182 , Scientific Intelligence. 



work) are not precisely exact," and that " the limit of error is conside- 

 rably within one degree,-— that it rarely exceeds 40 minutes, and is fre- 

 quently confined to a minute or two." * 



Now, though it is quite certain that the cleavage planes of calcareous 

 spar, sulphate of barytes, &c. meet at angles differing very little in va- 

 lue in different specimens ; yet, as there are hundreds of crystals in which 

 the cleavage planes are either not found at all, or are very imperfect, it 

 follows necessarily, that in general the forms of crystallized bodies must 

 he deduced from the inclinations of their natural planes. Even if there 

 are 50 crystals in which the cleavage planes meet at angles which do not 

 vary one second, the conclusion drawn by the Reviewer from Mr. Phil- 

 lips's own admission, remains substantially and undeniably true. The 

 variation of more than eight minutes produced in the inclination of the 

 faces of carbonate cf lime by an increase of temperature from 32° to 212", 

 must also be considered as affecting our confidence in crystallographic in- 

 dications, until the law of the variation shall be discovered. 



BOTANY. 



33. Bois deColophane. — On reading the account given in the first number 

 of our Journal of the laurel oil, Captain Carmichael observes, " it 

 brought to my recollection a tree I had often met with m the woods of 

 Mauritius, and which is there called Bois de Colophane; a Bursera if I 

 am not mistaken. From the slightest wound in the bark of this tree 

 there issues a copious flow of limpid oil, of a pungent turpentine odour, 

 which soon congeals to the consistence of butter, assuming the colour of 

 camphor. Like camphdr also, it burns with a vivid flame, and leaves no 

 residuum." This is probably the Bursera panniculata of Lamarck's Ew 

 cyclopedic Botanique, which is a native of the Isle of France, and of 

 which that author says, that an abundant whitish resin flows naturally 

 from the clefts of its bark. 



34. The late Baron de Schack. — We regret to learn that the Baron de 

 Schack, so well known to botanists and cultivators of plants, died last 

 September, at La Guayra in South America. He was a native of the 

 Austrian dominions, but had long resided in the island of Trinidad, from 

 whence he had, for many years, sent most valuable contributions of 

 plants, both to the Botanical Gardens of Glasgow and of Liverpool, and 

 likewise, we believe, to that of the Horticultural Society of London. He 

 discovered many new plants, particularly among the parasitical Orchidea 

 and the Tillanasice, some of which are already described, and others will 

 soon appear, that have recently flowered in our stoves. With great dif- 

 ficulty, and after many failures, the Baron de Schack succeeded in trans- 

 mitting to this country living roots of the Arracacha, one plant of which 

 has flowered at Liverpool, by an examination of which we are enabled 

 confidently to state, that it is the Conium moschatum of Humboldt. 



• In another place, Mr. P. admits, that " even the minute crystals, which are 

 generally the most perfect of all, rarely agree in the angles they afford." 





