MEMOIR XIX.] MODIFIED CHLORINE. 



Paragraphs subsequently added. ^ 



Chlorine is not the only elementary 

 which the radiations produce a change. In his 

 on phosphorus, Berzelius remarks: "Light produces in^ifcv 

 (phosphorus) a peculiar change, of which the intimate 

 nature is unknown; and which, so far as we can judge 

 at present, does not alter its weight. It makes it take a 

 red tint. This phenomenon occurs not only in a vac- 

 uum, even in that of a barometer, but also in nitrogen 

 gas, in carburetted hydrogen, under water, alcohol, oil, 

 and other liquids. When we expose to the sunlight 

 phosphorus dissolved in ether, oil, or hydrogen gas, it in- 

 stantly separates under the form of red phosphorus ; it 

 undergoes very rapidly this modification in violet liglit, 

 or in glass vessels of a violet color. The light of the 

 sun makes it easily enter into fusion in nitrogen gas, but 

 it does not melt in hydrogen, and in the torricellian 

 vacuum it sublimes in the form of brilliant red scales " 

 (Berzelius, Traite, torn, i., p. 258). 



Again, when speaking of phosphuretted hydrogen, he 

 says: "Exposed to the influences of the direct solar light 

 this gas is decomposed, a part of the phosphorus sep- 

 arates under the form of red phosphorus, and is depos- 

 ited on the interior surface of the glass. If we cover 

 the vessel which contains the gas imperfectly, no phos- 

 phorus is deposited on the covered spaces " (Ib., torn, i., 

 p. 265). 



As Berzelius does not give these experiments as his 

 own, and I do not know to whom we are indebted for 

 them, I repeated some of them. Among other corrobo- 

 rative results it appeared that a piece of phosphorus of 

 a pale or whitish color, in a vessel filled with pure and 

 dry carbonic -acid gas, placed in the sunshine, rapidly 

 exhibited the phenomenon in question. Eventually the 



