90 



A. Pedlcr— 



On the past and present 



[No. 2, 



It is then evident that, in the analysis of water, the point to be aimed 

 at would be, the detection o£ the presence of those impurities whether they 

 be of the nature of germs or not, which would give rise to the diseases just 

 mentioned, but unfortunately in the present state of science, we are quite 

 unable even to say with any certainty whether such germs of disease will ever 

 be isolated, and it is therefore clearly out of the power of the chemist to 

 detect their presence in any sample of water. Failing therefore in this 

 endeavour, the chemical analyst has to rest content with the detection and 

 estimation of other substances, such as organic nitrogenous matter etc., 

 which cannot be present in water, unless it has previously been in contact 

 with the various forms of impurity, which we denominate sewage ; and if 

 such bodies are present in quantity, it is fair to infer that these gei'ms or 

 other bodies which produce the zymotic diseases, and which are undoubted- 

 ly present very frequently in sewage, may also be present in the sample of 

 water. It has also been clearly shown, that in many instances water which 

 is impregnated with animal or vegetable organic matter, even assuming 

 any specific poison to be absent, will give rise to various unpleasant 

 symptoms, such as diarrhoja, etc. It is therefore quite permissible and 

 necessaiy to condemn any sample of water which is to be used as a potable 

 or domestic supply, if it contains any quantity of organic matter, more 

 especially if the oi'ganic matter be of animal origin. 



The methods of water analysis have been improved very greatly during 

 the past fifteen years, but even now there is a very warm discussion being 

 carried on as to the respective merits of at least three distinct processes, and 

 oj)inions differ materially as to which method gives most accurate and relia- 

 ble results. The two methods for the determination of the amount of organic 

 matter present in water, which have met with the greatest amount of 

 support, are those of Professors Wanklyn and Frankland. 



The method proposed by Prof. Wanklyn, which consists in the conver- 

 sion of the nitrogenous organic matter into ammonia by boiling with an 

 alkaline solution of potassium permanganate, has the immense advantage 

 of being quickly performed with tolerably simple apparatus, and a whole 

 water analysis by this method does not occupy more than a few hours. 

 Against this method there is the well recognized fact, that it sometimes fails 

 to detect and estimate the whole of the nitrogenous organic matter present 

 in the water. It is therefore possible that a water may escape the con- 

 demnation which it deserves, but I believe it is generally accepted that 

 a water which is condemned by this process must be really of very bad qua- 

 lity. 



The method of analysis which was introduced by Dr. Frankland is 

 an extremely elaborate one, and requires tlie use of very delicate and expen- 

 sive aj^paratus. The greatest drawback to this process is however, the 



