original thinkers, he bestowed little attention on books of opinion, or theory; but chiefly confined himself to such as abound in facts, and afford the materials for speculation. His reading for many years had been principally directed to accounts of voyages and travels, especially those relating to Oriental nations; and there was no book of this description, possessing even tolerable merit, with which he was not familiarly conversant. His acquaintance with such works had supplied him with a great fund of original and curious information, which he employed with much judgment and ingenuity, in exemplifying many of his particular opinions, and illustrating the most important doctrines in the philosophy of commerce and government.

Of his leading practical opinions, sufficient intimations have been, given in the course of the preceding narrative. They were of a liberal and enlightened cast, and such as might be expected from the character of his genius and understanding. Among them must be particularly mentioned an ardent, but rational, zeal for civil liberty; which was not, in him, a mere effusion of generous feeling, but the result of deep reflection and enlarged philosophic views. His attachment to the general principles of freedom originated from his strong conviction of their influence in promoting the wealth and happiness of nations. A due regard to these principles he considered as the only solid foundation of the most important blessings of social life, and as the peculiar cause of that distinguished superiority, which our own country so happily enjoys among the nations of Europe.

Of his moral qualities, it is scarcely possible to speak too highly, He described himself as naturally passionate and irascible, and as roused to indignation by any act of oppression or wanton exercise of power. The latter feeling he always retained, and it formed a distinguishing feature of his character. Of his irritability, a few traces might occasionally be discovered; but they were only slight and momentary. His virtuous dispositions appeared on every occasion, and in every form, which the tranquil and retired habits of his life would admit of. He had a high sense of honour and duty; and was remarkable for benevolence and kindness, especially towards his inferiors and dependents. But his merits were most conspicuous in the intercourse of social life. His amiable temper, and unaffected desire of giving pleasure, no less than his superior knowledge and talents, had rendered him highly acceptable to a numerous and distinguished circle of society, by whom he was justly valued, and is now most sincerely lamented. But the real extent of his private worth, the genuine simplicity and virtuous independence of his cha racter, and the sincerity, warmth, and constancy of his friendship, can only be felt and estimated by those, to whom he was long and intimately known, and to whom the recollection of his talents and virtues must always remain a pleasing, though melancholy, bond of unión.

ARTICLE II.

Observations on Crystallization. By John Redman Coxe, M. D. Professor of Chemistry, Philadelphia.

THE efficacy of temperature in augmenting the solvent power of liquids is laid down by most chemical writers. This is more especially 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 temperature, 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 crystallization of salts; and the proof advanced is, 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 solution 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, numerous objections to its truth; yet so numerous are the anomalies that present themselves in experimenting upon this subject, that I am 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 I have tried it. Nitrate of potash and muriate of ammonia, both nearly as soluble as Glauber's salt, when secured from atmospheric pressure, by corking the phial, or tying a bladder over the mouth, precipitate in regular crystals as the solution 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

same results. I have kept some vessels thus exposed to the full atmospheric pressure for three days, without any consolidation; and others, during all the intermediate periods, with similar results. Sometimes one or more will crystallize, whilst others continue fluid. I have made these experiments in phials holding from two drachms to 16 ounces; in receivers of a globular and oval shape, from half a pint to half a gallon; some with short, and others with long necks; and in open glass jars of one to two inches diameter, and eight or nine long; so that the form of the vessel in no way appears to influence the result. Nor has the quantity of solution in the vessel any influence, since it is the same when filled to the top, or when only filled to one-fourth or one-fifth part. The result was the same when I employed the common Glauber's salts of the shops, the native, or the artificial, made by the direct combination of the constituents. In one experiment made with the artificial sulphate I filled three equal phials, two were closely corked, the third remained open, and all were placed beside each other to cool. In four hours one of the corked solutions was regularly crystallized in solid transparent crystals, one-fifth only of the mass being in a liquid state, which did not consolidate by shaking, or by withdrawing the cork. The contents of the other corked, and of the uncorked phial, both continued fluid; and both became solid by shaking, without withdrawing the cork of the closed one.

4. Solutions as above, after remaining exposed, have even not crystallized when briskly shaken, and some time afterwards without any apparent cause, have assumed the solid form.

5. Solutions as above, and closely secured, have failed to become solid, when the cork has been drawn, or the bladder punctured, for some moments, and even minutes; and in a few cases when even agitation was employed in addition: and these, in like manner, when least expected, have suddenly crystallized.

6. Solutions as above, both corked and uncorked, have gradually deposited regular transparent firm crystals, in some instances two inches in length; in others, in irregular masses, at the bottom of the vessel-the fluid above, in these cases, continuing clear and saturated; and when shaken, sometimes consolidating in the usual

way.

7. Solutions as above, both corked and uncorked, after thus depositing these regular crystals at the bottom, have, without an apparent cause, become consolidated above them, whilst remaining untouched.

8. Solutions as above (especially in a mattrass with a neck nearly two feet long), have, after considerable exposure and frequent agitation, refused to crystallize, even although continued at intervals for

The crystals which form suddenly in these solutions are always of a soft, spongy, silky, striated, appearance; and do not exhibit the firm, transparent, glassy, appearance of the common crystals of Glauber's salt.

more than an hour; yet by then turning the vessel, so as to pour out a little from the neck, the crystallization has immediately occurred.

