82 Proceedings of the Iloyal Physical Society. 



The peculiarity of the mode of water analysis which I have 

 adopted is, that while it gives a sufficiently correct indication 

 of the quantity and quality of the saline matter present, it 

 has for its special object the determination of the nature and 

 amount of deleterious organic matter with which a water may 

 be contaminated. It is not my wish nor do I attempt to 

 show in an analysis of water the total amount of organic 

 matter present ; what I give my almost undivided attention 

 to is, the determination of the amount of deleterious organic 

 matter together with other objectionable constituents, as nitric 

 acid, iron, lead, copper, arsenic, etc. 



My analysis when finished is reported in the form indicated 

 in table B. There it will be seen I set forth the total amount 

 of solid matter which the water contains, and that is divided 

 into (1.) Volatile Eesidue, and (2.) Fixed or Saline Eesidue, 

 which latter is generally examined to ascertain which salt or 

 salts it is mainly composed of Then I estimate by means of 

 the beautiful process, first proposed I believe by Wanklyn, 

 the amount of ammonia existing as such in the water, which, 

 together with the amount of ammonia obtainable from organic 

 sources by the action of an alkaline solution of potassium 

 permanganate at a boiling heat, gives a very correct indication 

 along with other things of the amount of deleterious organic 

 matter present, and therefore a good basis for the foundation 

 of an opinion as to the suitability of the water for dietetic 

 purposes. 



The next ingredient mentioned in the table, viz., nitric acid, 

 I test for with great care, as I believe this is a good guide so 

 far as to the purity of water. Nitric acid, it is well known, 

 arises from the decomposition of peculiar kinds of organic 

 matter under certain circumstances, and as nitrates are very 

 soluble, they generally find their way into the water along 

 with part of the organic matter from which they have arisen, 

 and so their presence becomes an indication of contamination. 

 As water, however, may contain nitric acid and yet be perfectly 

 free from organic contamination, I do not place implicit 

 reliance on this test. The next ingredient is chlorine ; this 

 substance is found in considerable quantity in water which 

 has been contaminated with sewage. As it may, however, 



