SLATES. 357 



Thus it is with the processes of nature, where mecha- 

 nical and molecular laws intermingle and create ap- 

 parent confusion. Their mixture constitutes what may 

 be called the noise of natural laws, and it is the vocation 

 of the man of science to resolve this noise into its com- 

 ponents, and thus to detect the underlying music. 



The necessity of this detachment of one force from 

 all other forces is nowhere more strikingly exhibited 

 than in the phenomena of crystallisation. Here, for 

 example, is a solution of common sulphate of soda or 

 Glauber salt. Looking into it mentally, we see the 

 molecules of that liquid, like disciplined squadrons 

 under a governing eye, arranging themselves into bat- 

 talions, gathering round distinct centres, and forming 

 themselves into solid masses, which after a time assume 

 the visible shape of the crystal now held in my hand. 

 I may, like an ignorant meddler wishing to hasten 

 matters, introduce confusion into this order. This may 

 be done by plunging a glass rod into the vessel ; the 

 consequent action is not the pure expression of the crys- 

 talline forces ; the molecules rush together with the 

 confusion of an unorganised mob, and not with the steady 

 accuracy of a disciplined host. In this mass of bismuth 

 also we have an example of confused crystallisation ; but 

 in the crucible behind me a slower process is going on : 

 here there is an architect at work ' who makes no chips, 

 no din,' and who is now building the particles into 

 crystals, similar in shape and structure to those beauti- 

 ful masses which we see upon the table. By permitting 

 alum to crystallise in this slow way, we obtain these 

 perfect octahedrons ; by allowing carbonate of lime to 

 crystallise, nature produces these beautiful rhomboids ; 

 when silica crystallises, we have formed these hexagonal 

 prisms capped at the ends by pyramids ; by allowing 

 saltpetre to crystallise we have these prismatic masses, 



