1815.] ‘ «On Crystallization. ‘7 103 
I have tried similar experiments with other salts, of which E 
shall barely state the ontlines. 
1, Sulphate of Magnesia.—Boiling saturated solutions of this 
salt, corked and uncorked, like the before-mentioned ones, some- 
times crystallize, and sometimes continue fluid, I have never ob- 
served the beautiful satin-like crystallization perceptible in the sul- 
phate of soda; but the crystals fall down in minute grains, like sand, 
diffused through the solution, gradually sinking to the bottom. 
2. Alum, as above.—Crystals formed at the bottom; the re- 
mainder continued fluid, eyen when shaken; when the cork was 
withdrawn, shaking produced no effect for nearly a minute, when 
the same sand-like precipitation ensued, commencing from the top. 
When this ceased, it appeared nearly solid; but by standing for 24 
hours, more than one-half was fluid. 
3. Sulphate of Iron exhibited an appearance nearly similar, to 
that of alum. 
4. Sulphate of Copper.—The same, with some occasional varia- 
tion, even in the same solution. 
5. Sulphate of Zinc remained fluid for 24 hours, although a 
boiling saturated solution was employed, and frequent agitation. 
6. Subcarbonate of Soda (sal sod) boiling and saturated. In one 
case (corked) it became nearly solid when cold, from the spontane= 
ous crystallization. The same solution subsequently deposited, 
whilst corked, a smaller quantity of spontaneous crystals ; and after 
drawing the cork and shaking, small granular crystals speedily 
clouded the solution. The same resulted in uncorked solutions. 
_ 7. Muriate of Lime, saturated and boiling, crystallized, when 
corked, completely throughout: subsequently, dissolved by heat 
again, and corked, it remained fluid, until shaken without uncorking, 
when a crystallization as beautiful, and nearly resembling that of 
sulphate of soda, took place, with an extrication of more caloric 
than in avy of the preceding cases. 
8. Muriate of Ammonia, corked and uncorked; boiling saturated 
solutions became solid as they cooled, with a firm crystallization, 
9. Nitre deposits regular crystals at the bottom, both in corked 
and uncorked phials; but 1 never perceived any further result, ex- 
cept by the slow evaporation of the fluid. 
{ have tried a number of other salts, but the results are not worth 
Glauber’s salis have repeatedly refused to crystallize, even when exposed to the. 
full pressure of theair, and that for days. Now itis to be remembered that such 
solutions had cooled from at least 212% to near the freexing point, and yet were 
enabled to hold that portion of salt in solution, which our theories presume to de- 
od on the additional temperature, What was it that thus enabled the water to 
maintain its fluidity and transparency, although charged with such a quantity of 
solid matter, in opposition to atmospheric pressure and a diminished temperature 
of at Jeast 150°? Can it possibly have depended on a quantity of latent heat only 
equal in the above experiment of Dr. Higgins to 50°? And is not the fact that 
water itself has been cooled down to 20° or 25° below the freezing point without 
congealing, evidence that something more than a certain quantum of latent heat is 
essential to the fluidity of water, &c, Other objections to this theory present 
themselves, but thiy is not the place for cqueidermg them, 
