Note 242 — MINERAL POISONS.

In order to close the end of the tube, where a blow-pipe is not to be procured, (which, says Dr. Bostock, we may suppose upon these occasions will often be the case) the end is to be placed in a common fire until it is completely softened, and a pair of small tongs being at the same time made red hot, the tube is to be withdrawn from the fire, and the heated end pinched by the tongs, and at the same time bent up at an acute angle, so as to be brought parallel to the body of the tube. The tube is then to be heated a second time, and being again firmly pinched by the hot tongs, the end will be found to be completely impervious.