Memoir on Dr. Olbers* Viand. 279 



futphuret; but if I might be allowed a conjecture on a fub- 

 j eel with which I am not yet acquainted, it appears that we 

 cannot refufe to acknowledge in it the exiftence of hydrogen. 

 In my opinion, its great volatility cannot refult from two 

 fubftances, fuch as charcoal and 'fulphur, which not only are 

 much more fixed, but which contain no other fubttances dif- 

 pofed to affume the elaftic ftate. 



I fhall here remark, by the bye, that they fay, that by 

 heating in a retort a mixture of fulphur and charcoal, no- 

 thing is obtained but a little gas, of a bad odour, infoluble 

 in water; and that Kirwan, on the contrary, fays, fpeaking 

 of hepatic air, thai having treated with fire, fulphur and 

 charcoal whieh be had before kept a long time in a red 

 heat, he obtained hydrogen gas in great abundance* 



It is not exact to fay, " that an experiment proved to 

 them, that 100 parts of carbonic acid are eompofed nearly 

 of 28 parts of charcoal and 72 of oxygen ;" — a refult given 

 by Lavoifler. This great man, in the conclufion of his me- 

 moir, in which the refults prefented differences, expreffes 

 himfelf as follows: — "The experiments made fince incline 

 me to believe, that the proportions in charcoal are forced ; 

 and I am of opinion, that the quantity of carbon contained 

 in a quintal of carbonic acid does not exceed 24 pounds, 

 and that of oxygen is at leaft 76 pounds/' 



His opinion would be verv different from that of C. Cle- 

 ment and Deforme, if they (hould flill prove that charcoal 

 is an oxide which contains already 32 per cent, of oxygen, 

 though it is more inflammable than the bafe to which it is 

 indebted for its inflammability, carbon, or the diamond. 



XLVIIt. Memoir on the tenth Vianet difcovered by Dr. 

 Olbers. Read in the Public Sit t. tig of the French Na- 

 tional Injlitute, July $th 3 by Jerome Lalande. 



▼ ▼ HEN we announced, in the laft public fitting, the 

 difcovery of a planet by M. Piazzi of Palermo, we were far 

 from thinking that, in three months, we fhould have to make 

 known a difcovery of the lime kind. It was alfo by a for- 

 tunate accident that this tenth planet was difcovered ; but 

 accident could favour none but an intelligent and indefati- 

 gable aftronomer. 



On the 28th of March, at nine in the evening, Dr. Ol- 

 bers of Bremen was obferving Piazzi's planet, with which 

 aftronomers have been engaged for a year. He was examin- 



T 2 ' ins 



