DURING CHEMICAL COMBINATION. 67 



The volume of phosphorus, arsenic, and sul- 

 phur vapours is still further augmented on 

 uniting with hydrogen and other permanent 

 gases. The specific gravity of these vapours, as 

 deduced from the experiments of Dumas and 

 Mitscherlich,(who converted them into the gase- 

 ous state by heat,) are 4*444, 10-625, and 6'666 

 (see table, page 61); but when phosphorus vapour 

 unites with hydrogen, its volume is augmented 

 fourfold that is, from 25 to 100, as in phosphu- 

 retted hydrogen. Sulphur vapour is expanded 

 still more on uniting with hydrogen, viz. from 16 

 to 100, as in sulphuretted hydrogen, as before 

 stated. Now it must be remembered that the va- 

 pours of phosphorus, sulphur, mercury, and ar- 

 senic, have little or no elasticity, unless at high 

 temperatures ; from which it follows, that their 

 volume and elastic force are augmented on uniting 

 with hydrogen, by acquiring from it a sufficient 

 amount of caloric to produce the effect. These 

 views will be more fully expanded when I come 

 to treat of the natural forces of caloric. 



When thus investigated in connection with the 

 cause which moves atoms, and the law by which 

 they are united and separated, the atomic theory 

 embraces the whole science of nature. But until 

 the mutual relations of sethereal and ponderable 

 matter shall be better understood, the theory of 

 atoms, and consequently that of chemistry, must 

 remain involved in profound obscurity a lifeless 



