caustic soda from ball 
soda, whilst cooling ; during the formation of cyanogen and 
cyanide of potassium, in blast furnaces; and in considerable 
quantities when caustic soda is purified by the nitrate. 
In nature, ammonia, in a state of combination, is found 
in variable quantities among the saline product of volcanoes; 
in sea and rain water; in bituminous coal; in urine; in 
guano; in the excreta; of animals and reptiles, especially of 
serpents; and in the atmosphere, especially that of large 
towns. 
Many unsuccessful attempts have been made to directly 
convert the nitrogen of the atmosphere into ammonia. Of 
these we may mention one, which consisted in passing a 
mixture of air, carbonic oxide, and steam over red-hot 
hydrate of lime, whereby ammonia and carbonic acid are 
formed. A plan for the indirect application of atmospheric 
nitrogen in the preparation of ammonia was suggested by 
Margueritte, in which it was proposed that cyanide of 
barium should be prepared, and its nitrogen converted into 
ammonia by the aid of a current of superheated steam at 
572° Fahr. (3000 C.). According to the description of this 
process in a patent-not, however, in practice-native car- 
bonate of baryta is calcined with about 30 per cent, of coal 
tar, for the purpose of rendering the mass porous, as well 
as more readily convertible into caustic baryta at a lower 
temperature. The carbonaceous mass is, after cooling, 
placed in a retort and kept at a temperature of 5720 Fahr. 
(3000 C.), while air and aqueous vapour are forced in, the 
result being the formation of ammonia in considerable 
quantity, and carbonate of baryta, which is again used. 
The ammonia of commerce and its salts, are chiefly pre- 
pared from the ammoniacal liquor of the gas-works, as well 
as that obtained from bone and animal charcoal factories. 94 
ACETIC ACID AND VINEGAR, ETC. 
By the addition to the crude ammoniacal liquid of sulphuric 
or hydrochloric acid, the corresponding salts are procured, 
which are more or less purified by evaporation and crystalli- 
zation. The carbonate is prepared by sublimation from the 
sulphate or chloride, and chalk. The largest quantity of 
ammonia is obtained when the gas-retorts are kept at an 
orange-red heat, and the distillation is prolonged as long as 
practicable. 
Ammoniacal gas for the laboratory may be prepared as 
follows:-a mixture of fresh hydrate of lime with an equal 
weight of sal ammoniac (both substances being dry and in 
fine powder) is introduced into a glass flask or retort, the 
Fig. 16. 
beak of which communicates with one end of a U-shaped 
tube filled with small fragments of recently burnt quick- 
lime. To the U-shaped tube another glass tube, about io 
inches long is attached, having its further end bent so that 
it can be placed under a gas-jar, on the shelf of a mercu- 
rial pneumatic trough, as shown in the annexed engraving. 
The joints being made air-tight by collars of india rubber, 
heat is gradually applied by means of a spirit-lamp, and as 
soon as the air contained in the apparatus is expelled, the 
gas is collected for use; powdered quicklime may be sub- 
stituted for the hydrate in the above process, but a much 
greater heat will then be required for its liberation. Or it AMMONIA. 
95 
may be more easily collected by displacement. In this case, 
the mercurial trough may be dispensed with, and the glass 
jar be suspended mouth downward on a retort stand; it 
must be so arranged that the end of the bent tube shall pass 
about half-way up it. As the ammonia is given off from 
the flask it displaces the air from the jar, which may be 
known to be full when a piece of turmeric paper placed near 
the neck turns brown. The jar must be perfectly dry. 
Ammonia is a compound of three volumes of hydrogen 
and one volume of nitrogen, condensed into two volumes; 
and consists by weight of 82'35 parts of nitrogen, and 17'65 
parts of hydrogen. Its formula, is NIL. 
Ammonia is a gaseous, colourless, invisible gas; highly 
pungent, acrid, and irritating, and with a strongly alkaline 
reaction. It is irrespirable, unless very largely diluted with 
air; extinguishes combustion; and burns slowly in oxygen. 
Its specific gravity is 0'589 ; 100 cub. inches weigh 18'26 gr. 
Under a pressure of 6'5 atmospheres, at 500 Fahr. (io° C.), 
it forms a transparent, colourless liquid of the sp. gr. 0'731 ; 
at 60° Fahr. (15'5° Cent.) this liquid becomes expanded into 
1,009 times its volume of ammoniacal gas; at - 400 F. 
( - 40° C.) and under ordinary atmospheric pressure,it forms 
a colourless liquid which at - 1080 Fahr, freezes into a white 
translucent crystalline substance.* It is highly basic, and 
neutralizes the strongest acids; its salts are either volatilized 
or become decomposed at a red heat or below it, those with a 
volatile acid subliming unchanged and those with a fixed 
acid losing their ammonia. Ammonia is decomposed into 
its elements by transmission through a red-hot tube; and 
when brought into contact with metallic oxides or spongy 
platinum at the same high temperature, the newly evolved 
* Fabaday. 96 
ACETIC ACID AND VINEGAR, ETC. 
hydrogen unites with the oxygen of the oxide or of the at- 
mosphere and forms water. Water at 500 Fahr. (io° C.) 
absorbs 670 times its volume of this gas; hence it cannot be 
collected over w'ater. The saturated solution has a sp. gr. of 
0'875. concentrated aqueous solution boils at 1300 
(54'4° C.) and freezes at - 400 Fahr. ( - 400 0.). It is also 
largely soluble in alcohol. When the electric spark is passed 
through the gas, it is resolved into its constituent elements. 
Ammonia may be recognized by-1. Its pungent odour. 
2. By turning vegetable blues green, and vegetable yellows 
brown; the original colour, however, being quickly re- 
stored, particularly by the application of heat. 3. By pro- 
ducing dense white fumes when brought into contact with 
gaseous hydrochloric acid, 4. By the Nessler test, which 
occasions in solutions containing the smallest quantity of 
ammonia, a yellow or brown tinge. 5. If a saturated 
solution of arsenious acid is mixed with a solution of nitrate 
of silver, containing 2 per cent of the salt, a trace of am- 
monia causes the formation of a tri-argentic arsenite of a 
canary yellow colour. 6. A very delicate test for ammonia 
is afforded by an aqueous solution of carbolic acid. On 
adding to a liquid containing the smallest quantity of am- 
monia, or an ammoniacal salt, a few drops of this solution, 
and then a small quantity of a filtered solution of chloride of 
lime, the liquid becomes green, especially when warmed. 
Ammonia when inhaled, undiluted with air, is an irritant 
poison, producing spasm of the glottis, convulsions, and 
death. Even when diluted, it acts as a powerfully acrid 
and local irritant. Applied to the skin it causes vesication. 
The use of the pungent odour of common " smelling salts," 
in syncope, headache, &c., is well known. Largely diluted 
with air, it has been extolled in chronic hoarseness, asthma, 
&c., and as an antidote to the fumes of bromine, chlorine, 
and hydrocyanic acid. AMMONIA. 
97 
Ammonia is employed in numerous processes in chemistry 
and the arts; chiefly in the form of " liquor of ammonia/' 
" spirits of hartshorn," &c., and in combination under the 
form of salts. In the industrial arts, liquid ammonia is 
mostly used for the preparation of archil from various 
species of lichen; for the purification of coal-gas; and, as 
in Carre's machine, for the artificial production of ice. In 
its pure or gaseous state it possesses little practical interest. 
Ammonia, Solution of. Syn. Solution of Ammonia, 
Liquor Ammonias, Ammonium Hydrate, Ammonia. Am- 
moniacal gas readily dissolves in water, one volume of which 
Fig. 17. 
absorbs about 670 volumes of ammonia, much heat being 
liberated during combination, and the solution increasing 
greatly in volume. 
Solution of ammonia may be prepared for the laboratory 
by distilling, in a tubular retort, equal weights of sal ammo- 
niac and freshly burned quicklime. The lime is slaked 
and made into a paste with water before admixture, and the 
gas evolved is passed through a set of Woulfe's bottles 
partially filled with water, as shown in the drawing above. 
In conducting the operation, the heat should be cautiously 
applied during the evolution of the ammonia; and on no 98 
ACETIC ACID AND VINEGAR, ETC. 
account should the bottom of the retort become red-hot. 
The balloon or bulb interposed between the neck of the 
retort and the first bottle is for the purpose of arresting any 
sublimed chloride of ammonium that may have escaped de- 
composition. When the gas has all passed over, the retort 
should be heated so as to fuse the residue of chloride of 
calcium, which should then be poured out. 
If pure, solution of ammonia leaves no residue when 
evaporated to dryness ; this shows the absence of lime com- 
pounds, and if it give no precipitate or cloudiness when 
after neutralization with nitric acid it is treated with barium 
Fig. 18. 
A, Cylindrical Iron Retort. 
IB, Furnace for ditto. 
C C C C, Stoneware Receivers. 
DDDD, Connecting Pipes. 
J? F, Waste Pipe and Receiver. 
G, Safety Tube. 
chloride or argentic nitrate, it contains neither a sulphate 
nor a chloride. It should not be coloured by sulphuretted 
hydrogen. A more or less brown tint denotes the presence 
of organic compounds, derived from the substances from 
which it has been produced. The best method for the re- 
moval of these is the filtration of the ammoniacal solution 
through charcoal. The charcoal should afterwards be 
washed, and the washings added to the retorts when these 
are charged for a fresh distillation. AMMONIA. 
99 
Solution of ammonia is prepared on the large scale, from a 
mixture of about equal parts of freshly-slaked lime and 
sal-ammoniac or sulphate of ammonia, which is heated in 
an iron cylinder or retort connected with a set of refrigera- 
tors ; the latter consisting of a row of stoneware bottles 
with double necks, containing water, and kept very cold. The 
general arrangement of the apparatus used in this manu- 
facture is exhibited above, and with the accompanying 
references will be easily understood. The condensers, when 
in use, are surrounded with cloths (not shown in the en- 
graving) kept wet by means of very cold water, a constant 
current of cold air being at the same time made to pass 
over them. The pipe D leading from the retort is several 
feet long, and is advantageously passed through a wooden 
screen, in order that the radiated heat of the retort and 
brickwork of the furnace, may be intercepted as much as 
possible. 
There are two methods of carrying out the process. In 
one the dry pulverulent ingredients are mixed together, and 
the resulting gas passes over into the water placed in the re- 
ceivers. In the other the lime is made into a pap with 
water, and the ammonia salt, in coarse powder, being added 
to it, the whole is rapidly blended together, before closing 
the retort and applying heat. In either case a proportionate 
quantity of water is put into the condensers, and the opera- 
tion is nearly similar; but the latter method requires the 
least heat, and so far as the receivers and refrigerators 
are concerned is perhaps more easily managed. It 
is that always followed when sulphate of ammonia is em- 
ployed. 
An aqueous solution of ammonia is in constant demand 
in the laboratory, both as a reagent and for precipitating 
the oxides of the heavy metals. Liquid ammonia is now 
very frequently made by distilling the sulphate with caustic 100 
ACETIC ACID AND VINEGAR, ETC. 
soda, the value of the residual sulphate of soda, and the 
ease of manipulation, compensating for extra cost. 
Among the plans having for their object the production 
of an ammoniacal solution, more or less concentrated, for 
many technical purposes, and for the preparation of salts, 
may be mentioned :- 
i. That of Watson (patent dated 1838), in which gas- 
liquor mixed with a proper quantity of freshly slaked lime 
is distilled from a spacious retort or still into a receiver con- 
taining cold water, until a large amount of steam passes 
over with the gas, when the strong alkaline liquor forming 
the distillate, and called the first portion, is drawn off1. The 
distillation is then continued, when a weaker and impurer 
solution is obtained, called the second portion The first 
portion is then re-introduced into a retort or still with a 
small quantity of fresh lime, and the distillation repeated. 
The patentee calls the product the first portion of the second 
distillation. It is a strong ammoniacal liquor, sufficient for 
all the purposes of scouring, cleaning, and conversion into 
commercial ammonia-salts. It may be further purified by a 
third distillation; the second portion of each operation 
being transferred again to the still with the next fresh 
charge of gas-liquor, 
2. A modification of Coffey's still,* patented by Mr. 
W. E. Newton (1841), under the name of the Ammonia 
still, is extensively employed in the manufacture of liquid 
ammonia. By Newton's process, which is a continuous one, 
solution of ammonia, of varying density and of considerable 
purity, can be obtained from gas-liquor, bone-spirit, ammo- 
niacal salts and liquids. The body of the apparatus is of 
* An engraving and description of this still as employed in spirit- 
making are given under Stills, vol. i. of " Churchill's Technological 
Handbooks." AMMONIA. 
101 
wood, the chambers are lined with lead, and the diaphragms 
are of perforated sheet-iron. The management of the 
apparatus varies with the form in which it is desired to 
obtain the product. When the ammonia is required to leave 
the upper chamber of the rectifier in the form of gas, either 
pure or impure, the steam which ascends, and the current 
of ammoniacal liquor which descends, are regulated in such 
relative proportions that the latter remains at or near the 
atmospheric temperature during its passage through some 
of the upper chambers, becoming successively hotter as it 
descends, until at length it enters into ebullition ; in which 
state it passes through the lower chambers, either to make 
its escape or to enter a cistern provided to receive it. If, 
on the contrary, the ammonia is required to leave the upper 
chamber in combination with the vapour of water, the 
supply of steam entering below must be in such proportion 
to that of the ammoniacal liquor supplied from above, that 
the latter may be at or near the boiling temperature in the 
upper part of the apparatus. Crude liquor and ammonia- 
salts, before being submitted to distillation, are first treated 
with the requisite quantity of quicklime, which in the first 
case removes most of the impurities of the crude liquid; 
and in the second, by combining with the acid of the salt, 
liberates the ammonia. In addition to ammonia, carbonic 
acid and other volatile substances may be generated during 
the distillation. Sometimes the carbonate of ammonia pro- 
duced under these circumstances may not be objected to; 
but when gaseous ammonia alone is desired, means must be 
taken to keep the carbonic acid out.* 
3. Mallet's Apparatus. This, which is employed in 
many of the large gasworks, is shown in vertical section in 
* For a full description of the " Ammonia still," see Newton's 
" Patent Jour.; " " Pharm. Jour.," xiii. 64. 102 
ACETIC ACID AND VINEGAR, ETC. 
Fig. 19. AMMONIA. 
103 
the accompanying woodcut. Steam is forced into large 
receptacles, which are filled with gas-water, by which means 
the carbonate of ammonia is volatilized. When lime is 
added, ammonia gas is evolved, and if this is conveyed into 
weak sulphuric acid, sulphate of ammonia will be the re- 
sulting product. 
The apparatus consists of two cylindrical boiler-plate 
vessels, a and B. a is heated directly by the fire, and has a 
leaden tube, c, which dips into the liquid contained in b, 
this vessel being so placed as to catch the waste heat from 
the fire, b and e are man-holes ; a and a! are stirrers. By 
means of the tube d the fluid from B can be run off into A. 
Gas-water is poured into both vessels, and lime added; am- 
monia is liberated, whilst carbonate of lime and sulphide of 
calcium are formed, and these latter remain in the vessels 
after the volatilization of the ammonia. The vessel D is 
also filled with ammoniacal water, and when the operation is 
in action this water, already warmed, is run by the aid of 
the tube h from D into B. E is a gas-water tank, from which 
d is filled by means of g. The ammonia set free in A is, 
with the steam, conveyed by the pipe c into b, thence 
through c' into the wash-vessel c, and thence again through 
c" into the first condenser n. The partially condensed 
vapour now passes into the condensing vessel F, the worm of 
which is surrounded by cold water. The dilute ammonia 
is collected in G, and forced by means of the pump r into c, 
from whence it is occasionally removed by means of a syphon 
into either A or B. The non-condensed ammoniacal gas is 
carried from g through a series of Woulfe's bottles, 
the first bottle (h) containing olive-oil, which retains 
any hydrocarbons that may be present in the gas; the 
bottle I contains caustic soda ley, in order to retain other 
impurities; the bottle k is half-filled with distilled water. 
The ammoniacal gas, having passed through K, is con- 104 
ACETIC ACID AND VINEGAR, ETC. 
veyed to the large wooden tank (lined with lead) l, filled 
with diluted sulphuric acid, if it is intended to prepare sul- 
phate of ammonia, or with water, if solution of ammonia be 
required. The vessel L is placed in a tank of water; i is a 
small pipe for introducing acid, while the tube leading to M 
serves to carry off any unabsorbed ammonia, m being likewise 
filled with acid. 
4. Rose's apparatus consists of a, a boiler; b and C, two 
vessels in which the gas-liquor is warmed by means of the 
tubes e and/' through which and g the steam and ammonia 
gas evolved in A pass to the absorption vessels n, E, and F, 
the connexion between E and F being made by means of the 
gas-filters G and h. By means of the tubes I and m, each 
of which is fitted with a stop-cock, the gas-liquor can be run 
into the boiler a. a is filled two-thirds with gas-liquor and 
one-third with slaked lime. The gas-filters g and n are 
filled with freshly-burnt charcoal, which retains any em- 
pyreumatic substances that might be carried over by the 
ammoniacal gas. The vessel d is filled with hydrochloric acid, 
and pure water is poured into E and f. a, being two-thirds 
filled with the gas-liquor, and the rest of the apparatus put 
into working order, the fire is lighted. The ammoniacal gas 
evolved in a passes with the steam into e and f, where a 
portion of the steam is condensed and retained as water. 
Into the boiler a is fitted a tube 6, containing a ther- 
mometer surrounded by brass fittings, for the better con- 
duction of the heat. When this thermometer indicates 197'6 
Fahr. (92° Cent.) to 201-2° Fahr. (940 Cent.), the tap h is 
opened, and the tap i (which up to this time has been kept 
open) shut, so that the gas may pass into the hydrochloric 
acid contained in D, until the vessels G and h have been 
filled with fresh charcoal, an operation which is required at 
the beginning of the working as well as when the tempera- 
ture has risen in a to 204-8° Fahr. (96° Cent.), 208-4° Fahr. AMMONIA. 
105 
(98° Cent.), and 2120 Fahr. (ioo°Cent.). This having been 
done, the tap i is again opened. 
When the temperature has reached 217*4° Fahr. (103° 
Fig. 20. 
Cent.), taking the boiling-point of the liquid at 212° Fahr. 
(ioo° Cent.), all the ammonia is expelled, and the liquid is 106 
ACETIC ACID AND VINEGAR, ETC. 
then run off by opening the stop-cock a. A fresh charge 
of gas-liquor and slaked lime is then put into the boiler, 
and the operation repeated. When the temperature in a 
reaches 217-4° Fahr. (1030 Cent.) the liquid in b becomes 
heated to 1940 Fahr. (90° Cent.), and that in C from 77° 
Fahr. (250 Cent.) to 86° Fahr. (30° Cent.). The vessel F 
holds from 26 to 33 gallons of water, which is converted 
into solution of ammonia, having a specific gravity varying 
from 0'910° to 0'920° : c and n are glass safety-tubes. 
5. In Lunge's apparatus the gas-water is heated in a 
boiler, and the liberated ammoniacal gas passed into sul- 
phuric acid. 
6. By Hompesch's method, bituminous schist being sub- 
jected to destructive distillation, yields gaseous ammonia, 
which by the usual treatment can be employed for the pre- 
paration of ammoniacal salts. 
Whatever form or process is adopted for the preparation 
of liquid ammonia, it is absolutely necessary to keep the 
receivers as cool as possible, by means of snow, ice, or a 
current of very cold water, for the purpose of promoting 
the absorption of the gas and preventing its loss. On the 
small scale, the glass receivers or bottles may be most con- 
veniently surrounded with ice, or a freezing mixture, and 
two or more of them should be furnished with safety-tubes. 
On the large scale, a capacious oblong retort, usually of iron 
and sometimes of lead, is employed. The retort is furnished 
with a large opening or tubulature conveniently situated 
for inserting the charges, and withdrawing the residuum of 
the distillation. The tubulature, oi' opening, is closed by 
means of a large and accurately ground iron stopper, or 
with a door secured by screws. The stopper is well greased 
before being placed in position, and a powerful lever em- 
ployed when it is required to be taken out. Should it 
become fixed, a cloth moistened with cold water, and care- AMMONIA. 
107 
fully wrapped round it, without touching the neck of the 
retort, by causing it to contract, will enable the operator to 
remove it with facility. Sometimes a large iron kettle 
is employed instead of a retort. The kettle has a moveable 
and accurately fitting lid secured in its place like that of a 
Papin's digester, and a large and long iron tubulature in its 
centre, in which is inserted another cast-iron tube, bent at 
right angles, for conveying the gaseous ammonia to the 
receivers. This form of vessel has the advantage over the 
retort of exposing a larger opening for the removal of the 
residuum of the process. In either case the distillatory 
vessel is imbedded in sand supported by fire-brick, and is 
not exposed directly to the heat of the furnace. Before 
commencing the distillation, the joints are all well luted, to 
avoid leakage. The following are good lutings:-I. Wax, 
resin, and turpentine melted together. 2. Freshly slaked 
lime made into a paste with bullock's blood or thin size. 
An excellent plan is to pass the gas, as it leaves the retort, 
through a silver or pewter worm or refrigerator set in a tub 
supplied with a stream of very cold water, by which it 
will be sufficiently cooled before it reaches the receivers, to 
obviate the necessity of any further attention to them than 
keeping the cloths wrapped round them constantly moistened 
with cold water. The upper end of the worm should be 
connected, by means of a balloon-shaped adapter, with the 
still, and the lower end with the first receiver; the use of 
the balloon being to intercept any volatilized ammonia-salt 
that might be accidentally driven over by the heat being 
too high, or raised too suddenly. 
The heat should be gradually applied, and very cautiously 
raised, so as to prevent any of the sal ammoniac or sulphate 
being volatilized and passing over in an undecomposed state. 
Even towards the end of the process the heat should never 
be allowed to approach redness. 108 
ACETIC ACID AND VINEGAR, ETC. 
When the lime is slaked and papped with about four 
parts of water, a lower heat is required to expel the gas, 
and it passes over more easily and completely than when 
less water is employed. This plan should always be adopted, 
and is absolutely necessary when sulphate of ammonia is 
used; or the residuum of sulphate of lime would become so 
hard that it could only be removed from the retort with 
difficulty. 
The gas being wholly expelled from the retort, or other 
distillatory vessel, the receivers are disconnected, and 
the heat is raised sufficiently high to fuse the residual 
chloride of calcium, which remains if sal ammoniac has been 
employed, which is then baled or poured out. Glass retorts 
often suffer fracture at this stage; but should they escape, 
it generally happens that they are broken when they are 
heated for a second operation. Hence, it is rarely that a 
retort, even when carefully handled, can be used more than 
twice. 
When crude sulphate of ammonia is employed it is 
advisable that the first receiver should contain only a small 
quantity of water, the use of which is to purify the gas 
which passes through it, and to retain any traces of volatile 
empyreumatic or oily matter which may be carried over 
with it. 
