CheTiikal Philosophy, gl 



present generally considered as erroneous, was by 

 no means an useless effort of mind. Before the 

 publication of his theory, the different branches of 

 this science had been studied in a manner too de- 

 tached and unsystematic; experiments had been 

 made with too little accuracy ; and scarcely any lu- 

 minous and generalizing views had yet been given 

 of the subject. In the fair and ingenious fabric of 

 Stahl, the scattered fragments produced by pre- 

 ceding inquirers v^ere arranged and combined 5 

 experiments began to be conducted with a spirit 

 of more acute and precise observation; and the 

 whole aspect of this department of philosophy be- 

 came more regular and scientific. 



Assuming his theory, as in general the only true 

 one, and proceeding on its fundamental principles, 

 the philosophers who followed him devised consi- 

 derable improvements, and made many important 

 discoveries. The Rev. Dr. Hales revived the pur- 

 suit oi pneumatic chemistry, which had been gene- 

 rally neglected since the time of Mayow; and, in- 

 deed, the honour of being the father of this branch 

 of the science belongs more eminently to him than, 

 to any other individual. He found that m^any sub- 

 stances were readily convertible from the fixed ta 

 the gaseous state, and vice versa ; he carried his in- 

 quiries into the effects of fermentation^ dissolution, 

 combination, combustion and respiration, further 

 than any who had gone before him; he made 

 great improvements in the necessary machinery 

 and apparatus for pneumatic experiments; and, on 

 the whole, was the author of many valuable addi- 

 tions to the science. Soon aftervrards Dr. Black 

 published the celebrated doctrine of latent heat — 

 a doctrine of fundamental importance, and of 

 great extent in its relations. He also ascertained 

 the existence and some of the properties of ^fixed 

 air, since called carbonic acid §as — -a substance 



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