1813.] Oxide of Iron from Oxide of Mangmiese. 289 



nese. This being exactly the opposite of the statement of Dr. 

 John, it follows that he must somehow or other have fallen 

 into an error. 



M. Bucholz conceives that the triple salt is formed in the 

 following manner : The muriate of iron containing always an 

 excess of acid, this excess acts upon the alkali of the oxalate, 

 and reduces it to the state of a superoxalate ; but this last salt 

 seizes a portion of the oxide of iron, and thus forms the triple 

 salt. Bucholz was surprised at the fine green colour of this 

 salt, which it retains notwithstanding the red oxide of iron, 

 which forms one of its constituents, and which usually gives a 

 brown or yellow colour to those bodies with which it unites. 



These crystals assume the form of aflat four-sided prism, the 

 extremities of which terminate in two oblique facets. The taste 

 of this salt is sweetish, and slightly astringent. It dissolves 

 readily in water, and the solution has a greenish yellow colour. 

 The pure alkalies precipitate the iron in the state of red oxide. 

 When calcined there remains a considerable alkaline residuum. 

 'I'll is, combined with its other properties, leaves no doubt about 

 its composition. 



Article IX. 



Memoir on (he Determination of the Specif c Heat of the 

 different Casts. By MM. F. Delaroche, 'M.D. and J. E. 

 Berard. 



(Continued from p. 219.) 



Section II. 



Determination of the Specific Heat of some Gases, that of Air 

 icing considered as unity. 



Tin: process which we have followed in the experiments 

 that we have made on the different gases being the same for all, 

 and this process having been sufficiently explained in the pre- 

 i . ding section, we think it unnecessary to enter into a detailed 

 account of the experiments which we made on each particular 

 : we think it sufficient to present the results of them in the 

 following table.* 



• The hydrogen pas which we employed was obtained by dissolving ziuc 

 in diluted lalphnric acid ; the carbonic acid gas, by dissolving white marble: 

 tiir oxygeo, by distilling hyperoxymuiiate of potash] the gaseous oxide of 

 note bj decomposing nitrate of ammonia] olefiant gu>, from u mixture of 

 alcohol and sulphuric acid ; carbonic ox hie gas, by heating dry white marble 

 mixed wiilt chare >al exposed to a strong hi*at. 



Vol. II. N IV. T 



