158 Proceedings of the Royal Society 
whether the blood can, indeed, be retained in its liquid form in the 
manner stated. 
The trials I have instituted have been of two kinds — one by re- 
ceiving blood in a cooled vessel, cooled by snow, and kept in snow ; 
the other, by receiving it in a vessel of low temperature in a freez- 
ing mixture of salt and snow, and, when frozen, transferring it to 
snow, with the intent to see whether, after thawing (the freezing- 
point of blood being lower than that of water) it would continue 
liquid or would coagulate. 
The results of both trials — and they were more than once made 
— were negative. The blood used was that of the sheep, procured 
at the slaughter-house ; the quantity (the subject of the experi- 
ment) half a cubic inch \ and the vessels into which it was received, 
tubes of thin glass about half an inch in diameter. 
So small a quantity of blood was employed on account of the 
greater facility of lowering its temperature, whether to the freezing- 
point of water, or to the lower degree requisite for the freezing of 
the blood itself. 
As regards the first mode of trial, in each instance, the blood in 
snow, at a temperature of 32° or 33° F., was found coagulated in 
about a quarter of an hour. The coagulum was somewhat softer 
than had the coagulation been more rapid without any interference 
— i. e., in about two minutes. 
As regards the second mode of trial, the coagulum formed after 
the thawing of the frozen blood was also softer than common ; 
and the more so, it seemed, the longer the blood had been kept in 
the frozen state previous to liquefaction, as if the fibrin had thus 
been rendered less contractile. 
The parts of the quotation given, in which it is said that blood 
kept fluid at the freezing-point of water will coagulate when its 
temperature is raised, and may be “ cooled and warmed till near 
coagulation for three or four successive times,” I do not, I must 
confess, well comprehend. 
That blood may be rapidly frozen in small quantity, and rapidly 
thawed, and this more than once, I ascertained many years ago ;* 
and just now, using sheep’s blood, I have had the results con- 
*' .Researches, Physiological and Anatomical, ii. p. 77. 
