210 Miscella)teous Intelligence. 



Lime 22.45 containing 6.20 = 2 of oxygen, 



Protoxide of iron 13.69 3.12= 1 



Water 39.61 35.21 = 11.5 



The ferro-prussiate of lead was prepared, by adding solution 

 of nitrate of lead to ferro-prussiate of potassa, the latter being 

 in excess, the precipitate was then washed and dried. In 

 consequence of the vicinity of the point of perfect dryness to 

 that at which the salt began to effloresce, it was difficult to 

 ascertain the quantity of water, but Mr. Berzelius is inclined to 

 consider that, as with the ferro-prussiate of potassa, so also 

 the water in this salt contains as much oxygen as is contained 

 in both the bases together. On analysis 100 parts gave, 



Oxide of lead . . 70 containing 5.09 = 2 of oxygen, 



Protoxide of iron 11.9 2.57 = 1 



Loss 17.7 



These analyses of compounds taken from the three classes of 

 bases, suffice to prove, that whatever be the state of the 

 iron in those salts, it requires in the state of protoxide half as 

 much oxygen as the radical of the other base. 



The second section of M. Berzelius' Memoir contains an ac- 

 count of experiments on the acid of these salts. The first ex- 

 periments, in which sulphuretted hydrogen, and fused boracic 

 acid were made to act on the salt, accorded with the opinion 

 advanced by Mr. Porret, that the iron existed in the metallic 

 state; but not considering them as decisive, the investigation 

 was carried on still further. A portion of the anhydrous ferro- 

 prussiate of potassa was heated with peroxide of copper, and 

 this gas collected over mercury, it was a mixture of carbonic 

 acid and nitrogen, in the proportion of three volumes of the 

 former to two volumes of the latter, and no water was pro- 

 duced ; when the experiment was repeated at a higher tem- 

 perature, the same result was obtained ; when the residue was 

 digested in water an alcaline solution was obtained which 

 precipitated carbonate of lime with lime-water. As these pro- 

 portions differ from those of Mr. Porret and Doctor Thomson, 

 the apparatus was tested by analyzing the cyanuret of mercury 

 in it; the carbonic acid then exactly doubled the azote in 

 volume, and by other trials the mode of operating was found 

 to be perfectly efficient and correct. 



The analysis was repeated with the ferro-prussiate of baryta, 

 and the volumes of gases were again as 3 : 2. 



It now became of importance to ascertain how much carbonic 

 acid was retained by the bases of the salts analyzed, and 

 whether these bases remained in the state of common car- 

 bonates, or were in some other state. To determine this point, 

 carbonate of potassa was heated with six times its weight of ox- 

 ide of copper, and at a red heat, carbonic acid gas was liberated ; 

 so that it appears, the oxide of copper has the power of 



