Afialyds of the Hot Springs at Bath. 349 



to the atmosphere in a vessel of broad surface. After it iiad 

 remained about 16 hours, a small quantity of carbonate of 

 iime was deposited by the evolution of carbonic acid gas. 

 The precipitate was perfectly white, and had not the slightest 

 appearance of containing oxide of iron. To this water in- 

 fusitm of galls was added w ilhout occasioning the least al- 

 teration of colour. 



(/') As the quantity of o.vide of iron in the water is evi- 

 dently extremely small, it may be imagined that it was pre- 

 cipitated with the carbonate of lime, but escaped observation 

 from the minuteness of the quantity. To obviate this ob- 

 jection, some of the water was closely stopped in a phial for 

 four or five davs : upon examination it was found to possess 

 its transparency perfectly, and without having afforded any 

 precipitate; to some of this, infusion of galls was added 

 without producing the slightest indication of oxide of iron. 



(c) Some of the water which had been cooled so as to re- 

 tain its transparency, was heated to its original temperature; 

 infusion of galls was then added, but without producing any 

 effect. 



The facts exhibited in Experiments (/•) and (c) have been 

 lonf known, and have given rise to an idea that the iron is 

 volatilized. Although this opinion is incompatible with 

 facts already mentioned, yet it may not be amiss to show 

 more particularly that it is completely erroneous. As it can- 

 not be imagined that the temperature of the water is sufficient 

 to volatilize mere oxide of iron, the existence of some sub- 

 stance capable of carrying it off must have been supposed. 

 That muriatic acid and muriate of animonia possess this 

 power at high temperatures is well known, but no uncom- 

 bined muriatic acid or muriate of ammonia is present. Hy- 

 drogen gas is said also to be capable of volatilizing iron; but 

 the gas evolved fronj the water has been shown to consist of 

 nitrogen gas and a small quantity of carbonic acid gas, and to 

 neither of these gases, alone or combined, has any such power 

 been attributed. If, however, they really possess it in this 

 instance, they must be regarded as the solvent of the iron, 

 and the effect produced upon infusion of galls must be. de- 

 rived 



