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V.—Some Observations on the Coagulation of the Blood. By Joun Davy, M.D., 
F.R.S. Lond. and Edin. 
(Read 18th April 1859.) 
In a recent work * of an elaborate kind, displaying much ability, its author, Dr 
RicHarpson, has endeavoured to prove that the cause of the coagulation of the 
blood is of a chemical nature, and referable to the escape of a volatile matter, 
and that the volatile matter is ammonia. 
It is not my intention at present to consider the various circumstances which 
he brings forward in favour of his conclusion. [ shall restrict myself to a few 
observations which I have made, the results chiefly of trials instituted for the 
purpose of testing his speculations, and of satisfying myself, if possible, on the 
subject. 
If the coagulation of blood depend on the escape of ammonia in any form, 
that is, however combined, and is purely a chemical phenomenon, it follows, 
that the escape of the volatile matter being prevented, the blood should remain 
liquid. 
To determine this by experiment does not seem to be a difficult matter, whether 
as regards the means required or the results to be obtained. The blood I have 
chosen for trial has been that of the common fowl, obtained by dividing the great 
vessels in the neck. I have selected it because the blood of birds exhibits the 
phenomenon in question in the most striking and rapid manner. [| shall describe 
a few of the experiments made. 
Experiment 1.—A half-ounce vial} in a few seconds was filled with blood to 
within a quarter of an inch of its neck, and was immediately closed with a glass 
stopper. In two minutes coagulation had taken place throughout; now, on with- 
drawing the stopper, a glass rod, dipped in muriatic acid, was brought near, as a 
test of ammonia; no fume, not the slightest, was perceptible. The blood, still 
warm, was next mixed with hydrate of lime; no ammoniacal odour could be 
detected. 
Experiment 2.—Two ounces of blood were received in a glass vessel, into which 
two drops of aqua ammoniz had just before been poured; as soon as caught, it 
was gently moved by inclining the vessel backwards and forwards, to favour the 
action of the volatile alkali; in less than two minutes coagulation had taken place. 
A distinct odour of the volatile alkali was emitted, and when a plate of glass, 
* The “ Cause of the Coagulation of the Blood,” being the Astitzy Cooper Prize Essay for 1856 
with Additional Observations and Experiments, &c, By B. W. Ricuarpson, M.D , 8vo, London, 1858, 
+ The capacity was greater; it held 298 grains of water. 
VOL. XXII. PART I. O 
