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(CHEMICAL AND BACTERIOLOGICAL.) BY WILLIAM P. MASON, Professor of Chemistry, Rensselaer Polytechnic Institute; Member of the American Philosophical Society, the American Chemical Society, the American Public Health Association, the American Water-Works Association, the New England Water- Works Association, the Franklin Institute, etc., etc. FIRST EDITION. J^&2/900 nous. NEW VORK:---—--■—■» JOHN WILEY & SONS. London: CHAPMAN & HALL, Limited. 1899. \/Wh Copyright, 1899, BY WILLIAM P. MASON. ROBERT DRUMMOND. PRINTER, NEW YORK. PREFACE. Knowledge of ordinary quantitative analysis is here necessarily assumed; therefore the merest sug- gestions are given for determination of the mineral matters present in a water, while the items properly lying within the scope of a sanitary examination are dealt with more at length. Upon the bacteriological side, only so much is touched upon as has been demonstrated to be of real service to the water examiner; leaving the great field of ultimate differentiation to be further explored, and rendered still more practically useful, by the professed bacteriologist. Rensselaer Polytechnic Institute, Troy, N. Y., February, 1899. CONTENTS. CHAPTER I. PAGF Introductory.................i Popular Misconception as to the Character of Water Analysis. A Knowledge of the Source of the Sample Necessary to Proper Interpretation of Analytical Results. CHAPTER II. Chemical Examination of Water.........7 Directions for Sampling. Method of stating Analytical Results. Special Laboratory. Required. Turbidity. Odor. Taste. Temperature. Reaction. Color. Total Solids. Loss on Ignition. Hardness. Chlorine. Ni- trites. Nitrates. Organic Matter. Free Ammonia. Albuminoid Ammonia. "Required Oxygen." Lead. Copper. Iron. Zinc. Arsenic. Chromium. Alum. Phosphates. Analysis of Mineral Residue. Dissolved Gases. Conversion of " Parts per Million" into Grains per U. S. Gallon. CHAPTER III. Bacteriological Examination of Water......93 Preparation of Media. Bouillon. Nutrient Gelatin. Sugar Bouillon. Sugar Gelatin. Agar-Agar. Steriliz- ing. Sampling. Sowing Media. Incubating. Count- ing Colonies. Gas-forming Bacteria. Tests for Bacillus Coli communis. Difficulty of Detecting Bacillus typho- sis. Diagnostic Value of the "Colon Group." As to Bacterial Index of Faecal Pollution. Great Cold not Fatal to Bacteria. Enumeration of Organisms not Bac- terial. Index....................129 EXAMINATION OF WATER. CHAPTER I. INTRODUCTORY. A great deal of popular misconception exists upon the subject of the analysis of potable water, and it is commonly supposed that such an examination may be looked upon from practically the same point of view as the analysis of an iron ore. That this belief is founded on fallacy may, however, be readily shown. When an iron ore is submitted for analysis, the chem- ist determines and reports upon the percentages of iron,_phosphorus, sulphur, etc., found therein ; and at that point his duties usually cease, inasmuch as the ironmaster is ordinarily capable of interpreting the analysis for himself. Even should the analyst be called upon for an opinion as to the quality of the ore, the well-known properties of the several constituents make such a task an easy one, and, assuming the sample to have been fairly selected, the opinion may be 2 EXAMINATION OF WATER. written without any inquiry as to the nature of the local surroundings of the spot whence the ore was taken. A water-analysis, on the other hand, is really not an analysis at all, properly so called, but is a series of experiments undertaken with a view to assist the judgment in determining the potability of the supply. The methods of conducting these experiments are largely influenced by the individual preferences of the analyst, and are far from being uniform or always capable of comparison, thus often introducing ele- ments of confusion where two or more chemists are employed to analyze the same water. Some of the substances reported—" albuminoid ammonia," for in- stance—do not exist ready formed in the water at all, and are but the imperfect experimental measures of the objectionable organic constituents, which our present lack of knowledge prevents our estimating directly. Thus the numerical results of a water-analysis are not only unintelligible to the general public, but are not always capable of interpretation by a chemist, unless he be acquainted with the surroundings of the spot whence the sample was drawn, and be posted as to the analytical methods employed. It is very common for water to be sent for analysis, with the request that an opinion be returned as to its suitability for potable uses, while at the same time all information as to its source is not only unfurnished, INTR0D UCT0R Y. 3 but is intentionally withheld, with a view of rendering the desired report unprejudiced in character. Such action is not only a reflection upon the moral quality of the chemist, but it seriously hampers him in his efforts to formulate an opinion from the analyti- cal results. For instance, a large quantity of common salt is a cause for suspicion when found in drinking-water, not because of any poisonous property attaching to the salt itself, but because it is usually difficult to ex- plain its presence in quantity except upon the sup- position of the infiltration of sewage. Thus an amount of salt sufficient to condemn the water from a shallow well in the Hudson valley could be passed as unobjectionable if found in a deep-well water from near Syracuse, N. Y. Hence we see how important it is for the chemist to be fully acquainted with the history of the water he is to examine in order that he may compare his results in " chlorine " with the " normal chlorine " of the section whence the sample is taken. A knowledge of the history of the water is no less important in order to interpret the remaining items of a water-analysis. Some time since a water was sent from Florida to the author for examination, and was found to contain 1.18 parts " free ammonia " per million. Much " free ammonia " commonly points to contamination from animal sources, and had it not 4 EXAMINATION OF WATER. been known that the water in question was derived from the melting of artificial ice made by the am- monia process the enormous quantity of ammonia found would have condemned it beyond a peradven- ture. As it was, the water was pronounced pure, the other items of the analysis having been found unob- jectionable. Analytical results which would condemn a surface- water may be unobjectionable for water from an artesian well, for the reason that in the latter case high figures in " free ammonia," " chlorine," or " nitrates " are often capable of an explanation other than that of sewage-infiltration. Even though such a water should, at a previous period, have come in contact with objectionable organic waste material, yet the in- tervening length of time and great distance of under- ground flow would probably have furnished abundant opportunity for thorough oxidation and purification. " Deep " samples taken from the same lake, at the same spot and depth, will greatly vary in analytical results if the temperature of the water at the several dates of sampling should be markedly different, ow- ing to the disturbing influence of vertical currents. Again, suppose it is desired to determine whether or not the water of a large stream is so contaminated with up-stream sewage as to be unfit for a town sup- ply. An analysis of the water taken from the site of the proposed intake would very possibly be valueless, INTR0D UCT0R Y. 5 because the enormous dilution to which the admitted sewage would have been subjected would remove from the analytical results everything of an absolute character. Examinations of any real value in such cases should always be of a comparative nature. Samples should be taken above and below the point of contamination and again at the proposed intake. If the difference between the first and second samples, which is a measure of the pollution, be maintained, or nearly so, at the point of intake, then the water should be condemned, no matter how completely the ana- lytical results fall within the limits of the so-called standards of organic purity. Thus it is that a chemist must be in full possession of all the facts concerning the water which he is asked to examine, in order that his opinion as to its purity may be based upon the entire breadth of his past ex- perience, for in no branch of chemical work are ex- perience and good judgment better exercised than in the interpretation of a water-analysis. As Nichols has well said, " It is a great mistake to suppose that the proper way to consult a chemist is to send a sample of water in a sealed vessel with no hint as to its source. On the contrary, the chemist should know as much as possible as to the history and source of the water, and, if possible, should take the samples himself." However faithfully the various laboratory tests may 6 EXAMINATION OF WATER. be applied to decide the question of the fitness or un- fitness of a certain water for dietetic purposes, there is nothing upon which greater stress should be laid than a thorough personal knowledge of the surroundings of the source of supply. In other words, it is essential to make a careful and thorough " sanitary survey." It was years ago laid down as a golden rule " never to pass judgment upon a water the history of which is not thoroughly known," and the nearer this maxim can be lived up to to-day the fewer will be the mis- takes in the reports issued. CHAPTER II. CHEMICAL EXAMINATION OF WATER. In the taking of samples for so important a matter as a town supply the chemist should unquestionably personally superintend their collection ; but for in- dividual outlying waters printed instructions fre- quently have to be depended upon. Those issued by the author are as follows: DIRECTIONS FOR TAKING A WATER-SAMPLE. Large glass-stoppered bottles are best for sam- pling, but a two-gallon new demijohn * may be employed, fitted with a new soft cork. Be care- ful to notice that no packing-straw or other foreign substance yet remains in the vessel, and thoroughly rinse it with the water to be sam- pled. Do not attempt to scour the interior of the neck by rubbing with either fingers or cloth. After thorough rinsing, fill the vessel to overflow- * Stoneware jugs are not admissible for collecting water samples. Instances are known of masses of the salt used for glazing remaining in the interior. 7 8 EXAMINATION OF WATER. ing so as to displace the air, and then completely empty it. If the water is to be taken from a tap, let enough run to waste to empty the local lateral before sam- pling ; if from a pump, pump enough to empty all the pump connections; if from a stream or lake, take the sample well out from the shore, and sink the stoppered sampling-vessel towards mid-depth before removing the stopper (or cork), so as to avoid both surface-scum and bottom mud. In every case fill the vessel nearly full, leaving but a small space to allow for possible expansion, and close securely. Under no circumstances place sealing- wax upon the stopper, but tie a piece of cloth firmly over the neck to hold the stopper in place. The ends of the string may be afterwards sealed if necessary. Bear in mind, throughout, that water-analysis deals with material present in very minute quantity, and that the least carelessness in collecting the sample must vitiate the results. Give the date of taking the sample, and as full a description as possible of the soil through which the water flows, together with the im- mediate sources of possible contamination. Having secured the sample, the analysis should be begun at once, for the reason that water is liable to rapid changes in character during laboratory storage. For instance, the following analyses are of the same sample of water from the laboratory tap, drawn CHEMICAL EXAMINATION OF WATER. November 10, and allowed to stand in the sampling- bottle at ordinary room temperature : Nov. 10 Nov. 12 1 Nov. 13 Nov. 14 1 Nov. 15! Dec. is 1 •037 .220 4-5 trace •50 4-35 140 .042 .178 .042 .191 .050 • 175 .075 ■155 .060 .205 Albuminoid ammonia.. .. trace •525 4.6 trace • 55 4.2 trace .60 4.4 trace .60 4.1 none .60 4.6 This water shows gradual oxidation of the nitrogen contents to nitrates, but on the whole is fairly stable. As showing, on the other hand, how rapid and how irregular the storage changes may at times be, the following analyses by Liversidge are given : * December 11. 12. 13. 15- 16. 19. 20. 21. January 8 Horse-pond. si IO.OO 2.00 8.00 .00 .00 .00 .00 .00 O.50 O.07 7.00 2.00 4-00 4.OO OO 00 OO 50 25 0.07 Fish-pond. O. 12 0. II 0.l6 o. 16 O.38 0.52 O.70 O.9O 1.38 1.50 e c 0.90 0.92 1.04 1.03 0.69 0.56 0.38 0.30 0.06 0.04 Peaty Water. 0 SB 0.19 0.04 0.13 O. 12 O.O4 O.O3 0.01 These are, of course, exaggerated cases containing high ammonias, but they serve to point out the neces- * Chem. News, lxxi. 249. 10 EXAMINATION OF WATER. sity of avoiding delay between the collection of the sample and the beginning of the analysis. At the most, very few days should intervene. Another example, chiefly interesting as showing the successive steps in the oxidation of organic nitrogen, is here given.