72 POPULAR LECTURES AND ADDRESSES. 



I have given above are applicable to express the 

 law of equilibrium between the moisture retained 

 by vegetable substances, such as cotton cloth or 

 oatmeal, or wheat-flour biscuits, at temperatures 

 far above the dew point of the surrounding 

 atmosphere. But although the energy of the 

 attraction of some of these substances for vapour 

 of water (when, for example, oatmeal, previously 

 dried at a high temperature, has been used, as in 

 the original experiment of Sir J. Leslie, to produce 

 the freezing of water under the receiver of an air- 

 pump) is so great that it might almost claim re- 

 cognition from chemists as due to a " chemical 

 affinity," and resulting in a " chemical combination," 

 I believe that the absorption of vapour into fibrous 

 and cellular organic structures is a property of 

 matter continuous with the absorption of vapour 

 in a capillary tube demonstrated above. 



