CHEMICAL RAYS. 



245 



a chemical agent. It also enables us to illustrate in our 

 laboratories actions which have been hitherto performed 

 only in the laboratory of Nature. A few of these actions 

 of a representative character will now be brought before 

 you ; and advantage will be taken of the fact that, in a 

 great number of cases, one or more of the substances into 

 which the waves of light break up , 

 compound molecules are compar- 

 atively involatile. The products 

 of decomposition require a greater 

 heat than is required by the va- 

 pors from which they are derived 

 to keep them in the gaseous form ; 

 and hence, if the space in which 

 these new bodies are liberated be 

 of the proper temperature, they 

 will not remain in the vaporous 

 condition, but will precipitate 

 themselves as liquid particles, thus 

 forming visible clouds upon the 

 beam, to the action of which they 

 owe their existence. 



The little flask, F, in the an- 

 nexed figure, is stopped by a cork, 

 pierced in two places. Through 

 one orifice passes a narrow glass 

 tube, a, which terminates imme- 

 diately under the cork; through 

 the other orifice passes a similar 

 tube, b, descending to the bottom of the little flask, which 

 is filled to a height of about an inch with a transparent 

 liquid. The name of this liquid is nitrite of amyl, in every 

 molecule of which we have 5 atoms of caxbon, 11 of hydro- 

 gen, 1 of nitrogen, and 2 of oxygen. Upon this group the 

 waves of our electric light will be immediately let loose. 



