Annual Report. ' 185 



1. On Natural Potash Deposits in German}', 



2. On Waters used for Irrigation. 



Umoliolesome Drinking-icaters. 



Public attention having been directed to the deficient and 

 frequently unwholesome supply of drinking-water, more especial I3' 

 in rural districts, a good many samples were sent to me for exa- 

 mination by members of the Socieiy. Amongst them several 

 were found to be totally unfit for drinking. 



As examples of bad water, I may mention two. In one of 

 them I found a considerable quantity of nitrogenous organic 

 matter, and an unusually large amount of oxide of lead, a con- 

 stituent which occurs but rarely in well-water. An accurate 

 determination gave me nearly one-half grain of oxide of lead in 

 the imperial gallon ; and I ascertained that this poisonous oxide 

 occurred in solution partly as bi-carbonate of lead, partly as 

 nitrate of lead. On inquiry I found that the water was naturally 

 very soft, and came from a well situated near a manure-heap, the 

 drainage of which no doubt passed into it in a more or less oxydised 

 condition. It is well known that in soils, more especially porous 

 sandy soils, animal refuse-matter gives rise to the formation of 

 nitrates, which act upon lead. It appears also probable that de- 

 composing animal matters exert a similar injurious effect upon 

 leaden pipes. The unfavourable position of the well in this 

 case fully accounts for the contamination of the water with dele- 

 terious animal matter, and the still more poisonous oxide of lead. 



The second sample of water, unlike the first, which was slightly 

 discoloured, was perfectly colourless, bright, and, as far as smell 

 and appearance went, quite unobjectionable. On examination, 

 however, it was found to contain an unusually large amount of 

 saline constituents, and amongst these no less than 19 grains of 

 nitrate of potash in the imperial gallon, as will be seen by the 

 subjoined analysis. 



An imperial gallon, on evaporation, left 72*05 grains of solid 

 residue (dried at 300° Fahr.), containing, — 



' Grains. 



Organic matter 1"51 



Oxides of iron and alumina, and traces of phosphoric acid ., 1*15 



Lime 15-12 



Magnesia 1*75 



Sulphuric acid 8*51 



Clrlorine 8-30 



Nitric acid 10-29 



Potash, soda and carl)onic acid 23-47 



Sohible silica 1-95 



72-05 



