DECOMPOSITION BY LIGHT. 101 



fche experimental tube unmixed with air or any other . 

 gas, the effect was substantially the same. Hence the 

 seat of the observed action is the vapour. 



This action is not to be ascribed to heat. As 

 regards the glass of the experimental tube, and the air 

 within the tube, the beam employed in these experi- 

 ments was perfectly cold. It had been sifted by passing 

 it through a solution of alum, and through the thick 

 double-convex lens of the lamp. When the unsifted 

 beam of the lamp was employed, the effect was still 

 the same ; the obscure calorific rays did not appear to 

 interfere with the result. 



My object here being simply to point out to 

 chemists a method of experiment which reveals a new 

 and beautiful series of reactions, I left to them the 

 examination of the products of decomposition. The 

 group of atoms forming the molecule of nitrite of amyl 

 is obviously shaken asunder by certain specific waves of 

 the electric beam, nitric oxide and other products, of 

 which the nitrate of amyl is probably one, being the 

 result of the decomposition. The brown fumes of 

 nitrous acid were seen mingling with the cloud within 

 the experimental tube. The nitrate of amyl, being 

 less volatile than the nitrite, and not being able to 

 maintain itself in the condition of vapour, would be 

 precipitated as a visible cloud along the track of the 

 beam. 



In the anterior portions of the tube a powerful sift- 

 ing of the beam by the vapour occurs, which diminishes 

 the chemical action in the posterior portions. In some 

 experiments the precipitated cloud only extended half- 

 way down the tube. When, under these circumstances, 

 the lamp was shifted so as to send the beam through 

 the other end of the tube, copious precipitation occurred 

 there also. 



