OF GASEOUS BODIES. 115 



There is no limit to the application of this doc- 

 trine in the phenomena of chemistry. 



If a piece of ice be introduced into a vessel 

 full of ammoniacal gas, the latter disappears ra- 

 pidly, and the ice is melted, forming a chemical 

 solution of ammonia (spirit of hartshorn). Now 

 it is obvious on a moment's reflection, that the 

 volume and elasticity of the ammoniacal gas are 

 destroyed by the attraction of ice for its caloric. 

 It is equally true, that the ammonia is chemically 

 combined with the ice by the same attraction, as 

 will be proved when I come to treat of chemical 

 solutions. Again, if one volume of hydrochloric 

 acid be mixed with one volume of ammoniacal 

 gas, they combine rapidly with evolution of much 

 heat, when they lose the gaseous or elastic state, 

 making a solid crystalline salt (sal ammoniac) 

 of a cubical or octohedral form. The atomic 

 weight of the acid is 37, and that of the alkali 

 17. (See Table of Atomic Weights, p. 5i.) 



In this case, there is an attraction of caloric by 

 the larger particles of the acid, by which those of 

 the ammonia are forced into chemical combina- 

 tion with them, forming compound particles of 

 still larger size, the weight of which is 54, com- 

 pared with hydrogen as unity. 



Thus it is evident that the repulsive poiver of 

 caloric, on which the volume and elastic force of 

 gases depend, is counteracted and diminished by 

 an affinity of ponderable atoms for caloric; and 

 that this attraction augments in a certain ratio as 



