444 Notice of some Recent 



stance must not be considered carbonate of magnesia as is 

 usually done, because it is soluble in this salt. The solu- 

 tion of these earthy salts may perhaps be attributed to their 

 decomposition, by the formation of carbonate of ammonia 

 and earthy muriates.* 



Action of Anhydrous Sulphuric Acid on Metallic Chlorides. 

 — When the vapour of this acid, either with or without 

 water, is brought in contact with common salt at an 

 elevated temperature, the sodium is oxidized by the sul- 

 phuric acid, while chlorine with sulphurous acid gas is 

 disengaged. The result, according to Rose, is different 

 when the chloride is finely pulverized, and placed in a 

 vessel surrounded with a freezing mixture. The vapour 

 of the acid is then rapidly absorbed without decomposing 

 it. The whole is transformed into a transparent mass, 

 which is a compound of chloride of sodium and anhydrous 

 sulphuric acid. When heated, it decomposes, being re- 

 solved into sulphate of soda, while chlorine and sulphurous 

 acid are disengaged. Chloride of potassium, muriate of 

 ammonia act in the same way ; but the chloride of copper 

 and barium in the anhydrous state do not. The same acid 

 unites with the nitrate and sulphate of potash, and with 

 sulphate of ammonia, all of them anhydrous salts.f 



Decomposition of Copper Salts by Phosphorus. — Accord- 

 ing to Vogel, when a stick of phosphorus is kept in a 

 solution of sulphate of copper, the liquid gradually loses 

 its blue colour and become colourless. In this state, the 

 solution does not contain even a trace of copper. On 

 evaporating the fluid, and heating the residue strongly, 

 sulphuric acid flies off, and phosphoric acid remains. The 

 phosphorus which is covered with a metallic coating of 

 copper becomes partly black in the space of a short time. 

 Below these leaves of copper, there is observed, on the 

 surface of the copper, another thin layer in plates of a 

 black colour without metallic lustre easily detached from the 

 phosphorus and very fragile. It possesses the properties 

 of phosphate of copper. In a solution of nitrate of copper 

 the same phenomena occur. The green solution of chloride 

 of copper becomes at first black when phosphorus is 

 placed in it, and then nearly colourless in a concentrated 



* Journ. flir prak Chim. vii. 453. t Journ. de Cliim. Med. Oct., 522. 