Pure solution of ammonia is most easily obtained from 
sal ammoniac; but crystallized sulphate of ammonia, often 
in the crude state, is commonly employed, on account of its 
lower price. When the sulphate is used, the addition of a 
few spadefuls of common salt to the mixture of sulphate 
and lime before distillation will prevent the caking of the 
residue left in the retort, should, the distillation be carried 
to dryness. 
Ammonium, Sesquicarbonate of. Syn. Carbonate of 
Ammonia, Sal Volatile, Salt of Hartshorn, Ammonite AMMONIA. 
109 
Carbonas. B.P. Probably 2NH1HC08 + NH4, NH2CO3, 
a mixture or compound of bicarbonate of ammonium and 
carbamate of ammonium. 
The commercial salt is prepared as follows:-i part of 
sulphate of ammonium and ij or 2 parts of chalk, both 
dry and in coarse powder,* are mixed together and put into 
iron retorts, similar to those used in the manufacture of 
coal-gas, in which they are heated to redness. Double de- 
composition takes place, and the liberated sesquicarbonate 
of ammonia ascends into cooled receivers, where it becomes 
condensed. The receivers are lined with lead or earthen- 
ware. Very frequently the receiver is connected by iron 
or lead pipes with a second one containing a stratum 
of water, which absorbs the free ammonia evolved during 
the process. 
The sesquicarbonate of ammonia of commerce usually 
occurs in the form of white, fibrous, translucent, or semi- 
translucent cakes, generally about two inches thick. It is 
less volatile and pungent than the neutral carbonate; it is 
soluble in 4 parts of water at 55° Fahr. (12*77° Cent.), 3*3 
parts at 62° (16'66° Cent.), 2*5 parts at 900 (32*22° Cent.), 
and 2 parts at 120° (48*88° Cent.); boiling water and alcohol 
decompose it, with the evolution of carbonic acid and am- 
monia ; by age or exposure to air, the surface assumes an 
opaque white colour, owing to the loss of part of its carbo- 
nate by volatilization, and the less volatile bicarbonate being 
left behind and forming a spongy crust on the remaining 
sesquicarbonate. Unlike the carbonate, it can neither be 
re-sublimed nor digested or distilled with either alcohol or 
water, without suffering decomposition. Its sp. gr. is 
0*966. 
* Some portion of the chalk should be in small lumps, the better to 
allow of the passage of the gas. 110 
ACETIC ACID AND VINEGAR, ETC. 
The composition of this salt varies according to its method 
of preparation. 
Commercial sesquicarbonate of ammonia is largely em- 
ployed for the removal of grease from woollen goods; by 
bakers to give lightness to their fancy goods, and to make 
extemporaneous bread and pastry; by the chemist and 
pharmaceutist for the preparation of other salts of ammonia, 
for the preparation of smelling-salts, and in analysis. 
In the manufacture of sesquicarbonate of ammonia on a 
large scale the distillation is usually carried on in cast-iron 
retorts, similar in size, shape, and character to those em- 
ployed in the manufacture of coal-gas, five or more being 
commonly set horizontally in the same furnace, as shown in 
the engraving; each retort has its mouth (a), through 
which the charge is introduced, closed with a movable door, 
which is securely fastened, as seen in the plate. Each retort 
is furnished, at the upper part of its further end, with an 
iron pipe (c), to carry off the evolved vapours to the con- 
denser or receiver. The latter consists of two large square 
leaden chambers (b, c), fitted with movable covers luted on, 
and movable bottoms, so as to permit of the easy removal of 
the sublimed salt. The first receiver communicates with the 
second by means of two large leaden tubes (cZ) near its centre. 
The second receiver contains a stratum of water, the object of 
which, as before explained, is to absorb the free ammoniacal 
gas. To the bottom of the chambers is attached a leaden pipe, 
as shown at e, for drawing off the liquid product of distillation. 
During the process of sublimation the pipe is closed with a 
wooden plug. The solution which is drawn contains carbo- 
nate of ammonia. It is evaporated and crystallized. Both 
chambers are placed on strong wooden supports or scaffold- 
ing, so as to bring them on a level with the retorts. 
The sublimation is generally carried on night and day for 
about fourteen days, a fresh charge being inserted in the AMMONIA. 
111 
retorts daily. At the end of the fourteen days the covers 
of the chambers are lifted, the bottoms let down to the 
ground, and the crude carbonate is detached by heating the 
outsides of the lead chambers. 
The substances employed produce monocarbonate of am- 
monia; but it is practically impossible to prevent loss of 
ammonia in the process, as a portion is always dissociated 
into nitrogen and hydrogen gases, by passing along the red- 
hot surface of the top of the retort. It sometimes happens 
that an explosion occurs when the doors of the retort are 
Fig. 2i. 
opened, owing to a stream of hot air passing into the cham- 
bers and mixing with the hydrogen, which then becomes 
fired by the heat. When impure sulphate or other ammo- 
nia-salt is used in the manufacture of the sesquicarbonate, 
the resulting salt, being impure and discoloured, is re- 
sublimed in iron pots furnished with movable 
leaden heads, which are kept cool by means of a current of 
air circulating over them, a little water drawn from the 
bottoms of the chambers being introduced into the sublim- 
ing-pots to render the product translucent. These pots are 112 
ACETIC ACID AND VINEGAR, ETC. 
arranged in sets, as shown at D in the engraving. The heat 
is applied either by means of a flue passing from the retort- 
furnace (a, b), or by a water bath heated in the same manner; 
the latter being the preferable method, as the temperature 
should not be greater than about 1400 Fahr. (6o° Cent.), 
and never exceed 1500 Fahr. (65'5° Cent.) to 1550 Fahr. 
(68-33° Cent.). 
The charge of a retort usually consists of about 70 to 72 
lbs. of ammonium sulphate, or 57 to 58 lbs. of the chloride, 
to 1 cwt. of chalk; or about these proportions. The pro- 
duct is about 40 lbs. of the crude salt, which by careful 
re-sublimation, yields about 39 lbs. of marketable carbonate 
of ammonia. Pure hydrated sesquicarbonate of ammonia 
may be prepared by exposing a saturated solution of the 
ordinary salt to a temperature of 320 Fahr. (o° Cent.), when 
it becomes deposited in large transparent octahedral crystals 
with a rhombic base. 
Commercial carbonate of ammonia is also obtained from 
bones or animal matter by dry distillation. 
Carbonate of ammonia, like the chloride and sulphate, is 
now scarcely ever prepared on the small scale, that of com- 
merce being not only cheaper, but sufficiently pure for all 
the purposes of medicine and the arts. 
Bicarbonate of ammonium in conjunction with chloride of 
sodium is employed in the manufacture of carbonate of 
soda, by what is known as the " ammoniacal soda process," 
the only one which has hitherto sustained competition with 
the well-known 11 Leblanc method." 
The ammoniacal soda process was first patented by Dyar 
and Hemming in June 1838, and although the patentees 
used equal weights of chloride of sodium made into a satu- 
rated solution, and powdered commercial carbonate of 
ammonia (which was a mixture of carbonate and sesqui- 
carbonate), they suggest as preferable the employment of AMMONIA. 
113 
bicarbonate of ammonia. The following equation explains 
the decomposition :- 
NaCI + (NH4)H,Co3 = NH4C1 + NaH,Co3. 
The resulting bicarbonate of soda being but very slightly 
soluble in the chloride of ammonium solution, is precipitated 
in crystals, which, after removal of the supernatant liquor, 
are exposed to a temperature of about 7000 Fahr. 
This drives off half the carbonic anhydride of the bicar- 
bonate, as well as a small quantity of carbonate and chloride 
of ammonium, both of which are condensed in a leaden 
chamber, whilst mono-carbonate of sodium remains behind. 
The solution of chloride of ammonium, consisting in great 
measure of that salt with small quantities of carbonate 
and chloride of sodium and carbonate of ammonium, is then 
boiled, whereby the carbonate of ammonium is driven off and 
also condensed in the leaden chamber. The solution is next 
evaporated to dryness, and the residue being mixed with 
carbonate of lime and heated, the ammonium chloride is 
converted into carbonate, which is carried into the same 
leaden chamber, the contents of which are again employed 
for acting upon a fresh quantity of salt, chloride of calcium 
remaining behind. This regeneration of carbonate of 
ammonium makes the process a continuous one. Of the 
various methods founded on the above, that by Solvay, of 
Couillet, near Charleroi, is the only one which has proved 
remunerative. 
Ammonium, Chloride of. NH4C1. Syn. Muriate of 
Ammonia, Sal Ammoniac, Hydrochlorate of Ammonia. 
This salt appears to have been originally obtained in Egypt 
by sublimation from the soot of camels' dung. It has been 
found native in Bucharia, and is sometimes met with in the 
vicinity of coal-mines in which conflagrations have taken 
place, as well as in volcanic districts, where it is associated 114 
ACETIC ACID AID VINEGAR, ETC. 
with lava. In this country it is manufactured chiefly from 
the crude ammoniacal liquors obtained as secondary products 
in the manufacture of coal-gas,* and animal charcoal. 
1. From gas-liquor.-The crude ammoniacal liquor of 
the gasworks is, either before or after distillation,f neutral- 
ized with hydrochloric or sulphuric acid, choice being made 
of that acid which is the cheaper and more easily obtainable. 
When hydrochloric acid is employed, the saturation is 
usually effected by allowing the acid to flow from a wooden 
vessel or tank, lined with lead or gutta-percha, into an 
underground reservoir or tank containing the ammoniacal 
liquor. This vessel has an exit tube passing into the 
chimney or shaft, which carries off the sulphuretted 
hydrogen and other offensive gases liberated during the 
mixing of the liquids. Sometimes the gas liquor is 
accumulated in enormous covered wooden tuns, holding 
from 10,000 to 20,000 gallons or more, and the acid is 
poured in from gutta-percha carboys, raised by cranes, 
and mixed with the liquor by means of powerful 
agitators, the offensive fumes being got rid of either by 
being carried into the steam-engine chimney, or by being- 
made before doing so, to traverse the boiler fire. The 
quantity of acid employed of course depends on the 
ammoniacal strength of the gas-liquor. The usual propor- 
tions are to 2 lbs. of the former to each gallon of the 
latter; but in all cases sufficient acid should be added to 
impart a very faint acid reaction to the mixture. This 
done, the saline solution, now containing chloride of am- 
* It has been calculated that every million tons of coal consumed 
in the London gasworks yields, 9723 tons of ammonium chloride. 
+ The distillation is generally conducted in a large wrought-iron 
boiler, connected with a rude modification of Coffey's still ; the ob- 
ject being to obtain the concentrated liquor as free from tar as prac- 
ticable. AMMONIA. 
115 
monium, is, aftei' repose, ready to be pumped or run off into 
the evaporators. 
The evaporation of the crude saline solution is usually 
carried on in large square or rectangular cast-iron vats, of 
very moderate depth, and from 1000 to 1500 gallons or 
more capacity. These are encased in brickwork, and are 
heated by a furnace, of which the flues pass in a sinuous 
course beneath the lining of brickwork on which the vats 
or pans rest. During the concentration of the liquid the 
tar, &c., which separates and floats upon the surface, and 
which seriously impedes evaporation, is from time to time 
removed by skimming. As soon as the sp. gr. reaches 1'25, 
any excess of acid in the solution is exactly neutralized 
with a little fresh ammoniacal liquor, which not only 
prevents any waste of acid, but precipitates any ferric salt 
that may be present, and would contaminate the ultimate 
product. After being allowed a short time to settle, the 
hot liquor is ready to be transferred to the crystallizers. 
The vessels employed in the crystallization are pans or 
tubs, usually circular, and about seven or eight feet wide 
by two and a half to three feet deep; they are generally 
set on the ground, but sometimes embedded either partially 
or wholly. The saline liquor being pumped or run into 
these vessels at a little below the boiling temperature, 
crystallizes as it cools. Whilst cooling it is occasionally 
stirred or agitated, to prevent the formation of large 
crystals, which would prove inconvenient in the subsequent 
part of the process. The time occupied in the crystalliza- 
tion varies, according to the size of the crystallizers and the 
weather, from three or four to eight or even ten days. The 
mother-liquor of the crystallizers is pumped back into the 
evaporating-pans for further concentration. The crude 
blackish chloride of ammonium obtained as above is con- 
taminated with tarry and oleaginous matter, free acid, 116 
ACETIC ACID AND VINEGAR, ETC. 
water, &c.; from part of which it is freed by exposing it in 
a layer about four inches deep, on a cast-iron plate gently 
heated by a zigzag flue of a small furnace, until all the 
water is expelled; care being taken that the heat never 
rises high enough to volatilize the salt. This operation is 
generally performed under a dome, or the expanded throat 
of a large chimney. The salt will now have become of a 
greyish-white colour, and is ready for the next operation. 
The crude dried salt of the last process is finally purified 
by sublimation. For this purpose cast-iron pots lined with 
clay are employed. These pots, which are heated from 
below and by means of flues running round their sides, are 
Fig. 22. 
shown in the annexed engraving. The crude grey salt is 
beaten down into them until they are about two-thirds filled, 
when the heads or capitols are fitted on, and heat applied. 
The heads, which are very heavy and usually made of lead, 
but less frequently of iron, have the form of a dome or a 
hemispherical cup, with a small tube or hole at the apex, in 
which a plug is loosely placed, to permit the escape of steam. 
They are so made as to fit closely and firmly on the flat rim 
or flange of the sublimers, and are retained in their places 
during use both by their weight and by two or three 
clamps provided for the purpose. They are also furnished 
with three rings, set at equal distances, to allow of their AMMONIA. 
117 
being lifted oft', or moved by means of a pulley and chains. 
Economy both in time and labour is gained by the use of 
subliming pots as large as practicable ; instead of being flat, 
the bottoms of these pots should be raised in the centre.* The 
regulation of the heat is of the utmost importance. If the 
temperature employed be too high, the sublimed salt will be 
contaminated with empyreumatic matter, while some of it 
will be carried beyond the dome and lost; and if it be ex- 
treme, the head may be altogether blown off, and the con- 
tents of the pan scattered about the building; whilst, on the 
other hand, if the heat employed be too low, the resulting- 
cake of sal ammoniac will be soft, spongy, and either grey 
or yellowish. The proper temperature is said to be known 
by two or three drops of water readily boiling, and being 
dissipated in vapour, when placed on the head or cover of 
the sublimer ; but the water should not spit or dance about, 
or be raised by the heat from contact with the metal. The 
usual practice is to keep the fires " briskly up until the sub- 
limers and their surroundings attain a sufficient degree of 
heat; they are then slackened, and maintained at a mean 
temperature."f The sublimation occupies from five to nine 
days; but it is customary to raise the heads once, or even 
twice a week, to ascertain the progress made; the fires 
having been purposely neglected or checked for some hours 
previously. The process is finally stopped before the whole 
of the crude salt in the pots is volatilized; since the heat 
required for that purpose would lead to the decomposition 
of the carbonaceous impurities, and cause them to give off 
volatile hydrocarbons, which would materially lessen the 
purity and beauty of the product. The unsublimed portion 
* " Chemistry as applied to the Arts and Manufactures." 
t Muspratt. 118 
ACETIC ACID AND VINEGAR, ETC. 
in the pots forms a conical mass, which is technically called 
the " yolk." This is shown in the accompanying plate. 
The sublimation having been carried to a sufficient extent, 
the fires are allowed to die out. The domes, after cooling, 
are lifted oft*, and the attached hemispherical cakes or 11 bells " 
of sal ammoniac or hydrochlorate of ammonia are at once 
removed. These vary from two to five inches in thickness, 
and from 45 or 50 lbs. to 1000 lbs. and upwards in weight, 
according to the size of the sublimers in which they have 
been condensed. They are generally nearly pure, except in 
the outer part which has been in contact with the metal. 
From the subliming-house they are taken to the store or 
Fig. 23. 
packing-house, and after having been scraped, tb remove 
the discoloured portion, are either preserved entire, or are 
broken up into convenient pieces, which are then packed in 
casks or barrels. In either state they are then ready for 
the market. 
When sulphuric* acid is used to neutralize the ammoniacal 
liquor, the process is generally the same as when hydrochlo- 
ric acid is employed; but the brown salt obtained by the 
crystallization, and subsequent desiccation, is of course crude 
* Sp. gr. 1'33 to 1-38. AMMONIA. 
119 
sulphate of ammonium, instead of chloride. Before being 
put into the sublimers, the crude sulphate is intimately 
mixed with about an equal weight of common salt. 
When the ammoniacal liquor is found to be rich in 
carbonate of ammonium, gypsum is employed as a source of 
sulphuric acid. 
Another method consists in converting the solution of the 
crude sulphate into a solution of the chloride, during the 
process, by the addition of chloride of sodium. Both these 
methods are described further on. 
2. From bone-liquor, &c.*-The ammoniacal liquor, 
technically called " bone-liquor " or " bone-spirit," and for- 
merly known under the name of 11 spirit of hartshorn," is 
essentially a solution of carbonate of ammonia more or less 
contaminated with volatile empyreumatic oil. Its conversion 
into sal ammoniac may be easily effected by saturating it 
with hydrochloric acid, after first removing the empyreu- 
matic oil floating on the top. Upon the addition of the 
acid a great many solid impurities separate, and these must 
be got rid of by filtration of the liquid through canvas, 
which retains most of them. Two or three filtrations are 
necessary. When by this means the liquor has become clear, 
it is pumped or conveyed into leaden or iron boilers, and 
* The bone-liquor employed in England is chiefly obtained from 
the manufacturers of bone-black or animal charcoal; but on the 
Continent, the liquor obtained by the destructive distillation of 
animal offal, such as blood, flesh, horn, hoofs, woollen rags and waste, 
hair, scrapings of hides, leather cuttings, is employed for the pur- 
pose. The preparatory process by which this liquor is procured is 
essentially the same in each case ; save that with the animal offal 
the temperature should not exceed a red-brown heat, for if it does 
the resulting charcoal is not suited for the manufacture of ferro- 
cyanide of potassium and Prussian blue. These bone-liquors have 
usually a density ranging between 8° and 90 Baume (Ure ; = sp. 
gr. 1'056 to 1'063). 120 
ACETIC ACID AND VINEGAR, ETC. 
evaporated until a pellicle begins to form, when it is pumped 
or run off into the crystallizers, the resulting crystals being 
properly drained and dried. The salt thus obtained may be 
purified either by sublimation or by recrystallization. The 
whole series of processes closely resemble those already de- 
scribed, but they are less troublesome, owing to the absence 
of the tarry and other foreign matters which impede and 
complicate the operation when gas-liquor is employed. 
Another method in use, more especially on the Continent, 
and one equally applicable to any crude ammoniacal liquor 
rich in free ammonia or its carbonates, consists in the em- 
ployment of sulphate of lime instead of sulphuric acid to 
neutralize the alkali. For this purpose the ammoniacal 
liquor is passed through a series of three or four covered 
wooden filters lined with lead, each containing a layer of 
crushed gypsum to the depth of three or form inches. 
These filters are usually set on stages one above another, and 
each communicates with a cistern placed beneath it by 
means of a leaden pipe furnished with a stop-cock. This 
last is not opened until the liquor has remained some little 
time in the filter ; and a pump throws back once, or oftener, 
upon each filter, what has already passed through it, before 
it is allowed to run into the next lower one. The liquor in 
each filter is not allowed to stand higher than from two to 
three inches above the surface of the gypsum ; and the 
lowest or last filter is supplied with fresh gypsum at each 
separate charge of fresh liquor. A little water is lastly passed 
through the filters to wash out the portion of sulphate of 
ammonia absorbed or retained by the filtering media. 
In this way the gypsum of the filters is converted into car- 
bonate of lime at the expense of the carbonate of ammonium 
in the solution; whilst the ammonia of the latter decom- 
poses the gypsum, and becomes converted into sulphate of 
ammonium, which, with some free ammonia, is found in the AMMONIA. 
121 
filtrate. Sulphuric acid is next added to the filtered liquor 
to completely neutralize the free and carbonated alkali still 
existing in it, after which it is evaporated in a leaden boiler, 
with frequent skimming to remove floating oil, until of 
the sp. gr. i'i6o. Common salt, in sufficient quantity to 
convert all the sulphate of ammonium in the liquid into 
chloride by double decomposition, is now added, with con- 
stant stirring; after which the clear portion is eithei- 
pumped or syphoned off into a somewhat deep reservoir or 
tank, where it is allowed to settle. The liquid, after suffi- 
cient repose, is pumped from the reservoir to the boilers and 
evaporated, with frequent agitation, so long as the sulphate 
of sodium now existing in it falls to the bottom in granular 
crystals. These crystals are at intervals scraped to the 
cooler portion of the pan or boiler, whence they are removed 
by copper rakes and shovels into draining-hoppers placed 
near the edges of the pan. The liquor in the boiler is now 
a strong solution of sal ammoniac, but still containing a 
little sulphate of soda, from which it has to be freed by 
crystallization. With this object it is further concentrated, 
and then run or pumped into the crystallizers. In thirty 
or forty hours, or longer, the mother-liquor is run or pumped 
off. The mass of newly formed crystals is then drained 
and slightly washed, first with a little weak solution of sal 
ammoniac, and next with a very little cold water, after 
which they are again well drained. The crude chloride of 
ammonium thus obtained is converted into the pure salt by 
desiccation and sublimation, as before described. 
In France, where this method is very generally employed, 
the sublimation is commonly conducted in stoneware or 
earthenware balloons or bottles coated with loam. These 
bottles, about eighteen to twenty inches in height in 
the body, are either surmounted with inverted cups or 
heads ten or twelve inches high, or simply covered with a 122 
ACETIC ACID AND VINEGAR, ETC. 
tile, in which latter case the sublimate collects in the upper 
part or neck of the balloon, which is so situated as to be 
above the action of the fire. A number of these vessels are 
set on the dome of a furnace, which is perforated with holes 
or slits, to allow the heat to pass through; whilst their 
necks or heads are sheltered from the action of the fire by 
plates of iron or earthenware, having semicircular indenta- 
tions on their edges, so that when placed together they form 
a level surface, through which the necks of the sublimers 
protrude and fit closely. The fire is nicely regulated, so as 
to cause the salts to condense in the upper and cooler part 
of the vessels, or in the heads, as the case may be; and great 
care is taken to clear the necks occasionally with a skewer, 
to prevent choking and consequent bursting of the vessels. 
In Scotland, where a similar process is also commonly 
pursued, the sublimers are generally 11 cast-iron pots, lined 
with fire-proof tiles: the condensation being effected in 
globular heads of green glass, with which each of the iron 
pots is capped." * 
Gas-liquor is chiefly composed of carbonate of ammonium, 
with chloride, sulphate, sulphide, cyanide, and sulphocyanide 
of the same radicle. On neutralization with hydrochloric 
acid or sulphuric acid, these are converted into chloride or 
sulphate of ammonium, according to the acid used. By 
sublimation with chloride of sodium, the sulphate of ammo- 
nium is converted, by double decomposition, into chloride of 
ammonium, which sublimes; and sulphate of sodium, which 
remains in the subliming-pot. A similar change occurs when 
the solution of the sulphate, prior to crystallization, is de- 
composed by the addition of chloride of sodium, or any 
other chloride. When the gas-liquor is at once converted 
into chloride of ammonium by the addition of hydrochloric 
* Ure's "Diet, of Arts, M. and M.," 5th ed. i. p. 143. AMMONIA. 
