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APPENDIX. 



THE MICROSCOPICAL EXAMINATION OF WATER. 



IT must have struck most persons, as it lias myself, as 

 a remarkable circumstance that water analysts should 

 lay so much stress on the presence in water of chlorides, 

 nitrates, and ammonia, when these compounds are 

 inorganic and harmless. Why is it that, whereas a 

 few years ago chemists said plainly, " This or that 

 water contains so much organic matter," that now 

 " organic matter " should be estimated from " organic 

 elements," " oxygen consumed," or " albuminoid am- 

 monia ? " The reason of this change is, that the 

 several processes which promised to verify the weight 

 of organic matter in a water have proved very un- 

 reliable, and at the present time no process is known 

 by which the actual weight of organic matter can be 

 determined. So far as the public is concerned this is 

 perhaps a misfortune, but to the chemist it is of less 

 moment, for although the actual weight of organic 

 matter cannot be determined, yet it is possible, by 

 estimating the amount of organic carbon in water, or 

 in some other way, to obtain a comparative measure of 

 the quantity, while the presence of chlorine (sodium 

 in the water) and of nitric acid and ammonia, act as 

 tell-tales of the presence of sewage and animal matter 

 respectively. No doubt, every step in a water analysis 

 is undertaken with an object and reveals a fact. Al- 

 though this may be very interesting when it is known, it 

 is evidently a language that must be thoroughly under- 

 stood and read before it can become of the slightest 

 value to any one. It is almost impossible for any ques- 

 tion about water to be broached without the analysis 

 or report of some chemist or another being brought 

 forward to refute and confound you j it is therefore 



