274 Professor Fuchs on Opal, and 



when the minerals with which they come in contact are amorphous, 

 and probably this is also a concurring cause of silicates being so 

 suited to plants, and of a volcanic soil being generally so fruit- 

 ful ; since by the action of fire many silicates become developed, 

 or, if I may use the expression, from being quartzate become 

 opalate, and thus become more accessible to plants. 



In the same manner as silica passes through vegetable bodies, 

 phosphate and carbonate of lime pass without doubt through 

 animal bodies, and the latter is probably at first given out in the 

 form of a jelly when it forms shells, pearls, corals, &c. 



Since at the present time attention is particularly directed to 

 crystals, and since investigators have pursued the subject in its 

 whole depth and breadth, sometimes also entering into points of 

 which nature seems to know nothing, and also being even so bold 

 as to speak of crystallization in organic bodies ; I have thought 

 it proper to cast a glance on the amorphisin of bodies, and to 

 notice it particularly, being of opinion that it is to be regarded 

 as a peculiar and very important condition of aggregation of 

 compact bodies. It has indeed been already slightly touched on 

 by some, but never to my knowledge has any one treated of it 

 distinctly and fully. 1 know well that there are many points of 

 difficulty connected with it, but I believe that they v/ill afterwards 

 be cleai'ed up. It may perhaps be said that amorphism of bo- 

 dies admits of no idea being attached to it, that it is a nonentity; 

 we can as little make an abstraction of form as of space, &c. 



I must here expressly remark, that by amorphism ov Jbrmless- 

 ness, I understand nothing else than absence of crystallization; 

 that there are compact bodies which show no trace of it, and al- 

 together are so constituted that we can form no conclusion in 

 regard to them, can hardly be doubted. For crystalline form, 

 something else, something fixed and conformable to nature, must 

 be substituted, which, in relation to the external form of amor- 

 phous bodies or aggregates, cannot happen, since that is acci- 

 dental and may be infinitely varied, but which can happen solely 

 in respect to the smallest portions of aggregation, and such with- 

 draw themselves from observation. Further, this substitute 

 must be the same in all these bodies, since all, as has been said 

 above, have a strong resemblance to one another. But what can 

 this be ? According to my conception, nothing but the sphere, 