* Eighty samples of water, including all classes of surface-water, were examined at various intervals after standing, and gave the following re- sults : " The-organic matter in suspension decays in about seven days, as is shown by the increase in * free am- monia.' In about fourteen days this ' free ammonia ' has disappeared, and ' nitrite ' has taken its place, reaching a maximum in about twenty-one days. Later the ' nitrite ' also disappears, and in twenty- eight days, or more, all the nitrogen has been con- verted into the form of ' nitrate.' When the sus- pended matter is removed by filtration through paper, or by precipitation with alumina, no change occurs, unless free ammonia were present at the outset." Hitherto no small confusion has existed, on ac- count of the many ways in which the results of water- analyses were stated, but this difficulty, it is to be hoped, will be gradually done away with by the ac- ceptance of the method recommended in the report * Report of the Massachusetts Board of Health, 1890, 865. CHEMICAL EXAMINATION OF WATER. II of the committee of the American Association for the Advancement of Science, appointed to examine into this and other water questions.* The committee recommended that all results be given in parts per million in zveight. This method has the advantage that a litre, or fraction thereof, of water, having been operated upon, and the substances found having been determined in milligram'mes, no long arithmetical calculations will be required. Of course the assumption is made that a litre of water weighs a kilogramme—a true enough state- ment for potable waters, but one capable of introduc- ing error where mineral waters are dealt with, whose specific gravities are appreciably above unity. In such a case the water to be analyzed is actually weighed, or else its weight is estimated from the known specific gravity and volume. Water should not be filtered before analysis. If sediment be present, it should be equally diffused by thorough shaking before measuring. The reason for this is that a water-analysis should represent the water as the consumer uses it, and not in a condition improved by filtration. * The preliminary report of the committee may be found in the Journal of Analytical Chemistry, vol. iii., page 398. 12 EXAMINATION OF WATER. Water-analysis cannot be properly conducted in a general laboratory, because many of the tests would be ruined by the fumes common to such a locality. A separate room, reserved exclusively for water-work, is the best arrangement. The author finds it con- venient to have the woodwork therein painted white and to have a broad titration shelf fixed across the window, with a black curtain capable of being pulled down to the level of the titration-dish. Excellent con- ditions are thus given for noting slight differences in colors. The appearance and turbidity of a water are best de- termined by using a brass tube 2\ inches in diameter and 2 feet long, closed at the ends by disks of quarter-inch plate glass held in place by screw-caps (Fig. i).* Such tubes are easily cleaned and give satisfaction. For the purpose of measuring the amount of turbidity, a standard is prepared, consist- ing of one gramme of exceedingly fine kaolin (ob- tained by elutriation) suspended in one litre of dis- tilled water. Each c.c. of this preparation will con- tain one milligramme of suspended clay. Having nearly filled the duplicate observation-tube with distilled water, enough of the " clay standard " * Such tubes may be obtained from Richards & Co., No. 30 East 18th Street, New York City. CHEMICAL EXAMINATION OF WATER. 13 is added to make the " turbidity " equal to that of the water under examination in the other tube. Knowing the volume of water operated upon and the amount of " clay standard " used, the " turbidity " Fig. i. expressed in parts per million can readily be calcu- lated. It should be noted that although the tube containing the " clay standard " is, of necessity, not completely full, yet by inclining its barrel towards a horizontal position the required observation depth of two feet is easily obtained. Any quickly subsiding material present should be classed as " sediment " rather than " turbidity." To 14 EXAMINATION OF WATER. determine the same it would be best to decant the water from above such deposit and then catch it upon a weighed filter or in a Gooch crucible. Odor and Taste.—It is customary to report such odor and taste as a water may possess, although in the great majority of cases very little information is derived from such examination, because of the fre- quency of negative results. A good water may be possessed of a slight marshy odor, while one of ex- tremely dangerous character may be limpid, tasteless, and odorless. The test is best applied both before and after heating the water nearly to the boiling-point, and after thorough shaking in each case. Both taste and odor are sometimes very pro- nounced, as when such organisms as " Asterionella " are present in quantity. Fortunately, disease has never been traced to such occurrence, however objec- tionable the water may be from an aesthetic stand- point. Organisms of this character are revealed by a microscopical examination. Temperature.—A cool water should, if possible, be supplied for public use, but studies of temperature are rare, for the sufficient reason that considerations of much greater weight determine the selection of a CHEMICAL EXAMINATION OF WATER. 15 source of supply.* Should many temperature read- ings in deep water, as in a lake, be decided upon, no better device could be chosen for the work than the " thermophone," invented by Warren and Whipple. The following is clipped from a description issued by the present makers, E. S. Ritchie & Sons, Brookline, Mass. : " The thermophone is an electrical thermometer of the resistance type. It is based upon the principle that the resistance of an electrical conductor changes with its temperature, and that the rate of change is different for different metals. " The operation of taking a reading is as follows : Having connected the leading wires to the proper binding-posts of the indicator-box, the current is turned on and the telephone held to the ear. A buzzing sound in the telephone is found to increase or diminish according as the pointer is made to ap- proach or recede from a certain section of the dial. By moving it back and forth a position may be found where the telephone is silent. When at this point, the hand indicates the temperature of the distant coil. Instruments of ordinary atmospheric range, i.e., from 15° to 1150 F., may easily be read to o.i° even by an * The extreme variation of temperature for Croton water, as delivered by the street hydrants in New York City, for the year 1894 was: On February 24................................ 34° F. On August 4................................... 76° F. i6 EXAMINATION OF WATER. inexperienced observer. With a smaller range, or with an instrument having a larger dial, a greater pre- cision may be obtained. " It is more sensitive than a mercurial or other expansion thermometer, because the rate of change of resistance per degree is greater than the rate of ex- pansion of liquids or solids, and, moreover, slight changes in resistance may be more easily and ac- curately measured than slight changes in length or volume. " It sets quicker than most mercurial thermom- eters. In obtaining the temperature of water of vari- ous depths one minute has been found to be sufficient time to allow for setting. " It is independent of pressure." * The reaction of potable water is commonly slightly alkaline, although waters holding much free acid in solution, usually sulphuric, are by no means rare. Determination.—Place 100 c.c. of the water in a cas- serole, and titrate with N/io hydrochloric acid, using methyl orange as an indicator. Should the water be originally acid, make it slightly alkaline with a known * The deepest sounding found on the Challenger expedition was in lat. n° 24' N., long. 1430 16' E. The depth was 4475 fathoms. Temperature of bottom-water................. 33-9° F. of surface-water..................8o° F. Most of the thermometers employed were crushed by the great pressure of five tons per square inch. CHEMICAL EXAMINATION OF WATER. 17 amount of potassic hydrate before titration. It is con- venient to report alkalinity as representing so many parts of CaC03 per million of water, and to note that such a form of result is quickly obtained by multiply- ing the number of c.c. of hydrochloric acid, used in the above titration, by fifty. Acidity is best stated in the same terms using a negative sign. Color.—Prof. A. R. Leeds has proposed the most convenient method for stating the color of a water.* Observations are made by the use of 50-c.c. " Nes- sler" jars, and unity of color is that caused by " nesslerizing" 1 c.c. of the standard ammonium chloride solution, diluted to 50 c.c. with ammonia- free water, in exactly the same manner as in the de- termination of " free ammonia." (Page 53.) Turbid waters should be filtered before reading the color. The investigations of the Boston Water Board show that both iron and manganese often enter largely as a cause of color in water from the stagnant layer of a deep pond, but the color of a purely surface water is mainly due to solution of organic material.f * For cases of special investigation the Hazen " platinum" standard gives most excellent results, although somewhat more difficult to apply. (Am. Chem. J., xiv. 300.) fAn excellent paper by Mrs. Ellen H. Richards on "The Coloring Matter of Natural Waters" is published in /. Am. Chem. Soc., January, 1896. 18 EXAMINATION OF WATER. Having accomplished the foregoing preliminary observations, the examination proper comes now in order ; but before going further a word should be said upon the vexed question of " standards for in- terpretation of analytical results." The establishment of a hard-and-fast " standard " is simply an impossibility. Results which would be considered satisfactory for one locality might be en- tirely inadmissible in another. Local standards are the proper ones by which to be guided, and it is to be regretted that local " normals" are not more fre- quently found on record. For Massachusetts and Connecticut the informa- tion is more full, as is instanced by the fine charts of " normal chlorine " prepared by the State Boards of Health. Following the description of each analytical process to be given hereafter there will be found a paragraph headed " Comparates," but the expression must not be permitted to mislead. The author's intention is simply to place before the reader sundry data and the opinions of various authorities, and he absolutely dis- claims any desire to set boundaries to the free use of the analyst's good judgment. The term " compa- rates " is possibly a poor selection, but, with the above explanation, it will serve in place of a more lengthy expression. CHEMICAL EXAMINATION OF WATER. 19 TOTAL SOLIDS. Source.—Material dissolved or suspended in water is naturally derived from the strata through which the water passes, or the surface over which it flows. Thus are obtained waters of all degrees of hardness (see " Hardness ") and of great variety of color and turbidity. Determination.—Thoroughly shake the vessel con- taining the sample and then measure out 100 c.c. of the unfiltered water by means of a pipette into a weighed platinum dish. Evaporate to dryness on the water-bath, being careful to place a filter-paper between the dish and the water in the bath in order to prevent any deposit of impurities on the under side of the dish. (A better plan is to make use of a porcelain water-bath filled with distilled water.) When dry, place the dish and contents in an air-bath and maintain the temperature at 1050 C. for half an hour.* Cool in a desiccator and weigh. Replace in the air-bath and repeat the weigh- * M. Albert-Levy, of the Montsouris laboratory, Paris, dries this residue at 1800 C. for twelve hours before weighing. He gives the following illustration of how differently various waters act when dried at 125° C. and 1800 C: 125°. 1800. Vanne................................... 231 231 Ourcq................................... 483 445 Marne................................... 328 289 Drain St. Maur.......................... 300 2go 20 EXAMINATION OF WATER. ing at intervals of half an hour until a constant weight be obtained. The final weight, less the known weight of the dish, will give the amount of total solids. This weight multiplied by ten will give the weight of solids per litre of water, which, expressed in milligrammes, will represent parts per million. The " loss on ignition " is obtained by gradually rais- ing the dish and its contents to redness and reweigh- ing after cooling in a desiccator. It is important to note that while no quantitative results of much value are to be expected from the ig- nition in question, yet considerable insight may often be obtained as to the character of the water by ob- serving the intensity of the charring and the presence or absence of fumes. As Dr. Smart says : " The blackening during the process is of more interest than the mere loss of weight. No matter how few parts are lost, if the lining of the capsule blackens all over and the carbon is afterward dissipated with difficulty, the water is to be viewed as suspicious. What are called ' peaty ' waters here con- stitute the exception." * Angus Smith pointed out that " in waters contain- ing nitrates and nitrites no organic matter would be apparent on burning unless more should be present than these salts could oxidize "—a fact always to be borne in mind. * Report Nat. Board of Health, 1880. CHEMICAL EXAMINATION OF WATER. 