CONSTITUENTS OF PLANTS. Ill 



How much more wonderful and inexplicable does 

 it appear, that bodies which remain fixed in the 

 strong heat of a fire, have under certain conditions 

 the property of volatilizing and, at ordinary tempera- 

 tures, of passing into a state, of which we cannot 

 say whether they have really assumed the form of a 

 gas or are dissolved in one ! Steam or vapours in 

 general have a very singular influence in causing 

 the volatilization of these bodies, that is, of causing 

 them to assume the gaseous form. A liquid during 

 evaporation communicates the power of assuming 

 the same state in a greater or less degree to all sub- 

 stances dissolved in it, although they do not of 

 themselves possess that property. 



Boracic acid is a substance which is completely 

 fixed in the fire ; it suffers no change of weight 

 appreciable by the most delicate balance, when ex- 

 posed to a white heat, and, therefore, it is not vola- 

 tile. Yet its solution in water cannot be evaporated 

 by the gentlest heat, without the escape of a sensible 

 quantity of the acid with the steam. Hence it is 

 that a loss is always experienced in the analysis of 

 minerals containing this acid, when liquids in which 

 it is dissolved are evaporated. The quantity of 

 boracic acid which escapes with a cubic foot of 

 steam, at the temperature of boiling water, cannot 



seducing for the youthful and philosophic mind, which would penetrate 

 the deepest depths of nature, without the assistance of the shaft or 

 ladder of the miner. This is poetry, but not sober philosophical 

 inquiry. 



