CHEMISTRY. 



143 





be plainly seen that the coloring-matter is de- 

 posited equally in its interior. When the albu- 

 men method has been used, the fiber appears 

 entirely without color. At various points dyed 

 bits of coagulated albumen will appear gummed 

 to the fabric, and some of these particles will 

 be found isolated in consequence of the macer- 

 ation. 



H. L. Greville separates carbon disulphide as 

 a residual product from coal-gas, which he 

 finds to exist in the proportion of from thirty 

 to forty-eight grains in the hundred feet of 

 crude gas. It is removed by using gas-purify- 

 ers containing lime through which gas has been 

 passed containing H 2 S, but no COa. When 

 saturated the lime has a bright orange-red color. 

 By distilling this lime with water, OS 2 is ob- 

 tained, amounting to between 1 and 2 per 

 cent, on the amount of substance taken. Picked 

 specimens yielded from 3 to 4 per cent. 



Analytic Chemistry. Willis G. Tucker, in a 

 paper read before the Albany Institute, has 

 made a critical estimate of the value of the 

 principal methods for the chemical analysis of 

 water, and has exposed the present condition 

 of science and practice on the subject. The 

 methods at present in use, each of which has 

 its advocates, are, the permanganate process, 

 which employs permanganate of potash to 

 determine the amount of oxidizable matter in 

 the water ; Wauklyn and Chapman's albumi- 

 noid-ammonia process, which aims to estimate 

 the amount of putrescible nitrogenous matter ; 

 and Frankland and Armstrong's combustion 

 process, by which the relative proportions of 

 nitrogen and carbon in the impurities are de- 

 termined. No one of them enables us to rec- 

 ognize the real morbific material which wa- 

 ter may contain, or is able to distinguish with 

 certainty between disease -producing constitu- 

 ents and the less harmful and innocent matter 

 of organic origin. Some advantage may be 

 gained, but it is not decisive, by using two or 

 all of them together. All attempts to establish 

 definite standards, so that the points for and 

 against a water can be counted up, and a bal- 

 ance struck, have failed. With the means at 

 present at our command, waters which are very 

 pure, chemically, of medium purity, and foul, 

 may be distinguished, but whether these waters 

 are therefore safe to use, doubtful or harmful, 

 must be a matter of opinion, and is not to be 

 decided by the analytical results. Dr. Buchan- 

 an, of the Local Government Board of Great 

 Britain, says, on this point, that while we must 

 ever be on the watch for indications that chem- 

 istry affords of contaminating matters gaining 

 access to our waters, we must go beyond the 

 laboratory for evidence of any drinking-water 

 being free from dangerous organic pollution. 

 The chemist can, indeed, tell us of impurity 

 and hazard, but not of purity and safety. Chem- 

 ical analysis may reveal to us the presence of 

 compounds which have doubtless resulted from 

 the decomposition of animal matter ; and, while 

 there may be no certainty of its producing spe- 



cific disease, we shall err on the safe side if we 

 refuse to use the water. And an analysis may 

 assure us that a given water is of such a degree 

 of purity that the probabilities are that it car- 

 ries with it no harmful matter; but this kind 

 of evidence is always to be received with cau- 

 tion, unless the results of the examination are 

 borne out by other evidence proving that pol- 

 lution is not probable. While it can not tell us 

 that a water is absolutely safe or necessarily 

 harmful, it can tell us that it contains those 

 constituents which may reasonably be believed 

 to accompany harmful matter. Prof. Mallet 

 confirms this view in the report of the Na- 

 tional Board of Health for 1882, where he 

 holds that it is not possible to decide abso- 

 lutely upon the wholesomeness or unwhole- 

 someness of a drinking-water by the mere use 

 of any of the processes for estimating organic 

 matter or its constituents ; that such processes 

 must be used in conjunction with the investi- 

 gation of other evidence of a more general 

 sort as to the source and history of the water, 

 and should then be deemed of secondary im- 

 portance ; that there are no sound grounds on 

 which to establish such general standards of 

 purity as have been proposed, looking to exact 

 amounts of organic carbon or nitrogen, albu- 

 minoid ammonia, oxygen of permanganate con- 

 sumed, etc., and that two entirely legitimate 

 directions are open for the chemical examina- 

 tion of the organic constituents of drinking- 

 water the detection of very gross pollution, 

 and the periodical examination of water-sup- 

 plies in order that the normal or usual charac- 

 ter of the water having been previously ascer- 

 tained, suspicious changes which may occur 

 shall be detected and investigated. 



Dr. Curtis C. Howard, of Stirling Medical 

 College, Columbus, Ohio, recognizing the de- 

 sirability of finding tests for impurities in wa- 

 ter available for physicians' use, suggests that 

 they should fulfill the conditions of requiring 

 no apparatus and but one or two reagents, and 

 of giving results which, manifested either by 

 the appearance of a color or a precipitate, are 

 at once recognized by the eye. The most con- 

 siderable impurities in water are attended by 

 the presence of nitrites and chlorides. For 

 nitrites the most delicate reagents, and the 

 most satisfactory, for Dr. Howard's purpose, 

 are sulphuric acid and naphthylamine hydro- 

 chloride. If water containing not more than 

 one-thousandth part per hundred thousand of 

 nitrous acid be treated, with a drop of hy- 

 drochloric acid and a drop each of solutions 

 of these reagents, after standing fifteen^or 

 twenty minutes, only the faintest tint of pink 

 will be perceived. If a marked pink be pro- 

 duced, the quantity of nitrites is sufficient to 

 indicate serious contamination. In sewage 

 and in the water from a few wells, the color 

 was a deep carmine, and the quantity present 

 was from twenty to sixty-six times the limit 

 stated. The reagents for chlorides are nitric 

 acid and silver nitrate, which produce in water 



