On a Substance from the Elm Tree, called Ulmin. 205 
The ulmin made use of in the following experiments, 
had been freed from the fragments of bark by solution in 
water and filtration, and recovered in a dry state by the 
evaporation of the solution on a water bath. 
2. In lumps, ulmin appears black ; but in thin pieces it 
is seen to be transparent, and ofa deep red colour. 
In a dilute state, solution of ulmin is yellow; in a con- 
centrated one, dark red, and not unlike blood. 
When solution of ulmin dries, either spontaneously or 
‘by being heated, the ulmin divides into long narrow strips 
disposed in rays to the centre, which curl up and detach 
themselves from the vessel, and the fluid part seems to draw 
together, and becomes remarkably protuberant. Solution 
of ulmin slowly and feebly restores the colour of turnsol 
paper reddened by an acid, 
3. Dilute nitric acid being poured into a solution of 
tlmin, a copious precipitate immedately formed. The 
mixture was thrown on a filter. The matter which has 
been considered as a resin remained on the paper, and a 
elear yellow liquor came through. This yellow solu- 
tion, on evaporation, produced a number of prismatic 
crystals looking like nitrate of potash. They were tinged 
yellow by some of the resin. This mixture, heated in a 
gold dish, deflagrated with violence, and a large quantity 
Of fixed alkali remained. 
Dilute muriatic acid caused an exactly similar precipita- 
tion in solution of ulmin to nitric acid, and the precipitate 
was the same resin-like substance. The filtered liquor af- 
forded a quantity of saline matter, which, after being freed 
by ignition from a portion of dissolved resin, shot into 
pure white cubes of muriate of potash, as appeared by de- 
composing them by nitric acid. 
Sulphuric, phosphoric, oxalic, tartaric, and citric acids 
occasioned a similar precipitation in solution of ulmin. 
Distilled vinegar produced no turbidness in it; and the 
mixture being exhaled to dryness, at a gentle heat, was 
found to be again wholly soluble in water. But when the 
mixture was made to boil, some decomposition took place. 
On adding muriatic acid to a mixture of solution of ulmin 
and distilled vinegar, a precipitate was produced, as ina 
mere solution in water. 
The nitric and muriatic acids received a small quantity 
of Jime and iron from the ulmin, and I believe also a little 
Magnesia ; but these can be considered only as foreign ad- 
eraree. 
To acquire an idea of the quantity of potash in ulmin, 
four 
