43$ DISEASES OF IRRITATION. SECT. XXXII. $, 



various chemical ones, which are adapted to the 

 numerous glands, and to the other organs of fenfe. 



2. The momentum of the progreflive particles of 

 blood is compounded of their velocity and their 

 quantity of matter : hence whatever circumftances 

 dirninim either of thefe without proportionally in- 

 creaiing the other, and without fuperadding either 

 of the general ftimuli of heat or diftention, will 

 tend to produce a qinefcence of the arterial fyftem, 

 and fiorn thence of all the other irritative motions, 

 which are connected with it. 



Hence in all thofe confutations or difeafes where 

 t'he blood contains a greater proportion of ferum, 

 which is the lighteft part of its composition, the 

 pulfations of the arteries are weaker, as in nervous 

 levers, chlorolis, and hyfteric complaints ; for in 

 thefe cafes the momentum of the progreflive parti- 

 cles of blood is lefs : and hence, where the denfer 

 parrs of its compolition abound, as the red part 

 of if, or the coagulable lymph, the arterial pulfati- 

 ons are (honger 5 as in thofe of robuft health, and 

 in inflammatory difeafes. 



That this ftrmulus of the momentum of the par- 

 ticles of the circulating fluid is of the greateft con- 

 feqnence to the arterial aclion, appears from the 

 experiment or injeding air into the blood veflels, 

 \vhichfeems to deftroy animal life from the want 

 of this ftimulus of momentum ; for the diftention 

 of the arteries is not diminiihed by it, it poiTerTes 

 no corrofive acrimony, and is lefs liable to repafs 

 the valves than the blood itfelf ; iince air-valves in 

 all machinery require much lefs accuracy of con- 

 flruction than thofe uhich are oppofed to water. 



3. One method of recreating the velocity of the 

 blood, and in confequence the momentum of its 

 particles, is by the exercife of the body, or by 

 the fusion of its furface : fo, on the contrary, too 

 great indolence contributes to decreafe this ftimulus 



of 



