392 Mr. Brodie's Experiments and Observations 
probable that it must undergo the usual change in the capil- 
lary system of the greater circulation also, since these changes 
are obviously dependent on and connected with each other. 
The blood in the aorta and pulmonary veins was not more 
florid, and that in the vena cava and pulmonary artery was 
not less dark-coloured than under ordinary circumstances. 
We may moreover remark, that the most copious secretions 
in the whole body are those of the insensible perspiration 
from the skin, and of the watery vapour from the mouth and 
fauces, and the effect of these must be to lower rather than to 
raise the animal temperature. Under other circumstances also 
the diminution of the secretions is not observed to be attended 
with a diminution of heat. On the contrary, in the hot fit of 
a fever, when the scanty dark -coloured urine, dry skin, and 
parched mouth indicate that scarcely any secretions are taking 
place, the temperature of the body is raised above the natural 
standard, to which it falls when the constitution returns to its 
natural state, and the secretions are restored. 
It has been observed, by a distinguished chemist, that “ the 
experiments to determine the specific heat of the blood are of 
so very delicate a nature, that it is difficult to receive them 
with perfect confidence/’* The experiments of Dr. Crawford 
for this purpose were necessarily made on blood out of the 
body, and at rest. Now,- when blood is taken from the vessels, 
it immediately undergoes a remarkable chemical change, se- 
parating into a solid and a fluid part. This separation is not 
complete for some time ; but whoever takes the pains to make 
observations on the subject, can hardly doubt that it begins to 
take place immediately on the blood being drawn. Can expe» 
* Thomson’s History of the Royal Society, p. 129. 
