196 Miscellan ies . 



cle became so great, as it was found to give to letter paper a finer 

 and more uniform shade than cobalt, he had resolved to give great 

 extension to his manufactory, and had purchased nine miles from 

 Lyons a situation, where he was forming an establishment large 

 enough to supply the article in quantity sufficient for the consump- 

 tion of the country, and to reduce the price of it to 16 francs per 

 pound. 



Cobalt he thinks will eventually be confined to the vitrification and 

 and coloring of porcelain. Ultra-marine is unchanged by caustic 

 alkalies, and therefore very favorable to the dyer, and is used in pa- 

 per staining, artificial flower work, and oil painting. Crape is per- 

 fectly dyed with it, and acquires a blue of extraordinary brilliancy 

 and solidity. — Annales de Chimie. 



26. Magnesium, the metallic radical of Magnesia. — The improved 

 method of obtaining this metal, as practised by M. Bussy and im- 

 proved by Just. Liebig, is to procure first chloride of magnesium by 

 evaporating to dryness equal parts of hydrochlorate of magnesia and 

 sal ammoniac, and projecting the mixtures in small portions into a red 

 hot platina crucible, and continue the heat until all the sal ammoniac 

 is evaporated and the chloride remains in quiet fusion. 



A mass is thus obtained of chloride of Magnesium, white, transpa- 

 rent, and having much resemblance to pure mica. 



Introduce from ten to twenty balls of potassium of the size of a pea, 

 into the bottom of a perpendicular glass tube from three to four lines 

 in diameter. Put the chloride of magnesium, in large pieces, upon the 

 potsassium, heat it over coals till it begins to melt, then by inclining 

 the tube, cause the potassium, which is now fluid, to flow through the 

 chloride. The latter becomes reduced with the disengagement of 

 light. The mass, when cold, is to be treated with water, and there 

 collects, at the bottom of the vessel, a quantity of small metallic glob- 

 ules, as white as silver, very brillant and very hard. These may be 

 forged and filed, — they are not changed by water, hot or cold. 



This metal dissolves in dilute acetic acid with the disengagement 

 of hydrogen, without leaving the least residuum. The solution con- 

 tains, besides magnesia, no foreign metallic oxide. With nitric acid, 

 at common temperatures, much nitrous gas is disengaged, and with 

 sulphuric acid, sulphurous acid gas. 



When heated in air or in oxygen, this metal burns with brilliancy 

 at a temperature at which bottle glass softens. The interior of the 



