232 LAVOISIER. 



of his processes in point of accurate admeasurement, 

 the same inferiority of his experiments to his reasons, 

 the same happy generalization of facts observed by 

 others, the same turn for throwing doctrines and disco- 

 veries not his own into one combined system. 



The discoveries of Black had, long before M. Lavoisier 

 entered upon his scientific pursuits, directed the attention 

 of philosophers to the important subject of gaseous bodies, 

 to their production by the absorption of heat, and to the 

 combinations into which they enter with other substances, 

 so as to alter the nature of these. The great doctrines 

 of causticity and of latent heat, with the existence of fixed 

 air, and its evolution in respiration, fermentation, and 

 combustion, had been established, and had formed a new 

 era in chemical science. Fixed air was discovered in 

 1754; latent heat before 1763. Mr. Cavendish had pro- 

 secuted these inquiries with success; he had examined 

 some of the properties both of fixed air and of hydrogen ; 

 had determined their specific gravities, and had shewn 

 that they are always the same from whatever substances 

 they may be obtained. His experiments were published in 

 1766. Soon after this time Dr. Priestley began his brilliant 

 course of discovery. A new scene had been opened to 

 philosophers ; they were like infants gazing on the material 

 world, every object of which is new to them, and whose 

 whole existence is one continued gratification of curiosity. 

 Aware from former discoveries that various kinds of air, 

 each having its peculiar properties, exist in nature, he 

 was of course ever expecting to meet with them; and, 

 accordingly, he soon found that the air of the atmosphere 

 yields one of these, which on a false theory he termed 

 phlogisticated, but which others have termed azote, being 



