98 Mr. W. Brande's Chemical Researches on the Blood , 
The fluid which oozes from serum that has been coagulated 
by heat, and which, by physiologists, is termed serosity , is 
usually regarded as consisting of gelatine, with some uncom- 
bined soda, and minute portions of saline substances, such as 
muriate of soda and of potash, and phosphate of lime, and of 
ammonia. Dr. Bostock regards it as mucus.* 
From some experiments which I made upon the serum of 
blood, on a former occasion, I was induced to regard the se- 
rosity as a compound of albumen with excess of alkali, and to 
consider the coagulation of the serum analogous to that of the 
white of egg, and of the other varieties of liquid albumen. 
To ascertain this point, and to discover whether gelatine 
exists in the serum, I instituted the following experiments. 
Two fluid ounces of pure serum were heated in a water 
bath until perfectly coagulated : the coagulum, cut into pieces, 
was digested for some hours in four fluid ounces of distilled 
water, which was afterwards separated by means of a filter. 
The clear liquor reddened turmeric paper, and afforded a 
copious precipitation on the addition of infusion of galls, and 
when evaporated to half an ounce, it gelatinised on cooling. 
It was rendered very slightly turbid by the addition of dilute 
sulphuric and muriatic acid ; but alcohol produced no effect. 
From the result of these trials, it might have been concluded 
that gelatine was taken up by the water, but as an alkaline so- 
lution of albumen forms an imperfect jelly when duly concen- 
trated, and as albumen and gelatine are both precipitated by 
tannin, I was inclined to put little reliance on the appearances 
just described, until I had examined the solution by the more 
accurate method of electrical decomposition. 
* Transactions of the Medical and Chirurgical Society of London, Vol. I. p. 73. 
