DECOMPOSITION BY LIGHT. 101 



the 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 re- 

 gards 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 pass- 

 ing it through a solution of alum, and through the 

 thick double-convex lens of the lamp. When the un- 

 sifted 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 chem- 

 ists a method of experiment which reveals a new and 

 beautiful series of reactions, I left to them the exam- 

 ination 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 oc- 

 curred there also. 



