C64 3 



VI. On a Substance from the Elm Tree, called Ulmin. By James: 

 Smithson, Esq. F. R. S, 



Read December lo, i8ia. 



1. 1 HE substance now denominated Ulmin was first made- 

 known by the celebrated Mr. Klaproth, to whom nearly 

 every department of chemistry is under numerous and great 

 obligations.* 



Ulmin has been ranked by Dr. Thomson, in his System of 

 Chemistry, as a distinct vegetable principle, on the ground of 

 its possessing qualities totally peculiar and extraordinary. It 

 is said, that though in its original state easily soluble in water 

 and wholly insoluble in alcohol and ether, it changes, when 

 nitric, or oxymuriatic acid is poured into its solution, into a 

 resinous substance no longer soluble in water, but soluble in 

 alcohol, and this singular alteration is attributed to the union 

 to it of a small portion of oxygen which it has acquired from 

 these acids.* Being possessed of some of this substance which 

 had been sent to me some years ago from Palermo, by the 

 same person from whom Mr. Klaproth had received it, I be- 

 came induced, by the foregoing account, to pay attention to it^ 

 and have observed facts which appear to warrant a different 

 etiology of its phenomena, and opinion of its nature, from what 

 has been given of them. 



The ulmin made use of in the following experiments, had 



• Dr. Thom80m*» Syst. of Chem. Vol. IV. p. 696. Fourth edition. 



