440 CAVENDISH. 



ments, except on the nature of the diamond, led to no 

 material extension of our chemical knowledge. Stript 

 of the plumes in which he sought to array himself, re- 

 pulsed from the avenues by which he would fain have 

 intruded himself among those whose experiments led 

 at once to great discoveries, he is now, on all hands, 

 allowed to have never made us acquainted with a single 

 new gas, or a new substance of any kind, or, except 

 as to carbon, with a single new combination of the 

 old. He did not, like Black, discover carbonic acid 

 or latent heat he did not, like Priestley, discover 

 oxygen he did not, like Scheele, discover chlorine 

 he did not, like Davy, discover the alkaline metals 

 or like Cavendish, by direct experiment, show how 

 water and nitrous acid are constituted or, like Ber- 

 thollet, explain of what ammonia consists. But it is 

 equally confessed that, by sound and happy reasoning 

 on the experiments of* others, he showed how the 

 process of combustion and of calcination takes place, 

 and to him and his individual researches we owe the 

 important discovery that fixed air, however generated, 

 whether by respiration or by combustion or by fermen- 

 tation (its three great sources, as proved by Black), is the 

 combination of oxygen and carbon. Nor is it any deroga- 

 tion from his claims to the title of a discoverer of physical 

 truths that his generalization pushed too far made him 

 regard oxygen as necessary to all combustion and all 

 acidification, whereas it has been found that heat and 

 light are abundantly evolved both by the combustion of 

 metals and sulphur in close vessels by the combustion 

 of hydrogen and azotic gas and by the combination of 

 metals with chlorine ; and also that chlorine, an acid 



