48 WRITINGS OF JAMES SMITHSON. 



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 dis- 

 posed in rays to the centre, which curl up and detach them- 

 selves 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 

 ulmin, a copious precipitate immediately formed. The 

 mixture was thrown on a filter. The matter which has 

 been considered as a resin remained on the paper, and a 

 clear yellow liquor came through. This yellow solution, on 

 evaporation, produced a number of prismatic crystals look- 

 ing 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 

 afforded 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 

 decomposing 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 in a 

 mere solution in water. 



The nitric and muriatic acids received a small quantity of 

 lime and iron from the ulmin, and I believe also a little \ 



