361 Mr. J. Hunter on the Absorption of Gases by Charcoal. 



Equal quantities of camphor were placed in glass capsules before 

 a window, and were wetted with the same number of drops 

 from the end of a glass rod. The liquids were water, benzole, 

 ether, chloroform, bisulphide of carbon, and alcohol. A similar 

 weight of camphor was left untouched for comparison. The cam- 

 phor disappeared by evaporation at very different rates ; but the 

 experiment requires to be repeated with more care before nume- 

 rical results can be given. It illustrates probably only a case of 

 adhesion. The liquids partly dissolve, spread out the camphor, and 

 attach it with more or less force to the capsules. I have also 

 observed that where camphor has been touched with bisulphide 

 of carbon, &c. and then exposed to the light in stoppled bottles, 

 a creeping kind of vegetation is formed; and unless the tem- 

 perature be higher than that of the air in the shade, the deposits 

 are very different from those obtained from camphor not embar- 

 rassed by the presence of another vapour. 



The whole subject of the action of vapours on camphor is a 

 curious one and might repay further inquiry; but as far as my 

 notes at present extend I should, by quoting them, merely 

 multiply facts without leading to any useful principle. I fear 

 that this communication requires an apology on that ground. 

 I remain, Gentlemen, 



Your obedient Servant, 

 King's College, London, C. ToMLlNSON. 



April 2, 1863. 



LI. On the Absorption of Gases by Charcoal. 

 By John Hunter, Scholar, Queen's College, Belfast*. 



I AM induced to publish rather sooner than I intended the 

 following preliminary results f of a series of experiments 

 with which I have been engaged for some time on the absorp- 

 tion of gases by charcoal, in consequence of observing that a 

 paper on the same subject has lately been read before the Rcyal 

 Society. 



In this inquiry I have followed nearly the same method which 

 was employed by Th. de Saussure in his well-known memoirs on 

 the absorption of gases by charcoal and other bodies. The gases, 

 carefully dried, were collected over mercury, and after their 

 volume had been observed the charcoal was introduced. It was 

 heated to redness before each experiment, and while in a state of 

 incandescence immersed under mercury. My first object was to 

 ascertain the absorbing power of different kinds of charcoal; and 



* Communicated by the Author. 



