Chemical Science. 389 



When the sulphuric acid was diluted with half its weight of 

 water, it had no action on the linen, cold ; but heated, it formed 

 a homogeneous paste, which, mixed with water, resembled 

 boiled starch ; farther diluted, it appeared like an emulsion. 

 When observed in the sun, a number of brilliant scales were 

 seen in it, as in a solution of soap. By standing, it deposited a 

 substance resembling starch in appearance, but not having its 

 properties. The liquor separated, gave a very small quantity 

 of gum. 



If the cloth be moistened with nitric acid, there is no alteration 

 at common temperatures, but exposed to a hot-water bath until 

 nitrous gas begins to form, it is converted into a white and 

 uniform paste exactly like that obtained by the sulphuric acid. 

 Washed and dried, it had a satin appearance, especially 

 when reduced to powder ; if moistened, a slight hissing was 

 heard, and it formed a paste. It is not soluble in potash, and 

 appears to be the ligneous matter of the linen very slightly 

 altered. 



The gum obtained by the action of sulphuric acid on "linen 

 was purified by precipitating it by sub acetate of lead, and de- 

 composing this compound by sulphuric acid. The liquid was 

 evaporated to a sufficient degree, and the sulphate of lead 

 being separated, the gum was thrown down by alcohol. The 

 sulphuric acid it retained was separated by heating it with 

 oxide of lead, and the small quantity of lead still retained in 

 solution, then separated by sulphuretted hydrogen : the fil- 

 tered liquor being evaporated, the gum was obtained as pure 

 as possible. 



The gum then resembled gum-arabic. It was transparent, 

 of a slight yellow colour, inodorous, insipid, though it red- 

 dened tincture of turnsole, and appeared to behave like an 

 acid. The fracture was vitreous. It adhered strongly to the 

 vessels in which it was evaporated, and formed on them a 

 shining kind of varnish. It formed a mucilage less tenacious 

 than that of gum-arabic. Heated, it burnt, giving out a 

 strong odour of sulphurous acid, occasioned by the presence of 

 sulphuric acid in such a state of combination as to be incapable 



