On a Substance from the Elm Tree, called Ulmin. 207 
it lies, it dissolves immediately and abundantly. This so- 
lution 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, &ce. 
Hence it appears that ulmin is not a simple vegetable 
principle 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 extractives than to the resins. 
English Ulmin. 
T 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 di- 
vided as ulmin does, when dried in the same manner. It 
did not, however, 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-elass, and partly to its containing 4 
considerable excess of alkali; for it differed also from the 
Palermo ulmin by becoming soft in the air, and its solu- 
tion strongly restored the blue colour of reddened turnsol 
paper. 
Nitric acid, added to a filtered solution of this ulmin, 
immediately caused a precipitate in it, and the filtered solu- 
tion, on evaporation, afforded numerous crystals of nitrate 
of potash, 
This English ulmin made a considerable effervescence 
with acetous acid, which the Palermo ulmin had not been 
observed to do. This acetous solution, in which the acid 
was in excess, was exhaled dry, and repeatedly washed with 
spirit of wine. No part of the brown matter dissolved. 
Water dissolved this brown residuum readily and entirely. 
This solution did not sensibly restore the blue colour of 
reddened turnsol paper, Exhaled to a dry state, the matter 
Jeft did not separate from the watch-glass quite as freely as 
Palermo ulmin, which bad been treated with acetous acid ; 
but it seemed no longer to grow moist in the air. Redis- 
solved in water, and nitric acid added, the mixture became 
thick from a copious precipitate. + 
he 
