THEIR CAUSE. 273 



throwing it into cold water, it remains transparent, elastic, and so 

 soft that it may be drawn out into long threads ; but that, after a 

 few hours or days, it becomes again hard and crystalline. 



The remarkable fact here is, that the amorphous sugar or sul- 

 phur returns again into the crystalline condition, without any 

 assistance from an exterior cause ; a fact which shows that their 

 molecules have assumed another position, and that they possess, 

 therefore, a certain degree of mobility, even in the condition of 

 a solid. A very rapid transposition or transformation of this kind 

 is seen in arragonite, a mineral which possesses exactly the same 

 composition as calcareous spar, but of which the hardness and 

 crystalline form prove that its molecules are arranged in a dif- 

 ferent manner. When a crystal of arragonite is heated, an inte^ 

 rior motion of its molecules is caused by the expansion ; the 

 permanence of their arrangement is destroyed ; and the crystal 

 splinters with much violence, and falls into a heap of small 

 crystals of calcareous spar. 



It is impossible for us to be deceived regarding the causes of 

 these changes. They are owing to a disturbance of the state of 

 the equilibrium, in consequence of which the particles of the 

 body put in motion obey either other affinities, or their own 

 natural attractions. 



But if it be true, as we have just shown it to be, that mecha- 

 nical motion is sufficient to cause a change of condition in many 

 bodies, it cannot be doubted that a body in the act of composition 

 or decomposition is capable of imparting the same condition of 

 motion or activity, in which its atoms are, to those of certain 

 other bodies : or, in other words, of enabling other bodies with 

 which it is in contact to enter into combinations, or suffer de- 

 compositions. 



The reality of this influence has been already sufficiently 

 proved by the facts derived from inorganic chemistry ; but it is 

 of much more frequent occurrence in the relations of organic 

 matter, and causes very striking and wonderful phenomena. 



By the terms fermentation, putrefaction, and eremacausis, 



are meant those changes in form and properties which compound 



organic substances, undergo when separated from the organism, 



and exposed to the influence of water and a certain temperature. 



13* 



