DR DAVY ON THE COAGULATION OF THE BLOOD. 533 
red, but with little change of consistence; no serum had separated. After twenty- 
eight days, the blood in the vial had become darker and softer and less viscid, 
whilst that in the wine-glass retained its tenacity and consistence and colour. 
These results appear to me clearly to show,—1st, That there are no indications 
afforded of the escape of volatile ammonia during the coagulation of the blood of 
the fowl, or of its presence in the blood ;—2d, That the addition of ammonia in a 
notable quantity does not prevent coagulation ;—3d, That a sudden reduction of 
the temperature of the blood, even when fully exposed to the air, has a greater 
influence in retarding the coagulation than the assigned cause of its fluidity, the 
volatile alkali, when added. 
The few trials I have made with the sesquicarbonate and neutral carbonate 
of ammonia have given results equally unfavourable, as they appear to me, to the 
hypothesis. I shall mention briefly two. 
Experiment 7.—272 grains of blood were received into the half-ounce vial, con- 
taining 12 grains of water and 4 grains of the sesquicarbonate of ammonia. An 
hour and a-half after, the blood continued fluid; no separation of lymph had 
taken place, and no change of colour: three quarters of an hour later, it had par- 
tially coagulated ; this was in its inferior portion, the upper remaining liquid. 
The bottle was perfectly tight; no air had escaped; none had entered. On the 
day following, on withdrawing the stopper, the whole was found coagulated: the 
clot formed was soft and viscid, of a dark hue, and without any separation of 
serum. Under the microscope, the red corpuscles were distinct, some appearing 
nearly of their natural form, some elongated, but none in piles. The blood had 
a strong ammoniacal odour. 
Experiment 8.—To 20°5 grains of water, containing 2°9 grains of the neutral 
carbonate of ammonia, 234 grains of blood were added, in the manner described, 
and in a vial of the same capacity. Partial coagulation occurred in about twelve 
minutes, and in fifteen it was complete throughout; the crassamentum was soft 
and florid. After twenty-four hours, it was a little firmer, but no serum had se- 
parated, nor had any exuded after forty-eight hours, when it was of moderate 
firmness. 
Thus it appears that these salts of ammonia, used in small quantities, have the 
effect of retarding coagulation, analogous in this their influence to most of the 
salts of the alkalies; and, like them, we know that in a large proportion they pre- 
vent it, and yet that on dilution with water coagulation takes place.* 
I shall now briefly notice some other experiments which I have made with 
the same intent as the preceding, viz.:—the testing of the hypothesis advanced, 
that the presence of ammonia in the blood is the cause of its fluidity. My respect 
for its author, and the reputation that his work has acquired, induce me to go rather 
more into details than otherwise I should have felt inclined to do. The experi- 
* See my “ Researches Physiological and Anatomical,” vol. t1., p. 105, for instances. 
