1815;] On. Crystallization. 101 
ARTICLE II. 
Observations on Crystallization, By John Redman Coxe, M. D. 
Professor of Chemistry, Philadelphia. 
Tue efficacy of temperature in augmenting the solvent power of 
liquids is Jaid down by most chemical writers. This is more espe- 
cially the case with the class of salts; to which, however, some 
“exceptions occur, as in muriate of soda, which is nearly equally 
‘soluble in boiling water, and in water at the common atmospheric 
temperature. There is, nevertheless, something as yet not well 
understood, that appears to me operative in such cases, independent 
entirely of temperatufe, even in the instances of our most soluble 
salts, as Glauber’s, or the sulphate of soda and some others, 
It is almost universally asserted by authors on the subject, that 
atmospheric pressure is essential to the ciystallization of salts ; anid 
the proof advanced jis, that if a phial, nearly filled with a boiling 
saturated solution of Glauber’s salt, be closely corked whilst filled 
with vapour, so as to exclude the atmospheric pressure ; this solu- 
tion will remain, even when cold, perfectly fluid, and may be 
shaken without becoming solid: but if the cork be withdrawn, the 
sudden impulse, from the air rushing into the phial, immediately 
induces the crystallization of the mass, with a sensible evolution of 
heat. 
Now this beautiful and interesting experiment, which is usually 
shown in every course of chemical lectures, certainly at first sight 
appears to prove the position advanced. There are, however, nu- 
merous objections to its truth ; yet so numerous are the anomalies 
that present themselves in experimenting upon this subject, that I 
dm unable to form any theory or speculation on their causes, 
1. If the above position were true, then certainly, by a parity of 
reasoning, we should expect every other saline solution, in which a 
boiling heat is employed to promote its fullest state of saturation, to 
be affected in a similar way ; but this is not the case as far as L have 
tried it. Nitrate of potash and muriate of ammonia, both nearly 
as soluble as Glauber’s salt, when secured from atmospheric pres- 
sure, by corking the phial, or tying a bladder over the mouth, pre- 
cipitate in regular erystals as the selution cools. This fact alone is 
sufficient to overturn the theory advanced to explain the case stated 
of the Glauber’s salt;—but, 
2. A perfectly saturated solution of Glauber’s salt, thus carefully 
corked at a boiling heat, has repeatedly crystallized throughout, 
without any exposure to the atmospheric pressure; whilst a solution 
of equal strength, and prepared and secured in every respect as the 
former, has, whilst standing beside it, remained perfectly fluid, 
3. Saturated solutions of salts as above, uncorked, evince the - 
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