24 



On Ulmin. 



von Stamm elnes XJlme)* that is. Chemical experiments on a 

 gummy juice from the stem of an Elm, The substance on 

 which his experiiiients were made was sent him from Palermo in 

 1802 ; and he coniectures that tl]e species of elm from which it 

 exuded was the ui-nus nigra. What species he refers to, by the 

 name of ulmus nigra, it is difficult to guess ; as 1 am not aware 

 that any such name was ever given by botanists to any species of 

 elm whatever. This substance, according to Klaproth^ possessed 

 the following properties, 



Xt was solid^ hard^ of a black colour, and had considerable 

 lustre. Its powder was brown. It dissolved readily in the 

 mouth, and was insipid. It dissolved speedily in a small quantity 

 of water. The solution was transparent, of a blackish brown 

 colour ; and even when very much concentrated by evaporation, 

 was not the least mucilaginous or ropy ; nor could it be em- 

 ployed, like mucilage of gum» to paste substances together. 



It was completely insoluble both in alcohol and ether. When 

 alcohol was poured into the aqueous solution, the greatest part of 

 the substance precipitated in light brown flocks. The remainder 

 was obtained by evaporation, and was not sensibly soluble in 

 alcohol. The alcohol, by this treatment, acquired a sharpish 

 taste. 



When a few drops of nitric acid were added to the aqueous 

 solution, it became gelatinous, lost its blackish brown colour, 

 and a light brown substance precipitated. The whole solution 

 was slowly evaporated to dryness, and the reddish brown powder 

 which remained was heated with alcohol. The alcohol assumed 

 a golden yellow colour; and when evaporated left a light brown, 

 bitter, and siiarp resinous substance. Chlorine was found to 

 prod 15 ce precisely the same effect as nitric acid. 



When the exi)datioD from the elm was burnt, it emitted little 

 smgkc or fiance, and left a spongy, but firm, charcoal ; which^ 

 when heated suiTicienily in the open air, burnt all away, except 

 a little carbonate of potash. 



In the third edition of my System of Chemistry, I inserted 

 this siihstance as a peculiar vegetable principle, under the name 

 of ulmin Though I had some suspicion that it might be the 

 same with the peculiar substance previously discovered by Vau- 

 quelin in the diseased exudation from the common elm {ulmus 

 carnpesiri^s) ; yet, as I had no means of verifying this suspicion, 

 and had no hopes of being able to procure any of the exudation 

 described by Klaproth, I did not venture to hint my suspicion, 

 being sppreheiisiv^e that it might contribute to increase the con- 

 fusion of a branch of cher/iistry by no means remarkable for its 

 precision. 



Fortunately, Mr. Walter Coulson, on reading the account of 



Gehlen's Journal, vol. iv. p. 329. 



