Mr Hunter on Varimis Methods of Water Analysis. 181 



power of chemistry, as at present known, to estimate ; indeed, 

 to my knowledge, " chloride of potassium " invariably appears 

 in the report as a constituent of the residue, and that whether 

 or not such a compound exists therein. There are other items 

 to which I could with equally good grace take exception, but 

 all of these I will pass over, save the last, which is that of 

 organic matter and nitrates. I may explain this item is the 

 loss which a water residue suffers on being exposed to a red 

 heat. Now, such a method of stating a result obtained in 

 such a way may not only be misleading, but may, indeed will 

 most probably be, quite erroneous, because it is quite well 

 known that when nitrates are simply ignited, they are not by 

 any means all volatilised ; and if, as is almost certain to be 

 the case, the nitric acid which is present is combined with 

 such a base as sodium, then, although the acid be decomposed, 

 the base still remains, but, be it granted, in another relation ; 

 thus it is clear that the loss on ignition of a water residue 

 can be no measure of the amount of nitrates present. The 

 same objection holds good as regards organic matter; and I 

 may sum this part of the subject up by stating that a water 

 residue may suffer considerable loss by being exposed to a red 

 heat without even a trace of organic matter or nitrates being 

 present. 



The determining the organic constituents of a water is, 

 however, a most important point — in fact is the most import- 

 ant, and in the hands of analysts who are abreast of the times, 

 receives by far the most attention. As can easily be under- 

 stood, the quality rather than the quantity of organic matter 

 in water is the great question to settle ; and, thanks to Pro- 

 fessor Wanklyn, chemists are now in possession of a process 

 by which they can readily and very certainly determine that; 

 and to this process I will now direct my remarks. 



The ammonia existing in water, whether in the saline or 

 albuminoid form, can be estimated with beautiful exactness ; 

 and not only can the amount of these nitrogen compounds 

 be ascertained, but also, as was very clearly shown by that 

 excellent paper read at our last meeting, the origin or nature 

 of these can be also made known. 



This part of the process, viz., determining whether the 

 VOL. ly. u 



