FIG. 168. LAVOISIER. 



CHAPTER XIV. 



CHEMISTRY OF THE EIGHTEENTH CENTURY. 



THE researches of Van Helmont, Boyle, and Mayow had the effect 

 of greatly attracting the attention of chemists to gases. It would 

 almost seem as if they had instinctively foreseen that the whole science 

 would ultimately rest upon the knowledge of gases. It would not be 

 easy in the present day for any man of ordinary education to realize 

 to himself the darkness which at the beginning of the eighteenth cen- 

 tury concealed the whole question of gases even from the best intel- 

 lects. Researches had to be made to obtain even the most elementary 

 knowledge of the properties of the gases in mines, and of those pro- 

 duced in fermentation, respiration, and combustion. In the earlier 

 part of the eighteenth century no one more contributed to increase our 

 knowledge of gases than STEPHEN HALES (1677 1761), by whose 

 labours also juster notions of the economy of plants were promulgated. 



241 



