1 24 Memoir upon the Conversion oj ligneous Bodies into 



water without depositing any particle of carbon. The liquor 

 saturated with chalk furnished by evaporation a deep brown re- 

 siduum of a sharp sugary savour. When heated, it exhaled va- 

 pours of sulphurous acid. 



Conversion of ligneous Bodies into XJlmine hj the Action of 

 Potash. 



We have seen that wood appropriates to itself the elements of 

 sulphuric acid and water, in order to pass into the state of gum, 

 and that the latter by a new distribution of its principles can be 

 transformed almost entirely into sugar and a small quant.ty of a 

 particular acid. We now proceed to show that, by extracting 

 from wood the proportions of oxygen and hydrogen necessary 

 for making water, it may be converted into a substance in which 

 the carbon predominates, and which appears to me to have a great 

 analogy to uhnine. M. Vauquelin is, I believe, the first who has 

 made known natural ulmine as a particular substance *. He 

 found it in combination with potash in the purulent ulcers of old 

 elms, the mass of the wood of which liad been in part eaten up 

 and destroyed by suppuration. It was not until seven years after 

 that Klaproth made mention of it: it appears that he had lost 

 sight of the experiments of the French chemist ; which may be 

 believed, since he attributes to it properties which do not belong 

 toit. Berzelius, Smithson, and Thomson afterwards directed their 

 attention to it. The first of these chemists thought that it formed 

 a constituent part of the bark of almost all trees ; but it appears 

 to present many varieties. I have found it in large enough quan- 

 tities in the bark of the beech tree, partly combined with potash 

 associated with a gum, a particular red matter, a small quantity 

 of tannin, and a principle the odour of which is exactly similar 

 to that of vanilla. 



It is by studying the action of potash upon wood, that I suc- 

 ceeded in producing ulmine artificially. I began by ascertaining 

 for certain that, contrary to the opinion of Mr. Thomson, pure 

 ligneous matter is insensibly soluble in potash; but that it is other- 

 wise when, along with that alkali of commerce made caustic, an 

 equal quantity of sawdust and a little water are heated in a silver 

 or iron crucible, in order to torrefy it ; for, by taking care con- 

 tinually to agitate the mixture, the sawdust at length softens and 

 dissolves almost instantaneously, swelling considerably. 



If the crucible be withdrawn from the fire, and a little water 

 poured into it, the whole matter dissolves with extreme facility, 

 except a slight residuum formed of silex, carbonate of lime, phos- 

 phate of lime, and some traces of vegetable matter j and a deep 



• Aun. de Chimie, t. xxi. p. 44. 



I brown 



i 



