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could make, that the quantity of air extrad;ed was ttVt part of 

 the blood. 



I was invited by another furgeon to be prefent when he fliould 

 open a vein in one of his pupils ; but upon this occafion the blood 

 iffued very flowly, and as it were, drop by drop. Some of this 

 blood I put into a glafs tube which had had rain water in it, and 

 applied the operation of drawing out the air, which I found 

 amounted to ^J-^ part of the blood. 



Now, iince we fee that blood, when it firft iflues from the veins, 

 contains in it no air, we may be confirmed in the opinion of rejeft- 

 ing thofe fayings of medical men, who, when they are called to lick 

 perfons complaining of pains in this or that part, tell them, that the 

 wind has got into the part, or that it is a windy complaint, and the 

 like ; whereas they ought rather to fay, that the veffels in that part 

 are obll:ru6ted, that the blood or juices have not their free courfe or 

 circulation ; and thefe kind of obIl:rud:ions caufe pain, and fome- 

 times fwellings in different parts of the body. 



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