Chap. II.] Chemical Philosophy), 97 



Stahl, the scattered fragments produced by preced- 

 ing inquirers were arranged and combined ; expe- 

 riments began to be conducted with a spirit of 

 more acute and precise observation ; and the \vlioIe 

 aspect of this department of philosophy became 

 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 of 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 many 

 substances were readily convertible from the fixed 

 to the gaseous state, and vice versa ; he carried his 

 inquiries into the effects of fermentation, dissolu- 

 tion, combination, combustion, and respiration, 

 further than any who had gone before him ; he 

 made great improvements in the necessary machi- 

 nery and apparatus for pneumatic experiments ; 

 and, on the whole, w^as the author of many valua- 

 ble additions to the science. 



The doctrine of Latent Heat was first taught by 

 Dr. Black, of the university of Edinburgh, in the 

 year 1757- His discovery, and the doctrine which 

 he founded on this discovery, may be considered 



* The rev. Stephen Hales, D. D., was born in 1677. He 

 was a great chemist and vegetable physiologist. Beside many 

 Gommunications to the Royal Society, he published two vo- 

 lumes of Statical Essays^, which are highly esteemed. He died 

 in 1761. 



Vol. I. H 



