Results of the Labours of Continental Chemists. 211 



rate, then filtrated anew and evaporated to crystallization. 

 The precipitate effected by the alcohol is the bitartrate of 

 soda, whiclr may again be employed for preparing chlorate 

 of soda by adding it to a hot solution of sixteen parts of 

 chlorate of potash in four times the quantity of water, leaving 

 the mixture to cool, filtrating and evaporating the solution to 

 forty parts. {Afch. der Phanu., xxiii. p. 306.) 



After continued rain, a heap of coals which lay exposed to 

 the weather was observed to smoke, and to be on fire in the 

 interior ; when separated it was found in the middle to be in 

 full combustion. In the neighbourhood of this part the coals 

 were half-roasted, forming an almost compact mass, and be- 

 tween them was found a bright yellow, soft, saltlike substance. 

 This proved on examination to be sulphate of magnesia ; the 

 ashes of coals contain magnesia, the burning pyrites afforded 

 the sulphuric acid. Dr. Mohr compares it to the formation 

 of cyanide of potassium at the Clyde iron-works*. How the 

 sulphate of magnesia became collected into masses is not so 

 easily explained. {AnJiale?i der Pharmacie, xxxv. 239.) 



Kersten has employed with advantage a mixture of hydro- 

 chloric acid and finely powdered chlorate of potash, added in 

 small portions, as proposed by Berzelius for oxidizing and 

 dissolving metals and metallic sulphurets, even for the ana- 

 lysis of the native metallic sulphurets, the sulphur being 

 quickly and easily converted into sulphuric acid. M. Ker- 

 sten, moreover, observed that finely powdered iron pyrites 

 was perfectly decomposed by boiling with chlorate of potash, 

 without any addition of acid, the sulphur being converted into 

 sulphuric acid, and the iron remaining undissolved in the 

 form of peroxide. [Berzelius' s Jahresbericht^ xix. p. 288.) 



The difficulty of obtaining the hyposulphite of soda in good 

 crystals, according to the usual methods, has induced C. F. 

 Capaun to make known the following modified plan, by 

 which in the shortest time considerable quantities of the 

 salt can be prepared, and of a kind which leaves nothing 

 further to be desired. A solution of caustic soda is boiled with 

 sulphur so long as any of this. is dissolved, the liquid poured 

 from the undissolved sulphur put aside to cool, and then a 

 current of sulphurous acid gas jjassed through it, until a test 

 filtered from the separated sulphur has still a wine-yellow co- 

 lour — it contains therefore still undecomposed sulphuret of 

 sodium, — and by no means appears colourless. The liquid 

 is now filtered and evaporated in a porcelain basin over a 



[• Described by Dr. Clark in L, & E. Phil. Mag. vol. x. n. 329.— Edit.] 



P2 



