180 THE HISTORY OF SCIENCE 



nium. No doubt what gave special zest to his study 

 of the alkalis was the hope of overthrowing the doc- 

 trine of French chemists that oxygen was the essen- 

 tial element of every acid. Lavoisier had given it, 

 indeed, the name oxygen (acid-producer) on that sup- 

 position. Davy showed, however, that this element is 

 a constituent of many alkalis. 



In 1810 he advanced his controversy by explaining 

 the nature of chlorine. Discovered long before by 

 the indefatigable Scheele, it bore at the beginning of 

 the nineteenth century the name oxymuriatic acid. 

 Davy proved that it contained neither oxygen nor 

 muriatic (hydrochloric) acid (though, as we know, 

 it forms, with hydrogen, muriatic acid). He gave 

 the name chlorine because of the color of the gas 

 (^Xcopcfc, pale green). Davy studied later the com- 

 pounds of fluorine, and though unable to isolate the 

 element, conjectured its likeness to chlorine. 



He lectured before the Dublin Society in 1810, 

 and again in the following year ; on the occasion of 

 his second visit receiving the degree of LL.D. from 

 Trinity College. He was knighted in the spring of 

 1812, and was married to a handsome, intellectual, 

 and wealthy lady. He was appointed Honorary Pro- 

 fessor of Chemistry at the Royal Institution. His new 

 independence gave him full liberty to pursue his 

 scientific interests. Toward the close of 1812 he 

 writes to Lady Davy : 



"Yesterday I began some new experiments to 

 which a- very interesting discovery and a slight acci- 

 dent put an end. I made use of a compound more 

 powerful than gunpowder destined perhaps at some 

 time to change the nature of war and influence the 



