350 LIQUID PARTS OF ANIMALS. 



cohol, nitric acid, sulphuric acid, and muriatic acid, and by a sa- 

 turated solution of carbonate of potash, but rendered more liquid 

 by ammonia. He subjected it to distillation, and obtained what 

 he called volatile salt of human blood, doubtless carbonate of am- 

 monia. He obtained also empyreumatic oils, and a caput mor- 

 tuum or fixed residue, very difficult to incinerate. He observ- 

 ed that the ashes left after the combustion of human blood had a 

 brick red-colour ; though he does not seem to have suspected the 

 presence of iron in them. 



Boyle attempted to determine the proportion between the se- 

 rum and crassamentum of blood. But his method was so inac- 

 curate that it is needless to state the result. He found the speci- 

 fic gravity of serum 1-193. The serum was coagulated by acids 

 and by carbonate of potash ; but not by ammonia. It was co- 

 agulated also by corrosive sublimate. It seems needless to state 

 the results obtained by the distillation of serum as, from the in- 

 fant state of chemistry, when these experiments were made, they 

 could lead to no useful information. 



In the year 1719, Dr Jurin made some experiments to deter- 

 mine the specific gravity of blood, which approached considera- 

 bly nearer the truth than those previously made by Mr Boyle.* 

 He showed by decisive experiments that the crassamentum was 

 specifically heavier than the serum, though the contrary had been 

 inferred from the experiments of Boyle. He found the specific 

 gravity of human serum in seven experiments to vary from 

 1-0286 to 1-0302 ; the mean of the seven being 1-0295. The 

 specific gravity of human blood in five trials he found to vary 

 from 1-051 to 1-055 ; the mean of the five being 1-0533. Dr Ju- 

 rin made some experiments to determine the specific gravity of 

 the crassamentum, and concluded it to be about 1*126. But his 

 method was not susceptible of accuracy. 



Boerhaave's System of Chemistry, first published in 1732, con- 

 tains nothing more on the chemical properties of blood than had 

 been long before stated by Boyle. 



In a note to Dr Lewis's translation of Neumann's Chemistry, 

 published in 1759, the fibrin of blood is first mentioned, and 

 the method of obtaining it detailed ; though it is not distinguish- 

 ed by any name. 



Leewenhoek observed the globules of the blood as early as the 



* Phil Trans. Vol. xxx. p. 1000 f Works of Casper Neumann, p. 551. 