123 
acid, the sublimation merely purifies the salt. Similar 
changes occur when bone-spirit is employed. 
Chemically considered, this salt consists of equal volumes 
of gaseous ammonia and hydrochloric acid gas condensed 
into the solid form ; or by weight, according to the ammonia 
theory, of- 
Atoms. 
Equiv. wt. Per cent. 
Ammonia (NH.S) .... 
Hydrochloric acid (HOI) . 
I .. 
. I .. 
•• 17 
* 36-5 ■ 
• • 3178 
.. 68'22 
Hydrochlorate of Ammonia (NH3 HC1) . i 
Or, according to the ammonium theory, of- 
Atoms. 
Ammonium (NH4) i .. 
Chlorine (Cl) . . . . . i 
. 53-5 ... 100 
Equiv. wt. Per cent. 
• 18 ... 33-65 
• 35'5 - 66-35 
Chloride of Ammonium (NH4C1) 
• I .. 
• 53'5 • 
.. 100 
The sal ammoniac of commerce is found under the form 
of large white hemispherical cup-like cakes or masses, or 
in large fragments, which are sections of them. It possesses 
a tough, fibrous, crystalline texture, and is very difficult 
to powder. It is odourless, has a saline taste somewhat 
sharp or acrid, and sublimes without either fusion or decom- 
position. It does not attract moisture upon exposure to the 
atmosphere. It slightly reddens litmus ; dissolves in rather 
less than 3 parts of cold water, the temperature of which 
suffers considerable reduction, and in about 1 part of boiling 
water; it is soluble in alcohol; and when carefully crystal- 
lized from water forms distinct octahedra or cubes, usually 
small and aggregated together in rays or feathery masses. 
By slowly evaporating its aqueous solution, it may be some- 
times obtained in cakes an inch in thickness. It is anhy- 
drous. Sp. gr. 1'450 (1-570) (Miller). 
The cakes of commercial chloride of ammonium always 
contain some iron in the form of protochloride when freshly 
sublimed. This speedily becomes converted into perchloride 124 
ACETIC ACID AND VINEGAR, ETC. 
on the outside by exposure to the air. Owing to this cause 
the cakes are generally yellow on the exposed surfaces. 
Chloride of ammonium, when pure, should form a colourless 
solution with water; wholly sublime upon the application of 
heat; and neither chloride of barium nor sulphuretted 
hydrogen should affect its solution. A solution, to which a 
few drops of nitric acid have been added, should not yield 
a blue precipitate with ferrocyanide of potassium. It often 
contains sesquichloride of iron, and sometimes lead; both 
of which may be readily detected by the above tests.' Its 
complete volatility may be easily determined by heating in 
the flame of a candle a small fragment held on the point 
of a knife. 
In the arts, chloride of ammonium, combined with car- 
bonate, is chiefly used in the coating and soldering of metals, 
in the preparation of alloys, and in dyeing. It is often 
mixed largely with snuff, to give it a factitious pungency. 
It is constantly employed in the chemist's laboratory as a 
reagent; and owing to the cold produced during its solution, 
forms an important ingredient in most frigorific mixtures. 
The methods previously described are those by which 
commercial chloride of ammonium is usually if not almost 
entirely obtained; the various improvements or modifica- 
tions from time to time introduced into its manufacture 
chiefly being confined to minor details, and the form or size 
of the apparatus and machinery employed, do not therefore 
affect the general principles on which the processes are 
based. Under this latter head may be mentioned the pro- 
cess which has for its object the entire removal of the iron 
present in the crude salt, part of which, if it be not removed 
before sublimation, becomes volatilized and contaminates 
the ultimate product. To obviate this evil, Mr. Brewer 
passes a few bubbles of chlorine through the hot concen- 
trated solution of the salt, previous to its crystallization, AMMONIA. 
125 
by which the protochloride of iron is converted into the per- 
chloride, which, being acted on by the ammonia always 
present in the liquor, is precipitated as ferric hydrate, with 
the formation of a small additional quantity of sal ammoniac. 
In the application of this method, the only precaution 
necessary is to avoid employing more chlorine gas than is 
necessary to peroxidize the iron, lest a portion of the ammo- 
nia salt becomes decomposed with the evolution of nitrogen. 
The temperature of the liquor is kept up, after the action 
of the chlorine has ceased, until the whole of the brown 
flocculent oxide of iron has subsided, when it is at once 
decanted or filtered into the crystallizers. 
Another modification devised by Wilson is to effect neu- 
tralization of the crude ammoniacal liquor by distilling 
it, and passing the fumes in at the lower end of a hollow 
shaft or column filled with coke, down which the acid trickles; 
the resulting solution of sulphate or chloride of ammonium 
being received in proper cisterns, conveniently situated near 
the base of the column. 
In Mr. Spence's method of obtaining ammonia-salts from 
gas-liquor or bone-spirit, a series of cylindrical boilers or 
reservoirs, usually four in number, are so placed that the 
contents of each upper one may be drawn off into the one 
next below it. Each boiler has an exit-pipe which carries 
the vapour generated in it to that next above it, whilst that 
of the highest boiler passes off to a tank containing the 
acid necessary to form the salt. The top boiler is connected 
with the reservoir of gas-liquor, which is already mixed with 
milk of lime, by a charging pipe furnished with a stop-cock 
turned by a floating ball, so as to keep the surface of the 
liquor constantly at the same height. High-pressure steam 
enters the lower boiler, by which its ammonia is driven 
through the connecting-pipe into the next boiler, and so on 
in succession, until it leaves the highest boiler in a concen- 126 
ACETIC ACID AND VINEGAR, ETC. 
trated state, and thus enters the acid-tank. When this last 
contains moderately strong hydrochloric or sulphuric acid, 
the resulting solution of chloride or sulphate of ammonium 
(as the case may be) is sufficiently concentrated to be at 
once run off into the crystallizers. As soon as the liquor in 
the lowest boiler is exhausted of its ammonia, its contents 
are drawn off, and replaced by that of the next boiler, 
which is followed by a like descent throughout the whole 
series. 
Among improvements having for their object the substi- 
tution of cheap chlorides * for the more expensive commer- 
cial acids, may be mentioned those of- 
i. Mr. Laming ^patent dated 1843), who employs a strong 
solution of chloride of calcium for converting the ammonia 
of gas-liquor into the chloride. 
2. Mr. Hills (patent dated 1846) employs chloride of 
magnesium t in the same way ; and by a subsequent patent 
proposes to convert the ammonia eliminated in the distilla- 
tion of coal into the chloride, by mixing chloride of magne- 
sium with the coal in the retorts, or by introducing the 
chloride into a retort appropriated for the purpose. The 
heat dispels the chlorine of the chloride in the form of hy- 
drochloric acid, and this, uniting with the ammoniacal 
vapour, forms chloride of ammonium, which is retained in 
the liquor of the condenser. From this liquor the salt is 
obtained by evaporation and crystallization in the usual way. 
Mr. Hill's process, it is stated, did not prove a commercial 
success. 
3. Mr. Croll (patent dated 1849) converts the crude 
ammoniacal vapours that issue with the coal-gas from the 
* Particularly such chlorides as are the " waste or by-products " 
of other manufactures. 
+ Of the Epsom salt-works, &c. AMMONIA. 
127 
retorts into the chloride, a solution of which he obtains by 
passing the gas through a solution of crude chloride of manga- 
nese,* consisting of i cwt. of the salt in 40 gallons of water; 
this solution being run into one of the ordinary vessels used 
for purifying the gas. The manganic solution absorbs the free 
ammonia and its salts, converting them into the chloride, 
whilst a corresponding proportion of oxide of manganese is 
precipitated. As soon as the liquor in the purifier is fully 
saturated, it is drawn off, and replaced by a fresh quantity; 
whilst the saturated liquor containing the chloride, after 
subsidence or filtration, is evaporated, and treated as usual. 
The resulting manganic oxide can be reconverted into chlo- 
ride by heating three parts of it with four parts of common 
salt to redness in a furnace for two hours or more; 140 lbs. 
of the mixture thus produced are added to 140 gallons of 
water, and ammoniacal gas is passed into the resulting liquid, 
with the formation of chloride of ammonium. The man- 
ganic oxide left in this second operation, by treatment with 
the required acid, can thus be employed for the production 
of another quantity of the salt. Crude chloride of iron may 
be substituted for the chloride of manganese in the above 
process, or sulphate of manganese, in which case, the pro- 
duct of course will be sulphate of ammonia, instead of the 
chloride. 
4. Mr. Laming (patent dated 1850) also proposes the use 
of various salts and mixtures for retaining and condensing 
the ammoniacal vapour of coal-gas as it passes from the 
retorts through the purifiers. Of these, the principal are 
chloride of calcium, obtained by decomposing chloride of 
iron by means of hydrate of lime; chloride of iron, ob- 
tained by decomposing sulphate of iron with chloride of 
* Owing to the re-generation of this substance into manganic oxide 
by Mr. Weldon's chlorine process, its utilization for the above pur- 
pose becomes impracticable. 128 
ACETIC ACID AND VINEGAR, ETC. 
sodium; chloride of magnesium; a mixture of sulphate of 
lime and sulphate of iron ; or of moist precipitated oxide of 
iron with carbonate of lime, carbonate of magnesia, or mag- 
nesium limestone; or one containing sulphate of magnesia., 
or chloride of magnesium or calcium, or one or more of 
them, in combination with oxide of copper, either with or 
without lime or magnesia, or with both or either of them, or 
their carbonates. These salts or compounds are mingled 
with sawdust, or some other porous substance not acted on 
by the gas, before being put into the purifiers; and after 
they become saturated with the vapour, the newly formed 
chloride or sulphate is washed out of the mass with water. 
Besides the usual sources of commercial sal ammoniac 
and other ammonia-salts, it has been proposed to obtain 
them from guano, peat,* and shale, as noticed under Ses- 
quicarbonate of Ammonia, the substance employed to 
effect the neutralization or decomposition of the ammoniacal 
liquor being in this case either hydrochloric acid or a 
chloride. In France large quantities of ammoniacal salts 
are manufactured from ammonia obtained during the con- 
version of coal into coke, in coke-ovens. This process, as 
well as that for condensing the ammonia given off from 
blast furnaces, is at present attracting much attention 
amongst chemists and manufacturers. 
In Young's Patent (1841) for "obtaining ammonia and 
its salts," a mixture of 2 parts of guano and 1 part of hy- 
drate of lime, or other caustic alkali, after thorough admix- 
ture, is distilled in a vertically placed retort, at a moderate 
heat, gradually increased until the bottom of the retort 
becomes red hot. The ammoniacal portion of the fumes 
evolved is absorbed by the cold water contained in a suitable 
* Peat yields from 22 to 25 lbs. of ammonium salts per ton.-Sir 
R. Kane. AMMONIA. 
129 
condenser, whilst the other gases eliminated by the process 
pass off uncondensed. By subsequently passing carbonic 
acid gas into the liquor of the condenser, a solution of car- 
bonate, bicarbonate, or sesquicarbonate of ammonia is 
formed. By nearly filling the condenser with diluted hy- 
drochloric or sulphuric acid, instead of with water, a solu- 
tion of chloride or of sulphate of ammonia is obtained. In 
the above process ammonium carbonate and hydrocyanic 
acid are frequently the two principal products of the distil- 
lation, and these pass over and are absorbed by the water in 
the receiver, which then becomes a solution of ammonium 
carbonate and cyanide. By neutralizing this liquid with 
hydrochloric acid, and adding to it the necessary quantity of 
ferrous chloride, Prussian blue is formed and precipitated. 
This being separated by filtration, the filtrate which is an 
aqueous solution of ammonium chloride, after the precipita- 
tion of the iron by ammonia, is evaporated and crystallized 
in the usual manner; whilst the Prussian blue, being boiled 
with the requisite amount of caustic potash, and afterwards 
evaporated and crystallized, is converted into ferrocyanide, 
or yellow prussiate of potash. 
Stale urine, saturated with hydrochloric acid or with sul- 
phuric acid diluted with about twice its weight of water, 
yields on evaporation chloride or sulphate of ammonia, ac- 
cording to the acid used. 
Chloride of ammonium is now wholly prepared on the 
large scale, and never by the dealer or retailer, by whom it 
is only occasionally refined or purified in small quantities, 
for chemical and medical purposes. The sal ammoniac of 
commerce is found to be sufficiently pure for all its ordinary 
applications in the arts; but when wanted of greater purity, 
it is broken into pieces, and re-sublimed from an earthenware 
vessel into a large receiver of earthenware or glass. The 
product, which is in a finely divided crystalline state, is popu- 130 
ACETIC ACID AND VINEGAR, ETC. 
larly known as " refined sal ammoniac," " double-refined 
sal ammoniac," and " flowers of sal ammoniac." 
The chemically pure chloride of ammonium may be pre- 
pared -i. By bringing its gaseous constituents-ammonia 
and hydrochloric acid-into contact. During the combina- 
tion much heat and even light are generated, and the 
anhydrous solid salt is precipitated in a minutely divided 
state, which under the microscope is seen to be crystalline. 
2. By boiling a saturated solution of the commercial salt 
with Yoth of its volume of strong nitric acid, till no more 
chlorine is evolved, redissolving the salt which crystallizes 
out on cooling, and again heating the solution with -/^th of 
its volume of strong nitric acid. 
3. It may be also easily and conveniently prepared by 
saturating pure and moderately dilute hydrochloric acid with 
ammonia or its carbonates, and evaporating the solution until 
a pellicle forms, when crystals of the chloride separate as the 
liquid cools. A similar but rather more violent reaction 
occurs when gaseous chlorine is brought into contact with 
gaseous ammonia, or is passed into a nearly saturated solution 
of ammonia or its carbonates; but in this case nitrogen is 
evolved at the expense of the ammonia; moreover, the 
process is attended with considerable danger. 
The manufacture of sal ammoniac is usually a distinct 
business, and is carried on to a very great extent in the 
neighbourhood of London, the London makers supplying 
the chief portion of that used in England. A large quan- 
tity is, however, made at Manchester and Liverpool. A 
small quantity is imported from Germany. That from 
Brunswick is in the form of sugar-loaves. An inferior 
quality is also imported in chests from the East Indies. 
The red bands frequently seen in the sal ammoniac of 
commerce are said to arise from the workmen falling asleep 
and allowing the fire to go down, and then suddenly raising AMMONIA. 
131 
the heat too high.* They consist chiefly of ammonio- 
chloride of iron. To obtain chloride of ammonium free 
from iron, about 5 per cent, of superphosphate of lime, or 3 
per cent, of phosphate of ammonia are added to the crude 
salts before sublimation. 
Ammonium, Citrato of. (NH4)2HC0H.O7. Syn. 
Diammonium Citrate, Citrate of Oxide of Ammonium. 
A concentrated solution of citric acid, gently heated, is 
slightly supersaturated with sesquicarbonate of ammonium, 
in fine powder, and the resulting liquid is crystallized by 
refrigeration in close vessels, or by evaporation in vacuo. If 
heat be employed in the evaporation of the solution, an acid 
citrate will be formed.' 
Chiefly used as a chemical test. An extemporaneous 
citrate, made with lemon-juice and drunk effervescing, is 
employed as a saline draught and a mild aperient and dia- 
phoretic. 
Ammonium, Ferrocyanide of. (NH4)4FeC6N6.3 Aq. 
1. Saturate a solution of hydroferrocyanic acid with ses- 
quicarbonate of ammonium in slight excess ; evaporate the 
solution at a heat below ebullition, and crystallize by re- 
frigeration. 
2. Digest ferrocyanide of lead or of iron in a solution of 
sesquicarbonate of ammonium, at a gentle heat, for some 
time; then filter, evaporate, and crystallize. 
It is isomorphous with ferrocyanide of potassium; it is 
easily crystallizable, very soluble in water, and is decomposed 
by ebullition. 
Ammonium, Molybdate of. (NH4)2MoO4. 1. Native 
sulphide of molybdenum, after being well roasted, is reduced 
to line powder, digested with solution of ammonia, and 
the mixture filtered, and the filtrate evaporated to dryness ; 
* Muspratt. 132 
ACETIC ACID AND VINEGAR, ETC. 
the residue, molybdate of ammonium, is then dissolved in 
water, and purified by crystallization. 
2. Molybdic anhydride is treated with excess of strong 
ammonia in a closed vessel. Alcohol is then added when 
the molybdate is precipitated. This is then dried over 
quicklime. 
Molybdate of ammonium occurs in small white scales, 
soluble in 570 parts of water; the solution reddens litmus 
paper; and dissolves in the alkalies, forming alkaline molyb- 
dates. It is used in the preparation of molybdenum blue and. 
in calico-printing, but the scarcity of the acid precludes its 
extensive employment in the arts. Molybdate of ammonium 
is the salt principally used in dyeing. Silks and cottons passed 
through a solution of this salt, then through a bath soured 
with hydrochloric acid, and, lastly, without washing, through 
another of protochloride of tin, are dyed of a rich and 
permanent blue colour. A solution of molybdate of ammo- 
nium in excess of nitric acid forms a valuable agent as a 
test for phosphates, with which it gives a beautiful yellow 
precipitate of phospho-molybdate of ammonia. 
Ammonium, Nitrate of. NH4NO3. 1. Let nitric acid 
be diluted with 3 or 4 times its weight of water, then 
saturate the mixture with sesquicarbonate of ammonium, 
evaporate by a gentle heat, and crystallize. When the salt 
is not required in a crystalline form, it should be evaporated 
to dryness at about 2120 Fahr. (ioo° Cent.), and the heat 
carefully raised to about 250° Fahr. (121° Cent.) ; the fused 
salt is then poured on to a polished slab of iron or stone, 
and when solidified, broken up and put into bottles. In this 
form it is best fitted for the preparation of nitrous oxide gas. 
2. Or it may be obtained by the double decomposition of 
ammonium sulphate and potassium nitrate. The potassium 
sulphate separates first, and the solution of ammonium 
nitrate is concentrated, and left to crystallize. AMMONIA. 
133 
When the evaporation of the solution is conducted at a 
heat under ioo° Fahr. (37'7° Cent.), the salt is obtained in 
beautiful hexagonal prisms; when at 212°Fahr. (ioo° Cent.), 
in long silky fibres ; when by rapid evaporation and fusion, it 
forms a white, compact, and usually foliated mass. It dis- 
solves in about twice its weight of water; is slightly deli- 
quescent; melts at 2300 Fahr. (xio° Cent.), and is decom- 
posed into nitrous gas and water at 460° Fahr. (238° Cent.). 
It deflagrates, like nitre, on contact with heated combustible 
matter. 
Ammonium nitrate is mostly used as a source of 
nitrous oxide or laughing gas; 1 lb. avoir, yields nearly 
4g cubic feet of gas ; mixed with water, it forms a useful 
freezing mixture. By evaporating its solution to dryness, 
the salt may be recovered unaltered, and employed for 
another refrigeration. Care, however, should be taken not 
to expose it to too great a heat, as at a certain temperature 
it deflagrates with violence. 
Ammonium, Oxalate of, (NH4)2C2O4, may be prepared 
by neutralizing a hot solution of oxalic acid with sesqui- 
carbonate of ammonia ; evaporating and crystallizing. 
Oxalate of ammonium crystallizes in beautiful, colourless, 
long, rhombic prisms, which effloresce in the air; it is 
slightly soluble in cold and freely soluble in hot water; 
heated in a retort, it yields ammonia, carbonate of ammonia, 
cyanogen, and carbonic acid, and oxamide, which sub- 
limes. 
Chiefly used as a test for calcium, with which it produces 
a white precipitate soluble in nitric acid; also to separate 
lime from magnesium, as it does not precipitate the salts of 
this latter metal. 
Ammonium, Sulphate of. (NH4)„SO4. Syn. Sulphate 
of Ammonia. Crude sulphate of ammonia exists in con- 
siderable quantity in the soot from pit-coal; and it is 134 
ACETIC ACID AND VINEGAR, ETC. 
obtained, as a secondary product, from the ammoniacal 
liquor of gasworks and animal charcoal manufactories. 
It is also found native, associated with sal ammoniac, in the- 
neighbourhood of volcanoes, under the name of mascagnine, 
massagnine, or mascagnite ; and a considerable quantity is 
obtained in Tuscany as a by-product in the manufacture of 
native boracic acid. 
i. Saturate dilute sulphuric acid with sesquicarbonate of 
ammonia in slight excess; filter, gently evaporate, and 
crystallize. 
2. Heat the commercial salt with fths its weight of 
strong sulphuric acid till decomposition ensues, then add a 
small quantity of nitric acid, and heat the liquid until it is 
decolourized. 
The common method of making crude sulphate of am- 
monia consists in putting gas-liquor into an iron boiler, and 
passing superheated steam through it into sulphuric acid of 
about 1'36 to 1'40 sp. gr., till the acid is saturated, or nearly 
so, when the somewhat acid solution is run into tanks lined 
with lead, and crystallizes as it cools. 
Ammonium sulphate crystallizes in long, flattened, six- 
sided prisms; soluble in 2 parts of cold and 1 of boiling water; 
fuses, with loss of one atom of water, at about 280° Fahr. 
(1370 Cent.); and is volatilized, with entire decomposi- 
tion, at about 5340 Fahr. (2790 Cent.), giving as result, 
sulphite of ammonium, free sulphurous acid, and nitro- 
gen : by long boiling, its solution becomes acid from loss of 
ammonia. 
The crude sulphate of ammonium is principally used in the 
preparation of sal ammoniac and sesquicarbonate of ammonia, 
and for manure. "A mixture of 10 percent, of this sul- 
phate with 20 per cent, of bone-dust, some gypsum, and 
farm-yard manure, forms a very fertilizing compost, appli- AMMONIA. 
135 
cable to a great variety of soils." * It is also largely employed 
in the manufacture of alum. 
The manufacture of commercial sulphate of ammonia has 
been already explained under Ammonium Chloride. All that 
is necessary is to saturate with sulphuric acid the solution 
of ammonia, crude or otherwise, obtained in the manner 
before described, and then to evaporate the solution until 
the salt crystallizes out. At other times, however, instead 
of adding the acid to the ammoniacal liquor, the latter, 
either at once or after treatment with lime, is sub- 
mitted to distillation, and the evolved alkaline vapour is 
passed into the acid (previously somewhat diluted), con- 
tained in a large receiver or cistern, or a series of them; 
the salt being obtained by evaporation and crystallization. 
The evaporating pans are sometimes heated by steam and 
sometimes by direct exposure to the fire. When the last 
method is used, unless great vigilance be exercised in regu- 
lating the temperature, decomposition of the sulphate of 
ammonia may take place, either with the formation of a 
sulphide which attacks the pan, or the evolution of sulphur- 
etted hydrogen. This quickly manifests itself by its odour, 
and necessitates the lowering or putting out of the fire. 
