30 History of physical Science from [July, 



directly by the mixture of muriate of platinum and common salt, 

 a fine lemon-yellow precipitate falls, and the mother water 

 remains nearly colourless. But these two salts, though so differ- 

 ent in their appearance, are composed of nearly the same pro- 

 portions of constituents. The first contains most water and 

 acid, while the one formed by the addition of soda seems to 

 contain the most metal. 



When sulphuric acid is mixed with muriate of platinum, if the 

 mixture be long enough boiled, and a sufficient quantity of sul- 

 phuric acid be employed, the whole of the muriatic acid is driven 

 off, and a sulphate of platinum formed. This sulphate, when 

 concentrated, appears black ; but it becomes green when 

 diluted with water. It is deliquescent, and does not seem 

 capable of crystallizing. When mixed with sulphate of potash 

 and evaporated, a green flocky precipitate falls, and the liquid 

 becomes almost colourless. This precipitate is a triple com- 

 pound of sulphate of platinum and sulphate of potash. — (Ann. de 

 Chim. et de Phys. v. 264, 392.) 



4. Composition of certain Carbonates. — Professor Berzelius in- 

 forms us that he has been occupied of late in making experiments 

 on the combination of carbonic acid with certain bases. He 

 finds that there exists a kind of double salt, composed of the 

 carbonate and hydrate of the same base, in which the carbonate 

 is destitute of water of crystallization. The blue carbonate of 

 copp.er is a compound of two atoms of carbonate of copper with 

 one atom of hydrate. Magnesia alba is a compound of three 

 atoms of carbonate of magnesia with one atom of hydrate of 

 magnesia. The subcarbonate of zinc, both the artificial and the 

 native, is a compound of three atoms of subcarbonate of zinc 

 and one atom of hydrate of zinc. — (Ann. de Chim. et de Phys. 

 vii. 206.) 



The analyses of the blue and green carbonates of copper, by 

 Mr. Richard Phillips, do not well agree with these statement of 

 of Berzelius. According to Mr. Phillips, the green carbonate of 

 copper is a compound of 



Peroxide of copper 72-2 or 1 atom nearly 



Carbonic acid 18*5 1 atom 



Water 9-3 1 atom 



100-0 

 He found the blue carbonate to be a compound of 



Peroxide of copper 69-08 or 3 atoms 



Carbonic acid 25*46 4 atoms 



Water 5-46 2 atoms 



100-00 



Here the carbonic acid is obviously too great to admit of the 

 supposition that any portion of the oxide is not united with it. 

 — (Royal Institution Journal, iv. 273.) 