21 Comparates* Average in sundry waters known to be pure.... 69 " " polluted.. 725 These averages are really of but small sanitary value, for the reason that a polluted water may be low in total solids, or vice versa, according to the charac- ter of the soil through or over which the water flows. The Rivers Pollution Commission of Great Britain gives as averages out of 589 samples of unpolluted waters analyzed for total solids: Rain ....................... 29.5 Upland surface............... 96.7 Deep well................... 432-8 Spring...................... 282.0 Dr. Smart (Nat. Board of Health, 1880) : Safe limit.................... 3°° To be condemned............. 1000 A. R. Leeds (Water Depart. Wilmington, 1883) : Standard for American rivers. .. 150 to 200 Wanklyn regards as permissible. 575 * See page 18. 22 EXAMINATION OF WATER. HARDNESS. Before entering into the question of quantitative es- timation, let it be premised here that "hardness" may be classified under two heads, viz., " Permanent " and " Temporary." The former is occasioned by the pres- ence of calcium sulphate, and other soluble salts of calcium and magnesium, not carbonates, held in solu- tion by the solvent action of the water itself ; such a water cannot be materially softened by boiling under ordinary pressure. " Temporary " hardness is caused by carbonates of calcium and magnesium held in solution by carbonic acid present in the water. Boiling such a water ex- pels the carbonic acid, whereupon the salts separate from solution.* Many samples of water possess both " permanent " and " temporary" hardness, and the analyst is at times called upon to report each separately ; but * With some it is considered that the calcium is present as a soluble bicarbonate which breaks up upon boiling into car- bonic acid gas and insoluble normal carbonate; but, as A. H. Allen says, it is not necessary to assume the existence of cal- cium bicarbonate (which compound has never been isolated) in order to account for the solubility of calcium carbonate. One water which he examined evolved very small quantities of car- bon dioxide on boiling, and yet the precipitated calcium carbonate was large in amount. He considers it " probable that calcium carbonate is capable of existing in a soluble colloid condition, changing, on boiling the liquid, to the ordinary in- soluble modification." (/. Soc. Chem. Ind., vii. 801.) CHEMICAL EXAMINATION OF WATER. 23 more commonly the total hardness covers all that is required. Ordinary hard soap is somewhat complex in structure, but for practical purposes we may consider it to consist of sodium stearate, NaC18H3502. This salt, coming in contact with the calcium carbonate or sulphate contained in a hard water, is immediately de- composed, with formation of insoluble calcium stearate acording to the following equations : CaC03+2NaC18H3502=Ca(C18H3502)2+Na2C03 or CaS04+2NaC18H3502=Ca(C18H3502)2+Na2S04. Of course none of the soap can be depended upon for detergent purposes until all the calcium salts pres- ent have been thus provided for; hence the enormous waste resulting from the use of some waters may readily be imagined.* * " While no exact rule can be given for estimating the in- creased expense to a community caused by the use of hard water, in general it may be said (Eng. News, January 31, 1885) that each grain of carbonate of lime per gallon of water causes an increased expenditure of 2 ounces of soap per 100 gallons of water. The Southampton water contains about 18 grains of lime and magnesian salts per gallon. With such hard water it is probable that the increased expense for soap in a household of five persons would amount to at least $5 to $10 yearly; hence the inhabitants could afford to pay a higher water-rate by the amount of this difference for a soft-water supply." (Engineering News. April 16, 1892.) 24 EXAMINATION OF WATER. In undertaking the estimation of hardness advan- tage is taken of the reaction above stated. A solu- tion of soap of known strength is prepared, and is then poured into a given quantity of the water to be examined, until a permanent lather is formed, where- upon, from the known quantity of soap used, the amount of " hardening " salts present may be calcu- lated. This soap test, commonly known as Clark's, is not accurate, and is in some respects unscientific; but it is not without value, especially in a locality such as Troy, N. Y., where the enormous laundries use soap by the ton. Soap Solution.—From a new cake of Castile (Syria) soap scrape ten grammes of shavings. Dissolve them in one litre of dilute alcohol (-J water). If not clear, filter, and keep tightly stoppered. Standardizing the Soap Solution.—Carefully weigh out one gramme of pure CaC03. Dissolve in a little HC1. Neutralize with a slight excess of NH4OH and dilute to one litre. Each cubic centimetre of this so- lution will contain an amount of calcium salt equiva- lent to one milligramme of CaCOs. Place 10 c.c. of this solution in an eight-ounce glass-stoppered bottle, make the volume up to ioo c.c. with pure water, and run in the prepared soap solu- tion from a burette, little by little (shaking after each addition), until a lather be formed which persists for CHEMICAL EXAMINATION OF WATER. 25 five minutes. Even when the amount of soap solu- tion required is approximately known, never add more than half a cubic centimetre at once, and never fail to shake after such addition.* Note the amount of soap solution used. Now re- peat the experiment, using ioo c.c. of pure water only (no calcium salt solution), and again note the amount of soap solution required. This second reading will give the amount of soap solution (no inconsiderable quantity) used up by the ioo c.c. pure water, and by subtracting the same from the reading obtained in the first instance knowledge will be reached of the quantity of soap required for the calcium salt alone. Estimate now the value of i c.c. soap solution in terms of calcium carbonate and record the result on the bottle. Perhaps an example would be in keep- ing : 8.2 c.c. soap solution are required for 10 c.c. CaCOa solution + 90 c.c. water. 0.6 c.c. soap solution are required for 100 c.c. water. Hence 7.6 c.c. soap solution are required for 10 mg. CaCOa only. Hence 1 c.c. soap solution corresponds to 1.316 mg. CaC03. * See Chem. News, August, 1886. 26 EXAMINATION OF WATER. Always place the date of standardizing on the bottle, and re-standardize frequently, as the soap so- lution is not permanent. Determination.—Place ioo c.c. of the water in the eight-ounce bottle, run in the standard soap solution in the manner already stated, read off the amount re- quired, multiply by the known value for i c.c. soap solution, multiply this again by ten, and there will be obtained the hardness expressed in so many parts of CaC03 per million of water. It was formerly customary to report hardness in " degrees " rather than parts per million, but the diffi- culty of deciding which of the several systems of de- grees was referred to provoked so much confusion that a change was made to the present simpler mode of expression.* Should a report of both temporary and permanent hardness be called for, the soap test must be made both before and after boiling. Any loss in volume due to the boiling must be, of course, made up, and any precipitate of calcium car- bonate removed by filtration before adding the soap solution. * In England the Clark scale is still in use. Each degree corresponds to one grain of CaCO per imperial gallon of water, i.e., one part in seventy thousand. Below 6 degrees is considered soft. CHEMICAL EXAMINATION OF WATER. 2"] If the hardness due to salts of magnesia be required separately, shake the water up with a little solid am- monium oxalate, filter off the' precipitated calcium oxalate on a dry filter, and determine the hardness in the filtrate. When a water is so hard as to require a greater amount of soap solution for the ioo c.c. of the water than suffices to saponify 23 mg. CaCOa, better re- sults are obtained by diluting the water with an equal bulk (or more, if necessary) of pure water, inasmuch as too heavy a precipitate of the calcium stearate ap- pears to interfere with the proper lathering. Of course the influence of the additional quantity of water must be allowed for. For constant results the hardness of a water should be taken at a temperature of 150 C* Leeds's method f for determining "permanent hard- ness " is very convenient : The measured water is boiled with a known excess of Na2COs. Precipitated CaCOs is filtered off, and the remaining Na2C03 de- termined by titration with standard acid and methyl- orange. The loss in Na2C03 is calculated to a cor- responding amount of CaS04. " Temporary hardness " is considered equal to the " alkalinity," previously determined. See page 16. Comparatcs.—The average hardness of good waters */. Chem. Soc, lxiv. ii. 347. f Modification of Hehner's method, see Analyst, viii. 77. 28 EXAMINATION OF WATER. as given by the British Rivers Pollution Commission stands : Rain......................... 3 Upland surface................. 54 Deep well..................... 250 Spring....................... 185 Wanklyn allows................ 575 Leeds's standard for American rivers, 50 for soft, 150 for hard. CHLORINE. Water is rarely found free from chlorine, yet, not- withstanding its almost constant presence, there is hardly a factor in the sum total of water-analysis tow- ards which attention is more quickly turned, or re- garding which there is closer scrutiny. In most instances, chlorine is present in the form of common salt, washed from the air or soil, or added as one of the constituents of sewage. Salt itself is, of course, unobjectionable in the quan- tity usually present, but, it being so largely used in our food, there is always warrant for suspecting sewage contamination where the figures for chlorine run high. True it is that those figures are at times mislead- ing, but they, like other data in water-analysis, must VI. \ J^|?^^^M\ ■^Sra. hS ^/>" i ^o S^s\Z 1*1 =?0l Y-i*H 4[^ fyv ^*M£~SP¥%) pf fiz \i^ Ataai v \>T;v. i/A: j£„M><"K'" ■pVA? k3 vm¥% W4v M Wf 4r*'Jl " * c * ' c & T .■-■/') ^ -u STATE BOARD OF HEALTH MAP OF THE STATE OF MASSACHUSETTS. —-^-;,,--■- — ™ « S H O WT N G The flgures underlined represent chlorines of ground- waters. NORMAL CHLORINE. w EXPLANATION, The amount of chlorine is expressed to parts per 100,000. The lines represent normal chlorine. The flgures show observed chlorines which are normal nr n«arlT7- sr>. J NORTH | ;anaa n / -A. 1.o I---■" .'T i WKST lHABTPORI>'?(1 vX,IABWmTON I $5^f 3 V' . a & ^ ^£v,— V" 'FT ,--/W& t> ■ftCJ ^ARTF-OBO' ! H \\. tt.™~—" k A „V jW !W BRISTOL 'i /} »* fk<> \£ \&. I NI V D \ IEW | FAIRriEU)), is ROOK WOOOBURV \ J^S} I * iKIBDlSjug JsoYrAlJNCTOIf' 1.9 ;' 5)/ -■ 9 9 Eli'' ^ .'RETHAMr.>9tri^ OXFORD T OWN 1$C* 0? \* .RIDGK I FIELD fHKDDINO ../mrarriNOTONj bV ~":thai PAWTBBBUB uwriEiji 5 #o-> to*. 4. \ n !-2.: „ V^**^ J\WBSTON\ %•. ~*< NEW \ ■' ^CAfTAAl 1/\ mavI *J t7 ^ 6 X & lj^j>tz? EXPLANATION. a Xf J*T> Chlorine is expressed in parts per million. The lines represent normal chlorine. The figures show observed chlorine in waters which are normal or nearly so. Figures underlined are from ground-waters. SHOWING DISTRIBUTION OF CHLORINE. Scale—7}4 miles per inch. ? CHEMICAL EXAMINATION OF WATER. 29 be considered with judgment, and due weight be ac- corded the character of local surroundings. If the district whence the water comes be naturally rich in salt, as is the case with the deep-seated waters of Central New York, such fact must be borne in mind when formulating an opinion as to quality. Comparison should be made with a local water, of the same general character, known to be pure ; and for that purpose State maps, such as those issued for the States of Massachusetts and Connecticut, are most valuable, and their construction is well worth the ex- penditure of public money. The influence of the sea upon the " normal chlo- rine " of these two States is made apparent by the charts referred to. Such influence is naturally marked in an insular country like England. Thus, Prof. Kinch reports the average amount of chlorine in the rain-water collected at Cirencester, England, during a period of twelve years to be 3.36 parts per million.* Variation in the chlorine-contents of rain-water always occurs inland, although not to the same de- gree as upon the coast. For instance, the mixed monthly rain and melted snow at Troy, N. Y., during 1896, contains the following amounts of chlorine : January............ 2.50 per million. February........... 1.07 * See also page 34. 