The wool fiber soon dissolves in the potash lye, while the vegetable fiber remains unaltered.

The solubility of the woolen fibers in potash lye is a ready means of ascertaining the percentage of wool fiber in the paper.

It is removed perfectly by rubbing the surface with a hard brush and warm potash lye; the plate is then ready for printing.

Phthisical sputa are dried and made moist with very much diluted potash lye (1 to 2 drops of a 33 per cent.