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After ttie blood had remained forty-four hours in the glafs, I 

 repeated the experiment of pumping, but I found fuch a fmall ad- 

 ditional quantity of air produced, that it was Icarce worthy of be- 

 ing noted. 



After twelve hours more had elapfed, I again drew off air from 

 the blood, but I perceived no alteration nor any increafe in the air 

 produced. 



After the blood had flood about five days and as many nights in 

 my lludy, I took fome of the ferum from the furface, and put it into 

 a new tube, wherein no liquor had ever been put : the length of 

 this tube was feventeen inches from B to C, and eleven inches from 

 A to B. 



This I treated in the fame manner as before, and perceived that 

 the air bubbles arifing from the blood, and the external air which 

 found its way into the glafs, occupied a fpace of five inches and 

 three quarters from C towards B. During my operation, I at- 

 tended carefully to the air bubbles as they arofe, and which grew 

 larger as they afcended, as I have before obferved ; and I faw fome 

 of them which were larger than others, rife to the furface fafter, 

 and fome of thofe larger ones afcended with five or fix times the 

 velocity of the fmaller ones. Some of thefe larger bubbles fre- 

 quently drove the fmaller on one fide, to make way for themfelves 

 in their afcent; but I never perceived any of thefe air bubbles unite 

 together, which I believe was only caufed by the vifcofity or tena- 

 city of the ferum in which they were formed. 



Hereupon I figured to myfelf the reafon why a larger air bubble 

 fooner reached the furface of the liquor than a fmaller one. For, if 

 the axis of a fmall bubble is as one, and that of a large one is as 

 three, the proportion of a column, which the power of afcent in 

 the fmaller bubble will overcome, is to the larger one as one to 

 nine, and the bulk of the bubble whofe axis is one compared with 

 that whofe axis is three, will be as one to t\\'enty-feven, and con- 

 fequently according to this proportion, the larger bubble v»ill ex- 



