On Respiration and Animal Heat. 21 
blood, by which the large quantity of heat 
can be received ito the lungs without at all 
raising their temperature. This object is pre- 
cisely what La Grange and Hassenfratz have 
had in view by their new theory; notwith- 
standing their pretended objections, they, in 
reality, adopt the very same principles which 
Crawford. had the merit to discover. 
_ The change they propose to make is this; 
the oxygen inspired, instead of entering im- 
mediately into combination with the carbone 
and hydrogen, as Crawford supposes, enters 
first of all into the blood, without depositing 
mauch of its heat; during the circulation, this 
oxygen gradually combines with the carbone 
and hydrogen, forming carbonic acid and water, 
and giving out heat in consequence, till the 
blood, on its return again to.the lungs, throws 
out the carbonic acid and water, and receives 
a fresh supply of oxygen. Every one must _ 
see, that these positions are necessarily depen- 
dent on the two essential characters of Craw- 
ford’s theory; namely, that of carbonic acid 
having a less capacity for heat than oxygenous 
gas, and that of arterial blood having a greater 
capacity for heat than venous blood. 
instead, therefore, of pulling down the 
mgenious edifice erected by Crawford, and 
building another in its place, as they imagine; 
