Chemical Analyst* of Potable Waters 



deemed of secondary importance in weighing the reasons for accepting 

 or rejecting a water not manifestly unfit for drinking on other grounds." 



" 3. There are no sound grounds on which to establish such gen- 

 eral 'standards of purity' as have been proposed, looking to exact 

 amounts of organic carbon or nitrog en, ' albumenoid-ammonia/ oxy- 

 gen of permanganate consumed, etc., as permissible or not." 



"4. Two entirely legitimate directions seem to be open for the 

 useful examination by chemical means of the organic constituents of 

 drinking water, namely: first, the detection of very gross pollution, 

 * * * * and secondly, the periodical examination of a water sup- 

 ply, as of a great city, in order that the normal or usual character of 

 the water having been previously ascertained, any suspicious changes 

 which from time to time may occur shall be promptly detected and 

 their cause investigated." 



It was proposed only to discuss chemical methods of examination in 

 this paper, and therefore no reference has been made to the microscop- 

 ical examination of water deposits, or to biological investigations. The 

 former are often of value, and from the latter it was at one time 

 thought, and this is still the opinion of many, that almost every thing 

 might be learned, and that chemical analysis had had its day, and was 

 destined to be entirely replaced by biological investigations. Whether 

 the results obtained so far have justified this view is certainly an open 

 question. In my opinion they have not. That such investigations 

 should be made in connection with chemical analyses is generally con- 

 ceded, and doubtless when our knowledge has increased very valuable 

 results may be obtained thereby, for the probable significance of some 

 classes of micro-organisms seems to be established; but as Mallet has 

 pointed out, basing his statement upon work done by Professor H. 

 Newell Martin, of the Johns-Hopkins University, Dr. George M. Stern- 

 berg, TJ. S. A., and others, there is the difficulty often presented 

 "either by the sparseness, or more frequently the abundance, of those 

 organisms in fairly estimating their average relation to the mass of 

 water," and " this difficulty is superadded, of course, to the imper- 

 fection of our knowledge as to the effects upon human health of 

 some closely allied — even hardly distinguishable — organisms of dan- 

 gerous and harmless associations, and of perhaps the same organism 

 in different stages of its life history." 



Two other subjects proposed for discussion remain to be briefly con- 

 sidered. And first as regards the dissemination of diseases by drink- 

 ing water, there is bo much evidence to support the view that polluted 

 waters are prolific sources of disease, that to deny such a cause as an 

 important factor in the propagation of many zymotic diseases, is, to 

 say the least, illogical. Countless sporadic cases of typhoid fever, for 