30 EXAMINATION OF WATER. March .. . April..... May..... June..... July..... August ... September October .. November December Mean........... 1.64 " While not strictly city rain-waters, the Troy sam- ples were doubtless somewhat affected by the neigh- borhood of the city. Ground-water is more directly influenced than rain- water by the presence of human habitation. Thus the Massachusetts Board of Health (1890 [1], 680) found that twenty persons per square mile will add, on the average, 0.1 part per million of chlorine to the water flowing from such district. The determination of chlorine in water is extremely simple. It depends upon the fact that if to a solu- tion of a chloride which has been colored yellow by addition of a little potassic chromate a solution of silver nitrate be added, white silver chloride will be produced until the last trace of chlorine be disposed 1.55 per million o.75 " " 1.25 " " 1.15 " " 1.05 " " 2.00 " 0.60 " 3.00 " " 2.25 2.50 " " CHEMICAL EXAMINATION OF WATER. 31 of, whereupon red silver chromate will begin to appear. The reagents required are : Standard Silver Solution.—Prepared by dissolving 4.8022 grammes of crystallized silver nitrate in one litre of water. Each cubic centimetre of such a solu- tion is of a strength sufficient to precipitate one milli- gramme of chlorine. A sample of this reagent a year old gave exactly the same results as when freshly pre- pared. In common with all other reagents for water- analysis, it should be kept in bottles having caps covering the stoppers, such as are used for volatile liquids. Potassium Chromate,Indicator.—Dissolve 2 grammes of the pure salt in 100 c.c. of distilled water. Sodium Carbonate Solution.—Dissolve 50 grammes of the pure salt in 300 c.c. of distilled water. Determination.—One hundred c.c. of the water to be examined are placed in a large " Nessler " jar ; 1 c.c. of the potassic chromate solution is added, which will give a distinct yellow color, and then the standard silver solution is run in from a burette, until the red tint of the silver chromate just appears. From the known amount of silver solution used the amount of chlorine present is obtained, and this, multiplied by ten, will give the chlorine in milligrammes per litre or parts per million. 32 EXAMINATION OF WATER. To determine with accuracy the first appearance of the red tint, it is best to make the examination in yel- low light. The writer uses a photographic " dark room " lantern with a front of yellow glass. Reflec- tion from a porcelain tile throws the light through the length of the " Nessler " jar, and side light is cut off by a black screen. For the sake of accuracy it is better, during the titration, to have a second jar of the water, also col- ored with potassic chromate, in order that the forma- tion of the red tint in the vessel operated upon may be, by contrast, more readily detected. Different waters, equally clear, and containing the same amount of chlorine, differ greatly in their ability to give a sharp "end-reaction." It therefore often aids the eye to prepare a third tube containing distilled water to which has been added the chromate indi- cator and i/io c.c. of the silver solution. This " over- dose " having been matched by operating upon the unknown water, allowance is made by subtracting i/io c.c. from the burette reading. Many waters possess such deep color, or such tur- bidity, as to interfere with proper titration ; under such circumstances it is best to shake the water with recently precipitated and washed aluminum hydrate and then filter it, or allow it to stand twenty-four hours in a tall glass cy1inder. The coloring matter or turbidity is thus sedimented, and the water cleared for use. CHEMICAL EXAMINATION OF WATER. 33 With waters high in chlorine it is often very diffi- cult to decide just when the red color begins to ap- pear, for the reason that it is hard to compare the clear yellow liquid of the comparison-vessel with one which has become turbid from precipitation of silver chloride. In such a case it is well to roughly determine the chlorine present, and then to make a second deter- mination, using for comparison ioo c.c. of the water to which has been added not only the chromate in- dicator, but also an amount of silver nitrate solution just short of that necessary to satisfy the chlorine present. By these means the eye is greatly aided in noting the slightest appearance of red tint, for in respect of turbidity both vessels are practically alike. It makes no difference at what rate the silver solu- tion is added during titration. Circumstances sometimes demand, for purposes of special comparison, a closer reading for chlorine than is possible when only ioo c.c. of the water are em- ployed. For such purpose it is best to place the measured quantity of water in a large porcelain casse- role and to make it slightly alkaline with Na2C03 before concentration. After reduction of the volume to ioo c.c. the process is continued as already de- scribed. It is important that the same volume (ioo c.c.) be 34 EXAMINATION OF WATER. always secured before running in the silver nitrate solution ; therefore distilled water must be added if the concentration should have been carried too far. The material loss of chlorine that may occur should the evaporation be conducted without the ad- dition of sodium carbonate is illustrated by the follow- ing experiment : To each of two litres of water 3.35 milligrammes of chlorine were added, in the form of common salt. To one of them was likewise added 0.1 c.c. sodium carbonate solution. Upon evaporating each to 100 c.c. and titrating they gave the following results : Water with cafbonate added........ 3.35 mg. of CI. Water with no carbonate added..... 3.25 " " " The porcelain of the dish does not interfere with this determination, but it is very important to care- fully scrub and wash down its sides after evaporation. Comparates. Average in sundry waters known to be pure. . . 2.75 a a a it a it a n , j <-> polluted. 58.3 The Rivers Pollution Commission reports the average amount of chlorine in 589 samples of unpol- luted English water as follows : Rain ....................... 8.22 Upland surface............... 11.3 Deep well................... 51.1 Spring...................... 24.9 CHEMICAL EXAMINATION OF WATER. 35 (Great Britain being an island, chlorine would naturally run high.) Wanklyn considers 140 as possibly suspicious. Frankland places the permissible limit at 50. Leeds's standard for American rivers, 3 to 10. Ordinary sewage, about no to 160. Human urine (average of 24 samples), 5872. NITROGEN AS NITRITES. Frankland writes: " When fresh sewage is added to water already containing nitrates, the latter are gen- erally reduced to nitrites," and it may be there are none to disagree with him ; but when he adds that " when nitrites occur in shallow wells or river-waters, it is highly probable that these waters have been very recently contaminated with sewage," Wanklyn op- poses such a view and declares that " nitrates and nitrites have been erroneously regarded as measuring the defilement of water." Finally, in the report of the National Board of Health for 1882, Mallet concludes: " With the facts of this investigation before me I am inclined to attach special and very great importance to the careful determination of the nitrites and ni- trates in water to be used for drinking." This statement of Prof. Mallet so entirely accords with the uniform experience of the writer as to force him to regard it as conclusive. It is based on most 36 EXAMINATION OF WATER. carefully conceived and executed experiments which " point strongly to the production of nitrites by oxi- dation of organic nitrogen, and their subsequent con- version into nitrates by further process of oxidation." Whether, therefore, the presence of nitrites be con- sidered due to reduction of pre-existing nitrates in presence of organic matter, or caused by direct oxida- tion of organic nitrogen, it becomes a necessity to estimate their quantity, for in either case the initial cause is probably contamination. Of the several methods used of late for the deter- mination of nitrites the second one suggested by Griess seems to be the most deserving of favor. It depends in principle upon the red coloration (" azobenzolnaphthylamine sulphonic acid") pro- duced whenever " sulphanilic acid " and " naphthyl- amine hydrochloride" are added to an acidified solution of nitrite. The test is exceedingly delicate and is capable of distinguishing one part of nitrogen as nitrous acid in one thousand million parts of water. The reagents are prepared as follows : Sulphanilic Acid.—Dissolve 1 gramme of the salt in 100 c.c. hot water. The solution keeps well. Naphthylamine Hydrochloride.—Boil -| gramme of the salt with 100 c.c. water for ten minutes, keeping volume constant. Place in glass-stoppered bottle. CHEMICAL EXAMINATION OF WATER. 37 The solution tends to grow slightly pink on standing, but not sufficiently so to interfere with its use. Standard Solution of Sodium Nitrite.—Sodium nitrite may be bought, but its purity is always to be questioned, and moreover it is too deliquescent a salt to be weighed with ease and accuracy. It is better, therefore, to prepare the silver salt, which may be readily handled, and from it the solution required may be made. To a cold solution of commercial sodium or potas- sium nitrite add a solution of silver nitrate as long as a precipitate appears. Decant the liquid and thor- oughly wash the precipitate with cold water. Dis- solve in boiling water. Concentrate and crystallize the silver nitrite from the hot solution. Dry in the dark at the ordinary temperature (using vacuum is better) and keep it in a black bottle. Weigh out .22 gramme of the dry silver nitrite. Dissolve in hot water. Decompose with slight excess of sodium chloride, cool if necessary, and dilute to one litre. Allow the precipitated silver chloride to settle, remove 5 c.c. of the clear solution, and dilute the same to one litre. This second dilution (which is the standard solution to be used) will contain an amount of nitrite per cubic centimetre equivalent to .0001 milligramme of nitrogen. Determination.—In order to undertake the deter- mination of nitrites place 100 c.c. of the water to be 38 EXAMINATION OF WATER. examined in a " Nessler " jar. Acidify with one * drop concentrated HC1. Add i c.c. of the sulphanilic acid solution, followed by I c.c. of the solution of hydrochloride of naphthylamine, mix.f cover with watch-glass, and set aside for thirty minutes. Pre- pare at the same time other " Nessler " jars contain- ing known amounts of the standard solution of sodic nitrite and diluted to the ioo-c.c. mark with pure distilled water (see page 51), adding the reagents as above. At the end of the time stated (thirty minutes) examine the depth of the pink color formed, and by comparing the unknown with the known an accurate determination of the amount of nitrogen present as nitrites may be made. Comparatcs.—In a report upon the presence of nitrites in eighteen " natural waters, believed from actual use to be of good, wholesome character," and collected from every variety of source, Mallet's deter- minations show an average of .0135 part nitrogen as nitrites per million parts of water. The average, by the same investigator, for nineteen waters " which there seems to be fair ground for believing have actu- ally caused disease " is .0403 part per million. * Addition of too much acid might cause nitrates to react as well. (Analyst, xii. 51.) f To accomplish this mixing it is best to use a stout glass rod ten inches long, at one end of which is fused a cross, composed of two pieces of glass rod Y\ inch in length. The mixer is used as a plunger. CHEMICAL EXAMINATION OF WATER. 39 The author's experience has been that the average amount of nitrites found in good waters is very much less than the value given by Mallet. In this connection it would be well to bear in mind Frankland's statement that " the presence of these salts in spring and deep-well water is absolutely with- out significance ; for although they are in these cases generated by the deoxidation of nitrates, this deoxida- tion is brought about either by the action of reducing mineral substances, such as ferrous oxide, or by that of organic matter which has either been imbedded for ages, or, if dissolved in the water, has been subjected to exhaustive filtration." This is merely another in- stance of how careful the analyst should be to become familiar with the source of the water before under- taking to pass judgment upon its quality. Nitrites should always be looked upon with sus- picion if found in ground- or surface-waters. The absence of nitrites, moreover, proves nothing. The author has recently had a most foul cistern-water for analysis which showed but a trace of nitrites and no nitrates, and yet the water was contaminated with the entire house drainage, and produced most serious illness. Leeds's standard for American rivers, 0.003. 40 EXAMINATION OF WATER. NITROGEN AS NITRATES. Taking Mallet's statement as final, that there is every reason for assuming that nitrates present in water may be but the further step in the oxidation of nitrogenous organic matter, it necessarily becomes important to obtain an estimate of this constituent, which, in Frankland's opinion, is a factor in the measurement of " previous sewage contamination." Nitrates are more liable to indicate putrefaction of animal rather than of vegetable tissue, not only be- cause of the greater quantity of nitrogen present in the former, but also on account of its more ready decomposition. Stoddart claims that " natural waters can, at most, obtain but from i/io to 2/10 grain of nitrogen as nitrates per imperial gallon (1.43 to 2.86 per million) from sources other than animal matter ; and practi- cally the whole of the nitrogen of sewage may be oxidized into nitric acid without diminishing the risk involved in drinking it." " The proposal to consider a water safe so soon as the nitrogen has assumed the oxidized condition, ir- respective of the quantity that may be present, is en- tirely irrational." * Rain-water washes a very considerable amount of Analyst, xviii. 