1882.] 



MICKOSCOPICAL JOUKNAL. 



227 



ers may now compare the American 



stands with the cut of the English 

 stand. 



Examination of Water and Air 



for Sanitary Purposes^ witli 



RemarJis on Disinfection.* 



It is well known that the presence 

 of chlorides, nitrites, etc., in water, 

 is indicative of contamination with 

 sewage, or with organic matter of 

 some kind, and, by general consent, 

 such waters are regarded as unsafe 

 for household use. On the other 

 hand, it must be admitted that the 

 constant use of such waters for drink- 

 ing is only occasionally followed by 

 diseases which can be attributed to 

 them. Certainly chlorides and nitrites 

 are incapable of producing contagious 

 diseases. Therefore, there must be 

 another element in those waters which 

 produce typhoid fever for example, 

 that may or may not accompany the 

 compounds mentioned. At present 

 it is almost universally conceded that 

 this element is a living microscopic 

 germ, which develops and multiplies 

 in the water. If this is true, it is ob- 

 vious that the results of a chemical 

 analysis are quite incompetent to 

 prove the healthfulness of a water. 



Granting this, it may be argued 

 that chemical examinations are quite 

 useless for sanitary purposes. The 

 fact is quite otherwise. For although 

 the chemist cannot detect the germs 

 of disease, which likewise baffle the 

 scrutiny of the microscopist, his ana- 

 lysis indicates the source of contami- 

 nation. It enables us, therefore, to 

 trace the contamination to its source, 

 and thus determine its nature. 



Perhaps it will be a somewhat start- 

 ling assertion to say that the drainage 

 from vaults containing human dejecta 

 is not necessarily unhealthful. Yet 

 the truth of it is demonstrated by the 

 immunity from contagious diseases 

 of thousands of families whose wells 



♦Abstract of an article by R.Hitchcock, 

 published in the Journal of the Franklin 

 Institute. 



are situated close by, and below, such 

 vaults. Sanitarians become greatly 

 excited over the condition of affairs 

 in this respect all over the country, 

 and they predict most direful epide- 

 mics. But, somehow, the epidemics 

 do not come. Chemists examine the 

 water. Boards of Health order the 

 wells closed, and families complain 

 of the injustice of it because they 

 have never suffered from the use of 

 the water. Evidently theory and 

 experience do not correspond. 



Nevertheless, the explanation is 

 simple enough. Let there be a single 

 case of typhoid fever in a house when 

 the well is thus contaminated, and 

 the probability is that those who 

 drink the water will also take the 

 disease. The germs will be carried 

 into the well. They may be dissemi- 

 nated from it through the entire com- 

 mimity, and the result would be, and 

 often has been, a wide-spread epi- 

 demic. This is a fact of observation, 

 and quite independent of any theory 

 of the origin of disease. Therefore, 

 chemical examinations of water are 

 of value, not in that they prove that 

 the water is unhealthful, but because 

 they indicate the possibility of its 

 becoming a vehicle of disease, and 

 point out the source of the con- 

 tamination. 



Air which is chemically pure may 

 be a vehicle of contagion ; and air 

 which is chemically very impure may 

 be perfectly harmless as regards con- 

 tagion. In other words, sewer gas, 

 whatever that strange combination of 

 odors may be, is wot, per se, a vehicle 

 of contagion. If it were, the popu- 

 lation of New York City would be 

 decimated every year. * * * * 



I would not say that the health of 

 the city was not affected by the con- 

 dition of the streets. Very likely it 

 was ; but the effect was merely that 

 of air contaminated by the gases 

 arising from the decomposition of 

 refuse matter, utterly incapable of 

 breeding a pestilence. Ammonia and 

 sulphuretted hydrogen, and the va- 

 rious other gases which arise in this 



