Chemical Science. 411 



acid, a composition nearly the same with that of the carbonate ob- 

 tained when precipitated from the muriate by carbonate of soda. 

 Hence the lithia was proved to be free from soda, and to have 352.06 

 as its number. 



Sulphate of lithia, formed from the carbonate and sulphuric acid, 

 was readily crystallizable by slow evaporation. It is freely soluble 

 in water, but not more in cold than hot. The crystals are oblique 

 quadrangular prisms, containing 85.70 of dry salt and 15.3 of water 

 percent. ; 100 parts of the dry salt, dissolved and decomposed by 

 baryta, gave 74 sulphuric acid and 26 lithia. The equivalent 

 number, according to this analysis, would be 352.1, and that of the 

 metal lithium 152.1. 



Muriate of Lithia. — When chloride of lithium is left to deliquesce 

 in the air, large regular crystals are gradually formed of muriate of 

 lithia. They have the singular property of becoming opaque when 

 touched, or put upon a filter, the opacity beginning at the place 

 touched. When the opaque crystal is pressed it falls into small 

 crystalline fragments. The opacity, therefore, arises from a spon- 

 taneous division of the large crystals, the cause of which is not yet 

 known. The crystals are right-angled prisms : they consist of 1 

 atom chloride of lithium and 8 of water, or experimentally 53.64 

 salt and 46.36 water per cent. When heated, the salt fuses and 

 loses chlorine. This is in consequence of the action of oxygen, and 

 the salt always becomes alkaline. — Annalen der Physik. 



10. Adulterations of the Iodide of Potassium. — The iodide of 

 potassium, or hydriodate of potassa, is so convenient a form of 

 iodine, that it is constantly retained amongst medical preparations. 

 Its utility and consequent value has led, as usual, to adulterations, 

 one of which is described by M. Pereira, where the extraneous 

 matter amounted to 77-hundredths of the whole. In this case the 

 substance added was carbonate of potash ; and it may easily be 

 supposed to what an extent errors of judgment may proceed amongst 

 medical men, when such fraudulent mixtures as these are placed in 

 their hands by the dishonest or deceived dealer. 



M. Pereira discovered the falsification whilst attempting to make 

 a solution of iodine in the hydriodate of potassa, a preparation kept 

 at the general dispensary. The supposed hydriodate refused to 

 dissolve the quantity of iodine which ought to have been taken up, 

 the carbonate present not having an equivalent power. — Med. Jour. 

 Ixii. 310. 



11. Preparation of red Ferro-prussiate of Potassa. — M. Kramer 

 has endeavoured to prepare this useful test by a process more ready, 

 and less troublesome, than that of Gmelin. By decomposing 

 •Prussian blue at a low temperature by chloride of potassium, he 

 obtained a liquid of a yellow colour when in small quantities, but 

 red in larger portions ; it did not precipitate persalts of iron, but 



oct.— dec. 1S29. 2 E 



