452 NATURAL HISTORY. 



Experiment solitary touching the two kinds of pneu- 

 maticals in bodies. 



842. All solid bodies consist of parts of two seve 

 ral natures, pneumatical and tangible ; and it is 

 well to be noted, that the pneumatical substance is 

 in some bodies the native spirit of the body, and in 

 some other, plain air that is gotten in ; as in bodies 

 desiccate by heat or age : for in them when the 

 native spirit goeth forth, and the moisture with 

 it, the air with time getteth into the pores. And 

 those bodies are ever the more fragile ; for the 

 native spirit is more yielding and extensive, especi 

 ally to follow the parts, than air. The native spirits 

 also admit great diversity ; as hot, cold, active, dull, 

 &c. whence proceed most of the virtues and qualities, 

 as we call them, of bodies : but the air intermixed 

 is without virtues, and maketh things insipid, and 

 without any exstimulation. 



Experiment solitary touching concretion and dissolu 

 tion of bodies. 



843. The concretion of bodies is commonly 

 solved by the contrary ; as ice, which is congealed 

 by cold, is dissolved by heat ; salt and sugar, which 

 are excocted by heat ; are dissolved by cold and 

 moisture. The cause is, for that these operations 

 are rather returns to their former nature, than 

 alterations; so that the contrary cureth. As for oil, 

 it doth neither easily congeal with cold, nor thicken 

 with heat. The cause of both effects, though they 

 be produced by contrary efficients, seemeth to be the 