9. The same solution in the mattrass above mentioned has frequently become completely crystallized when left uncorked; at other times a large mass, equal to half the volume of the solution, has crystallized regularly, in hard transparent crystals, the remainder of the solution continuing fluid.

10. Saturated mixed solutions of nitre and Glauber's salt, corked closely, have allowed the nitre to crystallize regularly at the bottom; whilst the Glauber's salt remained fluid, and on drawing the cork became solid in the usual way.

11. Solutions, by no means saturated, evince similar results with the above fully saturated ones, although not in so strongly marked a

manner.

12. One of the most singular and interesting facts connected with these experiments is, that in those cases in which (either in the corked or uncorked solutions) regular, firm, transparent crystals form, so soon as the residuary saturated solution above them solidi fies, either spontaneously, or by shaking, drawing the cork, &c. an immediate (or nearly so) opalescence, or loss of transparency, ensues in those first formed crystals, which gradually increases to a beautiful porcelainous whiteness. This I have almost invariably noticed under the above circumstances: I believe it arises from the gradual abstraction of the water of crystallization of the first formed regular crystals, by the mass of secondary crystals; for in one experiment made, I found the porcelainous mass, when dissolved in water, and regularly recrystallized, afforded a quantity of transparent crystals, superior in weight to those I employed, which could only arise from their re-obtaining their thus lost water of crystallization. How the secondary crystals operate in withdrawing this water from the first, I cannot form the most distant idea.

13. In those solutions in which spontaneous crystals have formed, in the course of a few days, if the secondary crystallization does not take place, a complete truncation of the summits of the crystals occurs, gradually forming a level of the whole, as in common cases; yet in several instances the solution above was sufficiently saturated to consolidate when shaken.

14. In one experiment two equal sized phials were filled to the top with saturated solutions; one was corked, the other was left open: in two hours the uncorked one had consolidated; the other was observed to have contracted above one-fourth of an inch, and continued fluid; it crystallized, however, as usual, when briskly shaken, without withdrawing the cork.

It should perhaps be mentioned, that this sudden crystallization always commences at the surface.

I have put the solutions, both corked and uncorked, into cold water, as soon as made, in order to expedite their cooling, and have found the same results generally as when suffered to cool gra

dually. The solution in open phials has sometimes cooled down to the temperature of the cold water (about 40°), and has then remained fluid in it for two or three hours; it has then sometimes crystallized in the soft spongy mass; at others in firm, well formed regular crystals.

*

15. Four or five phials have burst in which spontaneous regular crystals had formed, and over which subsequently a sudden consolidation of the residuary solution had taken place, after the change of colour was effected in the first crystals (as mentioned in No. 12), but whether from an expansion in the first or second crystals, I know not, as I was never present when this occurred.* I have never seen this fracture of the phial when only the regular crystals had formed, nor when only the spontaneous solidification took place. It is probably, therefore, somehow connected with the abstraction of the water of crystallization from the regular by the spontaneous spongy mass. In the above instances the crystals which had formed regularly were perfectly white, and were readily separated from the superior spongy ones by a little water gently poured over them, leaving them of the most perfect regularity, and forming a beautiful white crystalline preparation easily preserved, and not efflorescent, as in common cases.

In all the cases thus enumerated, such are the anomalies presented as to prevent my drawing one conclusion from them which could give me any insight into the causes that produce them. In some cases atmospheric pressure seems to operate, in others not; agitation sometimes, but not invariably. The whole series of experiments is so interesting, I trust this account may lead to further investigation, which may finally afford an explanation, and possibly lead to new views on the subject of crystallization generally. I can only add, that I never could promise myself, à priori, that any one case should certainly turn out as I expected; it appeared a matter of chance in a great degree, whether this or the other result should ensue. †

*I apprehend it must occur during the abstraction of the water of crystallization from the primary by the secondary crystals, which must be accompanied by a correspondent expansion.

+ In speaking of the effect of atmospheric pressure on saturated solutions of salts, Dr. Higgins details an experiment which he made in a narrow-necked glass mattrass of three gallons dimensions. It was fixed in a vessel filled with a saturated solution of sea salt: a solution of 144 oz. of Glauber's salts in 96 oz. of water, in a separate vessel, was filtered into the mattrass, which was filled twothirds by it, and the whole was made to boil so as to exclude the air by the vapour formed. A strip of wet bladder secured the mouth of the mattrass, and sustained the atmospheric pressure.

Two matirasses were thus prepared; they stood three days at a temperature between 400 and 50°, and were often shaken without crystallizing; as soon as the bladder was cut a few small concentric spicular crystals formed, and shot rapidly through the liquor till it was almost solid: the caloric evolved, raised the temperature from 60° to 90°, and in one experiment from 40° to 90°.

From this experiment connected with those above detaited, as also from many well-known facts, I am impelled to deny the perfection of Dr. Black's celebrated theory of latent heat. It will be observed that boiling saturated solutions of