480 



think, cannot fail to assist in suggesting the direction in which the 

 true solution is ultimately to be sought for ; yet I feel confident 

 that no full and true solution has as yet been found*. 



In the foregoing part of the present paper, I have shown reason 

 why stresses applied to crystals when in contact with the liquid from 

 which they have been produced, should be expected to cause them 

 to melt or dissolve away. The following line of reasoning to show 

 that stresses applied 'to a crystal will cause a resistance to the de- 

 position of additions to it from the liquid, or, in other words, a re- 

 sistance to its growth, will, I think, prove to be correct. When a 

 crystal grows, the additions, it seems to me, must lay themselves 

 down in a state of molecular fitting, or regular interlocking with the 

 parts on which they apply themselves ; or, in other words, they must 

 lay themselves down so as to form one continuous crystalline structure 

 with the parts already crystallized. It thus seems to me that, if a 

 crystal grows when under a stress, the new crystalline matter must 

 deposit itself in the same state of stress as the part is in on which it 

 lays itself. If, then, we consider a spiculum of ice growing in water, 

 and if we apply any stress, a pull for instance, to it while it is thin, and 

 then fix it in its distended state, and if then by the transference! to 

 the water beside it of cold taken from any other ice at the freezing- 

 point we cause it to grow, which it may do if there be no other 

 crystal of ice beside it more free than it to receive accessions, then 

 the additional matter will, I think, lay itself down in the same state 

 of tensile stress as the original spiculum was put into by the applied 

 pull. The contractile force of the crystal will thus be increased in 

 proportion to the increase of its cross sectional area. If it now be 

 allowed to contract and relax itself, it will give out, in doing so, more 

 mechanical work than was applied to the original spiculum during 

 distention. Hence there would be a gain of mechanical work with- 



* I have my brother's authority for stating that, although he believes the 

 physical principles suggested in his papers here referred to to be capable of 

 being developed into a true explanation of the phenomena, yet he considers 

 further investigation necessary, and does not feel confident as to the correct- 

 ness of that part of the explanation he offered, in which the mutual action of 

 two vesicles in a line oblique to that of maximum pressure is considered. 



t A theoretic air-engine for making such transferences of heat or cold was 

 used in the reasoning by which I determined theoretically the lowering of the 

 freezing -point by pressure; and the same is admissible here. 