By re-solution and a second crystallization the sulphate 
is generally obtained sufficiently pure for all commercial 
purposes. The mother-liquor, after being drained from the 
crystals, is returned to the acid cistern. When the salt is 
intended for use as manure, or (unless very rough) for con- 
version into sal ammoniac, this need not be had recourse to. 
When it is required in a higher condition of purity, it should 
be dissolved in hot water, filtered through animal charcoal, 
and re-crystallized. As soon as the crystals form they must 
* Ure. 136 
ACETIC ACID AND VINEGAR, ETC. 
be removed from the solution, drained, and dried on a 
heated fire-clay slab. 
Among modifications and improvements not previously 
noticed may be mentioned-• 
i. That of Dr. Richardson (patent dated January 1850), 
who mixes sulphate of magnesia, with the crude ammoniacal 
liquor, and thus forms a double sulphate of magnesia and 
ammonia, from which he obtains the sulphate of ammonia 
by sublimation. 
2. That of Michiel (patent dated April 1850), who 
prepares sulphate of ammonium by means of oxysulphate of 
lead obtained from galena or native sulphide of lead, by 
exposing it in a crushed state and in thin layers for two or 
three hours, to the heat of a reverberatory furnace. The 
resulting mixture of sulphate and oxide of lead is reduced 
to coarse powder, and well worked up with the ammoniacal 
liquor, when sulphate of ammonium and sulphide and car- 
bonate of lead are formed. The first is removed by treat- 
ment with water, and the residuum serves for the manu- 
facture of lead compounds, or may be reduced to the 
metallic state by fusion with charcoal. 
3. That of Mr. Laming (patent dated August 1852), in 
which a stream of sulphurous acid is transmitted through 
the liquor containing the ammonia, either in the free state 
or as carbonate, by which sulphite of ammonium is formed. 
This salt he oxidizes and converts into the sulphate of 
ammonia, by agitation and free exposure to the air. 
In the manufacture of beet-root sugar, large quantities 
of ammonia are given off during the boiling of the root. 
Renard, who has suggested the utilization of this by con- 
verting it into sulphate of ammonium, has estimated that in 
a beet-sugar factory, in which 200,000 cwts. of the root are 
used yearly, there might be obtained 887 cwts. of the salt. 
Ammonium, Sulphide of (neutral). (NHJ2S. Saturate AMMONIA. 
137 
strong solution of ammonia with pure sulphuretted hydro- 
gen gas ; then add a second portion of solution of ammonia 
equal to that first used, and preserve the resulting liquid 
in a well-stoppered bottle. 
Ammonium, Sulphydrate of. NH4HS. Syn. Sulphide 
of Ammonium, Hydrosulphide of Ammonium, Hydrosul- 
phate of Ammonia. By passing sulphuretted hydrogen 
gas, to saturation, through a mixture composed of strong 
solution of ammonia, i part, and distilled water, 4 parts. 
Prepared as above, sulphydrate of ammonium has a very 
fetid odour. When pure, it is wholly volatilized by heat, and 
does not render turbid a solution of sulphate of magnesium. 
Mineral acids decompose it, with the evolution of sulphur- 
etted hydrogen. By keeping, it decomposes and acquires a 
yellow colour. This yellow coloration does not, however, 
render it unfit for use as a reagent; but it must be borne 
in mind that it will now deposit sulphur when mixed with 
acids. In this state it proves valuable as a reagent to detect 
hydrocyanic acid, and as a solvent to separate metallic sul- 
phides thrown down by sulphuretted hydrogen. It is also 
employed by hairdressers for dyeing hair. 
Ammonium, Sulphocyanide of. NH4CNS. Prepara- 
tion-1. Neutralize hydrosulphocyanic acid with ammonia, 
and gently evaporate the solution to dryness by the heat of 
a water-bath. 
2. Digest hydrocyanic acid with yellow sulphydrate of 
ammonium, and after a time evaporate as before. 
A deliquescent white saline mass, very soluble in water, 
but seldom employed out of the laboratory in a pure state. 
Of late it has been obtained in considerable quantity as a 
crude product of the gas liquors. 
Ammonium. NH4 or (NH4)a. The name given to a 
group of atoms which play the part of a compound basic- 
radicle or metallic element. Although several attempts 138 
ACETIC ACID AND VINEGAR, ETC. 
have been made to isolate this substance, they have hitherto 
not been successful. When sodium amalgam is added to a 
solution of ammonium chloride, sodium chloride is formed, 
and ammonium set free; but this instantly unites with 
the mercury, giving rise to a light, bulky amalgam, which 
is quickly spontaneously resolved into ammonia, mercury, 
and hydrogen. 
Estimation of Ammonia and its Salts.-The estimation of 
the strength of ammonia solutions in commerce, is known as 
Ammonimetry, and depends upon their specific gravities. The 
percentage richness of solutions of ammonia, or of its carbo- 
nates, may be most accurately determined by Alkalimetry. 
For all the ordinary purposes of commerce and of the 
laboratory, the strength of pure solutions of ammonia may, 
however, be inferred with sufficient correctness from their 
density; and to this the term Ammonimetry is usually 
restricted. 
The specific gravity of the sample being found either 
by the hydrometer or specific gravity bottle, in the usual 
manner, its percentage strength may be seen by inspection 
of the table on opposite page. 
If the precise specific gravity sought cannot be found in 
the table, the difference between it and the next greater 
specific gravity must be taken for the numerator of a frac- 
tion, having for its denominator the difference between the 
greater and the next less specific gravity in the table. 
This fraction, added to the percentage of ammonia in the 
column of the table opposite the greater specific gravity, will 
give the true percentage sought. 
A simple means of ascertaining the strength of liquid 
ammonia during its manufacture, is to note the expansion 
the water undergoes by the absorption of the gas. This 
may be easily calculated when it is borne in mind, that 
water fully saturated with ammonia expands from three AMMONIA 
139 
Table.-Exhibiting the, relations between the specific gravity of 
Solution of Ammonia and the percentage strength for every 
variation of '00125 SP- fro™ '87500 to rooooo, at 62° Fahr. 
Abridged from the larger Table of Mr. J. J. Griffin. 
Sp. gr. of the 
Liquid Am- 
inonia. 
Pure Am- 
monia per 
cent., by 
Weight. 
Sp. gr. of the 
Liquid Am- 
monia. 
Pure Am- 
monia per 
cent., by 
Weight. 
Sp. gr. of the 
Liquid Am- 
monia. 
Pure Am- 
monia per 
cent., by 
Weight. 
'87500 
34'694 
•91750 
21'837 
■96000 
10'119 
•87025 
34'298 
■91875 
21'477 
'96125 
9-790 
"87750 
33'9d3 
'92000 
21'118 
•96250 
9-462 
33'5°9 
'92125 
20'760 
•96375 
9''3S 
■88000 
33'ii7 
•92250 
20'403 
•96500 
8'8o8 
■88125 
32'725 
■92375 
20'046 
•96625 
8-483 
■88250 
32'33o 
■92500 
19'691 
•96750 
8-158 
•88375 
31'946 
■92625 
19'337 
•96875 
7'834 
■88500 
31'558 
■92750 
18'983 
•97000 
7'5u 
"88625 
31'172 
•92875 
18'631 
•97125 
7'189 
•88750 
30'785 
•93000 
18'280 
•97250 
6-867 
•88875 
30'400 
•93125 
17'929 
•97375 
6'547 
•89000 
30'016 
•93250 
17'579 
■97500 
6'227 
■89125 
29'633 
•93375 
17'231 
•97625 
5'908 
■89250 
29'252 
•93500 
16'883 
•97750 
5'59° 
■89375 
28'871 
•93025 
16'536 
•97875 
5'273 
■89500 
28'492 
•93750 
16-190 
■98000 
4'956 
•89625 
28'133 
•93875 
15'846 
•98125 
4'641 
■8975° 
27'736 
•94000 
15'502 
■98250 
4'326 
■89875 
27'359 
•94125 
15-I58 
•98375 
4*011 
'90000 
26'984 
•94250 
14-816 
•98500 
3'698 
•90125 
26'610 
•94375 
14'475 
•98625 
3'386 
■90250 
20'237 
•94500 
14'135 
•98750 
3'074 
■90375 
25'865 
•94625 
13'795 
•98875 
2'763 
•90500 
25'493 
•94750 
13'456 
•99000 
2'453 
■9062.5 
25-123 
•94875 
I3'ii9 
•99125 
2'144 
•90750 
24'754 
•95000 
12'782 
•99250 
1'835 
•90875 
24'386 
•95125 
12-446 
•99375 
1'527 
*91000 
24*019 
•95250 
13*111 
•99500 
1*220 
•91125 
23'653 
•95375 
u'777 
•99625 
■914 
•91250 
23'288 
■955oo 
n'444 
•99760 
•609 
■91375 
22*924 
•95625 
1 I'm 
•99875 
■304 
•91500 
22-561 
'9575° 
10'780 
•91625 
22'198 
'95875 
10'449 
tor Water. 
The specific gravity of mixtures of pure solution of ammonia and 
pure water is precisely the mean of the specific gravities of their 
constituents (Davy; Dalton; Christison). In all solutions of 
ammonia, a quantity of anhydrous ammonia, weighing 212J gr., 
displaces exactly 300 gr. of water, and reduces the sp. gr. of the 
liquid to the extent of '00125 (Griffin). The strongest solution of 
ammonia which it is possible to prepare at 62° Fahr, has the sp. gr. 
•87500, and contains 34'694^ of pure ammonia, by weight, or 21,251 
gr. per gallon (Griffin).* 
* Mr. Griffin, in his "System of Ammonimetry," calls every 140 
ACETIC ACID AND VINEGAR, ETC. 
volumes to five. If each receiver be furnished with a gauge- 
pipe, the degree of expansion can be noted. On the small 
scale graduated glass receivers may be used. 
The above method can be controlled by drawing off a 
small quantity of the solution of ammonia under examina- 
tion, taking its specific gravity and referring to the above 
table. 
When the ammoniacal substance consists of pure solution 
of ammonia, or of a salt of ammonia with a feebly volatile 
acid, the percentage content of ammonia may be easily 
determined by saturating the substance with hydrochloric 
acid, driving off the excess of acid and moisture over a 
water-bath at 212° Fahr. (ioo° Cent.), until the residue 
ceases to lose weight, and calculating the ammonia from the 
amount of chloride of ammonium found. The operation 
is, where practicable, preferably performed in a platinum 
dish. 
When the sample consists of an impure or mixed 
substance, the mode of procedure is different. It is as 
follows:- 
A given weight of the sample is placed in a small retort, 
the end of which is made to dip into a vessel containing 
dilute hydrochloric acid. A. strong solution of caustic 
potash is then poured into the retort, and heat applied by 
means of a small spirit lamp. When all the ammonia has 
passed over, the acid solution is evaporated to dryness by 
the heat of a water-bath, and the residuum (chloride of 
ammonium) weighed. Each grain of the chloride thus 
found represents '31804 gr. of ammonia; 53-5 parts of the 
212) gr. of anhydrous ammonia a test-atom ; and every 7 water gr. 
measures a septem. Thus, a gallon of water (= 10 lbs.) contains 
10,000 septems. The degrees of his ammonia-meter range from 1 
to 100, and indicate the number of test-atoms of ammonia in one 
gallon of the liquid. AMMONIA. 
141 
former being equivalent to 17 of the latter. If the article 
for examination be a solid substance (as a salt), it may be 
dissolved in water, or in dilute acid, before being put into 
the retort. 
Or a known quantity of a standard solution of sulphuric 
acid diluted with water may be put into the receiver, and 
the gas passed into it. When this ceases to be evolved, the 
distilled liquid is poured from the receiver into a beaker, and 
a few drops of tincture of litmus being added, it is titrated 
with a standard soda solution, the quantity of which shows 
the amount of acid neutralized, from which data the per- 
centage of ammonia may be easily computed. 
If in the above process, the mixture in the retort shows 
any disposition to frothing, milk of lime may be used for 
the caustic potash solution. 
In accurate experiments in the laboratory, ammonia is 
usually weighed either as chloride of ammonium or as am- 
monio-platinic chloride (NH4C1)„, PtCl4 ; every gr. of the 
latter representing '07614 gr. of pure ammonia. 
The process is performed as follows :-The ammonia salt 
is dissolved in a little water, and hydrochloric acid added to 
faintly acid reaction. The solution is then evaporated over 
a water-bath to dryness. The resulting chloride of 
ammonium is then dissolved in a little water, and neutral 
solution of tetra-chloride of platinum added in not too great 
excess. 
The double chloride of platinum and ammonium thus 
formed is then carefully evaporated in a porcelain dish, at 
a temperature a little under 2i2°Pahr. (ioo° Cent.), nearly 
to dryness. Rectified spirit is then poured upon it, and it 
is allowed to stand for some time. 
The yellow salt which remains undissolved, is then poured 
with the spirit upon a weighed and previously dried filter; 
and washed with rectified spirit until the washings cease to 142 
ACETIC ACID AND VINEGAR, ETC. 
give a yellow colour. It is then dried at a temperature of 
2i2° Fahr. (ioo° Cent.) and weighed; the weight of the 
filter deducted from tire substance plus the filter gives the 
amount of ammonio-platinic chloride found. 
The above results may if necessary, be controlled by 
wrapping up the platino-ammonio chloride in the filter and 
igniting in a covered crucible. From the residue of the 
combustion, which consists of metallic platinum, the 
ammonia may be calculated. In conducting this experi- 
ment the heat must be very gradually raised. 
For the determination of the ammonia in those ammonia- 
cal compounds which are insoluble, recourse must be had to 
the " combustion method." 
Fig. 24. 
This is conducted as follows The sample is first care- 
fully dried over sulphuric acid, in the exhausted receiver of 
an air-pump. Ten or twenty grains are then intimately 
mixed in a warm unglazed porcelain mortar (standing on a 
sheet of clean paper) with ten times its weight of soda-lime.* 
This mixture is introduced into a combustion tube of hard 
Bohemian glass, about 16 or 18 inches long and % inch in 
diameter, with the end drawn out, and sealed as shown at 
a in the engraving. 
* Soda-lime may be made by slaking two parts of freshly burnt 
lime with an aqueous solution containing one part of caustic soda, 
and evaporating to dryness in an iron vessel. The substance so 
obtained is next moderately heated to redness for some time in a 
Hessian crucible; after which, while still warm, it is reduced to a 
moderately fine powder, and passed through a metal sieve. The 
powder should be preserved in a well-stoppered bottle. AMMONIA. 
143 
Into the posterior part of this tube, soda-lime to the ex- 
tent of about an inch has been previously introduced, then 
the mixture. 
The tube is then filled to within about 2 inches of its 
orifice with soda-lime; this last addition being made in 
small quantities at a time, after having been used to rinse 
out the mortar. The tube is then loosely plugged with a 
piece of previously ignited asbestos, and afterwards gently 
tapped on a table or bench, being held meanwhile in a 
horizontal position. By this means, a free passage is 
afforded for the gases which are given off during the 
combustion. 
Fig. 25. 
The tube is then connected by means of a perforated 
cork with a tubular bulb condenser (as shown in the 
engraving) containing moderately strong hydrochloric acid, 
or a known volume of titrated sulphuric acid, as noticed 
above. 
It is of the utmost importance that the apparatus should 
be perfectly air-tight. To ascertain this, a piece of burning 
charcoal is held to the bulb d; if on withdrawing the char- 
coal, after the escape of some bubbles of air into the middle 
bulb, the liquid assumes its original position, the connection 
is sound. The tube is then placed in the combustion-furnace 144 
ACETIC ACID AND VINEGAR, ETC. 
with the bulbs arranged, as shown in the engraving.* The 
furnace is gradually surrounded with glowing charcoal by 
'means of the screen c; the charcoal being first applied to 
the fore part of the tube, and so carried towards its end or 
beak. By this contrivance the ammonia is gradually expelled. 
Its disengagement should take place uninterruptedly, and 
not too rapidly, since directly the evolution of the gas ceases, 
if the tube be allowed to cool evei' so little, the hydrochloric 
acid will ascend into the combustion-tube and spoil the 
experiment. During the combustion, it is necessary to keep 
the anterior part of the tube tolerably hot, which not only 
prevents the formation of certain troublesome liquid hydro- 
carbons, that would pass over into the bulbs, but raises the 
asbestos to such a temperature that it cannot retain water, 
and with the water, ammonia. When the tube is of a full 
red-heat throughout its entire length, and the gas is all 
expelled, the experiment is at an end. 
The point a of the combustion-tube is then broken off, 
and any ammonia remaining in the tube is drawn into 
the hydrochloric acid by suction gently applied at the 
extremity 5 of the bulb condenser. 
The latter is then detached, and its contents emptied into 
a small platinum dish and rinsed out with water, and after- 
wards evaporated to dryness ; the resulting chloride of am- 
monium is dissolved in a little water, and by the addition of 
tetra-chloride of platinum is converted into the platino- 
ammonio chloride as before described, and weighed as such. 
Brom the amount of this, the centesimal quantity of am- 
monia is easily arrived at. 
* Instead of the above, Hoffman's combustion-furnace is now 
principally employed in this analysis, as it allows the heat to be 
more easily and equably regulated, than can be done with the 
charcoal one. AMMONIA. 
145 
For the estimation of very small quantities of ammonia 
the Nessler test is frequently had recourse to. 
This test is applied as follows :- 
Two clear white glass cylinders, as nearly as possible of 
the same height and width, each of 100 cubic centimetres 
capacity, and graduated, are taken. One cylinder being 
filled up to the 100 cubic centimetre mark with the solution 
containing the ammonia diluted with water, if necessary, 
two cubic centimetres of the Nessler solution are dropped 
into it by means of a pipette, and the whole well mixed. 
The liquid immediately becomes of a yellow or brownish 
tinge, according to the amount of ammonia in it. 
Into the other cylinder is dropped from a pipette a certain 
measured quantity of a very feeble solution of chloride of 
ammonium of known strength; after which the cylinder is 
filled up to the 100 cubic centimetre mark with distilled 
water, and 2 cubic centimetres of the Nessler solution added, 
the whole well stirred together. The colours of the two 
liquids are then compared, and if they are judged to be pre- 
cisely the same, the operation is finished. If, however, they 
differ in tint, another experiment with fresh water, standard 
ammoniacal solution, and Nessler solution, must beperformed, 
and this must be repeated until the two solutions agree in 
■colour. The quantity of ammonia which has been used to 
produce this result will of course denote the amount of 
ammonia in 100 cubic centimetres of the ammoniacal solu- 
tion under examination. In applying this test it is always 
best to distil off the ammonia, and to add the Nessler to the 
distillate. If more than 1 milligramme of ammonia be 
present in 100 cubic centimetres of the sample, this will 
become of too dark a colour for the comparison to be satis- 
factorily made.* 
* The plan generally adopted is to prepare standard solutions 
containing I, '09, '08, "07 to 'oi or '005 milligrammes in 100 c.c., 146 
ACETIC ACID AND VINEGAR, ETC. 
Nessler's test is made as follows :- 
Potassic iodide, 35 grammes. 
Mercuric chloride, 13 grammes. 
Distilled water, 800 cubic centimetres. 
Heat the above together to boiling, and stir until solution 
has taken place. To the liquid thus obtained, add a cold 
saturated solution of mercuric chloride, till the precipitate 
produced, just ceases to be dissolved by stirring. Then add 
to this, 160 grammes of solid potassic hydrate, and when 
this has dissolved, dilute with water until the whole measures 
1 litre. Nessler's solution should have a slightly yellowish 
tint. "When colourless it is not sensitive, and more mercuric 
chloride must be added. 
The standard solution of ammonia is prepared by dissolv- 
ing 3'15 grammes of ammonium chloride in 1 litre of dis- 
tilled water. This solution contains 1 milligramme of am- 
monia in 1 cubic centimetre of solution. 
Sometimes, though rarely, the quantity of ammonia is 
determined from the volume of nitrogen eliminated from it, 
of which 14 parts represent 17 parts of ammonia. 
and, having Nesslerized them, to dilute solutions of caramel to the 
same tint, and keep them for standards. The caramel solution keeps 
unaltered for any length of time. CHAPTER III. 
ALUM AND ALUM-MAKING. 
Alum is found native, either effloresced on the surface of 
bituminous alum-schist, as at Gcittwigg, in Austria; or 
united with the soil in the neighbourhood of volcanoes, as 
at Naples, Solfatara, Sicily, and the South of France ; where 
it is obtained by simple lixiviation and evaporation, a little 
potash being commonly added to convert the excess of sul- 
phate of alumina into alum. Native alum is also found in 
certain mineral waters in the East Indies. 
The principal sources of alum are-aluminous shales or 
schists, various kinds of clays, cryolite, bauxite, and felspar ; 
also certain mineral phosphates. In Britain the aluminous 
shales or schists are chiefly used. In the neighbourhood of 
Manchester, coal shale is extensively employed. At Tolfa, 
near Civita Vecchia, where the best Roman alum is produced, 
the source is stratified alum-stone. The manufacture of 
alum is technically said to be conducted according to the 
natural process when prepared from alum-schist or alum- 
ore ; and according to the artificial process, when made by 
acting on clay with sulphuric acid, and adding a potassium 
salt to the resulting lixivium. 
Alum from Alum-buck or Alum-stone.-Alum-rock is 
composed of the elements of potash-alum with an excess of 
alumina in the form of aluminic hydrate, and varying pro- 
portions of silica. It also frequently contains alunite in 
the crystalline form, and sometimes iron pyrites and man- 148 
ACETIC ACID AND VINEGAR, ETC. 
ganese. It is of volcanic origin, and has been produced by 
the action of sulphurous anhydride upon substances which 
contain much felspar. Alum-rock is a frequent constituent 
of the soil at Tolfa, near Civita Vecchia, at Muszag in 
Hungary, in some parts of France, and in some of the 
islands of the Grecian Archipelago. It is by far the most 
abundant source of commercial alum. To obtain alum from 
the alum-rock it is necessary to free it from the silica and 
other foreign substances, as well as from the alumina exist- 
ing in it as hydrate. The mineral is first burnt in kilns or 
iron furnaces, care being taken during the ignition to avoid 
the employment of too high a temperature, as well as the 
direct contact of the rock with the fuel. To attain this 
end the furnace is so arranged that the flame only shall be 
directed upon and through the material. When the vapours 
of sulphuric or sulphurous acid begin to be given off, this 
points to the decomposition of the aluminic sulphate, and 
the mineral must be removed from the furnace. By the 
above process of calcination, water has been expelled from 
the aluminic hydrate contained in the alum-rock, and the 
formation of an insoluble or basic sulphate of aluminum 
thus prevented. After its withdrawal from the furnace, the 
ore is either arranged in long heaps on a clay floor, or thrown 
into brick cisterns, where it is constantly moistened with 
water for two or three months, or until it has attained the 
condition of a soft mud. This mud being put into proper 
vessels, is lixiviated, and the clear solution evaporated down 
till it attains a density of about 1'115; 45° C. (1130 
Fahr.) when it yields alum in crystals. The alum produced 
by this method, which is that followed at Tolfa, is known 
as Roman ahem. 
