188 An Analysis of two Mineral 
VIII. THE APPEARANCES IN QUESTION 
ARE PRODUCED BY THE ACTION OF HE. 
PATIC GAS ON IRON AND MANGANESE. 
_- An observation of Bergman, though in_ part er- 
roneous, has conducted me, as J think, to the true 
cause of these appearances; and J am greatly mistak- 
en, if its consequences, when fully pursued, are not of 
considerable importance to chemical science. Berg- 
man has asserted, that hepatised water, in which iron 
filings have been kept for some days, in a well closed 
vessel, grows purple with tincture of galls: if the 
iron be dissolved by an acid, the colour approaches 
more to violet. He moreover adds, that the solu- 
tion of iron in hepatised water 7s not at all rendered 
turbid by prussiat of potash.* This latter fact ‘pro- 
mised to throw some light on the subject of my en- 
quiry, particularly when it was joined to the fact of 
the hepatic smell, which the water has when recently 
drawn (1.). I was the more strongly induced to pay 
attention to this combination, from the contradictory 
assertion of another very eminent chemist. Mr. 
Kirwan has denied that hepatic gas can dissolve iron 
or any other metal.t To ascertain this point, I have 
made numerous experiments with the greatest cau- 
tion and accuracy that I have been able to apply. 
The hepatic gas which I have used was obtained 
* Bergman’s Essays, Dissertation vii, 4, L, 
t Philosophical Transactions for 1786, 
