454 Mr. E. Solly on the Palo de Vaca 



pale yellowish olive green ; beneath the outer skin is a crust 

 of more than an inch and a half in thickness, of a deep chest- 

 nut colour, wherein seemed to be contained the lacteal fluid, 

 for on detaching it from the body of the tree, the milk oozed 

 through thousands of pores from the curved surface that had 

 embraced the trunk. The wood itself is white, close-grained, 

 and hard, resembling in every way the box wood of Europe. 



" I could not learn the precise period when the Palo de 

 Vaca flowers (if ever) or bears its fruit. Plants, (and many 

 are growing all about the trees,) will not live by even transport- 

 ing to Caracas. The temperature of the air at 8 o'clock a.m. 

 whilst at the foot of the tree, was 70° of Fahrenheit's scale*." 



The milk as I received it was evidently rather altered by 

 time ; it was of the colour and consistence of very rich 

 cream, having a sour and rather unpleasant odour, and a nau- 

 seous and acescent taste, accompanied by a somewhat gritty 

 feel on the tongue. When left undisturbed for some time in 

 a close bottle, a slight separation took place, a small quantity 

 of a pale yellow fluid sinking to the bottom. The specific 

 gravity of the sap was 1*085 at 60° Fahrenheit. 



Exposed to the air, the sap gradually contracted from the 

 evaporation of water, &c, and finally left a grey, transparent, 

 and very viscid mass. When a portion of the sap was poured 

 into water, it did not spontaneously mix, but fell to the bot- 

 tom as a bulky white precipitate; on agitation, however, it 

 easily mixed with the water, though after some hours' standing 

 a slight coagulum rose to the top. When boiled, the mix- 

 ture was immediately coagulated ; this was not effected either 

 by acids or alkalies. 



When the sap was distilled at a low heat, water holding 

 in solution acetic acid passed over, and a grey transparent 

 mass remained, similar to that left by the evaporation of the 

 sap exposed to the air ; when the heat was cautiously raised, 

 the mass fused, became of a pale yellow colour resembling oil, 

 and contained numerous dark flocks of an infusible substance 

 floating in it; 100 grains of the sap yielded on the average 

 38*0 grains of solid residue. In order to determine the na- 

 ture of this residue, it was repeatedly digested in cold aether, 



• This tree was first described by Alexander Humboldt in his Relat. 

 Hist., t. ii. p. 106, 130. See also Ann. de Chim. et de Phys. t. vii. p. 182. 

 It received the name Galactodendrum from Kunth, who imagined it to 

 belong to a new genus ; Synopsis Plantarum, t. iv. p. 198. I am only aware 

 of two detailed chemical examinations of the sap, one by Boussingault and 

 Rivero, Ann. de Chim. et de Phys., t. xxiii. p. 219; the other bv Dr. T. 

 Thomson, Trans, of the Royal Society of Edin., 1829. — E. S. [See Lond. 

 and Edinb. Phil. Mag., vol. vii., p. 501.— Edit.] 



