on the different kinds of Coal. 335 



Native graphite is not therefore a carburet, according to M. 

 Karsten ; it is a carbon, the pureness of which is altered by an ac- 

 cidental mixture of mineral matters which contain iron. The au- 

 thor concludes from this, that the differences which exist between 

 native graphite, glance-coal, diamond, and artificial graphite, 

 must not henceforth be attempted to be explained by the pro- 

 portion of iron which is observed in the first and last of these 

 substances. Let us rather avow, he adds, that our knowledge 

 is not yet sufficient to enable us to unveil the cause of the diffe- 

 rences in the phenomena which these substances present with 

 respect to light, and their other physical properties. 

 To he concluded in our next Number. 



Observations on the Cow4ree of the Caraccas ; and on the Cul- 

 ture of the Nutmeg-tree. In a Letter from Mr David Lock- 

 HAUT, Curator of the Botanical Garden in Trinidad to Ayl- 

 MEii BouRKE Lambert, Esq. F. R. S. V. P. L. S. &c. 



X HAVE just returned from an excursion to Caraccas, where I 

 collected the juice of the Cow-tree (Palo de Vaca), and I have 

 now the pleasure of sending you a phial of the milk, together 

 with a few leaves, and a portion of the root of the tree. The 

 Palo de Vaca is a tree of large dimensions. The one that I 

 procured the juice from, had a trunk 7 feet in diameter, and it 

 was 100 feet from the root to the first branch. The milk was 

 obtained by making a spiral incision into the bark. Carauo, the 

 place where I met with the tree, is about fifty miles east of La 

 Guayra, and at an elevation of from 1000 to 1200 feet above 

 the level of the sea. It is likewise found between Cape Codera 

 and Barcelona. The milk is used by the inhabitants where- 

 ever it is known. I drank a pint of it, without experiencing 

 the least inconvenience. In taste and consistence, it much re- 

 sembles sweet cream, and possesses an agreeable smell. I was 

 so fortunate as to procure some young trees and roots of the Palo 

 de Vaca, which I will endeavour to increase, and, if I prove suc- 

 cessful, you may expect to have a plant. I am sorry that I was 

 not able to collect any specimens worth sending during my visit 

 to Caraccas, my stay being limited to eight days, six of which 