The first crop of crystals, owing to the presence of a 
minute quantity of peroxide of iron, are of a slight red 
colour. Upon recrystallization, however, they are obtained ALUM AND ALUM-MAKING. 
149 
colourless. The insoluble alumina is left behind at the 
bottom of the lixiviating vessels. The proportion of the 
constituents of alum-rock varies with the localities whence 
it is obtained. Some samples are deficient in potash, in 
which case there is mostly an undue preponderance of 
alumina and sulphuric acid.* 
Alum from Alum-ore, Aluminous Schist or Shale.- 
Alum-ore, schist, or shale, is a bituminous clay slate with 
iron pyrites diffused through it, sometimes in the form of 
bright yellow, golden, or brassy-looking crystals, but more 
frequently in minute black particles. Large beds of alum 
schist are met with near Dusseldorf, in the Harz, in Bohemia, 
Belgium, and the Uralian mountains. 
In this country it occurs in large quantity in the lower 
beds of the coal formation at Whitby, in Yorkshire; and at 
Campsie and Hurlet, near Glasgow. The English and Scotch 
alum-schists are generally deficient in potash; the German 
ones, on the contrary, usually contain it in much larger 
quantity. Hence, whilst the British ores require the 
addition of variable quantities of alkali before they can be 
converted into alum, this is mostly unnecessary with the 
shales and alum earths of Germany. 
The following is the percentage composition of certain 
alum shales:- 
* According to Klaproth, alum-stone from Tolfa, neai' Civita 
Vecchia, consists of-Silica, 56'5 ; alumina, 19; sulphuric acid 
(S03), 16'5 ; potassa, 4; water, 3 ; loss 1 = 100. This exhibits an 
excess of about 3 per cent, of sulphuric acid, and about 14 per cent, 
of alumina more than arc requisite to form alum with the 4 per 
cent, of potash; proportions which therefore require to be supple- 
mented with a potassium or ammonium salt during the process of 
manufacture. According to Cordier, the alum-stone of Mont d'Or 
contains 1'4 per cent, of oxide of iron. 150 
ACETIC ACID AND VINEGAR, ETC. 
Whitby, York- 
shire. 
(Richaedson.) 
Campsie, near Glasgow. 
(Ronalds.) 
Top 
rock. 
Bottom 
rock. 
Top 
rock. 
Top 
rock. 
Bottom 
roek. 
Sulphide of 7 
iron (pyrites)) 
4*20 
8'3o 
Sulphide of 7 
iron (pyrites) $ 
4°'S2 
38'48 
9'63 (?) 
Silica. 
52'25 
iS'i6 
Silica 
15'4° 
i5'4i 
20-47 (?) 
Protoxide of iron 
8'49 
6'n 
Protoxide of iron 
2'18 
Alumina . 
18'75 
18'30 
Alumina . 
n'35 
11'64 
18'91 (?) 
Lime. 
1'25 
2'15 
Lime . 
1*40 
2*22 
■40 
Magnesia . 
•91 
'9° 
Magnesia . 
■50 
•32 
2'17 
Oxide of man-7 
traces 
traces 
Oxide of man-) 
■15 
ganese !> 
ganese 5 
Sulphuric acid) 
Sulphuric acid . 
:°5 
(S03) 3 
1 37 
2 30 
Potassa 
■90 
1-26 
Potassa 
■13 
traces 
Soda . 
* 21 
Soda . 
*20 
traces 
Carbon or bitu- 7 
27'65 c) 
Chlorine . 
traces 
traces 
minous matter J 
V ) 
Coal . 
4'97 
8-29 
Coal . 
8'51 
Water 
2'88 
2'00 
Water 
8 54 
Loss . 
4-60 
w 
Loss . 
2'X3 
3'13 
1'59 (?) 
100 
100 
100 
100 
100 
The mineral is placed in long heaps in the open air, and 
moistened from time to time with water, when it becomes 
gradually hot, and falls into a powdery condition. This 
decomposition commonly occurs either wholly or partially 
on the floor of the mine. If the ore does not possess this 
property on mere exposure to the air and moisture, it is 
broken into pieces, and laid upon a bed of brushwood and 
small coal to the depth of about four feet, when the pile is 
fired and fresh lumps of the alum mineral thrown on, until 
the mass becomes of considerable height and size. The 
combustion, as soon as established, is conducted with a 
smothered fire, until the calcination is complete, care being 
taken to prevent fusion or the disengagement of either 
sulphurous or sulphuric acid, from contact between the 
ignited stones and the carbonaceous fuel.* 
* The generality of alum-minerals require roasting, and their own 
bituminous matter is in many cases sufficient to produce the heat ALUM AND ALUM-MAKING. 
151 
To promote these ends, the heap at the proper time is 
mantled or covered with a layer of already calcined and 
exhausted ore, in order to protect it from high winds and 
heavy rains, as well as to moderate the heat, and let it 
proceed gradually, so that the sulphur present may not be 
lost or wasted by volatilization. The roasting is finally 
checked by a thicker 11 mantling," and the whole allowed to 
cool. When the roasting is completed, the pile is usually 
reduced to about half its original bulk, and has become open 
and porous in the interior, so that the air can circulate 
freely through it. To promote the draught, as the heap 
cools, a little water is sprinkled upon it, which, by dissolving 
out and carrying down some of the saline matter, renders 
the interior still more pervious to the atmosphere. The 
whole, when cold, or nearly cold, is, if necessary, still further 
exposed to the action of air and moisture. The time 
required to calcine the heap properly, including that taken 
by the burned ore to cool, varies, according to its size and 
the state of the weather, from three to nine, or even twelve 
months. 
In order to ensure a continuous supply of calcined ore for 
the lixiviating vessels, the different mounds or ridges are 
kept in all degrees of progress toward completion, from 
being only just kindled, to being thoroughly roasted and 
weathered. 
Dr. Rudolph Wagner says that alum-earths are unfit 
for calcination, unless they have been previously subjected 
to a year's weathering; otherwise there will be a loss of 
sulphate of aluminum amounting to one-sixth. 
required, which need not necessarily exceed 6oo° to 650° Fahr. 
(3i5°-343° Cent.), providedit be continued for a sufficient period. 
It is only when they are less bituminous or carbonaceous, that slack 
or sawdust, &c., is employed. 152 
ACETIC ACID AND VINEGAR, ETC. 
A method of roasting alum-schist, invented by Wilson, 
consists in exposing the purest obtainable ore to the air until 
it becomes disintegrated, and then placing it in an ordinary 
lime-kiln; the calcined earth being removed from the bottom, 
and its place supplied with unburnt shale at the top. In this 
process, great care is necessary to prevent the mass from 
fusing over. The process of calcination completed, the 
burnt ore is next placed in a series of tanks, where it is 
lixiviated. In some parts of Germany certain aluminous 
minerals are lixiviated without previous roasting. The ores 
being arranged in heaps, are exhausted by water, and the 
resulting solution collected in brickwork or clay reservoirs 
at the base of the mound. The crude liquor being condensed 
until it has a density of i'i6o, the alum, sometimes as 
potash, sometimes as ammonia alum, crystallizes out. The 
lixiviating vessels are sometimes made of wood lined with 
lead, and sometimes of stone. They are oblong in shape? 
and in England, France, and Germany, are mostly placed 
one above another. They are usually from 8 to io yards 
in length, 6 or 7 in breadth, and high. In Scotland 
they are arranged on the same level. The lixiviation 
process requires to be conducted with great care and 
judgment, for if too much water be employed, unnecessary 
time, trouble, and expense will be incurred in the subsequent 
evaporation. The objects of the alum-maker are to obtain 
a ley as concentrated as possible, and at the same time to 
exhaust the ore of its saline ingredients. When the tanks, 
usually arranged in sets of 4 or 5, are placed one above 
the other, they are two-thirds filled with roasted ore, and 
the one at the top filled with water, which after from eight 
to twelve hours is let off through a plug in the bottom to 
the next lower tank, and so on in succession through the 
series, by which means the lixivium becomes gradually 
stronger. ALUM AND ALUM-MAKING. 
153 
From the last vessel it is drawn off into a large cistern. 
The lixiviating tanks being meantime recharged with a 
fresh supply of the burnt earth, the first lixivium is pumped 
up into the top tank, and again passed through the series, 
after which it is drawn off into the clarifying vessels. 
Before it is ready for evaporation the lixivium should have 
a specific gravity ranging from 1'113 1,157 01' 1'160. 
When the specific gravity is lower, more shale must be 
added. The exhausted shale is mostly used for mantling 
fresh heaps or ridges. 
In Germany unexhausted shale is economized by subject- 
ing it to another lixiviation, either alone or mixed with 
fresh earth. 
The subsequent treatment of the lixivium depends upon 
the amount of sulphate of iron or copperas it contains. If 
this salt, ■which is an unvarying constituent in all alum-leys, 
should have been found by examination not to be present 
in quantities sufficient to make its collection remunerative, 
the ley is evaporated until of the density of 1'40, at which 
degree of concentration it deposits the sulphate of iron as a 
basic salt. The liquor, the colour of which is brick-red, is 
then run off into proper receptacles, where, after depositing 
suspended matters, it is conveyed into the precipitation 
tanks. When, as very frequently happens, the copperas is 
equal, or nearly equal, in quantity to the alum, it pays the 
alum-maker to collect it, and the preparation of the two is 
carried on together. The iron sulphate, instead of being 
precipitated as a basic salt, is then collected in the crystal- 
line form, after the lixivium, having reached the proper 
point of concentration, has become cool. The following is 
the rationale of the process :-The ley is first evaporated 
with scraps of old iron. The basic sulphate which is thereby 
formed is partly precipitated, setting free, sulphuric acid, 
which acting on a portion of the metallic iron, converts it 154 
ACETIC ACID AND VINEGAR, ETC. 
into sulphate with liberation of hydrogen, which gas con- 
verts the ferric to ferrous sulphate, and prevents during the 
evaporation the further oxidation of the latter into the 
insoluble basic salt. The mother-liquor which is left after 
the removal of the copperas crystals contains the sulphate 
of alumina. The formation of the crystals of green vitriol 
is frequently facilitated by placing branches of trees or 
sticks in the lixivium. By another method, the ley is evapo- 
rated until it has a specific gravity of 1'35 to 1-37, at which 
point the solution becomes a saturated one, and any further 
evaporation causes the rapid deposition of a portion of the 
copperas in the form of very small anhydrous or slightly 
hydrated crystals. Meanwhile the loss of water by evapo- 
ration is constantly replaced by fresh water. By this 
arrangement, whilst the quantity of dissolved copperas can- 
not accumulate, the amount of aluminic sulphate increases 
simultaneously with the precipitation of the copperas, until 
the liquid is saturated with it. To obviate supersaturation, 
which would lead to the deposition of the aluminic with the 
ferrous sulphate, the strength of the liquid at this stage is 
vigilantly noted by means of the hydrometer. The pre- 
cipitated sulphate of iron is then removed, and purified by 
crystallization, when it acquires its 7 molecules of water; 
whilst the aluminic sulphate can be easily obtained from the 
concentrated mother-liquor by crystallization. 
By Weisman's method, the ferric salts are precipitated by 
the addition of a solution of ferrocyanide of potassium ; 
after which the supernatant clear liquor, which is now a 
solution of nearly pure sulphate of alumina, is decanted and 
evaporated for future operations, until it either forms on 
cooling, a concrete mass, which is moulded into bricks or 
lumps, for the convenience of packing; or until it is suffi- 
ciently concentrated to be converted into alum by the addi- 
tion of a salt of potash or ammonia in the usual manner. ALUM AND ALUM-MAKING. 
155 
The product in each case is perfectly free from iron. By 
a similar addition of the ferrocyanide to a solution of 
ordinary sulphate of alumina or alum, the dyer may render 
them free from iron or iron-alum; when, as mordants for 
even the most delicate colours, they are equal to the very 
best Roman alum. 
The above plans of removing the iron salt are sometimes 
replaced by precipitating the alum instead of the sulphate 
of iron, by the addition of alkaline matter to the lixivium. 
The crystalline precipitate is purified by draining, re-solution, 
and recrystallization; whilst the sulphate of iron and Epsom 
salts contained in the mother-liquor, are obtained by subse- 
quent evaporation and crystallization; after which a fresh 
Fig. 26. 
crop of alum may be got from it by the use of an alkaline 
precipitant as before. 
When the ley or lixivium does not contain an excess of 
copperas, it is run from the clarifying vessels into the evapo- 
rating pans. The former are made of tinned or wrought 
iron, oi' lead. The liability of the tinned pans to corrode 
in contact with the ley, of the iron ones to crack, and of the 
leaden ones to melt, has led to the adoption in many alum- 
works of large cisterns of masonry, arched over with the 
same material. 
In the Hurlet works, near Glasgow, these pans are of 
enormous capacity. 
The ley from the calcined shale being first put into 156 
ACETIC ACID AND VINEGAR, ETC. 
the pan, and the furnace-fire at the end lighted, as shown 
in the engraving, the flame and heated air sweep over 
the whole surface of the ley, and cause its rapid evapo- 
ration, the evolved vapours and products of combustion 
escaping by the chimney. The evaporation is continued 
until the liquor has a density of 1'40. A lower density is 
best for those lyes which contain a large preponderance of 
aluminic sulphate. It is of great importance, after the 
evaporation and subsequent cooling of the liquor, that no 
crystals of aluminic sulphate should be found in the liquid. 
The concentrated liquid, being next conveyed to the cool- 
ing-vats, deposits basic sulphate of iron and sulphate of 
lime, whilst the clear or mother-liquor contains sulphate of 
alumina. 
The clear mother-liquor, after being conveyed to other 
pans, is now ready for mixing with the salts of potassium 
or ammonium, by the combination of its aluminum sul- 
phate with one of which, it is converted either into potash 
oi' ammonia-alum. Soda-alum is rarely prepared, as it pos- 
sesses the disadvantage of forming a salt very soluble in 
cold water. The potassium salts preferably used for this 
purpose, are the chloride or sulphate. Of the ammoniacal 
salts, the sulphate obtained from the ammoniacal liquor of the 
gas-works is generally employed. 100 parts of aluminum 
sulphate require for precipitation- 
Potassium chloride . . . 43'5 parts 
,, sulphate . . • 50'9 ,, 
Ammonium ,, . . . 47*8 ,, 
In this country the alum-maker gets his potash salts 
from kelp, carnellite, kainite, and as a waste product in 
the manufacture of beet-root sugar. 
The potassic sulphate occurs as an acid salt, as a second- 
ary product in nitric acid making, as well as when caustic ALUM AND ALUM-MAKING. 
157 
potash and carbonate of potassium are purified. It needs con- 
version into neutral sulphate before it can be employed in 
alum manufacture. In Germany potassic sulphate for this 
purpose, is obtained in abundance from kainite, which 
occurs among the Stassfurt salts. 
Stale urine and the ley of wood-ashes were formerly 
used as precipitants, but these have been abandoned. 
Before the addition of the precipitant to the mother-liquor 
it is necessary to ascertain the amount of the former that 
will be required.' To learn this, an assay of the mother- 
liquor is made by adding to a known quantity, so much of 
the alkaline salt in solution as shall form a liquor of a cer- 
tain density. The mixture is then set aside for a day, and 
the resulting alum being carefully washed in cold water, 
dried, and weighed, affords a criterion as to the amount of 
alkaline salt required for every gallon of mother-liquor. 
This test, however, owing to various modifying circumstances, 
can only be considered an approximate one. According to 
Knapp, more satisfactory results may be obtained by testing 
the mother-liquor with a volumetric solution of one of the 
alkaline salts to be used as precipitants. Knapp considers 
a solution of ammonium sulphate as the best test liquid. 
One part of ammonium sulphate is equivalent to 1'32 parts 
of potassium sulphate, and 1*13 of potassium chloride. 
A saturated solution of the ammonium sulphate being 
prepared, and its strength ascertained, is run from a 
burette on to a measured quantity of the aluminic mother- 
liquor, the mixture being actively stirred after each addition. 
The solution of the ammonium salt must be added as long 
as a precipitate is thrown down. When this no longer 
falls, the number of measures is read off, and by an easy 
calculation the amount of alkaline salt required for a given 
measure of mother-liquor can be arrived at. 
The mother-liquor having been drawn from the evaporat- 158 
ACETIC ACID AND VINEGAR, ETC. 
ing-pans into tlie cooling or precipitating stone cisterns, 
and its strength in aluminic sulphate having been ascer- 
tained, the requisite quantity of the alkaline salt in solution 
is next added to it, the powdery precipitate which is in 
consequence formed, being kept diligently stirred until no 
more powder is deposited. 
The powder technically known as 1' flour," is afterwards 
shovelled from the cisterns on to planks adjoining the 
cisterns ; the planks being arranged on the incline, so that 
the mother-liquor which drains from the powder shall run 
back into the cistern. As this, however, is not sufficient to 
free the flour from adhering impurities,* it is afterwards 
twice washed by being thrown into a suitable tub or tank, 
containing a small quantity of very cold water, the whole 
being gently stirred. By this means the adhering colour- 
ing matter is removed from the powder, and passes into the 
supernatant water, which is syphoned off from the flour as 
soon as this has subsided. 
The washing water, which contains a small quantity of 
alum, is run back into the cistern. Sometimes the hydro - 
extractor or centrifugal machine is used for washing the 
alum powder. In some alum-works the ley containing the 
aluminum-sulphate is drawn from the evaporating-pans into 
the cisterns upon the precipitant. When this method is 
adopted, the resulting alum, which is called "first alum," 
after being drained and washed on sieves, in tubs containing 
second alum mothers, or liquor which has been employed in 
washing in a subsequent stage of the operation, is thrown 
into a second boiler filled with the same kind of mother- 
* These chiefly consist of the chlorides and sniphates of iron 
and magnesia. In some works the liquor containing them is used 
for making impure alum, copperas, or ammonium sulphate. Epsom 
salt or magnesium sulphate is sometimes manufactured from the 
mother-liquor. ALUM AND ALUM-MAKING. 
159 
liquor, and the mixture heated by steam until it acquires a 
certain density. When all the impurities of the boiler have 
subsided, the clear liquor is run off by means of a plug, and 
conveyed to a second series of stone cisterns. After 
remaining in these for some four or five days, the alum 
deposits several inches in thickness on the sides and bottom, 
in the form of crystals, which are broken up, rinsed with 
very pure cold water, and drained. 
The next stage in the process is the conversion of the alum 
flour, or of the broken-up crystals, as the case may be, into 
large ones; these latter being very generally preferred by 
Fig. 27. 
the purchaser on account of their greater purity and freedom 
from contamination. To accomplish this, the flour is first 
placed in large covered wooden vessels lined with lead, and 
boiling water added in quantity only just sufficient to dis- 
solve it; the hot saturated solution which results being, next 
conveyed into the crystallizing vessels, or " roaching-tubs," 
as they are called. Very frequently, instead of boiling- 
water, steam, injected through a pipe let into the bottom of 
the vessel, is used to dissolve the flour, which is so arranged 
on perforated shelves as to expose as large a surface as pos- 
sible to the ascending steam. In some alum factories the 160 
ACETIC ACID AND VINEGAR, ETC. 
vessels are covered with a lid, in which are two openings, 
one of which is for the entrance of the steam, whilst in the 
other a large leaden funnel, with numerous small holes or 
perforations, is fitted. The flour being placed in the funnel, 
the steam is forced into the vessel, and in escaping through 
the funnel dissolves the flour, the concentrated hot solution 
of which falls to the bottom of the vessel, and is conveyed 
to the roaching-casks. In this operation some undissolved 
basic aluminum-sulphate, which is always left in the funnel, 
is added to the first ley, and precipitated. The roaching-casks 
are large wooden, somewhat conically shaped, vessels, lined 
with lead, 6 to 8 feet in height, and 3 or 4 in diameter at 
the top. They are composed of staves, which fit very ac- 
curately one into the other, and are kept together by strong 
iron hoops. The above engraving will convey an idea of 
their construction. 
A week or so (depending on temperature) after the hot 
saturated alum solution has been run into them, the hoops 
and staves are removed, any remaining mother-liquor is 
carried off by gutters into cisterns, and is subsequently 
utilized. 
The alum is then cut into square blocks, and being placed 
in casks, is ready for the market. 
In the previous processes, which may be described as the 
old methods of alum-making, the sulphuric acid of the salt, 
as has been shown, is obtained by the oxidation of the 
sulphur of the iron pyrites present in the alum-earths, 
schists, or shales. Within late years, however, other and 
more expeditious modes of preparing alum have largely 
come into use, particularly in this country. 
These methods, which consist in the direct treatment of 
certain aluminous minerals with sulphuric acid, comprise 
the manufacture of Alum from Clay :- 
1. Process of Allan & Chaptal.-Allan & Chaptal ALUM AND ALUM-MAKING. 
161 
were the first who obtained alum from clay. The 
process occupies a much longer time if uncalcined in- 
stead of burnt clay be employed. Pipe-clay makes the 
best alum. The more quickly the clay is decomposed 
by the acid, the sooner of course is the operation com- 
pleted. In some works there are contrivances for mixing 
the clay and the acid. Sometimes the two are put into 
shallow troughs lined with lead, and heated from beneath 
with flues, the mixture being at the same time kept well 
stirred. In some places the necessary quantity of acid is 
supplied in jets from a pipe pierced with small holes, 
attached to a cistern placed over a tank containing the 
clay, into which the acid falls, the two being mixed by an 
agitator worked by machinery. By the process of Taylor, 
of Bristol, the pipe-clay after being previously calcined and 
mixed with about an equal weight of sulphuric acid of 
specific gravity, 1'20 is run into a tub, in which it is heated 
for twelve hours, or until it attains a density of 1*3, by 
means of a coil of leaden pipe at the bottom of the vessel. 
The pipe is heated by steam, and the temperature main- 
tained at a point a little below that of boiling water. When 
the liquor is of the requisite gravity, it is run off into vats 
and treated with the alkaline liquid in the customary way. 
2. Clay free, or nearly free from carbonate of lime and 
oxide of iron, is chosen for this purpose. It is moderately 
calcined in lumps in a reverberatory furnace, until it becomes 
friable, great care being taken that the heat is not sufficient 
to indurate it, which would destroy its subsequent solubility. 
It is next reduced to powder, sifted, and mixed with about 
45 per cent, of its weight of sulphuric acid (sp. gr. 1*45), 
the operation being conducted in a large stone or brick 
basin arched over with brickwork. Heat is then applied, 
the flame and hot air of a reverberatory furnace being made 
to sweep over the surface of the liquor. The heat and 162 
ACETIC ACID AND VINEGAR, ETC. 
agitation are continued for two or three days, when the 
mass is raked out and set aside in a warm place for six or 
eight weeks, to allow the acid to combine more inti- 
mately with the clay. At the end of this time the 
newly formed sulphate of aluminum is washed out, the 
solution evaporated until of a sp. gr. of about 1'38 if 
for potash-alum, and 1'24 if for ammonia-alum, and the 
alkaline salt added. The remaining operations resemble 
those already described. Good alum may be produced by 
this process, at about two-thirds the cost of rock or mine 
alum. 
