RESEARCHES ON THE COAGULATION OF THE BLOOD. 103 
ever degree of truth it may contain, is very far indeed from 
representing the whole truth. 
“One of the most remarkable circumstances connected with 
blood that has been shed from the vessels is, that it refuses to 
coagulate below a temperature of 40° Fahr. or thereabouts. 
This is explained by Dr. Richardson, on the hypothesis that 
the low temperature prevents the evolution of ammonia,* 
while the rapidity with which coagulation takes place at high 
temperatures, seems to him satisfactorily accounted for by the 
increased volatility exhibited by the ammonia under such 
circumstances, i was myself at first disposed to accept this 
interpretation ; but subsequent reflection led me to think 
that, to say the least, it required confirmation. It occurred 
to me, that if it were true that the fluidity of blood below 40° 
was due to free ammonia retained in it, coagulation would 
take place immediately, in spite of the cold, if the alkali were 
neutralised by the addition of acid, provided the fibrine were 
not impaired in its coagulating property by the reagent 
employed. In order to ascertain whether this result would 
really follow, I poured blood freshly shed from a sheep into 
vessels surrounded by ice-cold water, and by this means 
succeeded in keeping some portions of it fluid for a con¬ 
siderable time, and found that it continued liquid notwith¬ 
standing the addition of dilute acetic acid in what I suppose 
must be sufficient quantity to overcome the feeble alkalinity 
of the blood, while the acidulated specimen retained the 
property of coagulating very rapidly when raised in tempe¬ 
rature. But on attempting to discover whether this blood 
was really acid in reaction, I found that its red colour entirely 
vitiated the indications of both litmus and turmeric; and 
even the serum obtained after contraction of the clot was too 
much tinged to admit of the satisfactory application of the 
test paper. 
“Being thus baffled in my experiments with the sheep, I 
had recourse to the horse, in which the red corpuscles subside 
with peculiar rapidity in the plasma, giving rise to the bufty 
coat well known to occur in the blood of that animal in the 
state of health, so that the opportunity would be presented 
of obtaining liquor sanguinis free from red corpuscles, to 
which the tests could be applied without risk of fallacy. 
Accordingly, yesterday afternoon, a horse having been placed 
at my disposal by my friend Mr. Gamgee, of the New Vete- 
* See Dr. Richardson’s ‘ Asllev Cooper Prize Essay,’ p. 303, where a fact 
is mentioned, indicating that no ammonia was given off at 34° Fain*, from a 
specimen of blood which had been artificially ammoniated, and which at 96° 
afforded distinct evidence of evolution of the alkali. 
