126 MEMOIR ON TEE SCIENTIFIC CHARACTER 



The Abbe Haiiy had advanced the opinion that calamines 

 were all of one species, and all mere oxides or " calces " t)f 

 zinc, containing no carbonic acid, and that their effervescence 

 with acids was duo to an accidental admixture of carbonate 

 of lime. Smithson's analyses completely overthrew this 

 opinion, and established these minerals in the rank of true 

 carbonates. 



His remarks on the action of the ores of zinc before the- 

 blow-pipe, evince much discernment in relation to the 

 eifects there observed. 



" The exhalation of these calamines at the blow-pipe, and the flowers 

 which thoy diffuse round them on the coal, are probablj' not to bo attributed 

 to a direct volatilization of them. It is more probable that they are the 

 consequence of the disoxidution of the zinc calx, by the coal, and the in- 

 flammable matter of the flame, its sublimation in a metallic state, and 

 instantaneous recalcination. And this alternate reduction and combustion 

 may explain the peculiar phosphoric appearance by calces of zinc at the 

 blow-pipe." 



" The apparent sublimation of the common flowers of zinc at the instant 

 of their production, though totally unsublimable afterwards, is certainly, 

 likewise, but a deceptious appearance. The reguline zinc, vaporized by 

 the heat, rises from the crucible, as a metallic gas, and is, while in this state, 

 converted to calx (oxide.) The flame which attended the process is a proof 

 of it. 



" The fibrous form of the flowers of zinc is owing to a crystallization of 

 the calx while in mechanical suspension in the air, like that which takes 

 place with camphor when, after having been sometime inflamed, it is blown 

 out." 



As incidental to this inquiry on calamines, he introduces 

 a remark of great interest in connection with the subject of 

 crystallization— a subject, which, when applied to a partic- 

 ular body of the highest interest to the arts, (I refer to 

 wrought iron,) has of late awakened great attention both 

 among practical and scientific inquirers ; and which has 

 been invested with a deep tragic interest by a recent la- 

 mentable occurrence in our own community : 



" A moment's reflection," says Smithson, " must evince how injudicious 

 is the common opinion of crystallization requiring a state of dissolution in 

 the matter, since it must be evident that while 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 oc- 

 casions them to present to each other the parts adapted to mutual union. 



" No state so completely affords these conditions as that of mechanical 

 suspension in a fluid, whose density is relatively, to their size, such as to 

 oppose a resistance to their descent in it, and to occasion their mutual attrac- 

 tion to become a power superior to their force of gravitation. 



" It is in these circumstances that the atoms of matter find themselves, 

 when, on the separation from them of the portion of fluid by which thoy 

 wore dissolved, thoy were abandoned in a disengaged state in the bosom of 

 n solution, and hence it is in saturated solutions sustaining evaporation, or 

 equivalent cooling, and free from any perturbing motion, that regular crys- 



