Notices respecting New Books. 367 



which the fluid central portion, at the moment before it 

 commenced to sohdify, was decanted from the crystaUized 

 part." Water also crystallizes by the abstraction of caloric, 

 and snow is often found crystallized in stella3 with six 

 radii. An English university professor of mineralogy ob- 

 served this at Petersburg, and gave a drawing of it in an 

 accoimt of his Travels, as if it had been a new discovery, al- 

 though Dr. Hooke many years ago published similar figures. 



Benzoic acid furnishes a familiar example of crystalliza- 

 tion efifected by sublimation, or the application of heat. 

 The instances of crystallization produced bv chemical affi- 

 nity are very numerous. The most simple and easy ex- 

 periment of this nature is, by adding highly rectified spirits 

 to aqueous solutions of the salts, when the spirits and 

 water unite, and the salts immediately resume their crystal- 

 line state. The crystallizations of silver, lead, zinc, &c. 

 are now become nursery amusements. Large and perfect 

 crystals, however, are still rarely produced by art. Mr. 

 Sims, of Norwich, has been more successful in obtaining 

 curious and magnificent crystals, than any other chemist 

 ot the age. Time, space, repose, light and air, are neces- 

 sary to crystallization. The effect ol light on solutions of 

 muriate of ammonia and prussiate of potash, when placed 

 to crystallize, is curious, and tends to prove the materiality 

 of light. The crystallization of those salts may be directed 

 at pleasure by the introduction of light at one side or an- 

 other of the vessels containing their solutions. Camphor 

 displays the same alTinitv for light. The electricity of cry- 

 stals is also noticed by Mr. A. The principal crystals 

 which become electric merely bv heat are borate of mag- 

 nesia, Brazilian topaz, tourmalin, prehnite (erroneously 

 printed phrcnite throughout the volume), crystallized oxide 

 of zinc, siberitc, lepidolito, and kaupolite. 



The figures in this work (wood-cuts) are tolerably ac- 

 curate, and the explanations are remarkably simple, and 

 easily comprehended. These advantages wc should think 

 fully sufficient to recommend it to public attention. It has 

 evidently cost the author much labour and expense, for 

 which he can receive no adequate remuneration, except that 

 of public approbation. He has very properly annexed the 

 classification of mineral* introduced by llauy, and generally 

 adopted by French mineralogists. 



Capt. Laskey has in the press, a scientific Description of 

 the Harilies in that magnifi'cent collection " The Ilunterian 

 Muicuni," now deposited at the College of Glasgow. It is 



intended 



