aSo French National Injlituie. 



each other only in the proportion of their principles, and par- 

 ticularly in the degree of the union of their nioleculae ; that 

 this proportion and this degree of union are invariable in the 

 cmnabar, and, on the other hand, very variable in the ethi- 

 ops : and, in the laft place, ihat cinnabar is compofed of 

 thirteen parts and one-third of fulphur, and eighty-fix parts 

 two-thirds of mercury. 



C. Seguin has written a tliird memoir on colophonium. 

 After having fliown that good colophonium is nothing but 

 refin completely purified from elTcntial oil, and from which a 

 portion of its hydrogen has been, taken; and after having 

 proved thai the colophonium ufcd in commerce is more or 

 lefs deficient,- he indicates a new procefs for obtaining it of 

 a good quality. 



Mineralogills had hitherto confidered the oifan'itc or ana- 

 taje of Haiiy as a peculiar kind of ftone. But Vauquelin, by 

 fubjetling this mineral to analyfis, has found that it is cryf- 

 tallized oxide of titanium. The anatdfe, therefore, muft 

 hereafter be clalied among metals, and in the tilanimn genus. 

 However, as the form of this mineral is not the fame as that 

 of native oxide of titanium, Vauquelin thinks there is rea- 

 fon to prefiuiic that the anatafe holds in combination fome 

 fubftance which has diliurbed the common order of cryftal- 

 lization ; and this lie propofes to verify when he can procure 

 a fiifticicnt quantity of this m.uter. 



C. Sage has defcribed in a memoir proceffes by which he 

 was enabli-d to feparatc, in the dry way, filver from cobalt, 

 and to purify the latter fubftance, as well as nickel, in fuch a 

 tiianner, that ihefe two femi-metals, when fufed into thin 

 plates, could be eafily magnetized according to Coulomb's 

 method; and that, when fiifpended by a filk thread, they 

 indicated the poles, and exhibited the magnetic phajnomena 

 obferved by Klaproth, E:faUv, and fome other philofophers. 



The (anie chemift read another memoir on the alteration 

 produced by light on fulphur.Ued red arfenic, known under 

 the name realgnr. He has {liown that this realgar and orp'i- 

 w^n/, or yellow ore of arfenic, are only the fame fubihmce 

 differently coloured; that light changes realgar into orpi- 

 ment; and that the latter mineral, \vhich pailes to the (tale 

 of realgar by the a6tion of fire alone, returns to that of orpi- 

 nient merely by the contaol of light. 



Botany. — C V'cntcnat has prel'entcd the fixth and feventh 

 number of his Dt/criptlon dcs Plantcs rares du Jard'in de 

 Ctls, &cc.; which C. Redoute jun. has enriched wiih his 

 drawings. 



In the fitting of the National Inn;ltute held on the 5th 

 of Germinal (26th JVlarchj, C. Lalande, having requelled 



leav-e 



