210 



The Sanitary Value of the 



potassium is added, and the distillation continued. Certain kinds of or- 

 ganic matter containing nitrogen are thus decomposed, giving off a 

 part or all of their nitrogen as ammonia, and since albumen is one of 

 these, the ammonia so obtained is called "albumenoid-ammonia," and 

 reported as such. 



This process was the first to come into general use which claimed to 

 distinguish readily putrescible nitrogeneous matter from those organic 

 substances which are with greater difficulty converted into ammonia, 

 and much importance was naturally attached to the results obtained 

 in distinguishing pollution due to animal matter from that of vegeta- 

 ble origin, but as different amounts of ammonia are yielded by the 

 same weights of different substances, and as the conversion of many 

 such into ammonia is by no means complete, the results can have no 

 absolute significance. On these and other grounds Frankland rejects 

 this method utterly. Tidy, likewise, while admitting that the procesB 

 might be used to discriminate between a water of excellent quality 

 and one exceedingly bad, holds that when water of intermediate char- 

 acter is under examination, it " utterly and entirely fails." It is to be 

 borne in mind, however, that both Frankland and Tidy are committed 

 to methods of their own, which they advocate not without the exhibi- 

 tion of a partisan spirit, and their conclusions are, therefore, hardly 

 entitled to the same weight as those of less prejudiced, though, per- 

 haps, less distinguished, experts. The rank and file of water ana- 

 lysts have accepted this method as affording very valuable informa- 

 tion, and in the elaborate Preliminary Report on the Results of an inves- 

 tigation made by direction of the National Board of Health, as to the 

 chemical methods in use for the determination of organic matter in 

 potable water, made by Professor Mallet of the University of Virginia, in 



1881, and printed in the, report of the National Board of Health for 



1882, the author, while he points out the defects of the process, finds 

 "that it is admittedly simple and easily carried out ; " that " the value 

 of the results depends more upon watching the progress and rate of the 

 evolution of the ammonia, than upon determining the total amount;" 

 and that " taking the results by this process as recorded, we find a 

 great deal of similarity between the figures for albumenoid ammonia 

 and those for organic nitrogen (by the combustion process), but with 

 frequent discrepancies of varying extent such as prevent the one being 

 taken as the accurate measure of the other." 



3. Frankland and Armstrong's combustion process. —This is the third 

 and last of the important processes now in use. It was brought forward 

 by its originators in 1867, and first described in print in the Journal 

 of the Chemical Society (London) for March, 1868, and is by far the 

 most elaborate method of any in use. It was employed by the liivers 



