146 Proceedings of Philosophical Societies. [Feb. 



Hence it would appear that they exist over a very considerabk 

 proportion of Europe. 



Article XIII. 

 Proceedings of Philosophical Societies. 



ROYAL SOCIETT. 



O.N Thursday, tlie 20th of January, was read a paper by Sir 

 Humphry Davy, entitled, Some Experiments and Observatio7is on 

 a new Substance which becomes a violet coloured Gas by Heal. The 

 substance in question was accidentally discovered, about two years 

 ago, by M. Courtois, a manufacturer of saltpetre at Paris. In his 

 processes for extracting soda from kelp lie found his metallic vessels 

 more corroded tliaa tbev ouy-bt to have been. In endeavourins; to 

 discover the cause of this he obtained the new substance. Tlie 

 mode of obtaining it is easy. Concentrated sulphuric acid is poured 

 upon tlie insoluble part of the kelp from which the soda has been 

 extracted. Heat is produced, and tl>e new substance appears under 

 the form of a violet vajwur, which condenses into crystals. M. 

 Courtois gave specimens of it to MM. Desormes and Clement, who 

 subjected it to experiments, and read a short paper on it at a meet- 

 ing of the Institute on Nov. 29, 1813. They stated that its specific 

 gravity was 4 ; that it becomes a violet coloured gas below the 

 temperature of boiling water; that it combines with metals, phos- 

 phorus, and sulphur, with alkalies and metallic oxides, and forms a 

 detonating compound with ammonia ; that it dissolves in alcohol 

 and ether ; and that by the action of liydrogen and phospliorus on 

 it an acid analogous to the muriatic is twmed. Gay-Lussac had 

 been supplied with a quantity of it by Clement, had subjected it to 

 experiments, and had read to the Institute on the 6th Decemiier 

 the memoir of which an abstract is putilished in tlie present Number 

 of the Annals oj Philosnphi/. Sir 11 umplny Davy was furnished 

 with a quantity of it by M. Ampere, and was thus enabled to make 

 experiments on it. The following is a pretty correct epitome of the 

 facts stated by Sir H. Davy in his paper; the novelty of tlie subject 

 having induced us to take some pains to state every thing with cor- 

 rectness :-f- . 



1. The new substance precijiitates nitrate of silver lemon yellow. 

 This precipitate fused at a low red heat, and became red. When 

 acted on by potash, it was decomposed, and oxide of silver formed. 

 Potasli boiled 'upon it yielded the peculiar sul;*tance when treated 

 with sulphuric acid. It was more rapidly acted on when exposed to 

 light thnn mt.iriate of silver, and was a distinct substance. \\ hen 

 the peculiar substance is heated in contact with silver a similar 

 compound is focpied.. 