293. CHEMICAL EXAMINATION OF WATER. 41 nitric nitrogen from the atmosphere ; thus an official report gives the following amounts of nitrogen as nitrates in sundry rain-waters, showing at the same time the tendency of neighboring towns to increase this item : England, interior....................19 cities......................22 Scotland, near the coast...............n interior....................08 cities......................30 Glasgow...................63 Montsouris, Paris, average of 18 years. .73 Nitrogen in the soil is increased by the fixing of atmospheric nitrogen through the agency of the roots of certain plants, such as peas, the process being aided by bacterial action.* Such fixed nitrogen eventually enters the ground- water, and a knowledge of the local " normal " for nitric nitrogen is consequently of advantage when studying the domestic well-waters of a neighbor- hood.f *An interesting experiment to show this was recently made in France. Peas were grown in a closed space, and the nitrogen lost by the confined air was found equal to what was gained by the ground and plants. No such fixation of nitrogen was ob- tained when the soil was previously sterilized. f Surface- and ground-waters of good quality are low in nitrates, for the reason that such material is quickly absorbed by growing vegetation. 42 EXAMINATION OF WATER. After having tried many ways for the determina- tion of " nitrates " in potable water the writer has adopted a modification of the old " picric acid method," as giving, on the whole, the greatest satis- faction. Phenol-sulphonic acid is made by the action of phenol on sulphuric acid : C6H5OH + H2S04 = C6H4(OH)S03H + H20. This reagent, reacting with nitric acid, forms tri- nitro-phenol, C6H4(OH)S03H + 3HNO3 = C6H2(OH)(N02)3 + H2S04 + 2H20, which in turn forms yellow ammonium picrate when acted upon by ammonium hydrate: * C6H2(OH)(N02)3 + NH4OH = C6H2ONH4(N02)3 + H20. The intensity of this yellow color, produced in the water under examination, is compared with standard colors of known strength, and the quantity of nitrate present thus determined. The interference of chlorides with this process, re- sulting in readings decidedly lower than the truth, is well known, but the method is so easy and convenient See Analyst, x. 200. CHEMICAL EXAMINATION OF WATER. 43 that it occurred to the writer to try the addition of sodium chloride to the comparison standards rather than abandon the process. The " chlorine " in the water under examination having been previously determined, an appropriate volume of standardized sodium chloride solution is added to each evaporation of standard potassium nitrate solution. Thus the water to be examined, and the nitrate solutions with which it is compared, all contain the same quantity of chlorine. The results are very satisfactory. If the chlorine be below six parts per million it does not interfere with the nitrate deter- mination. The solutions required are : P he nol-s id phonic Acid.— Sulphuric acid, pure and concentrated. 148 c.c. Distilled water..................... 12 c.c. Pure phenol....................... 24 grammes Standard Potassium Nitrate Solution.—Dissolve .7221 gramme pure KNOs in I litre distilled water. Dilute 100 c.c. of this solution to 1 litre with distilled water. This weaker solution, which is the standard employed, contains .01 milligramme of nitrogen as nitrate in each cubic centimetre. Standard Sodium Chloride Solution. — Dissolve 1.6497 grammes pure NaCl (made from metallic sodium) in i litre distilled water. Each cubic centi- metre will contain I milligramme of chlorine. 44 EXAMINATION OF WATER. Determination.—Evaporate ioo c.c. (or less, accord- ing to nitrate-contents) of the water to dryness on the water-bath, having previously added i/io c.c. sodium carbonate solution (see page 31) to prevent loss from volatilization of nitric acid. Thoroughly moisten the residue with 2 c.c. of the sulphonic acid. Add an ex- cess (about 15 c.c.) of ammonium hydrate. Make up to 100 c.c. in a " Nessler " jar, and compare the depth of color with those produced by operating upon dif- ferent amounts of the standard nitrate solution, which have been evaporated and treated under precisely similar conditions. To each selected volume of standard nitrate solu- tion there should be added before evaporation 1/10 c.c. sodium carbonate solution and an amount of standard sodium choride solution sufficient to cor- respond with the amount of chlorine previously found to exist in the water. These evaporations, both of the water and the com- parison standards, are best made in deep evaporating- dishes of glass 4^ inches in diameter, and easily hold- ing 100 c.c. After dryness is reached the dish, with its contents, should be at once removed from the water-bath. It is of the greatest importance that the conditions governing the operations to which the water is sub- jected should be strictly followed in preparing the comparison solutions. CHEMICAL EXAMINATION OF WATER. 45 In order to economize time, when dealing with waters low in chlorine, the writer makes use of a standard " nitrate color solution." This is made by evaporating 25 c.c. of the standard potassium nitrate solution, followed by addition of the other reagents in the way already detailed. The yellow liquid produced is diluted to 1 litre and kept in stock. Each c.c. thereof corresponds to .0025 mg. nitrogen as nitrate. Much time is saved by diluting measured volumes of this " standard color " to 100 c.c. for the preparation of the com- parison tubes. The solution keeps its normal strength of color quite well, but should not be trusted after having been a few weeks in stock. Before evaporating for the nitrate determination it is best to clear the water with aluminum hydrate as under " chlorine." (See page 32.) Comparates. Average in sundry waters known to be pure.....47 " " polluted. 7.19 Referring again to Mallet's report before quoted,* we find a very marked difference between the average amount of nitrates present in good, as compared with the quantity found in bad, waters. In thirteen samples of water " known to be pure " * Report National Board of Health, 1882. 46 EXAMINATION OF WATER. the nitrogen present as nitrates averaged 0.42 (the extreme limits being o and 1.04), while in twenty samples of water believed to be objectionable the average figures ran 7.239 (the extreme limits being o and 28.403). Such differences justify Mallet's statement that he regards the determination of nitrates as of great importance. Elkin : dangerously polluted if in excess of.. .. 6.00 Vienna Commission allows.................. 1.04 Hanover " .................. 2.60 Brandes " .................. 7.00 Fischer (Jour, fur Prakt. Chem.).............. 7.00 Leeds's standard for American rivers. .. 1.11 to 3.89 The Rivers Pollution Commission gives the follow- ing averages from 589 unpolluted English waters for nitrogen as nitrites and nitrates together: Rain ........................ 0.03 Upland surface................ 0.09 Deep well..................... 4.95 sPring....................... 3-83 As illustrating how widely the nitrates may vary in deep wells of good character the following list is taken from the Analyst, xx. 84 : Depth of Well in Feet. N as Nitrate. 200. Stratford.............. 0.00 200. Wimbleton ............ 0.43 CHEMICAL EXAMINATION OF WATER. 47 Depth of Well in Feet. N as Nitrate. 490. Chatham.............. 6.85 900. Southend.............. 0.71 600. Witham............... 6.43 160. Mistley................ 0.71 430. Braintree.............. 0.28 305. Colchester............. 0.00 400. Norwich............... 11.43 Fresh sewage is often found entirely free of either nitrites or nitrates simply because the organic nitro- gen present has had, as yet, no sufficient opportunity to become changed to the oxidized form. For in- stance, the sewage of Troy, N. Y., contains (sample of December, 1895) : Parts per Million. Free ammonia.............. .875 Albuminoid ammonia........ .675 Nitrogen as nitrates......... none Nitrogen as nitrites......... trace Chlorine.................. 31 " Required oxygen "........ 89 Total residue............... 489 Loss on ignition............ 315 A curious case of pure water with very high " nitrates " recently came under the writer's observa- tion. The water was from a deep rock-drilled well, which had been " torpedoed " by fifty pounds of nitro- glycerine. Note how important the " history of the 4§ EXAMINATION OF WATER. case " was to a proper interpretation of the analytical results in this instance. ORGANIC MATTER. A revolution has been wrought during recent years in the determination of organic matter in potable water. Methods have arisen and disappeared. Authors of the highest rank have combated each other in print, with a success in establishing their views that has not always been commensurate with their positiveness in stating them. It was in an effort to throw a little unprejudiced light upon the several processes of rival writers that Mallet undertook the investigation from the report of which we here so often quote- -an investigation that required a period of years for its accomplishment, and which marks an era in the history of water- analysis. As therein referred to there are three methods of estimating organic pollution worthy of special mention, viz.: (a) the combustion process of Frankland ; (b) the albuminoid ammonia process of Wanklyn ; (c) the " Forschammer " process as modi- fied by subsequent investigators. Concerning the first, which is a direct combustion of a water residue, after the manner of an ultimate organic analysis, we note the following in the Analyst for September, 1885 : " It is subject to many causes of error, and is of so extremely delicate a nature as CHEMICAL EXAMINATION OF WATER. 49 to be almost abandoned at the present time." In his report to the Philadelphia Water Board for 1884 Dr. Leeds, referring to this method, says : " The deter- minations were discontinued, because the amount of information which they afforded did not appear com- mensurate with the great labor which they involved." This remark of Dr. Leeds is almost identical with statements made to the author by Albert-Levy and other French authorities. In short, Frankland's combustion method is diffi- cult, liable to error in unpractised hands, and its re- sults are not indispensable for forming a correct opinion of the sanitary value of a water. A far more general method for obtaining informa- tion as to organic impurity is Wanklyn's Albuminoid Ammonia Process.—By the employment of this method a knowledge of the amount of " free ammonia " present is also obtained. We may outline the process as follows : The " free ammonia " is distilled from a measured quan- tity of the water, and its amount is determined by what is known as " Nessler's " method, which will be described later. A strongly alkaline solution of po- tassic permanganate is then added to another portion of the water and the distillation is repeated. Nitrog- enous organic matters are thereby broken up and the resulting ammonia (" albuminoid "), which distils over with the steam, is determined by the " Nessler " 50 EXAMINATION OF WATER. method in like manner as before. It must be noted that the so-called " albuminoid " ammonia does not exist ready formed in the water, but is a product of the decomposition of organic nitrogenous substances by the alkaline permanganate. The term is derived from the fact that " albumen " gives off ammonia in like manner when similarly treated. The reagents necessary are : "Nessler's" Solution.—Dissolve 16 grammes mer- curic chloride (HgCl2) in about half a litre of pure water. Dissolve 35 grammes potassic iodide (KI) in about 200 c.c. pure water. Pour the first solution into the second until a faint show of excess is indicated. Add 160 grammes solid potassium hydrate (KOH). Dilute to one litre, and finally add strong solution of mercuric chloride, little by little, until the red mer- curic iodide just begins to be permanent. Do not filter from excess of mercuric iodide, but let the same settle to the bottom of the vessel. The finished re- agent should have a pale straw color. It is improved by age. " Nessler's " solution will give a distinct brownish- yellow coloration with the most minute traces of am- monia or ammonium salts. If the quantity of am- monia be at all considerable, a brown precipitate will appear. The reaction in case of either precipitate or coloration will be CHEMICAL EXAMINATION OF WATER. 51 2(2KI,HgI2) + NH3 + 3KOH = NHg2IH20 + 7KI + 2H20. Pure Water.