Chemical Science. 387 



with cold sulphuric acid, of sp, gr. 1.827, and the mixture stirred ; 

 it heated, and much sulphurous acid gas was disengaged. The 

 wood became black, and appeared to be charcoal, 'but was not 

 so in reality. Water was poured on the mixture, and the black 

 powder separated ; when dry, it burned with flame. It did not 

 colour cold water, but with boiling water and alkaline solutions 

 gave a deep brown solution. It was nearly in the state which 

 the saw-dust would have acquired by exposure for some years 

 to air and moisture. The nearly colourless acid liquor, after 

 being saturated with carbonate of lime, gave on evaporation, a 

 yellow gummy matter, with a solution of which sub-acetate of 

 lead formed an abundant white magma. The gummy matter, 

 acted on by weak sulphuric acid, gave acetic acid, and a preci- 

 pitate of sulphate of lime. 



The experiment was repeated, with 16 grammes (247.1 gr.) of 

 the saw-dust ; but instead of mixing the whole quantity of ma- 

 terials at once, small portions of the wood were triturated at a 

 time, adding the acid by degrees ; still sulphurous acid was 

 disengaged, but a very thick tenacious mucilage was obtained. 

 This was diffused in water, and filtered through a cloth ; there re- 

 mained a black insoluble matter, weighing 5 grammes (77.2 gr.) 

 similar to that before-mentioned. The acid liquor, saturated 

 with chalk, and then evaporated, gave 10 grammes (154.5 gr.) of 

 a substance of a reddish brown colour. 



As MM. Fourcroy and Vauquelin state, that vegetable sub- 

 stances do not decompose sulphuric acid v/hen cold, M. Bra- 

 connot sought some other ligneous substance that would not 

 produce this effect, and ultimately selected hempen cloth ; 25 

 grammes (386.1 gr.)of this cloth, in small pieces, lost on drying 

 1 gramme (15.5 gr.) of water. It was moistened in a glass mor- 

 tar, with 34 grammes (525) of sulphuric acid added by portions, 

 and continually stirred with a strong rod of glass, that the acid 

 might penetrate all parts, and that the heat caused by each addi- 

 tion of it, might be dissipated before more acid was added ; 

 not llie slightest portion of sulphurous acid was disengaged. A 

 quarter of an hour after the mixture was made, it was rubbed 

 in the mortar ; the tissue of the cloth disappeared, and a very tena- 

 cious mucilage, homogeneous, and little coloured, was obtained 



