184 French Kaiioiial Ivjiitute. 



the bafe of this acid be got at, it muft be by means of the 

 moll: complicated affinities. 



■ A paper, by Mr. Howard, on his newly difcovered fuhaii- 

 nating oxyd of mercury, of the powerful effeifls of which we 

 have already taken fonie notice, was read on the 13th and 20th. 

 The procefs for preparing it we cannot yet fully dcfcribe, 

 but it confifts in digefting nitrat of mercury in alkohol. A 

 precipitate is thrown down, which, on being carefully_waflicd, 

 to free it from the nitrous acid, poflefles the fulminating pro- 

 perty formerly noticed. Experiments with this fubftance 

 ihould be carefully condufted, and in very fuiall quantities, 

 to prevent accidents. 



FRENCH NATIONAL INSTITUTE. 



Tn the public fitting of the 15th Nivofe, year 8, January 5, 



the followino- accoant of the labours of the Phvfical and Ma- 

 cs 



thematical Clafs during the preceding three months was read 

 by C. Cuvier. 



C. Guyton has prefented a table of the direft combina- 

 tions of forty-two chemical elements 3 that is to fay, of fub- 

 ftances which the chemiils have never been able to dccom- 

 pofe, and which they muft confider as hmple till proofs of 

 the contrarv are obtained. Thefe forty-two fubftances, com- 

 bined only two by two, give 861 different combinations, with 

 the half of which we are not yet acquainted. Combining 

 them three by three, and four by four, paying attention to 

 the proportions of the conftituent parts of each combination, 

 the number of the latter increafes in fuch a manner as to 

 excite aftonifliment. One might be inclined to confider our 

 ignorance refpefting the greater part of thefe combinations 

 as a proof of the imj)erfe6lion of fcience-; but fo far is this 

 from being the cafe, that it is by the immenfe progrefs fci- 

 ence has lately made that we are enabled to know that thefe 

 combinations are poffible. 



Among the Tibftances with w.hich modern chemiftry has 

 been lately enriched are in particular fome femi-nietals, one 

 of which, by its difcoverer, Profeflor Klaproth of Berlin, has 

 been called Uranite, from the planet Uranus of Herfchel, 

 as the^ coniraon metals received from the alchemifts the 



names 



