144 On the Composition and Properties of Drinking-Water, 
Spring and well waters, in districts where Lias-clay, Wealden, 
or Oxford clay abound, are sometimes charged with so much 
saline matter as to give them a decided mineral taste and to 
impart medicinal properties to them. 
A spring of that character occurs in a clay-bed at Purton, near 
Swindon. This spring is used, with considerable benefit, as a 
remedy for a variety of disorders ; and in addition to the usual 
constituents of mild saline waters, such as sulphate of soda 
(Glauber salt), sulphate of magnesia (Epsom salt), and chloride 
oi sodium, the water contains a considerable amount of carbonate 
of potash, and appreciable proportions of iodide of sodium and 
bromide of magnesium, which constituents do not occur in 
ordinary potable waters, and to which, no doubt, its medicinal 
virtue is partly owing. The alkaline carbonates give it a strong 
alkaline reaction. An analysis of the saline Purton water, 
which I made in 1859, yielding the following results in an 
imperial gallon : — 
Water of combination and organic matter (being loss 
obtained on heating residue, left on evaporation and 
dried at 320° Fahr.) 
Lime 
Magnesia 
Oxides of iron and ahimina, with traces of phosphoric) 
acid f 
Potash 
Soda 
Chloride of sodium 
Sulphuric acid 
Soluble silica 
Iodine 
Bromine 
Carbonic acid 
Grains. 
8-750 
34 
536 
25 
•736 
280 
20 
707 
49 
006 
34 
297 
165 
074 
1 
280 
056 
080 
33 
090 
traces 
Tliese constituents arranged into the compound, which pro- 
bably existed in the water, give the following results : — 
Grains. 
Organic matter and water of combination 8 * 570 
Sulphate of soda 112-239 
Sulphate of magnesia 77-208 
Bromide of magnesium ^ -092 
Iodide of sodium -066 
Chloride of sodiuui 34-297 
Sulphate of lime 83-873 
Sulphate of i)0tash 1-916 
Carbonate of potash 28-880 
Oxides of iron and alumina, with traces of phosphoric) 
acid j 
Soluble silica 1 
280 
280 
Solid constituents (dried at 320° Fahr.) per gallon 348-881 
The water contained further, free carbonic acid, 23-820 grains in the gallon. 
