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Analysis of the Vegetable Milk of tJte Hya-hya Tree of Deme- 

 rara. By Robert Christison, M. D., Professor of Medi- 

 cal Jurisprudence in the University of Edinburgh. Commu- 

 nicated by the Author. 



In a paper lately read before the Wernerian Society, and 

 published in The Edinburgh New Philosophical Journal for 

 January last, Mr Smith has given an interesting account of a 

 new kind of vegetable milk procured from a tree in Demerara, 

 which the natives term the hya-liya ; and which, according to 

 Mr Arnott's examination of the specimens sent to this country, 

 is a species of Taberncemmitana, a genus of the natural order 

 Apocynece. A portion of this vegetable milk having been sent 

 by Mr Smith to Professor Jameson, the chemical analysis of it 

 was entrusted to me, for the purpose of determining whether 

 any similarity exists between it and the singular vegetable milk 

 of Caraccas, lately made known to European chemists by Hum- 

 boldt, and analyzed by Bousingault and Mariano de Rivero. 

 The following is an account of the observations I have made oh 

 its properties and composition, which, it will be seen, are totally 

 different from those of the vegetable milk of Caraccas, and such 

 as render its nutritive quality doubtful. 



In the state in Avhich the juice arrived in this country, it con- 

 sisted of a small portion of a clear watery-hke fluid, and a white, 

 concrete, cellulated substance, not unlike pressed curd, which 

 fiUed nearly the whole bottle. It had an odour somewhat like 

 that of Dunlop cheese, with a slight peculiar aroma, and scarcely 

 any taste. 



The watery portion reddens litmus paper, and appears to con- 

 tain a Httle acetic acid ; for the fluid procured from it by distil- 

 lation has the odour of vinegar, and an acid reaction. But the 

 quantity of fluid was too small to allow me to determine its con- 

 tents more positively. 



The concrete matter is of snowy whiteness, brittle and pul- 

 verizable when cold, but easily softened by an increase of tem- 

 perature. At 100° F. it becomes ductile and viscid, and does 

 not recover its original firmness and hardness for more than a 

 day. At higher temperatures, it gradually becomes softer and 



