As flax, when dressed, consists almost entirely of lignine, if what has been separated from it is re- turned to the soil, it will no longer be an exhausting crop.

215 GUN COTTON Braconnot observed, in 1833, that, when starch was heated in strong nitric acid, until complete solution took place, if the solution was poured into a large quantity of cold water, a white pulverulent amorphous mass gradually subsided, and, on being dried, was highly combustible burning without any residue.

This substance was called " Xylodine :" and consists, according to Pettenkofer, of CHOsoNs 65 ; but, according to others, of C 12 H 8 Oi 8 N 2.

Pelouze in 1838, repeated the experiments of Braconnot, and ascertained that paper, linen, cotton and other ligneous substances, without altering their ap- pearance, gave apparently the same body if, being submitted for a few moments to the action of nitric acid, specific gravity 1 5, they were well washed with water, and dried : and he sug- gested its application, as a substitute for gunpowder.

But he, and other chemists, have since found, that what are obtained from starch, and from woody fibre, are not identical.