the Croonian Lecture. 
189 
extrication of carbonic acid gas, I was led to make the 
attempt to inject the coagulum with the common minute 
injection under the receiver of an air pump. The experiment 
was made in the following manner. A glass cup about 
an inch and a half deep, and nearly three inches in diameter, 
had blood from the arm drawn into it, till it was three 
parts full. The blood was allowed to stand in a cool place 
for 48 hours, the serum was then strained off, and about £ of 
the coagulum on one side was cut away and removed, and 
the cavity thus made was filled with common red size injec- 
tion in a fluid state ; not, however, quite so high as the 
surface of the coagulum. In cutting off a portion, the edge 
showed the coagulum to be very weak, much more so than 
it is commonly met with. The glass vessel was immediately 
put under the receiver of the air pump. Very early in the 
exhaustion, the carbonic acid gas was evolved in such quan- 
tity as' to keep the fluid injection in a state of agitation, 
which had the advantage of keeping it fluid; when the ex- 
haustion was increased, the evolvement was so rapid that it 
became necessary to work the pump very slowly. After 
the exhaustion had become nearly complete, the glass vessel 
and its contents were removed, and, with a view to fix 
and harden the coagulum, the glass vessel was placed in 
boiling water, which was renewed at short intervals, carefully 
preventing the water from coming in contact with the blood. 
This process melted the injection that had not passed into the 
coagulum, and allowed of its being poured off The coagulum 
even now was by no means very firm, but capable of sup- 
porting itself ; it was turned out upon a flat piece of glass* 
To make it dry more readily, and to prevent its going into 
