56 On the Conversion of ligneous Bodies into Gum, Sugar, &c. 



vides itself into charcoal and water, which by uniting itself to the 

 acid produces the heat which is developed ; but this heat appears 

 rather to be owing to the actual fixation of the elements of the 

 sulphuric acid and the water in the undecomposed vegetable sub- 

 stance. 



Being desirous of knowing whether the sulphuric acid diluted 

 with half its weight of water, could convert the ligneous mat- 

 ter into gum ; I moistened some cloth with this acid thus 

 reduced, but I did not obtain any mucilaginous mass. Exposed 

 to a gentle heat and agitated continually, it resolved into a very 

 homogeneous paste, wliich mixed with water gave a white sub- 

 stance resembling boiled starch ; further diluted it appeared like 

 an emulsion. On holding it up to the light, we remarked that 

 the white matter held in suspension was formed of a multitude 

 of brilliant spangles of extreme tenuity, nearly similar to what 

 may be observed in a solution of soap. This sort of emulsion 

 on being allowed to stand deposited, though very slowly, a snb- 

 stance which we took at first sight for starch, but which has 

 none of its properties ; it represented almost the whole of the 

 cloth employed. The liquor separated in this manner gave, after 

 being saturated with chalk, a small quantity of almost colourless 

 gummy matter, which appeared to me to contain but few traces 

 of sulphuric acid. ' 



If the cloth be moistened with nitric acid, it may also be con- 

 verted into a white starchy matter. No apparent alteration is 

 manifested at an ordinary temperature ; but by exposing the 

 mixture to a hot water bath until nitrous gas begins to be formed, 

 it is converted into a white and uniform paste, exactly similar 

 to that obtained by the sulphuric acid. Well washed and dried, 

 this matter had a slight satin appearance, especially when reduced 

 to powder ; if moistened, a slight hissing was heard, and it be- 

 came converted into a paste much divided. In potash it does 

 not undergo any sensible solution. It appears to be the ligneous 

 matter of the cloth very slightly altered, being nearly analogous 

 to what results from the putrefaction of rags for the preparation 

 of paper. It might be curious to inquire, whether during this 

 sort of fermentation gum and a little sugar are not formed, as 

 happens in respect of putrefied starch, according to the recent 

 observation of M. de Saussure. 



[To be continued.] 



VIII. Notices 



