278 Formation of Compound or Twin Crystals. 



applicable to this hypothesis, inasmuch as the elementary molecules 

 are not supposed to be divisible except at the instant of entering into 

 combination, and then it is merely a mutual divisibility. 



Arguments in favor of this hypothesis might be drawn from chem- 

 ical considerations. I might speak of the difficulty of comprehend- 

 ing how the juxtaposition of two atoms, absolutely indivisible par- 

 ticles, could produce a change in the quality of these atoms. I 

 might allude to the difficulty of accounting for the different densities 

 of isomeric bodies, on the hypothesis of juxtaposition. Analogical 

 conclusions in its favor might be derived from the fact that some 

 compounds act an elementary part. The difficulty of accounting 

 for the peculiarities of chemical combination and solution, might be 

 adduced, or at least the superior simplicity of the supposition, that 

 in the former case, there is an actual and intimate combination of 

 the particles, and in the latter merely a juxtaposition due to the 

 general attractions of matter for matter, modified to some extent in 

 each species of matter, by the idiosyncrasies of each ; and also from 

 this would arise the explanation of the fact that a saturated fluid 

 may still dissolve a third body ; for we may suppose that the parti- 

 cles of the two former may each of them, have this general attrac- 

 tion for a third body, although not more for each other. Reference 

 might also be made to the greater simplicity of the idea that the 

 molecules of alcohol for instance, are simple molecules of alcohol, 

 instead of an aggregate of four atoms of carbon, five of hydrogen and 

 one of oxygen. Indeed the facts are numerous which lend some 

 probability to the truth of the hypothesis. But Crystallography 

 appears to be more properly the judge of the forms of molecules. 

 From this science seems to come that ray of light which is to guide 

 us to this of nature's most hidden secrets. The geometrical regu- 

 larity and perfect symmetry of the forms of which it treats, clearly 

 indicate that they are dependent on certain forms in the ultimate 

 particles of matter, and we may hope, that by an attentive stu<jy of 

 the laws and facts of this science, conclusions may be deduced res- 

 pecting their forms that will admit of but little if any doubt. If the 

 various facts brought to light by the science of Crystallography, ad- 

 mit of a simple and satisfactory explanation on the above hypothe- 

 sis, and if more than this, the facts absolutely require its admission, 

 we can hardly hesitate in giving it our credence. Whether this is 

 so or not, will be considered in the following remarks, in which the 

 truth of the above hypothesis will be assumed and its sufficiency as 

 the ground work of a theory tested. 



