VOL. XXX.J PHILOSOPHICAL TRANSACTIONS. 421 



salts, that it might very well deserve the name of spirit. Its specific gravity 

 was 1080,1. 



Besides these, we had 7 dr. of volatile salt, 1 oz. of oil, and 8 oz. 4 dr. of 

 caput mortuum, which still retained some small remainder of the oil, as was 

 manifest from its taking fire at the flame of a candle. In this latter part of the 

 operation was lost 3 oz. 7 dr. 



Upon making due allowance for the difference between the specific gravities 

 of the 3 first portions of liquor and that of serum, as also for what was lost in 

 the two several parts of the operation, which we may reasonably conclude to 

 have been of a specific gravity nearly the same with that of the liquor drawn 

 off, it will be found, that the quantity of serum contained in this mass of 

 blood, was about -ff of the whole weight, and consequently that the quantity 

 of crassamentum was -^ of the same weight. 



If we calculate therefore on this supposition, that the weight of the globular 

 part of the blood is -^v ^^ ^^e whole, we shall find the specific gravity of a 

 blood globule to be to that of water as 1277 to 1000. If we follow the pro- 

 portion of -tV) which results from Mr. Boyle's experiments, the specific gravity 

 of a blood globule will be 1242. 



But this computation seems to be a great deal too large : for we cannot be 

 certain that the whole quantity of aqueous liquor was raised from the serum of 

 the blood. On the contrary, it is more than probable, that a considerable part 

 of it was afforded by the blood globules themselves; especially in the latter part 

 of the operation, when their texture must have been broken and dissolved by 

 the strong fire that was used. To prove this, we need only consider the con- 

 dition of the dried crassamentum, after the phlegm is drawn off, being now a 

 hard and brittle substance : whereas the globules in their natural state are soft 

 and yielding. For which reasons it may perhaps be more satisfactory, if we at- 

 tempt to find the quantity of the globular part of the blood after another 

 manner. 



It appears therefore from Mr. Boyle's observations, that the quantity of 

 serum, which may be poured off from the crassamentum, is about one half of 

 the whole mass. The remaining crassamentum consists of the blood globules, 

 and a quantity of serum filling up the interstices between them ; which, if the 

 globules keep their spherical form, may easily be found by the principles of 

 common geometry, to be nearly one half of the bulk of the crassamentum : 

 but if the globules by their pressure against each other change their figure, the 

 quantity of serum will be something less. 



If this quantity of serum, lying between the blood globules, be added to that 

 poured off, it appears that the serum contained in blood, is about |- of the 