3. Process of Pochin.-Fine china clay is heated in a 
furnace with access of air, and mixed with a suitable propor- 
tion of sulphuric acid of sp. gr. 1'52; the latter being 
considerably diluted with water, in order to moderate its 
action, which would otherwise be far too violent. The 
mixture is then passed into cisterns furnished with movable 
sides, where in a few minutes it heats violently and boils. 
The thick liquid gradually becomes thicker, until it is con- 
verted into a solid porous mass; the pores being produced 
by the bubbles of steam which are driven through it, owing 
to the heat resulting from the reaction of the ingredients on 
each other. This porous mass, known as " alum-cake " or 
" concentrated alum," appears perfectly dry, although re- 
taining a large amount of combined water. It also contains 
all the silica of the original clay, but in such a state of fine 
division that the whole appears homogeneous; whilst it 
imparts a dryness to the touch which can scarcely be given 
by pure sulphate of aluminum. From this substance a 
solution of pure sulphate of aluminum is easily obtainable 
by lixiviation and allowing the resulting solution to deposit 
its silica before using it, but for many purposes the presence 
of the finely divided silica is not objectionable. The sulphate 
of aluminum solution is adapted to all the purposes of dyeing ALUM AND ALUM-MAKING. 
163 
for which alum is employed; the sulphate of potash or of 
ammonia in the latter being an unnecessary constituent, and 
one merely added to facilitate the purification and subse- 
quent crystallization of the salt. To obtain alum from the 
porous alum-cake, the proper proportion of acid having 
been used in its preparation, or subsequently added, it is 
only necessary to precipitate its concentrated solution with 
a strong solution of a salt of potash, or of ammonia, or a 
mixture of them, and to proceed then as before. 
The Manufacture of Alum under Pressure.-M. Fau- 
del proposes for the use of paper-makers, alum-cake obtained 
by heating china clay with sulphuric acid under a pressure 
of 2 to 21 atmospheres in leaden vessels. 
i'5 parts of clay, heated to 1350 to 140° Cent, under 
a pressure of 3 to 3^ atmospheres with 1'8 parts of sulphuric 
acid of 1'525 sp. gr., yielded a cake which dissolved almost 
entirely in water. Its composition was- 
Water and impurities . . . '37'5 
Sulphate of alumina . . . . 37 -o 
Silicic acid . . . . . .19'5 
Free sulphuric acid . . . 6-o 
The free acid may be neutralized by the addition of 
alumina. (Dingl. Polyb.} 
From Felspar (by Turner's patent, dated 1842).-By 
this process potash felspar is ground in an edgestone-mill 
until it is as fine as sand, the felspar* being previously heated 
to redness, then plunged in cold water, by which its disinte- 
gration is greatly aided. 
The powdered substance is then treated with its own 
weight of potassium sulphate in a reverberatory furnace, 
previously raised to a red beat. 
* Felspar is a double silicate of aluminum and potassium. 164 
ACETIC ACID AND VINEGAR, ETC. 
When the mixture is in a state of fusion, potassium car- 
bonate, in quantity equal to the sulphate, is next thrown into 
the furnace, and the whole fused to a glass. By boiling with 
water this glass decomposes into a soluble silicate of potash, 
which dissolves, and an insoluble double silicate of aluminum 
and potassium which remains. This double silicate, after 
being well washed with water, is put into a leaden cistern, 
and boiled with sulphuric acid of sp. gr. 1*20 ; potash-alum 
being formed and silica liberated. The silica falls to the 
bottom of the cistern, whilst the supernatant liquor con- 
taining the alum is run off into coolers, when four-fifths 
of it crystallize out. The mother-liquor from the crystals, 
containing some silica, is next evaporated to dryness, and, 
the dry mass being treated with water, alum alone dissolves 
out, leaving the insoluble silica behind. The alum-liquoi* so 
obtained is afterwards sufficiently evaporated to produce 
crystals. 
By employing ammonium or sodium salts, instead of 
potash ones, the corresponding alums may be obtained. 
Alum from Cryolite.-i. Thompson's method.-Cryolite 
or Greenland spar is a double fluoride of aluminum and 
sodium. When decomposed by ignition with calcium car- 
bonate it yields sodium aluminate and calcium fluoride. 
From the ignited mass the aluminate of sodium is obtained 
by lixiviation with water, and carbonic acid gas is passed into 
the solution, when there result precipitated hydrated gela- 
tinous alumina and carbonate of soda, which remains in 
solution. If it be desired to obtain the alumina as an earthy 
compact precipitate, bicarbonate of soda is used instead of 
carbonic acid. While the clear liquor is boiled down for the 
purpose of obtaining carbonate of soda, the precipitated 
alumina is dissolved in dilute sulphuric acid; this solution 
is evaporated for the purpose of obtaining sulphate of 
aluminum (the so-called concentrated alum), or the solution, ALUM AND ALUM-MAKING. 
165 
after having been treated with a potassa or an ammonia salt, 
is converted into alum. 
2. Sauerwein's method is based upon the decomposi- 
tion of cryolite by caustic lime by the wet way. Very 
finely ground cryolite is boiled in a leaden pan with water 
and lime, the purer' the better, and as free from iron as 
possible. The result is the formation of a solution of 
aluminate of sodium and insoluble fluoride of calcium. 
When the fluoride of calcium has deposited, the clear liquid 
is decanted, and the sediment washed, the first wash-water 
being added to the decanted liquor, and the second and 
third wash-waters being used instead of pure water in a 
subsequent operation. In order to throw down the alumina 
from the clear solution very finely powdered cryolite in 
excess is added to the liquid, while being continuously 
stirred : alumina thereby deposits, and fluoride of sodium 
passes into solution. When no more caustic soda can be 
detected in the liquid, it is left to stand until it becomes 
clear. The clarified solution of fluoride of sodium is then 
drawn off, and the alumina treated as described above 
(i. Thompson's method). The solution of fluoride of sodium 
having been boiled with caustic lime, yields a caustic soda 
solution, which having been decanted from the sediment of 
fluoride of calcium, is evaporated to dryness. Recently the 
fluoride of calcium occurring as a by-product, has been used 
in glass-making. 
3. The decomposition of cryolite by sulphuric acid yields 
sulphate of soda, convertible into carbonate by Leblanc's 
process, and sulphate of aluminum free from iron. This 
method of decomposing cryolite is, however, by no means 
to be recommended, as owing to the liberation of hydro- 
fluoric acid peculiarly constructed apparatus is required, 
whilst the sulphate of sodium has to be converted into car- 
bonate. 166 
ACETIC ACID AND VINEGAR, ETC. 
Alum from Bauxite.-This mineral, occurring in some 
parts of Southern France, in Calabria, near Belfast in 
Ireland, and in other parts of Europe, contains about 6oper 
cent, of hydrate of aluminum, more or less pure. In order 
to prepare alum and sulphate of aluminum from bauxite, the 
mineral is first disintegrated by being ignited with carbonate 
of sodium, or with a mixture of sulphate of sodium and 
charcoal; in each case the lixiviation of the ignited mass 
yields aluminate of sodium, from which, by the processes 
already described under " Cryolite," alum or sulphate of 
aluminum and sodium are prepared. 
Alum from Blast-furnace Slag.-Lurmann recommends 
the slag to be decomposed by means of hydrochloric acid. 
From the resulting solution of chloride of aluminum the 
alumina is precipitated by carbonate of lime, any dissolved 
silica being precipitated at the same time. The alumina 
thus obtained is dissolved in sulphuric acid, the silica being 
precipitated and thus separated. 220 lbs. of slag, containing 
25 per cent, of alumina, yield 400 lbs. of alum and 68 lbs. of 
silica. 
Alum from Coal Shales or Schists.-By Spence's method 
(patent dated 1845) alum is obtained from the aluminous 
schists occurring under the coal measures of South Lanca- 
shire. A number of bricks, placed in parallel lines about 
4 inches apart, are so arranged as to form a series of air 
currents. A bed of burning coals is then made upon the 
bricks, and upon these the schist, previously broken into 
small pieces, is piled to the height of 3 or 4 feet. 
More shale is added every day, care being taken to avoid 
allowing the combustion to cease on the one hand, and to 
rise above a red heat on the other, so that the alumina may 
not be rendered insoluble in its subsequent treatment with 
sulphuric acid. 
The calcination requires about 10 days, and if it has been ALUM AND ALUM-MAKING. 
167 
properly conducted, the burnt ore has become soft and 
porous, and of a pale brick colour. The calcined shale is 
put into covered receptacles, each capable of holding 20 
tons, and digested from 36 to 48 hours in sulphuric acid of 
specific gravity 1'35 at a temperature of 2300 Fahr. (no° 
Cent.), the vapour from a boiler containing gas-liquor being 
at the same time passed into the mixture, in which the acid 
must be kept in excess. The ammoniacal salts thus carried 
into the digesters are decomposed by the acid. Any excess 
of ammonia is got rid of by the addition of lime. 
When the liquor has been found by experiment to be 
of the proper degree of concentration, it is removed to the 
coolers, large leaden vessels about 30 feet long, 17 wide, 
and i-9 deep. Here it is stirred continuously, with the 
object of causing small crystals to be formed. These 
crystals are washed with the mother-liquor dripping from 
blocks of alum, drained, and then thrown into a cylindri- 
cal box open at the bottom. Here they encounter a current 
of steam issuing from a perforated lead pipe. 
They are thus rapidly dissolved, the solution flowing into 
wooden tanks lined with lead, where it remains for three 
hours. 
From the tanks it is conveyed to large vessels, in which 
the greater part crystallizes; the liquid, which by condensa- 
tion yields more crystals, being run off by a hole made in 
the bottom of the crystallizing tub or cylinder. 
Alum from Rhodonda Phosphates.-In 1870 Spence 
patented a process for making alum from the Rhodonda 
phosphate, a native compound consisting of alumina with 
phosphate of iron in varying amount, occurring in 
Rhodonda, one of the West Indian Islands. The mineral 
is mixed with coal or coke, and calcined in a kiln in a red 
heat, like lime; or it may be ground and passed through a 
?o mesh to the inch sieve. Spence prefers the first method, 168 
ACETIC ACID AND VINEGAR, ETC. 
since it renders the ore more soluble, and oxidizes part of 
the iron, thereby rendering it insoluble. 
The phosphate prepared by either of the above methods, 
is then placed in leaden vessels and mixed with sulphuric 
acid of the specific gravity i'6, the proportion of acid vary- 
ing with the richness of the mineral in alumina. If it con- 
tains 20 per cent, of alumina, it will require an equal weight 
of acid; if 12 per cent., iths of its weight; and so on in pro- 
portion. 
The mixture is then heated by means of steam being 
blown into it, which causes the ore to dissolve and the 
liquor to acquire an increase of specific gravity. The liquid, 
however, must be carefully diluted so that it does not ex- 
ceed 1'45 specific gravity, or 900 Twaddle. This is done by 
adding water, or the weak liquids which are obtained as the 
operation goes on, the mixture meantime being kept in 
constant ebullition until all the mineral is dissolved, and 
nothing but an insoluble residue is left. The clear liquid 
being then conveyed into closed leaden vessels, steam 
charged with ammonia, and derived from the boiling 
ammoniacal liquor of the gas-works, is next passed into it,, 
from 600 to 900 gallons of gas-liquor being required for 
every ton of the phosphate, according to its richness in 
alumina. The liquid having been charged with the 
requisite quantity of ammonia, is then left at rest for a few 
hours, after which the clear solution, which now has a 
specific gravity of 1'4 (8o° Twaddle), is run into leaden 
coolers, in which the alum crystallizes out. By keeping* 
the liquid in these coolers for some days and frequently 
stirring, the yield of alum is increased. Spence states that 
every ton of the phosphate containing 20 per cent, of 
alumina, produces about tons of alum. After the re- 
moval of the alum from the mother-liquors, these, which 
chiefly contain free phosphoric acid, and the phosphates and ALUM AND ALUM-MAKING. 
169 
sulphates of ammonia, with a small amount of sulphate of 
iron, can be used for manurial purposes, either properly 
diluted or previously mixed with sawdust, the mixture being 
afterwards dried at a low heat. Salts of potash, either 
alone or in combination with ammonia, may be substituted 
for the gas ammonia; the sulphate of potash being pre- 
ferable to the chloride for this purpose, since the latter is a 
deliquescent salt. 
Alum from Boghead Coal-ash.-A process for the 
manufacture of alum from the ash or residue of the com- 
bustion of Boghead coal was patented in 1851 by Barlow 
and Gore ; but although this material contained 20 percent, 
of alumina, it was not found a convenient one for the pur- 
pose. 
Alum from Beet-root Sugar Solutions.-Duncan and 
Newlands' method.-The Beta alba contains a considerable 
quantity of potash salts, which it is essential should be 
removed, when this root is used as a source of sugar. In 
1871 Messrs. Duncan and Newlands, Brothers patented 
a process for getting rid of these salts by treating the syrup 
obtained from the white beet-root with solution of sulphate 
of aluminum. The sulphate of aluminum combines with the 
potash to form alum, which crystallizes out, and is thus 
separated from the saccharine solution. The process is con- 
ducted as follows :-The percentage of ash in the syrup is 
first estimated in the usual manner, by treatment with con- 
centrated sulphuric acid and subsequent incineration and 
weighing, one-tenth being deducted from the weight of the 
ash. Two-fifths of the weight of the ash, after making the 
deduction, are calculated as potash found, and for every 
1 part of potash, 9^ parts of sulphate of aluminum are re- 
quired, unless it has been previously ascertained that the sac- 
charine liquid, or the solution of sulphate of aluminum, con- 
tains sulphuric acid, either free or combined, in which case 170 
ACETIC ACID AND VINEGAR, ETC. 
the quantity of sulphate of aluminum necessary to convert 
the potash into sulphate is, according to the amount of the 
free or combined acid, either entirely or proportionately dis- 
pensed with. Of the 9g parts of the sulphate of aluminum, 
2g parts are required to convert the potash into sulphate. 
The amount of dry sulphate of aluminum having been calcu- 
lated upon the above data, the quantity of solution corre- 
sponding to this may be easily ascertained by consulting the 
following Table :- 
Table giving the percentage of sulphate of aluminum in 
solutions of different densities. 
Baume. 
Specific 
gravity. 
Per cent. 
Baume. 
Specific 
quantity. 
Per cent. 
22i 
1 '184 
34 
28 
1'225 
43 
24 
I-188 
35 
29 
i'235 
44 
244 
I '190 
36 
30 
1'245 
45 
25 
i'i97 
37 
31 
1-256 
46 
254 
1'201 
38 
3I< 
1-261 
47 
26 
I '206 
39 
32 
1 -267 
48 
26J 
I '211 
40 
32a 
1-277 
49 
27 
I'2l6 
4i 
34 
1'288 
5° 
274 
I '218 
42 
■ • 
The percentage amount of potash in the syrup to be 
operated upon having been estimated, the cold saccharine 
liquid is run into a tank, and there is added to it the cor- 
responding quantity of solution of sulphate of alumina, the 
mixture being kept in brisk agitation for from 15 minutes 
to an hour, by means of a mechanical stirring contrivance. 
It is then allowed to remain at rest for 4 or 5 hours, at the 
end of which time, the bottom of the tank is found covered 
with small crystals of potash alum, known as " alum-flour." 
In carrying out this part of the process, in order to 
obtain satisfactory results, as well as to avoid the production 
of glucose, the operation should be conducted-(1) as rapidly ALUM AND ALUM-MAKING. 
171 
as possible, compatible with the proper deposition of the 
alum ; (2) at as low a temperature as possible ; and (3) the 
two solutions should be at the greatest specific gravity com- 
patible with the deposition of the alum. This last condition 
is best fulfilled by using syrup having a density of 38° B. 
and sulphate of aluminum solution at 270 B. 
The crystals of alum having deposited at the bottom of 
the tank, the supernatant liquid is run off by means of 
taps fixed at different heights in the tank, into another 
vessel at a lower level. Here chalk made into a paste with 
water is added to it, and subsequently milk of lime, to com- 
plete saturation. 
To wash and dry the precipitated alum-crystals, a centri- 
fugal machine is used, but a small quantity of syrup is 
always found adhering to the crystals after they have been 
subjected to the action of the machine. However, after 
being mixed with a little cold water, and being a second 
time subjected to the action of the machine, the crystals 
lose the whole of the adhering syrup, and are fit for the 
market. 
In alum-making the least possible quantity of boiling 
water or liquor is employed for making the solutions, so 
that they may crystallize without evaporation, and thus 
economize fuel; and the mother-liquors of previous opera- 
tions are constantly employed for this purpose, when possible. 
Nor is anything which is convertible to use, from the drain- 
age of the heaps to the liquor and slime of the roaching- 
casks, allowed to be wasted. 
By whatever process or from whatever materials alum is 
obtained, it is absolutely necessary for the successful and 
economical conduct of its manufacture, that the precise 
composition of the mineral or minerals employed, should be 
exactly known. This can only be determined by actual 
analysis, which should be extended to several parts of the 172 
ACETIC ACID AND VINEGAR, ETC. 
same bed of shale or earth, and particularly to the upper 
and lower strata, which frequently differ in composition 
from each other, and thus require different subsequent 
treatment, or to be so apportioned as to afford a mixture, 
the essential ingredients of which, shall bear the proper 
ratio to each other. The necessity of this will be seen by 
reference to the composition of certain alum shales, as 
given in the table at page 150, wherein is shown the varia- 
tion in the amounts of iron pyrites, &c., in the top and 
bottom rocks. 
The presence of lime in alum-ore is most prejudicial, 
owing to its affinity for sulphuric acid being greater than 
that of either aluminum or iron. Ores containing it in any 
quantity, are therefore unfitted for the manufacture of 
alum. Magnesia is also prejudicial; but in this case the 
sulphate of magnesia left in the mother-liquors is not 
wholly valueless, as it may often be crystallized and sold as 
" Epsom salt." 
The ammonia-salt used in making alum is, as previously 
stated, generally the crude sulphate prepared from the am- 
moniacal liquor of gas-works, or that from the manufacture 
of sal-ammoniac by the destructive distillation of animal 
matter. Both these liquors may be used without previous 
conversion into sulphate of ammonia whenever there is an 
excess of sulphuric acid in the aluminous solution. 
Soda-salts are seldom, if ever, used as precipitants in the 
manufacture of alum, on account of the easy solubility of 
the resulting soda-alum-a property which unfits them for 
this purpose. 
In estimating the strength of his solution, the alum- 
maker takes as a standard a measure, or specific gravity 
bottle, capable of holding exactly 80 pennyweights of dis- 
tilled water. The excess of the weight of liquor, in penny- 
weights, over 80, or that of water, is called so many " penny- ALUM AND ALUM-MAKING. 
173 
weights strong. Thus one of 90 pennyweights (90 dwt.) 
is said to be " 10 dwt. strong;" or simply, " one of 90 dwt." 
These numbers correspond to degrees of Twaddle's hydro- 
meter, and may easily be found by dividing Twaddle's 
degrees by 2'5 or 2^ : or by multiplying them by 4, and 
pointing off the right-hand figure of the product for a deci- 
mal. The result is in alum-makers' pennyweights. 
Potassium alum crystallizes in regular octahedrons, often 
with truncated edges and angles ; and some- 
times in cubes, but only when there is a 
deficiency of acid in its composition, with 
the alkali in slight excess of the proper 
quantity.* It is slightly efflorescent in dry 
air: soluble in 18 parts of cold water, and 
in rather less than its own weight of boilingf 
water. It is insoluble in alcohol. Alum has a sweet, acidu- 
lous and very astringent taste, is styptic, and reddens 
litmus. Its solution dissolves zinc and iron, with evolution 
of hydrogen. When heated at 1970 Fahr, it melts, loses its 
water of crystallization, and becomes white and spongy, 
forming the substance known as burnt ahem. White heat 
decomposes it, with the evolution of oxygen, sulphurous 
anhydride, and steam; calcined with carbonaceous matter 
out of contact of air it suffers decomposition, and furnishes 
a pyrophoric residuum (Homberg's pyrophorus). When 
alum is ignited with alkaline chlorides, hydrochloric acid is 
liberated; this reaction also occurs when a concentrated 
solution of alum is boiled with the alkaline chlorides. Am- 
Fig. 28. 
* Lowel. 
Potash Alum. 
+ 100 parts of water at 320 Fahr. (0° Cent.) dissolve 3'9 parts 
,, ,, „ 68° ,, (200 Cent.) ,, 15'8 ,, 
„ „ „ 104° „ (400 Cent.) „ 31 -2 „ 
,, „ ,, 2120 ,, (ioo° Cent.) ,, 360'0 ,, 174 
ACETIC ACID AND VINEGAR, ETC. 
monia precipitates pure hydrate of aluminum from potas- 
sium alum, but only a subsulphate from the simple sulphate 
of aluminum; sp.gr. of the crystallized alum, 1'724, but 
when containing ammonia, often so low as 1'710. 
Potassium alum is easily recognized by its crystalline form, 
its taste, and by its complete solubility in water. With 
soda or potash its aqueous solution gives a white gelatinous 
precipitate soluble in excess; a platinum wire moistened 
with the solution, and some solution of nitrate of cobalt, 
imparts a deep sky-blue colour to the blowpipe flame ; and 
chloride of barium gives a white precipitate insoluble in 
nitric acid. 
When pure, solution of alum is not darkened by tincture 
of galls, or sulphuretted hydrogen, or altered in colour by 
ferrocyanide of potassium; nor does it give any precipitate 
with solution of nitrate of silver. 
The principal impurity, and one which renders alum unfit 
for the use of the dyer, is iron. This may be readily de- 
tected by the blue precipitate it gives with ferrocyanide of 
potassium, or the black precipitate with sulphide of ammo- 
nium, both of which are very delicate tests.* Lime, another 
very injurious contamination, may be detected by precipi- 
tating the alumina and iron, if there be any present, with 
ammonia, and then adding oxalate of ammonia to the boiled 
and filtered liquid. The liquid filtered from the last pre- 
cipitate (oxalate of lime) may still contain magnesia, which 
may be detected by the white precipitate caused, on the 
addition of an alkaline phosphate. Common alum fre- 
quently contains ammonia, from urine or the crude sulphate 
of the gas-works having been employed in its manufacture. 
* Good English alum contains less than TVth per cent, of iron; the 
best Boman or Italian alums seldom contain more than y^^ths per 
cent, of iron alum, notwithstanding their exterior colour. ALUM AND ALUM-MAKING. 
175 
Powdered alum is frequently adulterated with common salt, 
in which case it gives a white curdy precipitate with nitrate 
of silver, turning black by exposure to the light. 
