148 o5j METtonic SToxr?# 



announced the exisleiico of manganese in the meteofid 



stones analyzed by him, whicli fact is confirmed by those 



chemists n ho have since bestowed their attention on this 



subject. 



They contain M. Laugier, professor in the pliarniaccutical school of 



Paris, assistant naturalist and operator of analysis to tiie 



Museum of Natural History, in analysing a meteoric 



stone which fell at Verona in 16G3, has discovered a 



principle hitherto unobserved in stones of this kind. 



This principle is cht'oi/tc, and is the subject of the present 



memoir. 



Thcauthordis- " It is *'cry probable," says the author, '' that I 



covered It by ^]^q^^]([ j^.^^^. overlooked the ])resence of Chrome, had I 



using alkali as . ^ ' 



his first agent, not deviated from the method of analysis usually adopted. 



Acids have always been made use of, >rhich are perhaps 



the nrost natural and commodious agents ; but in this 



case I employed caustic alkali, -^vhich has the advantage 



of indicating the presence of chrome, however small may 



be its quantity, Avhilst it remains almost imperceptible 



\vhen held in solution by acids, particularly if blended 



with any quantity of iron, manganese, &c." 



f rocess So- '^^"^^^ following is the author's mode of separating the 



tiition in caus- chrome, and of determining its proportion: lie dissolved 



tic alkah; wash- q^^, pj^j.^. yf the stone in three parts of caustic alkali, and 



ing supersat. . , . 



tvith nitric washed the mass with distilled water, which received a 

 acid. Precipi- yellow colour, or a greenish-ycllow from the manganese : 

 chrome"by ni- ^" leaving the mixture to settle, the manganese fell to the 

 tratc of mer- bottom, and the liquor regained its pure yellow colour. 

 ^^^y' The solution was then re-mixed wilh the washing, and 



after being sufficiently diluted with water, to prevent the 

 precipitation of the silex, super-saturated with a slight 

 excess of liitric acid. Recently prepared ijitrate of luer- 

 cJury, at the minimum^ was poured into this solution, which 

 immediately threw down a red orange-coloured preclpi- 

 tate,-or chromate of mercury ; this was suffered to remain 

 till the next day to subside, when the supeitiUtant liquor 

 was decanted, and the precipitate washed in several wa- 

 ters, until deprived of all taste; it was then thrown into 

 a platiua crucible, the water evaporated, and the chromate 

 ofmetcury by desication decomposed into green oxido of 

 chrome, whose quantity amounted to about a himdrcdth 



part 



