52 NATURAL HISTORY. 



accelerating thereof is very worthy to be inquired. 

 It is effected by three means. The first is by cold ; 

 whose property is to condense and constipate, as 

 hath been said. The second is by heat ; which is 

 not proper but by consequence ; for the heat doth 

 attenuate ; and by attenuation doth send forth the 

 spirit and moister part of a body; and upon that, 

 the more gross of the tangible parts do contract and 

 sear themselves together ; both to avoid &quot; vacuum,&quot; 

 as they call it, and also to munite themselves against 

 the force of the fire, which they have suffered. And 

 the third is by assimilation ; when a hard body 

 assimilateth a soft, being contiguous to it. 



The examples of induration, taking them pro 

 miscuously, are many : as the generation of stones 

 within the earth, which at the first are but rude 

 earth or clay : and so of minerals, which come, no 

 doubt, at first of juices concrete, which afterwards 

 indurate : and so of porcelain, which is an artificial 

 cement, buried in the earth a long time ; and so 

 the making of brick and tile : also the making of 

 glass of a certain sand and brake-roots, and some 

 other matters ; also the exudations of rock-diamonds 

 and crystal, which harden with time ; also the indura 

 tion of bead-amber, which at first is a soft substance ; 

 as appeareth by the flies and spiders which are found 

 in it ; and many more : but we will spedk of them 

 distinctly. 



83. For indurations by cold, there be few trials 

 of it ; for we have no strong or intense cold here on 

 the surface of the earth, so near the beams of the 