The applications of alum in the arts and manufactures 
are numerous and important. It is extensively used in the 
preparation of mordants for dyeing and calico-printing; 
also to harden tallow and faits; to render wood and 
paper incombustible; to remove greasiness from printers' 
blocks and rollers; in the manufacture of the commoner 
kinds of paper; for whitening silver and silvering brass in 
the cold ; to aid in the separation of butter from milk ; to 
purify turbid water : to dress skins; to make lake and pyro- 
phorus; and as a lining, in conjunction witli sulphate of 
lime, for fireproof safes. 
It is also employed by the dishonest baker and the pub- 
lican-the latter using it as an adulterant for gin and beer. 
It is likewise an ingredient in spurious port-wine. 
In medicine, alum is used as a tonic and astringent, in 
doses of from 5 to 20 grains. One drachm of alum to half- 
a-pint of water forms a useful collyrium. In lead colic it is 
administered in doses of I drachm to 1 drachm dissolved in 
gum water, every three or four hours. Dr. Meigs says, 
a teaspoonful in water forms one of the best emetics in 
croup. 
It is also extensively used for clarifying liquors, and for 
many other purposes connected with the arts and wants of 
every-day life. 
Alum, Ammonia. H4N,Al,(SO4)2,i2H2O. Syn. Am- 
monio-aluminic Sulphate. This is an alum in which the 
sulphate of potassium is replaced by an equivalent of sul- 
phate of ammonium. As explained, it is mostly prepared 
by adding crude sulphate of ammonium to solution of sul- 
phate of aluminum. 
Much of the common alum, especially that prepared on 176 
ACETIC ACID AND VINEGAR, ETC. 
the Continent, contains both potassium and ammonium: in 
England it is manufactured in enormous quantities. As 
an astringent, and as a source of alumina in dyeing, it 
resembles potash-alum. It may, however, be readily dis- 
tinguished from the latter by the fumes of ammonia which 
are evolved when it is moistened and triturated or heated 
with caustic potash or quicklime, and by the residuum of 
its exposure to a white heat, being pure alumina; sulphate 
of ammonia, sulphuric acid, and. water having been driven 
oh. z Ammonia alum. 
ioo parts of water at 32° Fahr. (o° Cent.) dissolve 5'22 parts 
,, ,, 68° ,, (2O°Cent.) ,, 13'66 ,, 
,, ,, 1040 ,, (400 Cent.) „ 27-27 „ 
,, ,, 212° ,, (ioo°Cent.) „ 421-90 ,, 
Alum, Basic. A12K2(SO4)2. A variety of alum found 
native at Tolfa. On calcination and subsequent lixivation 
it yields ordinary alum. A similar substance falls as a 
■white insoluble powder, when newly precipitated alumina is 
boiled in a solution of alum. Basic alum is soluble in acetic 
acid. 
Alum, Chrome. See page 178. 
Alum, Iron. KFe(SO4)2,i2H2O. 
Preparation.-Take of peroxide of iron, 9 lbs.; sulphuric 
acid, 14 lbs.; dissolve, dilute the mixture with a sufficient 
quantity of water, and add of potassium sulphate, 10 lbs.; 
evaporate and crystallize. 
It occurs in beautiful octahedral crystals of a pinkish or 
pale violet colour. It has been employed as a mordant in 
dyeing black. 
Alum, Cubical. Syn. Neutral Alum. 
(1) Boil 12 parts of alum and 1 part of slaked lime 
together in water; let settle ; filter, and evaporate the 
filtrate. (2) Add to a solution of alum so much potassium 
or sodium carbonate as will begin to separate the alumina. ALUM AND ALUM-MAKING. 
177 
Neutral or cubical alum is frequently preferred by the 
dyer to common alum, since it has no chemical effect on 
ordinary colours. 
Alum, Roman. Syn. Roach Alum, Roche Alum. 
Roman alum is much esteemed by dyers as being nearly 
free from iron. That sold for it in England, is sometimes 
only ordinary alum coloured with Venetian red, Armenian 
bole, or rose-pink. 
The ordinary alum is coloured by shaking the lumps in 
a sieve over a vessel of hot water, and then stirring them 
up with the colour until the surface is uniformly tinged 
with it. In genuine Roman alum the colour not only covers 
the surface, but also partially pervades the substance of 
the crystals. 
Alum, Sodium. Al,NaSO„i2H„O. Soda-alum is a 
natural product. It also occurs crystallized in the mother- 
liquor of alum, when soap-makers' ley, which contains sodium 
chloride, is used in its preparation. Zelluca says it may 
be obtained by the spontaneous evaporation of sulphate 
of aluminum and sulphate of sodium. It does not occur 
in commerce for the reasons already stated. 
Alum, Sulphate.-The preparation of the crude alu- 
minum sulphate has been previously described. 
Crude aluminum sulphate is known as "concentrated 
alum." The commercial salt always contains free sulphuric 
acid, and frequently small quantities of potassium or 
ammonium alum. Sulphate of sodium has been found in 
that prepared from cryolite. 
Varrentrapp's analyses show that commercial aluminium 
sulphate varies greatly in composition. 
Four samples yielded the following results :- 
1234 
Alumina . . . 15'3 ... 12'5 ... 151 ... 13'0 
Sulphuric acid . . 38'0 ... 30'6 ... 38'0 ... 34'0 178 
ACETIC ACID AND VINEGAR, ETC. 
According to the formula, the quantity of sulphuric acid in 
these samples should have been :- 
i s 3 4 
35'8 ... 29-2 ... 43'3 ... 30-5 
In different parts of the same cake, the quantity of water 
was found to vary between 56 and 48 per cent. 
Alum, Sulphite. A12O3,SO3,4H2O. Dissolve recently 
precipitated aluminic hydrate in cold aqueous sulphurous 
acid; or pass sulphurous anhydride into water in which 
aluminic hydrate is suspended. When the solution is 
heated, the aluminium sulphite separates as a white earthy 
powder, which must be collected on a filter whilst hot, as it 
redissolves on cooling. Aluminium sulphite is insoluble in 
pure water, and becomes converted into sulphate when 
exposed to the air. This salt has been employed for puri- 
fying beet-root juice. 
Alums, other Varieties of.-The aluminium of common 
alum may be replaced by any other metal of the same group, 
such as iron, chromium, or manganese, giving rise to a 
series of salts having potassium alum fortheir type. 
Further, in the newly formed compound, as in potassium - 
alum, the second sulphate may also be replaced under 
similar conditions. The following are some of the chief 
salts of the series :- 
Potassium alum . . KA1(SO,)2,I2H2O 
Sodium ,, . . NaAl(Sd4)2,i2H2O 
Ammonium „ . . I-I4NA1(SO4)2,I2H2O 
Iron ,, . . KFe(SO4)2,12H2O 
Chrome ,, . . KCr(SO4)2,i2H2O 
Manganese „ . . KMn(SO4)2,I2H2O 
All these alums may be prepared by mixing together solu- 
tions of the respective sulphates in equivalent proportions, 
when crystals may be obtained by evaporation in the usual ALUM AND ALUM-MAKING. 
179 
manner. The presence of sulphuric acid in slight excess 
assists their crystallization. 
All the alums crystallize in octahedrons or cubes, and 
they all contain the same number of molecules of water. 
Aluminium. Al=27'5. Syn. Aluminum. This metal 
in various forms of combination, is very abundantly dis- 
tributed throughout nature. Combined with silica it forms 
the basis of all clays. Bauxite is a native hydrate of alu- 
minum, and cryolite a double chloride of aluminium and 
sodium. Plants contain it in minute quantity. 
Aluminium was first isolated by Wohler from its chloride 
in 1827, by igniting the latter with potassium; Oerstedt 
having previously, in 1826, failed to obtain it by the same 
method. Wohler's aluminium occurred as a grey metallic 
powder mixed with malleable tin-white globules. In 1854, 
Deville, who obtained it in a compact form, and in much 
larger quantity, substituted sodium for potassium, over 
which latter, the sodium possesses the advantages of being 
more easily prepared, and of effecting the reduction of the 
chloride with less violence, added to which, a smaller 
quantity is required. 
i. Deville's process for obtaining aluminium was as fol- 
lows :-200 to 300 grammes (about 7 to 10 oz.) of dry 
chloride of aluminium are introduced into a hard glass 
tube, and kept in position by two plugs of asbestos. A 
current of hydrogen, previously dried by being passed first 
through concentrated sulphuric acid, and afterwards through 
a tube containing fused chloride of calcium, is then trans- 
mitted through the tube, the chloride of aluminium being 
at the same time gently heated, so as to get rid of any free 
hydrochloric acid or chloride of sulphur, and quite free from 
air. Two or three small porcelain boats or trays, each con- 
taining about 3 grammes (about 46 or 47 grains) of sodium, 
carefully freed from naphtha by pressure between folds of 180 
ACETIC ACID AND VINEGAR, ETC. 
blotting-paper, are now placed in the tube, and the current 
of hydrogen re-established and continued throughout the 
operation. Heat is then applied to that part of the tube 
containing the sodium, at the same time that the chloride 
of aluminium at the other end of the tube is subjected to a 
regulated heat. When the chloride becomes volatilized and 
the sodium melts, a violent reaction, accompanied with the 
disengagement of much heat and vivid incandescence, takes 
place between the two. The chloride is partially reduced to 
metallic aluminium in the form of small globules, which 
are condensed in the boats, together with the double 
chloride of sodium and aluminium. In conducting the pro- 
cess, it is desirable that the end of the tube in which the 
sodium is situated, should be slightly raised, otherwise the 
melted chloride of aluminium will run down upon the fused 
sodium, and in combining with this latter set up so much 
heat, as to crack the tube. 
When the mass in the boat is cold, and is withdrawn from 
the glass tube, it is transferred to a porcelain one, through 
which hydrogen is passed; the volatile chloride of sodium 
and aluminium is driven over, and the residuum, consisting 
of small globules of aluminium, is lastly reduced to a solid 
mass or button, by fusion at a strong heat, under a layer of 
the fused double chloride of aluminium and sodium. 
The above process is more particularly suited for obtain- 
ing small quantities of aluminium for the laboratory. When 
the metal is required in large quantity, instead of the glass 
or porcelain tube just referred to, two cast-iron cylinders are 
employed, the anterior one of which contains the chloride of 
aluminium, and the posterior one a tray holding the sodium, 
of which io or 12 lbs. are commonly operated on at once. 
These cylinders are united by means of a smaller inter- 
mediate one, filled with clean scraps of iron, which serve to 
separate iron, free hydrochloric acid, and chloride of sulphur, ALUM AND ALUM-MAKING. 
181 
from the vapour of chloride of aluminium, as it passes 
through them. During the passage of the vapour of the 
chloride the smaller cylinder or tube is kept heated to from 
4oo°to6oo° Fahr. (204-4°-260° Cent.), but the two other 
cylinders are only very gently heated, since the chloride is 
volatilized at a comparatively low temperature, and the 
reaction between it and the fused sodium, when once com- 
menced, usually generates sufficient heat for the completion 
of the process. 
Amongst the several processes, many of them patented, 
that have from time to time been employed with varied 
success for the preparation of aluminium on a large scale, 
may be instanced the following :- 
2. MM. Rousseau Freres, & Morin (patent dated 
1856).-10 parts of pulverized chloride of aluminium and 
sodium, and 5 parts of pulverized fluorspar or cryolite, 
are mixed with 2 parts of sodium in small ingots, and the 
mixture thrown on to the hearth of a reverberatory furnace 
previously raised to the required temperature, the dampers 
and doors of the furnace being closed, to exclude air. 
Energetic action soon takes place, accompanied with the 
extrication of so much heat, that the walls of the furnace, 
as well as the mixture, become heated to bright redness. 
The reduction being finished, the mass in a state of fusion 
is run out through an aperture at the back of the furnace. 
The slag flows out first, and this is followed by the aluminium, 
which collects in a mass below the molten slag. With a 
reverberatory furnace and a hearth having a superficies 
of 16 square feet, 16 lbs. of metallic aluminium may be 
obtained at one operation. From the lower layer of slag, 
which consists chiefly of fluoride of aluminium, an additional 
quantity of aluminium in globules may be procured by 
pulverizing the fluoride, and passing it through a sieve. 
Alumina may be prepared from the fluoride. The great 182 
ACETIC ACID AND VINEGAR, ETC. 
advantage of this process is, that the metallic aluminium is 
scarcely contaminated with silicon. 
The process of Messrs. Bell, of Newcastle, is similar. 
They prepared the aluminium and sodium'salts as follows : 
Starting with a trisodic aluminate, which they obtain from 
bauxite, they decompose this by carbonic or hydrochloric 
acid, and by this means obtain hydrate of aluminium. The 
hydrate of aluminium is next mixed with common salt and 
charcoal, and the mass rolled into balls about the size of an 
orange, which are dried. The balls are then placed in 
vertical clay retorts heated to redness, and dried chlorine is 
passed through them. The result of the distillation is the 
double chloride of aluminium and sodium, which is carried 
over into the receiver. 
3. Professor Bose, of Berlin, obtained aluminium by 
fusing cryolite (a natural double fluoride of aluminium and 
sodium) with sodium and common salt. Pulverized cryo- 
lite, 2 parts by weight, is mixed with 1 part of common salt, 
and the mixture is arranged in a perfectly dry earthen or 
iron crucible, in layers alternating with sodium; 2 parts of 
sodium being used for every 5 parts of cryolite, a layer of 
cryolite is placed at top, and the whole covered with com- 
mon salt. The crucible and its contents are then rapidly 
heated in a wind-furnace, until the contents are entirely 
melted, and after being stirred with an iron rod, are left to 
cool. The aluminium generally separates in globules of 
considerable size. The processes of Percy and Dick are nearly 
the same. This method differs from the previous one in dis- 
pensing with the use of the double chloride of aluminium 
and sodium, the process for the preparation of which is a 
very tedious and costly one. The aluminium, however, is 
not so pure. Wohler proposed a modification of Bose's 
plan, which consisted in melting 7 parts of chloride of 
sodium with 9 parts of chloride of potassium. The fused ALUM AND ALUM-MAKING. 
183 
mass was then to be reduced to fine powder, and intimately 
mixed with its own weight of finely pulverized cryolite. 
This powder was then to be arranged in a dry earthen 
crucible, in alternate layers with sodium, in the proportion 
of i part of sodium to 5 or 6 parts by weight of powder. 
The crucible was next to be rapidly heated in a wind- 
furnace. A violent reaction takes place, during which part 
of the sodium is burnt ofi". The mixture was then to be 
heated for another quarter of an hour, until it became 
molten, after which it w'as allowed to cool. The aluminium 
was generally found at the bottom of the crucible in the 
form of a button, and sometimes amounted to a third of 
the proportion present in the cryolite. 
4. In 1856 a process was patented by Gerhard for 
obtaining aluminium by the reducing action of hydrogen 
at a red heat. Fluoride of aluminium, or the double 
fluoride of aluminium and sodium, is placed in shallow 
glazed earthenware dishes. These dishes stand in larger 
dishes containing iron filings. The dishes are then put into 
an oven heated to redness, and hydrogen gas, by means of 
a tube, is passed into the oven, and the heat increased. By 
means of an exit-pipe with a stop-cock, the supply and 
pressure of the gas can be arranged. The hydrogen com- 
bining with the fluorine to form hydrofluoric acid, this is 
absorbed by the iron, and the aluminium is left in the 
metallic condition. Although this process is said to have 
given satisfactory results, it has of late years been aban- 
doned by the inventor for the method by sodium. 
5. Aluminium may also be obtained by electrolysis. 
Bunsex first procured it by this means in 1854. 
Into a red-hot porcelain crucible, divided in two by a 
porous diaphragm of earthenware, he put double chloride of 
aluminium and sodium in a fused state, and then in each 
division he placed the ends of the carbon poles of a Bunsen's 184 
ACETIC ACID AND VINEGAR, ETC. 
battery, consisting of ten elements. The aluminium was 
reduced at the negative pole. In carrying out this opera- 
tion, the aluminium is very liable to be deposited in the 
pulverulent form, unless the temperature in the crucible is 
considerably higher than the melting-point of the salt. It 
is also necessary, all the time the deposition of the metal is 
going on, to keep on adding chloride of sodium to the cru- 
cible, the temperature of which should ultimately be in- 
creased to the melting-point of silver. 
By taking these precautions, the metal may be obtained in 
good-sized globules, which may be fused into a mass by 
throwing the globules into chloride of sodium, at a white 
heat. 
Of the above methods for obtaining aluminium in large 
quantities, those only have been found to answer in which 
the metal is reduced from the double chloride of aluminium 
and sodium, or from cryolite by sodium. Some years back 
there were two manufactories in France for the production 
of aluminium, in one of which the process of Messrs. 
Rousseau Freres & Morin was in operation. Messrs. Bell, 
of Newcastle, have given up its preparation for some years. 
In the preparation of aluminium the employment of too 
high a temperature is a frequent cause of failure. Whilst 
this may be avoided by care, the difficulty of eliminating 
certain foreign matters is not so easily overcome, owing to 
the facility with which these are taken up during its pre- 
paration from the material of which the apparatus is made, 
and from the substances from which it is prepared, which 
are seldom absolutely pure. 
Indeed, it is not too much to assert that chemically pure 
aluminium has not yet been obtained, and that even a very 
close approximation to it is of very rare occurrence. If a 
copper boat be used to hold the sodium, the product will be 
contaminated with copper. Again, chloride of aluminium ALUM AND ALUM-MAKING. 
185 
always contains chlorides of iron and silicon, both of which 
are volatile, and probably it takes up a further portion of 
impurity from the porcelain or earthenware of which the 
apparatus is formed. Then sodium is seldom uncontaminated 
with carbon or some compound of it; in which case, and 
also when it is not carefully freed from the naphtha in which 
it has been preserved, the resulting aluminium will contain 
carbon. The crucible, whether of porcelain or iron, in which 
the final fusion is made, also contributes to contaminate the 
metal. Hence the inferior whiteness and brilliancy of com- 
mercial specimens of aluminium. Commercial aluminium 
contains from 88 to 94 per cent, only of pure aluminium, 
and from 1 to 4 per cent, of iron, to 3 per cent, of silicon, 
and from-4 to 6 per cent, of copper. 
Pure aluminium resembles silver in colour and appearance, 
but is not so white or lustrous. The less pure varieties have 
a slightly bluish tint, somewhat like that of zinc. Aluminium 
is capable of receiving a fine polish. It has a specific gravity 
of 2'56, which by hammering may be raised to 2'57. It is 
both ductile and malleable, and may be rolled into thin 
sheets or drawn out into fine wire. By rolling, it becomes 
hard and elastic. 
Aluminium fuses at a temperature between the melting- 
points of zinc and silver, and when in the molten state may 
be easily run into moulds of metal or sand. Although 
when in the form of bars, it is an extremely sonorous metal, 
it does not possess this quality if cast into bells. It is a 
good conductor of electricity. It is not affected by either 
damp or dry air, or by oxygen at ordinary temperatures. 
Water, whether cold or boiling, has no action on it, and 
even steam at a red heat, only slowly oxidizes it. It is not 
acted on by concentrated nitric acid at ordinary tempera- 
tures, and only very slowly by the boiling acid; nor by 
dilute sulphuric acid, sulphuretted hydrogen, and the sul- 186 
ACETIC ACID AND VINEGAR, ETC. 
phides. It is, however, readily dissolved by hydrochloric 
acid, both concentrated and dilute, with the evolution of 
hydrogen, even in the cold, and by solutions of the alkalies, 
especially when assisted by heat. Commercial specimens of 
aluminium, owing to the presence of iron, silicon, and fre- 
quently of zinc, usually tarnish in damp air, and possess the 
properties of pure aluminium in a somewhat diminished 
degree. Those specimens which contain iron are more 
readily soluble in acids than the pure metal. 
In a finely divided state, aluminium, when heated to red- 
ness, catches fire and burns with great rapidity in the air, 
and in oxygen gas with intense brilliancy, the product in 
each case being alumina. 
Aluminium unites with many metals, and forms alloys, 
some of which give promise of technical value. An alloy 
of 100 parts of aluminium with 5 parts of silver, may be 
worked like the pure metal, but is harder and susceptible of 
a finer polish, whilst its property of not being affected by 
sulphuretted hydrogen and acids, remains unimpaired ; even 
3 per cent, of silver is said to be sufficient to impart to it 
the full brilliance and colour of pure silver. An alloy con- 
taining 10 per cent, of gold is softer and scarcely so malleable 
as the pure metal. With 6 per cent, of iron or 10 per 
cent, of copper it still remains tough and malleable; but a 
larger proportion of either of these metals renders it 
brittle. 
The presence of 2 or 3 per cent, of zinc or tin destroys 
its ductility and malleability, and also impairs its colour and 
lustre; whilst less than even $ per cent, of bismuth renders 
it brittle in a high degree. Small quantities of aluminium 
added to other metals, change their properties in a very 
remarkable manner. Thus, copper alloyed with 10 per 
cent, of aluminium has the colour and brilliancy of gold, is 
harder than bronze, very malleable, and may be worked at ALUM AND ALUM-MAKING. 
187 
high temperatures easier than the best varieties of iron. Made 
in these proportions, it forms cduminiiMn bronze, and is used 
as a substitute for gold ; with 20 per cent, it is quite white, 
and closely resembles silver; with more than 12 per cent, 
of aluminium the alloy is harder, but brittle. The alloy 
formed of 100 parts of silver with 5 parts of aluminium is 
as hard as the silver of our coinage, whilst the other pro- 
perties of the latter metal remain unaltered. 
The alloys of aluminium may be obtained by the process 
of Benzon. This method, which was patented by the 
inventor in 1853, consists in (1) heating alumina with an 
oxide of the other metal, both in equivalent proportions ; 
(2) or by heating alumina with the other metal in a free 
state, likewise in equivalent quantities, and with carbon in 
slight excess. The materials in both cases must be finely 
pulverized. The solder employed in working aluminium is 
an alloy consisting of copper 4 j parts, aluminium 6, and 
zinc 90. No flux is required. 
Hulot gets ovei' the difficulty of directly soldering 
aluminium by coating the surface with copper by electro- 
lysis, and then applying solder in the ordinary way. 
Although, from its properties, aluminium seems adapted 
for many useful every-day purposes, its employment has of 
late years, fallen into comparative disuse. At one time the 
eagles which adorn the standards of the French army were 
made of it, as well as cornets-a-piston, for which latter 
articles, its sonorousness especially adapted it. It is now 
only occasionally used for certain articles of plate and 
jewellery. At present its chief applications are in the 
manufacture of optical and surgical instruments, and 
the smaller decimal weights employed in the chemist's 
laboratory. 188 
ACETIC ACID AND VINEGAR, ETC. 
Salts of Aluminium. 
With the exception of the chloride, the ordinary alum- 
inium salts are generally colourless. Their solutions have a 
strongly astringent, somewhat sweetish taste, and an acid 
reaction. This last characteristic, joined to the tendency of 
its oxide to unite with basic oxides, indicates the possession 
by alumina of acid properties. In solution, the salts of 
aluminium are distinguished as follows :-Ammonia and the 
alkaline carbonates throw down a bulky white precipitate of 
hydrate of aluminium, which is nearly insoluble in excess 
of the precipitant. Caustic potash and soda give gela- 
tinous white precipitates, freely soluble in excess of the 
precipitant, from which the hydrate of aluminium is re- 
precipitated by chloride of ammonium, even in the cold. 
