CRYSTALLISATION AND COHESION. 51 



Let us take some simple case in illustration. In 

 quiet water we have very finely divided matter sus- 

 pended, and matter in a state of solution. The first i 

 slowly precipitated, and in process of time consolidates 

 into a hard mass at the bottom, presenting no particular 

 character, unless it has been placed in some peculiar 

 physical conditions ; when, as in nature, we have a 

 regular bedding which is intersected by lines of lamina- 

 tion or of cleavage, which we are, from experiment, 

 enabled to refer to the influence of current electricity. 

 The second the matter in solution is also slowly 

 deposited ; but it is accumulated upon nuclei which 

 possess some peculiar disposing powers, and every par- 

 ticle is united by some particular face, and an angular 

 figure of the most perfect character results. Many 

 pleasing experiments would appear to show that elec- 

 tricity has much to do in the process of crystallization ; 

 but it is evident that it must be under some peculiarly 

 modified conditions that this power is exerted, if, indeed, 

 it has any direct action. 



The same substances always crystallize in the same 

 forms, unless the conditions of the crystallizing body are 

 altered. It has been supposed that each particle of a 

 crystalline mass has certain points or poles which possess 

 definite properties, and that cohesion takes place only 

 along lines which have some relation to the attracting 

 or repelling powers of these poles. We shall have, 

 eventually, to consider results which appear to prove 

 that magnetism is universal in its influence, and that 

 this polarity of the particles of matter may be referred 

 to it. 



Be the cause of crystallisation what it may, it presents 

 to us in appearance a near approach in inorganic nature 

 to some of the peculiar conditions of growth in the 

 organised creation. In one, we have the gradual pro- 

 duction of parts and the formation of members due to 

 peculiar powers of assimilation, each individual pre- 



