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of the larger fyringe was two inches, the force applied muft be 

 equal to a weight of nineteen hundred and fixty pounds, following 

 the fame rule of proportion. This proves the great power I can ap- 

 ply with my fmall inftrument, which I have made ufe of for many 

 years. And thofe perfons who are any v/ife lliilled in the rules of 

 geometry and ftaticks, will eafily fee the truth of what I advance. 



In further profecution of my inquiries on this fubjecil, I ordered 

 the blood of a calf to be brought to me in a clean earthen pot : after 

 it had llood feventeen hours, and the thin liquor which is called the 

 ferum of the blood, llood at the top, I put fome of that ferum into 

 a glafs tube, concluding that if any air was to be found in the blood, 

 it would be in this part called the ferum, becaufe the globules which 

 give the blood its red colour, are heavier than the ferum, and, 

 confequently, muft contain a lefs portion of air. 



This ferum I treated in the fame manner as I had done the water, 

 and I faw, that in drawing out the pillon, a great quantity of air 

 bubbles arofe from the ferum ; thefe were ten times larger than 

 thofe I had feen iflue from the water, and adhered to the glafs like 

 froth. At length, having quite extrafted tlie pifton from the tube, 

 which was done very gently, for fear of breaking the glafs, I faw 

 that all the air bubbles, except a few, difappeared. This ferous 

 matter being thus Mdthout any preflure, I faw that the fpace occu- 

 pied by the air which had ifliied from it, ftood in the tube at the 

 heio-ht of one inch, and I computed that it was one three hun- 

 dred and ninety-lixth part of the faid ferum. 



I repeated this experiment on the ferum, which I took as care- 

 fully as I could, from the blood of a calf after it had ftood only two 

 hours out of the animal, and I found that the bubbles proceeding 

 from it, were not fo many by far, as thofe in the preceding expe- 

 riment, but of a larger lize. The fpace of air in the glafs when 

 the pifton was almoft wholly withdrawn, was from C to B, 

 four inches and two thirds of an inch. The pifton being veiy 

 flowly taken out of the glafs, I faw all the air bubbles vanifli, and 



