1893.] MICROSCOPICAL JOURNAL. 127 



On Some Recent Advances in Water Anjilysis and the Use 



of the Microscope for the Detection of Sewage 



Contamination. 



By GEO. W. RAFTER, 



ROCHESTER, N. Y. 



\^Read before the Buffalo, N. T., Microscopical Club, Dec. 12, i8g2.'\ 



It is quite within the memory of nearly every member of the 

 Buffalo Microscopical Club to recall the time when chemical 

 analysis alone was the only available method for determining the 

 sanitary value of a drinking water. Then came the develop- 

 ment of methods of bacteria culture, accompanied by a clearer 

 appreciation of the necessity, before deciding as to the whole- 

 sameness or unwholesomeness of a given water, of a thorough 

 study of the environment, or, in other words, of a study of the 

 various pollutions affecting the sources from which a supply is 

 drawn ; and finally the latest, and possibly quite as important as 

 any, the development of a method whereby the minute life other 

 than the bacteria can be quantitatively enumerated with an ac- 

 curacy which, while not absolute, is still sufficiently so for the 

 practical purpose of study of sanitary significance and compar- 

 ison. 



It is unnecessary to occupy time on this occasion either in de- 

 scribing just how the quantitative enumeration of the microscopical 

 forms in potable water is actually accomplished, or in pointing 

 out the part taken by the author in the final working of what is 

 known as the vSedgwick-Rafter method of making the micro- 

 scopical enumeration. It is sufficient to simply refer those in- 

 terested to the original paper with detail in the proceedings of the 

 Rochester Academy of Science.* The method there described was 

 also exhibited at the working session of the Buffalo meetinsfof the 

 American Microscopical Society and is referred to in the proceed- 

 ings for that year (1S89). 



There are, however, a few points of historical intei^est which 

 may be casually referred to here, namely, in relation to the work 

 of the Microscopical Section of the Rochester Academy of 

 Science, and the essential assistance received from a number of 

 friends in that body, without which it is probable the methods of 

 microscopical study of the minute life would have been some- 

 what less perfect than they are at the present time. The points 

 thus deserving record are briefly as follows : 



* Biological Examination of Potable Water. Proc. Roch. Acad. Sci., vol. i, pp. 34-44. 



The method is also described in Part II of the Special Report of the Massachusetts State Board 

 of Health (1890), on Water Supplies and Purification of Sewage, etc. , at pp. 808-811, where 

 may also be found an account of Professor William T. Sedgwick's Sand Method, etc. 



I'he method may aho be found described in the author's The Microscopical Examination 

 of Potable Water. D. Van Nostrand Co., 1892. 



Also see The Microscopical Examination of Water, by Gary N. Calkins, Assistant Biolo- 

 gist, in 23d Annual Report Massachusetts State Board of Health (1891), pp. 397-421. In this 

 paper the Sedgwick-Rafter method is fully described, certain improvements suggested, and pos- 

 sible sources of error pointed out : it may be referred to as the latest and most complete 

 expo.sition of the detail of the method of microscopical enumeration. 