—This must be prepared with great care, in a room free from the usual laboratory fumes. In short, as has been already said, the entire examina- tion of potable water should be undertaken in a local- ity other than a general working laboratory. The most suitable retort for this purpose is of copper, three gallons in size, and with a tin condensing worm. Fill it with good spring-water, distil, collect distillate in 50-c.c. " Nessler " jars, and to each successive jar- ful so collected add 2 c.c. " Nessler " solution.* After waiting five minutes, should a brown tint be observed upon looking through the liquid (longitudinally) at a white porcelain tile or piece of white paper, the pres- ence of ammonia is indicated. Continue the distillation and the " nesslerizing " of the successive 50-c.c. portions of the distillate until no coloration is obtained even after standing for five minutes. When ammonia ceases to be detected, the distilled water may be collected for use. The dis- tillation should not be pushed too far, both on ac- * The " Nessler " jars here used are carefully prepared, so as to have a uniform distance (S]4 inches) between the bottom of the jar and the 50-c.c. mark. No mixer or stirrer is ever em- ployed, as the high gravity of the " Nessler " solution causes it to quickly sink into and mix with the comparatively light dis- tillate. 52 EXAMINATION OF WATER. count of danger to the retort and of possible produc- tion of ammonia from decomposition of the organic material remaining in the bottom. Alkaline Potassic Permanganate.—Dissolve 200 grammes solid potassic hydrate (KOH) and 8 grammes crystallized potassic permanganate (K2Mn208) in 1250 c.c. of pure water. Boil down to one litre and keep for i:se. Sodic Carbonate Solution.—Dissolve 50 grammes of the pure salt in 300 c.c. pure water. Standard Ammonia Solution.—Dissolve 1.5706 grammes of pure dry ammonium chloride in half a litre pure water. Dilute 5 c.c. of this solution to half a litre with pure water. This second solution will represent a strength of .01 mg. of NH3 per cubic centimetre, and is the standard solution used. DETERMINATION OF FREE AMMONIA. Fit a one-quart glass tubulated retort to a large Liebig condenser,* letting the neck of the retort pass well into the conder sing-tube (3 or 4 cm.) and through a large-size soft-rubber stopper. This con- nection must be thoroughly tight. Place 200 c.c. pure water in the retort and add 10 c.c. of the sodic carbonate solution. Distil off two 50-c.c. jars of water, and " nesslerize " the second in order to be * For a description of the retorts, condensers, etc., used by the author see page 69. CHEMICAL EXAMINATION OF WATER. 53 sure that no ammonia yet remains in the retort. Any ammonia that may have resulted from the imperfect cleaning of the apparatus, or that may have been pres- ent in the sodic carbonate solution, will usually all go over in the first 50 c.c. of distillate, but the same quan- tity (i.e., 100 c.c.) must be distilled off in all cases in order that when the actual analysis of the unknown water is started upon the condition as to volume may be always constant. In fact, it may be conveniently stated here that perfect uniformity of conditions is a requisite for success in water-analysis. To the contents of the retort is now added half a litre of the water to be examined. Distil and catch the distillate in 50-c.c. " Nessler " jars. The rate of the distillation should be so man- aged as to allow about fifteen minutes for the filling of each 50-c.c. jar. Add 2 c.c. " Nessler " reagent to each jarful, and continue the operation with each suc- cessive portion of the distillate until no further re- action for ammonia is apparent after waiting five minutes. Usually four jars will be sufficient to carry off all free ammonia, but it is the author's custom to always distil off six. From a small burette measure definite amounts of the standard ammonia solution into several clean " Nessler " jars. Dilute each to the 50-c.c. mark with pure water, add 2 c.c. " Nessler " solution, and after 54 EXAMINATION OF WATER. standing for five minutes compare as to depth of tint with the distillates already " nesslerized." With a little practice it will be found easy, by varying the amounts of standard ammonia solution used, to pro- duce tints corresponding to those existing in the dis- tillates, and thereby a most accurate knowledge of the quantity of ammonia actually present may be ob- tained. Such ammonia existed ready formed in the water, either free or as an ammonium salt, and passed over unchanged with the steam ; it is therefore tech- nically known as " free ammonia." To make clear the calculation of results let us cite an example : Suppose the first jarful to have required 9 c.c. standard ammonia solution (diluted to 50 c.c.) to match its color when " nesslerized," the second one 3 c.c, and the third 1 c.c. Then, since each cubic centimetre of the standard ammonia solution corre- sponds to .01 mg. NH3, the whole amount of " free ammonia " present in the original half-litre of water would be : 1 °.......................09 2°.......................03 3°.......................01 4°.......................00 Multiplying this by two to obtain the quantity for an CHEMICAL EXAMINATION OF WATER. 55 entire litre, and remembering that I mg. is the millionth part by weight of a litre of water, we find the total " free ammonia " present in the water to be 0.26 part per million. ALBUMINOID AMMONIA. Throw out the residue remaining after the distilla- tion for free ammonia, clean the retort thoroughly, and refit it to the condenser. Place in the retort 200 c.c. pure water and 50 c.c. of the alkaline permanganate solution. Distil off three 50-c.c. jars, and " nessler- ize " the third one in order to insure freedom from ammonia. Add half a litre of the water under exam- ination, and proceed with the distillation, and the " nesslerizing " of the successive 50-c.c. portions of the distillate, as in the determination of free ammonia. The distillation is to be continued until six 50-c.c. jars are filled. The ammonia determined by this distillation will be total (i.e., "free" plus " albuminoid ") ; therefore from the Nessler reading of each jarful of distillate must be subtracted the read- ing for the corresponding jarful for " free ammonia ": the difference will give the " albuminoid ammonia " for that jar. The calculation is entirely similar to that for free ammonia, as stated. 56 EXAMINATION OF WATER. Interpretation of Results.—Concerning the interpre- tation of results, Wanklyn, the inventor of the method, is very dogmatic, and says : " The analytical characters, as brought out by the ammonia process, are very distinctive of good and bad waters, and are quite unmistakable. There is, indeed, hardly any branch of chemical analysis in which the operator is less exposed to the risk of failure." This statement is altogether too strong. Waters of high organic purity or those of gross pollution are undoubtedly easy to classify, but with the numerous cases which lie about the boundary-line between " good " and " bad " the greatest care is to be exercised in the reading of results and the passing of judgment. One rule, already mentioned, and upon which too much stress cannot be laid, is never to give an opinion con- cerning a water whose history and surroundings are not thoroughly known. The " free ammonia " in artesian wells is often ex- cessive, under circumstances that make animal con- tamination an impossibility, and even rain-water, freshly collected after periods of long drought, will often exhibit properties calculated to mislead the analyst. C. B. Fox gives the following determinations in pure deep-well waters : CHEMICAL EXAMINATION OF WATER. $7 Free Albuminoid Ammonia. Ammonia. Well 230 feet deep........ 0.80 0.05 " 250 " " ........ 0.76 0.04 " 3°° " " ........ 0.74 0.03 " 33o " " ........ 0.37 0.06 " 385 " " ........ 0.59 0.04 " " very deep "........ 0.41 0.07 This excess of free ammonia may be due either— " 1. To entrance of rain-water ; " 2. To the beneficial transformation of harmful organic matter into the harmless ammonia, through the agency of sand, clay, and other substances which act on the water in a manner similar to the action of a good filter ; " 3. To some salt of ammonia existing in the strata through which the water rises ; or, " 4. To the decomposition of nitrates in the pipes of the well. Mr. H. Slater suggests that the agent concerned in this reduction may, in the case of the deep-well waters, be the sulphide of iron which is found in the clay. " We conclude, then, that the presence of free am- monia in such comparatively large quantities in these deep-well waters is due to the reduction of nitrates and nitrites by sulphide of iron, or some kinds of or- ganic matter, or some other agent, such oxidized 58 EXAMINATION OF WATER. nitrogen salts having been produced in past ages by the oxidation of organic matter." * Free ammonia in deep-well water may, however, be derived from very objectionable sources ; as when surface pollution is admitted because of cleavage and fracture cracks in friable rocks, and because of the " dip " of the strata being nearly vertical. The writer has seen a number of such cases. Take, for instance, the water from a rock-drilled well in friable shale. The boring was 57 feet deep and was located in a city containing many privy- vaults, the nearest of which was 75 feet distant. The " free ammonia" reached the very high figure of 2.025, an7) in a ioo-c.c. " Nessler " jar. Dilute with 50 c.c. water and then pour in 25 c.c. of the incubated culture prepared above. A red colora- tion indicates indol, and is an additional evidence of the presence of B. coli. 7. Inoculate "nutrient gelatin" from the incubated culture obtained in 6. Let the plates develop as usual 112 EXAMINATION OF WATER. and observe if any of the non-liquefying colonies are whitish, with irregular, leafy outlines and showing lines more or less radial. Such characteristics point to B. coli. 8. Place a quantity of new milk in an Arnold's ster- ilizer for fifteen minutes, and afterwards allow it to stand overnight in a cool place. Siphon off the lower layer of milk, avoiding the cream. Place it in cotton-plugged test-tubes and sterilize as usual. Add to several of these tubes I c.c. of the incubated culture obtained in 6, and keep in the dark at room temperature. B. coli coagulates milk in from I to 3 days. Other forms usually take more time. 9. If inoculations from the colonies obtained in 7 or from the culture obtained in 6 be examined as " hanging-drop " cultures, the bacilli will be found to be motile if they be B. coli. This motility will be manifested, however, by only a portion of the bacilli present in the field, and its in- tensity will be far less than that shown by the typhoid bacillus. Smith's summary of characteristics of B. coli communis may very properly be given place here : * * Am. J. Med. Sci., Sept., 1895. BACTERIOLOGICAL EXAMINATION. II3 Colony : non-liquefying, opaque, whitish with ir- regular margin. Motile in hanging-drop culture. Coagulates milk in 1 to 3 days. Bouillon culture gives " indol " reaction. In fermentation-tube total gas = about 50 per cent. Most of the gas evolved during first 24 hours. Ratio of H to C02 = 2:1. Reaction of liquid in bulb of fermentation-tube, strongly acid. Differentiation of species, as has already been said, must be left for discussion to writers upon general bacteriology ; but a moment can be properly spent here upon the often broached topic of the recognition of the typhoid germ in water, and also a word added with reference to the diagnostic value of the demon- stration of the presence of Bacillus coli communis. Laws and Andrewes in their report to the London County Council show that the chance of discovering B. typhosis in sewage is exceedingly small. They en- tirely failed to find it in London sewage. Finally they examined the sewage flowing (without disinfection) from the Eastern Hospital at Homeston, which same received the dejections of forty typhoid patients. Out of a whole series of samples examined from 114 EXAMINATION OF WATER. this latter source only two colonies of B. typhosis were differentiated with certainty.* Similar experience has been recorded by practically all the recent observers, and consequently search for the typhoid germ in water is becoming very unusual. The present position of this question is tersely summed up by Dr. W. H. Welch : " We possess no satisfactory method for the deter- mination of the presence of the typhoid bacillus in water. With our present methods the most which can be expected from the biological examination of water as regards this question is the determination, not of the actual presence of the typhoid bacillus, but of the possibility or probability of its presence. Our principal guide at present in drawing conclusions as to the possible presence of the typhoid bacillus in suspected drinking-water is the recognition of faecal bacteria, and more particularly of members of the colon group." 1j This brings us down to our second query regarding the diagnostic value of the " colon group." Speaking of a bacterial index of faecal pollution, Stoddart says : " Until we are able to single out a form specifically associated with faecal matter, and at least as easily recognizable as the tubercle or diph- * See Rafter's " Water of Lake Erie," page 14. \J. Am. Pub. Health Asso., xx. 502. BACTERIOLOGICAL EXAMINATION. 