210 



Messrs. A. Downes and T. P. Blunt on [Dec. 19, 



We are justified, therefore, in concluding that, in this case at least, 

 the destruction of an organic body in light is due to the oxidation of 

 its hydrogen. 



Appendix. 



Vacuum Apparatus. — In conducting our experiments in vacuo, or in 

 a modified atmosphere, obtained by means of the Sprengel pump, it 

 was necessary to ensure that the tubes compared should be under 

 exactly similar conditions with regard to pressure ; and it seemed 

 desirable, therefore, to exhaust the pairs, or double pairs, at one opera- 

 tion. With this object an adapter was contrived, which, though simple 

 in its construction, proved so efficient that it may be worth while to 

 describe it in detail. 



Fig-. 3. — a, " shoulder." b, the point of sealing after exhaustion. 



A piece of glass tubing, 1\ inches long, f inch in diameter, and open 

 at both ends, which were slightly lipped, was fitted with two caoutchouc 

 stoppers, one of which, pierced with a single hole, served for connexion 



