Crystallization. 347 



CHAPTER XXXVII. 



CRYSTALLIZATION. 



Since we have got a habit of talking of the 'mineral "kingdom and of 

 organic kingdoms, we are apt, inadvertently, to get a half impression that 

 these are independent departments of nature in which the materials 

 used and the laws governing their movements and arrangements are 

 different and independent. It is our first duty to rid ourselves of this 

 false impression, and to come to a realization of the fact that nature is 

 onl}' one. We may call it all a mineral kingdom if we choose ; in which 

 case we are to consider every organic body as a lot of minerals ar- 

 ranged in a particular form, and therefore liable to a particular set of 

 reactions. Or we may call it all an organic kingdom, in which case the 

 so-called minerals become organic bodies of simple constitution. 



From very much that has gone before, we have reason to conclude 

 that organisms are built up, altered and amended, moved and operated 

 by forces chiefly external to themselves. If we inquire among the 

 minerals, at the first glimpse, we will be apt to suppose that they are 

 more independent of their surroundings. They seem to have their likes 

 and dislikes, their affinity for this, and their indifference to that. Their 

 affinities appear at first to be absolute and ultimate, belonging to them- 

 selves and not to be questioned ; theirs, just because they are, and al- 

 ways have been. But investigation shows that the so-called elementary 

 bodies are by no means exempt from the influence of energies external 

 to themselves. Even their very affinities are largely conditional in 

 fact, I think we may say wholly conditional on the action upon them of 

 external energy in the shape of heat, light, electricity, &c. We have 

 seen that the effect of various dynamic agencies upon bodies organized 

 into machines depends entirely on the form and make-up of the ma- 

 chines themselves. But every body is organized into a machine. The 

 atom, which is conceived by the chemist to be the smallest particle of 

 any element, is never found except in combination with others. There- 

 fore it is alwa}'s a part of a machine. There is nothing but a series of 

 machines from atoms to elephants. A molecule, which is the smallest 

 quantity of a compound that can exist by itself, is composed of at least 

 two atoms, and may be composed of a great many. So that even a 

 molecule is a machine whose reaction against any sort of energy de- 

 pends upon its structure ; that is, the number and shape of its atoms 

 and the manner in which they are attached to each other. Since two 

 bodies may be composed of the same kind of atoms in the same num- 

 ber, and yrt bo radically different by reason of the manner in which the 

 component atoms are stuck together, it follows that form alone tnav 