11 5 theria bacillus, we shall do well to avoid such expres- sions as contain ' index of faecal pollution.' It is an assumption to say that B. coli communis does not occur in abundance in organic matters other than animal excreta." * It is certainly the author's experience that the " colon group " is widely distributed, he having found it in waters that a " sanitary survey " would unques- tionably pronounce pure ; but it cannot be denied that its persistent presence in large numbers is an indication of pollution that must not be overlooked ; and, moreover, the proof of its absence serves to materially aid in formulating an opinion concerning the purity of a water. Bacteriologists will, of course, very properly, ex- tend their differentiations to the utmost limit, in the hope of positively establishing the much-needed " index of faecal pollution," but for routine water- work it is doubtful if it pay to go beyond the tests already given. Moreover, it should be said that to make such tests as have been here outlined of real value, they should be comparative in character ; and the interpretation of results should be based upon data furnished by closely related local standards. Samples for bacteriological work are far more * Analyst, xxii. 122 and 123. u6 EXAMINATION OF WATER. quickly damaged by keeping than are those intended for chemical analysis ; thus : SPRING-WATER, TROY, N. Y. Kept at room temperature. November 10..... 830 bacteria per c.c. 12..... 8,128 " " " 13..... 9,433 " " " 15..... 12,740 " " " Much more striking instances are given by Miquel. Thus for the Dhuis water : Temperature. Bacteria per c.c. 12 noon................ 16.60 C. 57 1-30 P.M................ I9.50 " 143 3p.m................... 20.90 " 456 For Vanne water Temperature. Bacteria per c.c. Immediate ........... 170 C. After 24 hours......... 21.20 " Also for Vanne water : Immediate........... 15-9° C After 2 hours.......... 20.60 ' " 1 day........... 21.00 ' " 2 days........... 20.50 ' " 3 days........... 22.30 ' 56 32,140 48 125 38,000 125,000 590,000 BACTERIOLOGICAL EXAMINATION. 117 Deep-well water (Frankland) : Immediate........... 200 C. 7 After 1 day........... 200 " 21 3 days........... 200 " 495,000 The last instance shows that multiplication of bac- teria is not to be accounted for by a simple increase of temperature. As has been already stated, it is exceedingly im- portant to keep water-samples at freezing tempera- ture during transportation to the laboratory. Germs do not commonly multiply at such a temperature, but, as has been shown in France, this does not hold good for waters heavily charged with bacterial food. In one instance " sea-water, constantly maintained at o° C, changed in bacterial contents from 150 to 520 per cubic centimetre in 24 hours." On the other hand, great cold is not surely fatal to germ-life. The author submitted cultures of ordinary bacteria to the temperature of solid carbon dioxide during man}- hours without causing their destruction, and more recently Ravenel has exposed them to the temperature of liquid air (—312° F.) with like result.* The number of bacteria per cubic centimetre in water-samples taken from the same source at differ- ent times will greatly vary with the season and changes in local conditions. Thus the Hudson River * Medical News, June 10, 1899. I 18 EXAM IN A TION OF WA TER. water sampled at the Troy intake shows the follow- ing variation in bacterial contents during the colder half of the year ; similar results for a Rensselaer County spring-water are also given : Hudson River. Spring. October .............. 1,487 158 626 November ............ \ 750 8,128 December............. 1,463 1,620 January............... 4,022 2,519 February.............. 3>322 166 March................ .... 8,520 a m i J'343 _ April................. \ 476 ( 17,665 The influence of high water in the river is well shown by the difference between the early and late April samples. Surface-washing is the cause of such an increase. The effect of melting snow, and conse- quent surface-washing, is also shown in the March sample of spring-water. In general it may be said that so long as a river is fed by springs, that is, during the hot months, the bacteria tend to remain low in numbers, but with the advent of floods germ-life increases in quantity, be- cause of the washing of the surface of the ground by heavy rainfall and melting snow. During the period BACTERIOLOGICAL EXAMINATION. Iig when severe frost ties up all surface sources the bac- teria again diminish in numbers. Miquel gives the following averages for bacteria per cubic centimetre of Seine water taken at Ivry, and for the Vanne spring-water supply of Paris : Seine. Vanne. January................ 52,670 400 February............... 43,120 1,625 March ................. 34.7JO 1,560 April................... 38,640 860 May................... 12,930 720 June................... 28,150 590 July................... 14,130 865 August................. 6,780 985 September.............. 20,220 465 October................ 22,350 495 November.............. 37,720 495 December.............. 78,950 525 or Spring................. 26,570 720 Summer................ 13,710 770 Autumn................ 46,340 5°5 Winter................. 43>5°° ^200 Annual mean.......... 32,53° 800 The River Seine, unlike the Hudson, is not affected in the spring by the melting of great masses of north- ern snow. 120 EXAMINATION OF WATER. A well-water will sometimes show great and irregu- lar variationL, in bacterial contents ; thus Buchner cites the following case from Munich : * July i.. . " 8... " 15.-. "21... "29... August 3 As has been said, Miquel permits only a few bac- teria to enter the culture-jelly of a single flask, accom- plishing this end by his system of dilution, and he then waits at least two weeks before making the count. This method is impracticable for routine water ex- amination, nor is it necessary for the obtaining of satisfactory results, although, of course, it has the advantage of permitting slowly developing colonies which would be otherwise lost in the crowd of lique- fying bacteria to grow sufficiently to be recognized, as is very evident from the figures of Miquel given below. Out of 1000 bacteria in water, sowed in culture- jelly, the following numbers of colonies will appear on the successive days : 600 bacteria per c.c. 1,200 " 4,000 " 80 " 10,000 " 400 " * " Das Wasser/' Fischer, 36. BACTERIOLOGICAL EXAMINATION. 121 ist day................ 20 colonies 2d " ................ 116 3d " ................ 118 4th " ................ 133 5th " ................ 143 6th " ................ 107 7th " ................ 88 8th " ................ 55 9th " ................ 41 10th " ................ 38 nth " ................ 33 12th " ................ 29 13th " ................ 30 14th " ................ 25 15th " ................ 24 " The complete analysis of a water may require from several weeks to several months of constant and difficult work; I may add that, in the present state of our knowledge, it is often impossible to complete it, for the reason that several of the species of bacteria we meet with are as yet unknown." (Miquel.) Sterilizing a water by heat is not so easy as most people imagine. Absolute sterility can be attained in about forty-five minutes by heating the water, under pressure, to 1150 C. Ordinary boiling for half an hour will destroy about 122 EXAMINATION OF WATER. 99 per cent of all bacterial life, and fortunately that which remains is entirely harmless. No pathogenic germs are capable of resisting such a temperature for half an hour. Experimenting with Seine water, which contained, at the ordinary temperature of 22° C, 848 bacteria per cubic centimetre, Miquel found the following de- crease in numbers of germs as the temperature was raised : Water maintained 15 Minutes at 43° C......... 5oc 6o° 7o° 8o° 9o° 100° Bacteria per c.c. remaining. ..... 64O ..... 132 ..... 40 ..... 27.2 ..... 26.4 ..... 14-4 ..... 5-2 For the enumeration of organisms not bacterial, in water, Mr. D. D. Jackson has devised a most valuable modification of the original Sedgwick-Rafter ap- paratus. The body of the filter is cylindrical, and 2 inches in diameter. The distance from the top to the conical base is 9 inches. The small cylindrical pro- longation of the cone's apex is 2\ inches long and BA CTERIOL OGICA L EX A MINA TION. 123 \ inch in diameter. A perforated rubber stopper, with its hole covered by a disk of fine bolting-cloth, is fitted to the smaller end of the funnel and about \ inch of carefully screened fine sand (between 80 and 100 mesh) is poured into the narrow tube and wet down with distilled water. ^\SK^WK^KSS rmssswmwsa Fig. 10. From 250 to 500 c.c. of the water under examina- tion are now permitted to filter through the sand. After the water has run through, the sand with the material strained off by it is washed into a test-tube by 5 c.c. of distilled water delivered from a pipette. The organisms, sinking in the test-tube much more 124 EXAMINATION OF WATER. slowly than the sand-grains, may be decanted, with the water in which they float, into a second test-tube. From this decanted portion, after agitation, I c.c. is delivered by a pipette to the covered " counting-cell," which it completely fills.* See Fig. 10. This excellent device will be found of great service in recognizing and enumerating the various forms of life commonly met with in waters. For purposes of general differentiation recourse must be had to the writings of biologists who have made such work a specialty. Particularly valuable is the recent publication by G. C. Whipple, " The Microscopy of Drinking-water," published by John Wiley & Sons. * These cells, together with all accessory apparatus, may be obtained of Richards & Co., No. 30 East 18th Street. New York City. INDEX. PAGE Acidity determination...................................... 17 Agar-agar................................................. 99 Albert-Levy, determination of oxygen...................... 84 , estimates bacteria by oxygen present.......... 88 , method for total solids........................ 19 Albuminoid ammonia determination........................ 55 Albuminoid ammonia process.............................. 49 , details to be observed........ 66 , sundry apparatus for......... 67 Alkaline potassic permanganate............................ 52 Alkalinity determination.................................. 16 Alterability, coefficient of.................................. 88 Alum, logwood test for...................................... 81 Aluminum and iron, determination of....................... 83 Aluminum hydrate used to clear water...................... 32 Ammonia, albuminoid, determination of.................... 55 Ammonia, free, determination of........................... 52 , high in rain-water.......................... 58 wells in ferruginous regions........ 59 , reduced by plants....................... • - 59 Ammonia, in deep wells, often excessive.................... 5° Ammonia process, interpretation of results.................. 5° Ammonia, rate of evolution important...................... 61 Ammonia solution, standard.............................. 52 Analyses of sundry waters................................. 64 Analyses, results of, how stated............................ " Analysis of mineral residue............................... 83 Analysis, water, requires separate laboratory............... 12 125 126 INDEX. PAGE Analytical results, interpretation of........................ 18 Angus Smith, observations on loss on ignition.............. 20 Apparatus for counting bacteria............................ 107 Appearance and turbidity, determination of................. 12 Arsenic in water........................................... 81 Atmospheric nitrogen fixed by roots........................ 41 Bacillus coli communis, diagnostic value of................. 113 , tests for........................... 109 Bacillus typhosis, chances of discovery small................ 113 Bacteria colonies, development of......................... 104 Bacteria, comparison growths on media of sundry reactions.. 98 developing upon successive days.................. 119 , gas-forming...................................... 109 , great cold not fatal to............................ 117 in river water, low in summer..................... 118 in same water, vary with season.................. 117 measured by dissolved oxygen present............ 88 , monthly averages in Seine water.................. 119 , time for counting colonies of...................... 106 , value of count of................................. 94 Bacteriological examination of water....................... 93 Bacteriological samples quickly damaged................... 115 Barium, determination of.................................. 83 Bouillon, preparation of.................................... 95 .sugar........................................... 98 Calcium bicarbonate, existence of......................... 22 Calcium, determination of.................................. 83 Carbon dioxide contained in one litre of water............. 89 , determination of............................ 89 Changes in samples during laboratory storage.............. 8 Chemical examination of water............................. 7 Chloride sodium solution, standard......................... 43 Chlorine.................................................. 