Phosphate of ammonium gives a white precipitate; iodide 
of potassium also a white one, passing into a permanent 
yellow. Bisulphate of potassium added to concentrated 
solutions, causes a precipitate of octahedral crystals of potash- 
alum. The salts of aluminium part with some of their acid 
at a red heat, and with most, if not the whole of it, at a 
white one. Aluminium compounds ignited on charcoal 
before the blowpipe, and afterwards moistened with a 
solution of nitrate of cobalt, and again strongly ignited, 
give an unfused mass, which on cooling appears blue by 
day and violet by candlelight; a test, however, which is 
inapplicable to fusible compounds of aluminium, and such 
as are not free, or nearly free, from other oxides. 
Aluminium, Acetate of. Syn. Acetate oe Alumina.- 
i. Pure hydrate of aluminium is digested to saturation in' 
strong acetic acid in the cold, and the resulting solution, 
after being filtered or decanted, is either evaporated by a very 
gentle heat to a gelatinous semi-solid consistence, or pre- 
served in the liquid state. ALUM AND ALUM-MAKING. 
189 
By spontaneous evaporation it may be obtained in long- 
transparent crystals. It is mostly met with in the gela- 
tinous semi-solid form. 
2. It may also be prepared by double decomposition 
from sulphate of aluminium and acetate of lead, baryta, 
or lime. The liquor separated from sulphate of lead is 
evaporated to dryness by a gentle heat. 
When a solution of acetate of aluminium is evaporated 
in contact with air, a basic acetate, which is insoluble in 
water, is formed, acetic acid being driven off. The feeble 
attraction between its acid and base constitutes its value as 
a mordant. 
Aluminium, Chloride of. A13C16. Syn. Sesquichlo- 
ride of Aluminum. A thick paste made of dry pre- 
cipitated alumina,* lamp-black, and oil, is made into pellets, 
and strongly ignited in a covered crucible, until all the 
organic matter is carbonized. The residuum, consisting 
of alumina and carbon, is then transferred to a porcelain 
tube or tubulated retort placed in a furnace; to the end of 
the retort next the furnace is attached a dry receiver. At 
the other end is an apparatus for evolving chlorine. The 
furnace being heated to redness, the chlorine, dried by being- 
carried through calcic chloride, is passed into the retort, and 
the resulting aluminic chloride is condensed in the receiver 
as a solid mass. 
2. On the large scale, chloride of aluminium may be 
made by passing dried chlorine gas into an iron retort or 
cylinder heated to redness, containing a mixture of alumina 
or clay, lamp-black, and tar, which has been previously 
calcined. The retort is connected with a cool chamber lined 
with tiles of earthenware. The vapours of the chloride of 
* Obtained by adding an alkaline carbonate to a hot solution of 
alum. 190 
ACETIC ACID AND VINEGAR, ETC. 
aluminium which are given off, condense in this chamber as 
a yellowish crystalline mass. Clay containing much iron 
must be previously roasted with coal or coke, and afterwards 
treated with a dilute acid. By this means the iron which 
becomes reduced to a metallic state, may be dissolved out. 
Aluminic chloride is volatile at a dull red heat, extremely 
deliquescent, and very soluble in water. Its chief use is in 
the prepartion of aluminium. 
Although alumina, like magnesia, is freely soluble in 
hydrochloric acid, the chloride of aluminium contained in 
this solution cannot be obtained in the anhydrous state, or 
even the solid form, by its evaporation ; as the chloride then 
undergoes decomposition with the formation of hydrochloric 
acid, which is volatilized, and alumina, which is left behind. 
Aluminium, Oxide of. (A12O3.) In the native state, 
alumina, nearly pure, is met with as corundum. This 
mineral, which occurs crystallized in six-sided prisms, is 
generally regarded as a sesquioxide of aluminium. In this 
form it has a specific gravity of 3-95 ; ranks in hardness 
next the diamond, and will cut glass. The ruby, sapphire, 
and topaz are varieties of corundum, coloured with small 
quantities of potassium chromate. Hyaline is a colourless 
variety of corundum. Emery, another native product, con- 
sists of alumina coloured with iron and manganese oxides. 
The mineral diaspore is a monohydrate, and turquoise a 
hydrated native phosphate of alumina. 
Alumina may be prepared artificially by any of the follow- 
ing formulae:- 
1. Alum is dissolved in about 20 times its weight of 
distilled water, and the solution is dropped slowly into 
pure solution of ammonia, until the latter is nearly but not 
entirely saturated, when the whole is set aside for some 
time. The clear supernatant liquid is then decanted, and 
the gelatinous precipitate is carefully and thoroughly washed ALUM AND ALUM-MAKING. 
191 
three or four times, with tepid distilled water ; after which 
it is collected on a filter, again well washed with water, and 
lastly, pressed and dried between bibulous paper, either 
without heat, or at a temperature not higher than 120° 
Fahr. (490 Cent.). The product is hydrate of aluminium. 
This hydrate may be converted into anhydrous alumina by 
exposure to a white heat in a covered crucible. The residuum, 
after ignition, is pure anhydrous alumina, or sesquioxide of 
aluminium. 
2. A boiling solution of alum is precipitated with car- 
bonate of ammonia, excess of the latter being avoided, and 
the resulting precipitate, after being thoroughly washed, is 
ignited. 
3. Ammonia alum, after being strongly ignited for some 
time, loses its water, ammonia, and sulphuric acid; anhy- 
drous alumina being left. 
Traces of sulphuric acid, however, are frequently present 
in alumina prepared by this method. 
4. By the ignition of sulphate of alumina. 
Alumina prepared by any of the above methods contains 
iron. To free it from this, Deville recommends the 
alumina to be dissolved in caustic alkali, and the iron to be 
precipitated by sulphuretted hydrogen. The supernatant 
liquid is then to be poured off", and reprecipitated by passing- 
carbonic acid through it. The alkaline carbonate, which in- 
variably accompanies the alumina so obtained, may be sepa- 
rated by digesting the alumina in a small quantity of dilute 
hydrochloric or nitric acid with the aid of heat. 
At all temperatures below that of the flame of the oxy- 
hydrogen blowpipe, factitious alumina is incapable of fusion. 
When exposed to the heat of the inflamed mixed gases, it 
melts into a colourless transparent crystalline mass resem- 
bling corundum. If, before the artificial alumina is sub- 
jected to fusion, a small quantity of potassium chromate be 192 
ACETIC ACID AND VINEGAR, ETC. 
placed in the crucible, the product of the fusion bears a 
great resemblance to the natural ruby. Similarly Deville 
has produced artificial sapphire. Alumina exposed to a 
moderately red heat, assumes the form of a light powder, 
soft to the touch. Anhydrous alumina is absolutely inso- 
luble in water, and also, after being strongly ignited, in most 
acids, concentrated hydrochloric or sulphuric excepted. In 
the crystalline state all acids fail to dissolve it. In both 
states it becomes soluble after fusion with caustic potash or 
soda. 
Aluminium Silicate. A substance which in its hydrated 
form is the chief and characteristic constituent of common 
clay. According to Brongniart and Malaguti, the essential 
and predominant ingredient of most varieties of clay is a 
hydrated aluminic silicate, having the formula A12O3 (SiO2)2, 
2H2O. Clay is formed by the disintegration of felspathic 
and silicious rock, by the combined action of air and water. 
Its plasticity when moist, and its capability of being made 
hard by heat, are properties which render it available for 
many useful purposes. The purest kind of clay is kaolin 
or china clay, which consists almost entirely of aluminium 
silicate. It is found in China; but a precisely similar sub- 
stance is obtained from deposits met with at St. Austel in 
Cornwall, and at St. Yrieix in France. Pipeday, a white 
clay nearly free from iron, is found in large quantity in the 
Isle of Purbeck : as its name indicates, it is used in the 
manufacture of tobacco-pipes. 
Potters' day, known as blue day, is found in many parts 
of the United Kingdom; that of Devonshire and Dorsetshire 
is much valued. It is used in porcelain-making. Loam, 
which is a much more mixed variety of clay, is used in 
making bricks ; it contains a large quantity of ferric oxide. 
Yellow ochre and red bole mostly consist of aluminium 
silicate, coloured with varying quantities of ferric oxide. ALUM AND ALUM.MAK1NG. 
193 
Fullers earth is a porous aluminic silicate or clay, found in 
large quantity at Reigate in Surrey. The constituents usually 
present in the ordinary varieties of clay used in the arts, are 
hydrated aluminic silicate, potash, lime, magnesia, and oxide 
of iron. The proportions in which these ingredients are 
present in different kinds of clay vary greatly, a cir- 
cumstance which largely influences the character of the 
compound. 
Thus, if lime, magnesia, or peroxide of iron predominate, 
the clay will be a very fusible, but not a plastic one. It 
will also be more easily acted upon by acids. An excess of 
silica, on the contrary, renders the clay less fusible. 
Pure clay is insoluble in water, and is very slowly attacked 
by nitric, or hydrochloric acids. When heated with sul- 
phuric acid, it is decomposed, aluminic sulphate being formed; 
this reaction being that which takes place in alum-making. 
Clay possesses considerable absorbent properties, by reason 
of which it is able to abstract and store up, as nutriment 
for growing crops, ammonia, applied in the form of manure 
to the surface. Way found its attraction for ammonia so 
powerful, that whilst sulphate and chloride of aluminium in 
solution were partially decomposed by the lime of the clay, 
with formation of a corresponding amount of sulphate or 
chloride of calcium, which passed into the liquid, the 
ammonia was retained by the clay. 
Aluminium Sulphate. A12(SO4)3,H2O8. Syn. Sesqui- 
sulphate of Aluminium, Neutral Sulphate of Aluminium. 
Pure aluminium sulphate may be prepared by saturating 
dilute sulphuric acid with hydrate of aluminium, gently 
evaporating and crystallizing. 
The preparation of the crude sulphate is described under 
Alum. INDEX. 
A 
Acetate of alumina, 53 
ammonia, 54 
baryta, acetic acid from, 14 
of lead, 57-60 
acetic acid from, 9, 15 
lime, 48 
brown, 48 
grey, 48 
manganese, 61 
potash, acetic acid from 8, 16 
soda, 48, 49 
acetic acid from, 5 
tin, 61 
zinc, 62 
Acetates, 52 
by Pauer's process, 47 
of copper, 54, 55 
of iron, 56 
of lead, basic, 60, 61 
Acetic acid, 1 
anhydrous, 62 
condensers, 31, 32 
from the acetates, 15 
acetate of baryta, 14 
copper, 16 
lead, 15 
lime, 9 
Christi's process, 
9, 10 
V blckel's process, 
9, 10 
soda, 4, 5 
potash, 8, 16 
aceto-chloride of cal- 
cium, 11 
alcohol, 39-43 
seaweed, 44 
wood, 18 
Acetic acid, miscellaneous for- 
mulas for, 43 
processes for obtaining, 4 
by Condy's process, 11,12,13 
by Kuhlmann's process, 14 
by Liebig's process, 6 
by Meisen's process, 8 
by Mollerat's process, 5 
properties of, 50 
retorts, 29, 30 
sources of, 2 
specific gravity, tables of, 
89-90 
synthetic preparation of, 44 
tests for, 51, 52 
Acetification, 2, 3 
Pasteur on, 3 
Acetimetry, 82-88 
Greville Williams' process, 
87 
Ure's process, 85 
Aceto-chloride of calcium, acetic 
acid from, 11 
Acetometer, Taylor's, 87 
Mohr's, 83 
Acid, acetic, 1 
pyroligneous, 18 
Halliday's process, 19 
Acidimeter, Bink's, 83 
Alcohol, acetic acid from, 39-43 
Allan and Chaptai's process for 
obtaining alum, 161 
Alloys of aluminium, 186, 187 
Alum, 147 
ammonia, 175 
basic, 176 
chrome, 178 
cubical, 176 
iron, 176 
Roman, 177 196 
INDEX. 
Alum, Roche, 177 
sodium, 177 
Alum from alum rock, 148 
alum schist, 149-160 
bauxite, 166 
blast furnace slag, 166 
beetroot sugar solutions, 
Duncan and Newland's 
process, 169-171 
boghead coal ash, 169 
clay, 161 
Allan & Chaptal's pro- 
cess, 161 
Bochin's process, 162 
under pressure, 163 
coal shales, Spence's process, 
166 
cryolite, Thompson's pro- 
cess, 164 
Sauerwein's process, 165 
felspar, Turner's process, 163 
properties of, 173 
Rhodonda phosphates, 
Spence's process, 167 
rock, 147 
shale, 149, 15° 
schist, 149, 15° 
sources of, 147 
stone, 147 
uses of, 175 
other varieties of, 178 
Aluminium, 179 
alloys of, 186, 187 
Bell's process for, 182 
Bunsen's process for, 183 
Deville's process for, 179 
Gerhard's process for, 183 
Rose's process for, 182 
Rousseau & Morin's process 
for, 181 
acetate of, 53 
chloride of, 189 
oxide of; 190 
properties of, 185 
salts of, 188 
silicate, 192 
sulphate, 177, 193 
sulphite, 178 
Ammonia, 92, 93 
estimation of, by the com- 
bustion process, 142-144 
Ammonia, estimation of, by the 
Nessler test, 145 
estimation of, by the tetra- 
chloride of platinum test, 
141 . . . 
Marguerite's suggestion for 
obtaining, 93 
solution of, 97, 99 
preparation of, 97 
Watson's process, 
100 
still, 100, 101 
tests for, 96 
uses of, 97 
Ammoniacal gas, how to obtain, 
94 
properties of, 95 
salts from urine, 129 
by Spence's method, 125 
soda process, 112, 113 
solutions, sp. gr. of, 139 
Ammonimetry, 138 
Ammonium, 137 
acetate, 54 
chloride, 113-124 
pure, 130 
citrate, 131 
ferrocyanide, 131 
molybdate, 131 
nitrate, 132 
oxalate, 133 
sesquicarbonate, 109 112 
sulphate, 133-136 
sulphide, 136 
sulphydrate, 137 
Anhydrous acetic acid, 62 
Aromatic vinegar, 16, 17, 18 
B 
Basil vinegar, 81 
Bauxite, alum from, 166 
Beetroot sugar solutions, alum 
from, 169 
Bell's process for aluminium, 
182 
Bink's acidimeter, 83 
Black pepper vinegar, 81 
Blast furnace slag, alum from, 
166 INDEX. 
197 
Boerhaave's process for making 
vinegar, 73 
Boghead coalash, alum from, 169 
Bole, red, 192 
Bower's process for pyroligneous 
acid, 21, 22 
Brandy, vinegar from, 44 
Bunsen's process for aluminium, 
183 
Burette, Gay-Lussac's, 83 
Mohr's 83 
Burnet vinegar, 8i 
c 
Camp vinegar, 81 
Caper vinegar, 81 
Capsicum vinegar, 81 
Carbonizer, Reichenbach's, 28 
Schwartz's, 27 
Celery vinegar, 81 
seed vinegar, 81 
Charcoal, removal of, from acetic 
acid, 34 
Cherry vinegar, 82 
Cherville vinegar, 81 
Chilli vinegar, 8i 
China clay, 192 
Chloride of aluminium, 189 
ammonium, 113-124 
from gas liquor, 114 
from bone liquor, 119 
by Croll's process, 127 
by Hill's process, 126 
by Laming's process, 
126, 127 
pure, 130 
removal of iron from, 
125 
tests of purity, 124 
uses of, 124 
Christi's process for acetic acid, 
9, 10 
Cider vinegar, 81 
Citrate of ammonium, 131 
Clay, 192 
alum from, 161 
Coal shales, alum from, 166 
Condensers for acetic acid, 31, 
Condy's process for acetic acid, 
II, 12, 13 
Copper, acetates of, 54, 55 
Corundum, 190 
Cress seed vinegar, 81 
Croll's process for chloride of am- 
monium, 127 > 
Cryolite, alum from, 164 
Crystal vinegar, 80 
Culinary vinegars, 81 
Currie vinegar, 82 
D 
Deville's process for alumi- 
nium, 179 
Diaspore, 190 
Duncan and Newland's process 
for alum, 167-171 
Dyarand Hemming'sammoniacal 
soda process, 112, 113 
E 
Elder eloweb vinegar, 81 
Emery, 190 
Essigbilder, 75 
F 
Felspar, alum from, 163 
Ferric salts, removal of, from 
alum, 154 
Ferrocyanide of ammonium, 131 
Fielding, 68 
Fry's process for pyroligneous 
acid, 23 
Fuller's earth, 193 
G 
Garlic vinegar, 81 
Gay-Lussac's burette, 83 
Gerhard's process for aluminium, 
183 
German or quick method of mak- 
ing vinegar, 74-78 
household vinegar, 81 198 
INDEX. 
Ginger vinegar, 81 
Gooseberry vinegar, 81 
Green mint vinegar, 81 
H 
Halliday's process for pyrolig- 
neous acid, 19, 20, 21 
Ham's process for making vine- 
gar, 74 
Hill's process for chloride of am- 
monium, 126 
Hompech's ammonia apparatus, 
106 
Horseradish vinegar, 81 
Hyaline, 190 
I 
Iron, acetates of, 56 
liquor, 56 
removal of, from chloride of 
ammonium, 124 
K 
Kaolin, 192 
Kuhlmann's process for acetic 
acid, 14 
L 
Laming's process for chloride of 
ammonium, 126 
Lead, acetate of, 57-60 
basic acetates of, 60 61 
Liebig's process for acetic acid, 
6, 7 
Lime, acetate of, 48 
Loam, 192 
Lunge's ammonia apparatus, 106 
Liirmann's process for alum from 
blast furnace slag, 166 
M 
Mallet's ammonia apparatus, 
102, 103 
Manganese, acetate of, 61 
Meisen's process for acetic acid, 8 
Mohr's burette, 83 
Mollerat's process for acetic acid, 
5 
Molybdate of ammonium, 131 
Mother of vinegar, 4 
N 
Neale & Duyck's process for 
making vinegar, 80 
Nessler's test, 146 
Newton's ammonia still, 100 
Nitrate of ammonium, 132 
0 
Onion vinegar, 81 
Otto's acetometer, 83 
Oxalate of ammonium, 133 
Oxide of aluminium, 190, 191 
P 
Pager's process for acetates, 47 
Pipeclay, 192 
Pochin's process for alum from 
clay, 162 
Potter's clay, 192 
Prussian blue, 129 
Pyroligneous acid, 18 
by Bower's process, 21, 22 
by Fry's process, 23 
by Solomon & Azulay's pro- 
cess, 23 
by Steedman's process for 
purifying, 24 
by Stoltze's process for puri- 
fying, 24 _ 
woods used in manufacture, 
36, 37 
R 
Raisin vinegar, 81 
Raspberry vinegar, 82 
Red bole, 192 
liquor, 53 
rose vinegar, 81 
Reichenbach's carbonizer, 28 
Retorts for distillation, 29, 30 INDEX. 
199 
Rhodonda phosphates, alum from, 
167 
Rose's process for aluminium, 182 
ammonia apparatus, 104, 105 
Rousseau and Morin's process for 
aluminium, 181 
Ruby, 190 
s 
Sapphire, 190 
Schwartz's carbonizer, 27 
Seaweed, acetic acid from, 44 
Seville orange peel vinegar, 81 
Shalot vinegar, 81 
Silicate of aluminium, 192 
Soda, acetate of, 48, 49 
Solomon and Azulay's process for 
pyroligneous acid, 23 
Specific gravity tables of acetic 
acid, 89, 90 
ammoniacal solutions, 139 
vinegar, 89 
Spence's process for alum from 
coal shales, 166 
for ammoniacal salts, 125 
for alum from Rhodonda 
phosphates, 167, 168 
Steedman's process for purifying 
pyroligneous acid, 24 
Stoltze's process for purifying 
pyroligneous acid, 24 
Strawberry vinegar, 82 
Sugar vinegar, 81 
beet vinegar, 80 
Sulphate of aluminium, 193 
ammonium, 133-136 
Laming's process, 126, 
136 
Richardson's, 136 
Michiel's, 136 
iron from alum works, 15 3,154 
Sulphide of ammonium, 136 
Sulphydrate of ammonium, 137 
Synthetic preparation of acetic 
acid, 44 
T 
Tarragon vinegar, 81 
Taylor's acetometer, 87 
Test, Nessler's, 146 
Tests for acetic acid, 51, 52 
for ammonia, 96 
Thompson's process for alum 
from cryolite, 164 
Tin, acetate of, 61 
Truffle vinegar, 81 
Turner's process for alum from 
felspar, 163 
Turquoise, 190 
u 
Ure's process of acetimetry, 85 
Urine, a source of ammoniacal 
salts, 129 
V 
Verdigris, composition of, 56 
Vinegar, 63 
adulterations of, 70, 71 
aromatic, 16, 17, 18 
basil, 81 
black pepper. 81 
burnet, 81 
by Boerhaave's process, 73 
from brandy, 44 
camp, 81 
caper, 81 
capsicum, 81 
celery, 81 
celery seed, 81 
cherville, 81 
cherry, 82 
chilli, 81 
cider, 81 
cress seed, 81 
crystal, 80 
culinary, 81 
currie, 82 
eels, 67 
elder flower, 81 
fungus, 78, 79 
garlic, 81 
by German or quick method, 
74 
German household, 81 
ginger, 81 
gooseberry, 81 
green mint, 81 
by Ham's process, 74 200 
INDEX. 
Vinegar- 
horse-radish, 81 
making, 63-68 
mother of, 4 
by Neale and Duyck's pro- 
cess, 80 
onion, 81 
raisin, 81 
raspberry, 82 
red rose, 81 
Seville orange peel, 81 
shalot, 81 
specific gravity, tables of, 89 
strawberry, 82 
strengths of, 69 
sugar, 81 
from sugar beet, 79, 80 
tarragon, 81 
truffle, 81 
by vinegar fungus, 78, 79 
from whisky, 80, 81 
white pepper, 81 
wine, 71 
Vblckel's process for acetic 
acid, 9, 10 
w 
Watson's process for solution of 
ammonia, 100 
Widemann's process for vinegar 
making, 80 
Weisman's process for removing 
ferric salts from alum, 154 1 
Whisky, vinegar from, 80, 81 
White pepper vinegar, 81 
Williams', Greville, process of 
acetimetry, 87 
Wilson's process of roasting alum 
schist, 152 
Wine vinegar, 71 
Wood distillation, apparatus used 
in, 24-33 
how conducted, 24-33 
Woods, relative amounts and 
strengths of products 
yielded by, 35, 36 
relative proportions of water 
in, 38 
used as sources of pyrolig- 
neous acid, 36, 37 
Y 
Yeast, substitute for, 77 
Yellow ochre, 192 
Young's process for ammonia and 
its salts, 128, 129 
z 
Zinc, acetate of, 62