Springs at Lemington Priors. 199 
prevent a minute quantity of common acid from 
passing over in the distillation of the oxygenated 
acid; and how readily this acid is itself decomposed: 
add to this the imperfect oxydation, perhaps, of the 
iron. If these circumstances are duly weighed, it 
seems probable, that this salt, when quite pure, 
would not at all sensibly decompose nitrat of silver. 
A slight impurity cannot be detected by acetite of 
lead, as a small quantity of muriat of lead is soluble 
in water. 
XII, FURTHER CONSIDERATIONS ON THE 
HEPATISED SOLUTIONS. 
Besides the oxygenated salts, I think it probable, 
that these solutions retain some sulphur; but, under 
what form, or in what combination, it is not easy to 
say. The residuum, after evaporation, has a pecu- 
liar smell, whereas the pure salts are inodorous. 
The stain left upon silver by the residuum ought, 
perhaps, to be attributed to this cause. Also the 
white matter, formed by the decomposition of oxy- 
genated muriat of mercury, seems to be a combina- 
tion of sulphur and mercury. In proof of this, it 
may be remarked, that the precipitate of this salt 
dissolved in simple hepatised water is white. Fur- 
ther, it is doubless true, that if hepatised water have. 
a small quantity of acid mixed with it, the solution 
of iron strikes a purple colour with galls. To point 
out the origin of this colour, mix iron filings and 
