cold; and wherefore bleeding 1 , even in asthenic 

 fevers, lessens the violence of the disease. On 

 these occasions, the effect cannot be owing to the 

 diminished bulk of the humours alone, since the 

 former diameter of the vessels is soon restored by 

 the absorption of new fluids, from the alimentary 

 canal; but the diminution of the colouring" matter 

 of the blood, and the production of heat, which 

 depends on it, must also have a considerable share 

 in it. Practitioners in physic will, no doubt, re- 

 collect circumstances in the course of their expe- 

 rience, which will give still greater probability 

 to this idea, 



By ascertaining the quantity of carbonic acid, 

 which is daily formed by respiration, we may 

 pretty nearly determine the quantity of heat, 

 which is necessary for maintaining the equable 

 temperature of the body. ALLEN and PEPYS 

 found, that a middle-sized person expires in 24 

 hours, 39,534 cubic inches of carbonic acid gas, 

 which, when weighed, makes 19,683 grains, or 39 

 ounces of carbonic acid. These contain 11 ounces 

 1 dram of carbon ; from which it follows, that a 

 middle-sized person wants, within 24 hours, as 

 much heat for keeping the body at -f- 32 * a 



* The Author uses the centigrade thermometer, 



