68 Mr. Smithson on a Substance from the 



lies, it dissolves immediately and abundantly. This solution 

 has all the qualities of a solution of ulmin, and, on exhalation, 

 leaves a matter precisely like it, which cracks and separates 

 from the glass, and does not grow^ moist in the air, &c. 



Hence it appears that ulmin is not a simple vegetable prin- 

 ciple of anomalous qualities, but a combination with potash of 

 a red, or more properly a high yellow matter, which, if not 

 of a peculiar genus, seems rather more related to the extrac- 

 tives than to the resins. 



English Ulmin. 



I collected, from an elm tree in Kensington gardens, a 

 small quantity of a black shining substance which looked like 

 ulmin. 



It was readily soluble in water, and the solution was in 

 colour and appearance exactly similar to a solution of ulmin. 



This solution, exhaled to a dry state on a water-bath, left a 

 matter exactly like ulmin, and which cracked and divided as 

 ulmin does, when dried in the same manner. It did not, how- 

 ever, rise up from the watch-glass in long strips, like the Sicilian 

 kind, but this may have been owing partly to its small quantity, 

 which occasioned it to be spread very thin on the watch-glass, 

 and partly to its containing a considerable excess of alkali, for 

 it differed also from the Palermo ulmin by becoming soft in 

 the air, and its solution strongly restored the blue colour of 

 reddened turnsol paper. 



Nitric acid, added to a filtered solution of this ulmin, im- 

 mediately caused a precipitate in it, and the filtered solu- 

 tion, on evaporation, afforded numerous crystals of nitrate of 

 potash. 



