Refpiration , and the Ufe of the Bloods 229 
ments in the food to this air, p. 336.; and stevenson 
thought, that the air which had circulated in the blood, 
and which had heated the blood too much, was exhaled 
by the lungs, p. 35 5- 
Others lay, that the air itfelf is not admitted into the 
blood, but only dome adive, fpirituous, and ethereal par- 
ticles ; that this vital fpirit paffes from the lungs to the 
heart and arteries, and at length becomes the animal fpi- 
rits, which are by this means generated from the aii, p. 
333. Others, who do not admit that the animal fpirits 
are derived from the air, ftill fay that fome other vital 
principle comes from thence. This vital principle mal- 
pighius fuppofes to be a faline vapour , listePi, a hot, 
inflammable, fulphureous fpirit ; vieussenius, a volatile 
acid fait, which keeps up the fei mentation of the blood, 
and bryan robinson, the aerial acid, which piefei\es the 
blood from putrefadion; preferves alfo its denflty, and 
ftrengthens the animal fibres. For this reafon he fup- 
pofes it is that we feel ourfelves refreflied in cold air, as 
it abounds with a more plentiful acid quality, p. 334. 
They who fuppofe that nitre is taken from the air into 
the blood, afcribe to that principle its fei mentation, its •. 
heat, and its denfity, p. 334. 
It is a received opinion, that one ufe of the lungs is to 
attenuate the blood, p. 359 5 and malpighius adds,, 
that by this means, the different particles of the blood 
become thoroughly mixed together; while others think 
that the blood is condenfed in the lungs; and others, that 
the globules, and all the finer humours, receive their con- 
figuration there, ibid . Some, without confidering the 
