2S0 French National Institute. 



added a portion of- it to some ?pecimeiis fusible by them- 

 selves, he deprived them of this property. From this he 

 explains the elTect of the exposure to air and humiditv, in 

 order to facilitate the flux of these minerals: this nnist hap- 

 pen, because there is some sulphuric acid, which dissolves 

 the magnesia, formed by the decomposition of the pyrites. 

 M. Hassenfratz, however, disputes this theory, and asserts 

 that he has seen infusible spathic iron ores, although they 

 contained no magnesia. He thinks that exposure to (he air 

 can only destroy the cohesion of the mineral. We shall 

 give an account of the judgment, when it is pronounced^, 

 upon this interesting question in metallurgy. 



M. Lelievre has described a mineral, which has been also 

 mistaken for a spathic iron, and which was found to contain 

 more than one half of oxide of manganese combined with 

 nearly one third of carbonic acid, and onlv 00* 8 of iron and 

 00" -2 and a half of lime. It is therefore a carhoncded man- 

 ganese, a new species in this genus. 



The same mineralogist has described a stone, which he 

 discovered in the island Ejba. It contains more than half 

 its weight in oxide of iron, and a little o.^ide of manganese. 

 The rest is formed of silex and lime. Its crystalline nucleus 

 is a prism with a rhomboidal base, colour black and 

 opaque, hardness a little inferior to that of feldsjjar, and 

 specific gravity four times that of distilled water. M. Le- 

 lievre names it Jenite, from the battle of Jena, one of the 

 most memorable events of this century. 



M. ' Baraillon, a correspondent of the hi'^torical class, 

 having discovered in the trenches, which he caused to be 

 cut in the antient Roman city of Ncris, near Montlucon, 

 some antient tin vasts, M. Mongez, member of the same 

 class, has liad the curiosity to ascertain their degree of pu- 

 rity. It results fioni the analyses made by M. Anfrye, in- 

 spector-general of the mint, that tliey contain nearly three 

 tenths and a half of lead. We know from the experiments 

 of M. Proust, that a similar alloy presents none of the dan- 

 gers generally conceived. 



\Vc nientioticd last vcar an iniport:.nt application of che- 



miit:y 