28 Chlorine determination.................................... 31 best made in yellow light........... 32 Chlorine, influence of sea upon normal..................... 29 in ground-water increased by human habitation... 30 , possible loss of, during evaporation.............. 34 Chromium in water........................................ 81 Clark scale of hardness.................................... 26 Clay standard for turbidity................................. 12 INDEX. YT.'J PAGE Coefficient of alterability................................... 88 Cold not fatal to bacteria.................................. 117 Colon group widely distributed............................. 113 Colonies of bacteria, development of......................• 104 , time for counting of................... 106 Color due to iron.......................................... 17 manganese................................... T7 organic material.............................. 17 Color, Leeds method for.................................... 17 removed by aluminum hydrate....................... 32 Color solution for nitrate, standard........................ 45 Coloring matter of waters.................................. T7 Combustion process of Frankland.......................... 48 Comparates, meaning of.................................... 18 Copper, determination of................................... 78 Counting bacteria, apparatus for............................ 107 Counting-cell for organisms not bacterial................... 126 Counting colonies of bacteria, time for...................... 106 Counting of organisms not bacterial........................ 125 Count of bacteria, value of................................. 94 Croton water, variation of temperature of.................. 15 Dilution method, Miquel's................................. 106 Dissolved gases, determination of.......................... 84 Dissolved oxygen in Seine water........................... 87 Directions for taking of water samples..................... 7 Dupre, remarks concerning standards of purity............. 63 Evaporation, possible loss of chlorine during............... 34 Fermentation.............................................. 99 Forschammer's process..................................... 74 Frankland, combustion process of.........................• 48 Free-ammonia determination................ .............. 52 Free ammonia in deep wells often excessive................ 56 Fuller, on reaction of media................................ 97 Gallon, parts per million converted to grains per............ 92 Gas-forming bacteria...................................... io9 Gases, dissolved, determination of........................ 84 Gelatin, nutrient........................................... 9 , sugar........................................... 9 German regulations for counting bacteria.................. 106 Glassware sterilizer..............................•........ I0° Ground-water, human habitation increases chlorine in....... 30 128 INDEX. PAGE Hardness, Clark scale of................................... 26 , degrees of...................................... 26 , determination of....................... ........ 26 , permanent...................................... 22 Leeds method for..................... 27 , temporary...................................... 22 Hard water, action of, upon soap.......................... 23 causes expense to community.................. 23 Hazen's method for color................................. 17 Hehner's method for permanent hardness.................. 26 History of a water, knowledge of, important................ 3 Indol reaction............................................. in Interpretation of analytical results, standards for........... 18 Iron and aluminum, determination of....................... 83 Iron as cause of color...................................... 17 Iron, determination of..................................... 79 Iron solution, standard..................................... 79 Jackson, apparatus for counting organisms not bacterial .... 125 Kaolin standard for turbidity............................... 12 Kubel's process............................................ 74 Lautenschlaeger's sterilizer for glassware.................. 101 Lead, determination of..................................... 78 Lead pipe, action of water upon............................ 79 Leeds method for color.................................... 17 permanent hardness...................... 27 Logwood, best method of obtaining......................... 82 Logwood test for alum..................................... 81 Loss on ignition, determination of......................... 20 Magnesium, determination of.............................. 83 Mallet, remarks concerning nitrites......................... 35 standards of purity............. 63 Manganese as cause of color................................ 17 Media, proper reaction for................................. 95 , sterilization of...................................... 96 to be kept in cool, dark place....................... 96 Michigan standard of purity for water...................... 90 Miller-McPherson counting apparatus...................... 107 Mineral residue, analysis of................................ 83 Miquel's dilution method................................... 106 Miquel flasks.............................................. 106 Naphthylamine hydrochloride.............................. 36 Nesslerizing, directions for................................. 51 INDEX. 129 PAGE Nesslerizing, temperature important during................ 70 Nessler jars, description of.............................. 51, 69 Nessler's solution.................................... ..... 50 Nessler standards, routine.................................. 72 ," smoky "............................. 72 Nitrate color solution, standard............................ 45 Nitrate determination...................................... 44 Nitrate potassium solution, standard....................... 43 Nitrates, nitrogen as....................................... 40 washed from air by rain.......................... 40 Nitrite, determination....................... ............. 37 , standard solution of sodium........................ 37 Nitrites in ground-water suspicious......................... 39 , nitrogen as....................................... 35 Nitrogen as nitrates....................................... 40 nitrites........................................ 35 , atmospheric, fixed by roots....................... 41 contained in one litre of water.................... 89 , successive steps in oxidation of organic........... 10 Nutrient gelatin............................................ 96 Odor and taste of water.................................... 14 Organic material as cause of color.......................... 17 Organic matter, determination of.......................... 48 Organic nitrogen, successive steps in oxidation of........... 10 Oxalic acid solution, standard.............................. 75 Oxygen-consuming capacity................................ 74 Oxygen contained in one litre of water..................... 89 Oxygen, dissolved, a measure of bacteria present........... 88 , determination of........................ 84 , pipette for determination of........... 85 Parts per million converted to grains per gallon............. 92 Permanganate, alkaline potassic............................ 52 Permanganate potassic solution, standard.................. 75 Phenol-sulphonic acid...................................... 43 Phipson's method for phosphates.......................... 82 Phosphates, determination of.............................. 82 Pipettes, sterilized........................................ 101 Plants reduce free ammonia................................ 59 Potassium chromate, indicator.............................. 31 Potassium nitrate solution, standard........................ 43 Potassium permanganate solution, standard................ 75 130 INDEX. PAGE Pure water, preparation of................................. 51 Rain, variation of chlorine in monthly..................... 29 washes nitrates from air............................. 40 Rain-water, free ammonia high in.......................... 58 Rate of distillation, proper................................. 70 Ravenel, exposes bacteria to temperature of liquid air...... 117 , method for preparing agar-agar................... 99 Reaction of media.......................................... 95 water, determination of......................... 16 " Required oxygen "....................................... 74 , determination of...................... 76 Results of analyses, how stated............................ 11 Richards logwood test for alum..... ...................... 81 on coloring matter of waters...................... 17 Samples, changes in, during laboratory storage............. 8 , directions for taking.............................. 7 for bacteriological work quickly damaged......... 115 , method of sowing................................ 105 , method of taking, for bacteriological work........ 102 , not to be taken in stoneware...................... 7 Sea, influence of, upon normal chlorine...................... 29 Sediment, determination of................................. 13 Seine water, dissolved oxygen in........................... 87 Seyler's method for carbon dioxide......................... 89 Silica, determination of................................... 83 Silver solution, standard................................... 31 Smart, observations on loss on ignition..................... 20 Smith's fermentation-tube.................................. 99 Smith, views concerning Bacillus coli communis........ no, 112 " Smoky," Nessler standards............................... 72 Soap, action of hard water upon............................ 23 Soap solution, standard.................................... 24 Sodium carbonate solution, saturated....................... 31 Sodium chloride solution, standard.........*.............. 43 Sodium nitrite, standard solution of........................ 37 Sowing samples, dilution method........................... 106 Sowing water samples, method of.......................... 105 Standard purity of water, Michigan........................ 90 Standards for interpretation of analytical results............ 18 Standards of purity, no ground for general................. 63 Sterilization of media...................................... 96 INDEX. 131 P^GE Sterilizer, glassware....................................... ioo , Lautenschlaeger's, for glassware................. 101 Stoneware jugs not admissible for sampling................ 7 Sugar bouillon............................................. g8 Sugar gelatin.............................................. 98 Sulphanilic acid........................................... 36 Sulphates, determination of................................ 84 Sundry waters, analyses of................................ 64 Taste and odor of water.................................... 14 Temperature determination................................ 14 of Croton water, variation in.................. 15 , thermophone for reading..................... 15 Tests for Bacillus coli communis........................... 109 Thermophone, for temperature reading..................... 15 Total solids, determination................................. ig , source of..................................... 19 Turbidity and appearance, determination of................ 12 Turbidity, observation tube for............................. 13 , standard........................................ 12 Uniformity of conditions necessary in water analysis........ 53 Wanklyn's albuminoid ammonia process.................... 49 standards for interpretation..................... 59 Water analysis requires separate laboratory................ 12 Water, pure, preparation of................................ 51 Wells, free ammonia in deep, often excessive................ 56 Whipple and Warren, inventors of thermophone............ 15 Yellow light best for chlorine determination................ 32 Zinc-bearing spring-water.................................. 80 Zinc, determination of . .................................. 80 SHORT-TITLE CATALOGUE of the PUBLICATIONS OF JOHN WILEY & SONS, New York. London: CHAPMAN & HALL, Limited. ARRANGED UNDER SUBJECTS. Descriptive circulars sent on application. Books marked with an asterisk are sold at net prices only. All books are bound in cloth unless otherwise stated. AGRICULTURE. Cattle Feeding—Dairy Practice—Diseases of Animals- Gardening, Etc. Armsby's Manual of Cattle Feeding....................12mo, $1 75 Downing's Fruit and Fruit Trees.........................8vo, 5 00 Groteufelt's The Principles of Modern Dairy Practice. (Woll.) 12mo, 2 00 Kemp's Landscape Gardening---.....................12mo, 2 50 Loudon's Gardening for Ladies. (Downing.)............12mo, 1 50 Mayuard's Landscape Gardening.......................12mo, 1 50 Steel's Treatise on the Diseases of the Dog................8vo, 3 50 " Treatise on the Diseases of the Ox..................8vo, 6 00 Stockbrulge's Rocks and Soils---..................... ,8vo, 2 50 "Woll's Handbook for Farmers and Dairymen............12mo, 1 50 ARCHITECTURE. 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