Chemical Science* 487 



with a greenish yellow gas, but this soon disappeared from action 

 upon the glass ; the latter was strongly corroded and covered with 

 a brown substance, which gave an intense purple colour to water. 

 The water into which the gas passed soon became red, and was 

 covered with a crust of rose-coloured silica. On dismounting the 

 apparatus, the glass receiver was found filled with fluo-silicic gas ; 

 and the retort, as before, with a yellow gas, becoming purple in- 

 stantly in the air. Hence it appears that a gaseous fluoride of 

 manganese was formed, of a greenish yellow colour, which, with 

 air, formed a red purple cloud, dissolved in water, producing a red 

 purple colour, and was decomposed by glass into manganesic acid 

 and fluo-silicio gas. No appearance of condensation took place in 

 the neck or other parts of the apparatus. 



In one experiment the neck of the retort was filled with fused 

 chloride of calcium to dry the new substance, but the fluoride 

 was violently decomposed j the neck of the retort rose to a high 

 temperature ; not a trace of gaseous fluoride [of manganese ap- 

 peared, but much pure chlorine. 



The red solution of the gas in water rapidly dissolved copper, 

 mercury, and silver, without the evolution of gas ; fluoride of sil- 

 ver, &c. and a protofluoride of manganese being formed. The 

 purple red solution has been preserved for months in glass vessels 

 without change. When evaporated slowly in a platina vessel, it 

 continually developes oxygen and vapours of fluoric acid; and there 

 remains a brilliant brown substance, which, by water, is con- 

 verted into a black subfluoride of manganese. — Annates de Chimie, 

 xxxvii. 101. 



18. Boruret of Iron. — Lassaigne. — Prepare a sub-borate of iron 

 by precipating persulphate of iron by borax ; wash and dry the pre- 

 cipitate, form it into a paste with water, and mould it into a small 

 cylinder ; when dry, place this cylinder within a porcelain tube, 

 heat it red hot, and pass pure dry hydrogen over it. Boruret of 

 iron is formed ; it acts slightly on the magnetic needle, and con- 

 sists of 77.43 of iron, 22.57 of borax, or one atom of each, nearly. 

 —Bull. Univ. A. ix. 135. 



19. Decomposition of Salts of Copper by Ebullition. — MM. Colin 

 and Taillifert have said, that when the blue or green carbonate of 

 copper is boiled with water, it became anhydrous and black, but 

 retained all its carbonic acid. M. Gay-Lussac finds this to be in- 

 correct, and that the black powder is nothing else than anhydrous 

 oxide of copper. If the ebullition be stopped so soon as the car- 

 bonate appears black, then the product will effervesce with acids; 

 but that is merely a consequence of incomplete change, the pro- 

 duct being, in such cases, a mixture of carbonate and oxide. All 

 the carbonates of copper tried^ lost their carbonic acid by this 

 process. 



Acetate of copper is also decomposed by ebullition 3 the acetic 

 acid flies off, and a brown oxide of copper remains 



