WRITINGS OF JAMES SMITHSON. 31 



common opinion, of crystallization requiring a state of solu- 

 tion in the matter; since it must be evident, that wtiile 

 solution subsists, as long as a quantity of fluid admitting of 

 it is present, no crystallization can take place. The only 

 requisite for this operation, is a freedom of motion in the 

 masses which tend to unite, which allows them to yield to 

 the impulse which propels them together, and to obey that 

 sort of polarity which occasions them to present to each 

 other the parts adapted to mutual union. No state so com- 

 pletely afibrds these conditions as that of mechanical 

 suspension in a fluid whose density is so great, relatively to 

 their size, as to oppose such resistance to their descent in it 

 as to occasion their mutual attraction to become a power 

 superior to their force of gravitation. It is in these circum- 

 stances that the atoms of matters find themselves, when, on 

 the separation from them of the portion of fluid by which 

 they were dissolved, they are abandoned in a disengaged 

 state in the bosom of a solution ; and hence it is in satu- 

 rated solutions sustaining evaporation, or equivalent cooling, 

 and free from any perturbing motion, that regular crystalli- 

 zation is usually efi'ected. 



But those who are familiar with chemical operations, know 

 the sort of agglutination which happens between the parti- 

 cles of subsided very tine precipitates ; occasioning them, 

 on a second diflusion through the fluid, to settle again much 

 more quickly than before, and which is certainly a crystal- 

 lization, but under circumstances very unfavourable to its 

 perfect performance. 



6. No calamine has yet occurred to mo which was a real, 

 uncombined, calx of zinc. If such, as a native product, 

 should ever be met with in any of the still unexplored parts 

 of the earth, or exist amongst the unscrutinized possessions 

 of any cabinet, it will easily be known, by producing a 

 quantity of arid vitriol of zinc exactly double its own 

 weight; while the hydrate of zinc, should it be found single, 

 or uncombined with the carbonate, will yield, it is evident, 

 1.5 its weight of this arid salt. 



