Note 18 — Chapter II
Reading edition
Limed sheep grains, or Pelts, which have been limed for splitting, contain from 3 per cent. to 6 per cent. CaO on the dry skin (see footnote, p. 7), and about 80 per cent. of water. In a typical case of a fully limed grain, the lime was found to be distributed as follows:—
Free uncombined lime (CaO)1·7 per cent. on the dry skin
CaO combined with skin2·5 "
CaO as carbonate, or other salts1·4 "
──
5·6
Thus, 75 per cent. of the total lime in the skin was in the caustic state. If the skin be cut during the progress of the bating operation, and a solution of phenolphthalein applied to the cut surface, the course of bating may be followed, and it will be found that the caustic lime disappears from the skin in a very short period of time, accompanied by the sudden collapse of the fibres. We shall treat of this more fully in Chapter III. After puering, the lime (CaO) contained in the skin, amounts to 0·5 to 0·9 per cent., calculated on the dry skin. This lime is in a perfectly neutral state, and is more or less in combination with the fibre of the skin. The exact state in which the lime exists in the skin after puering is not known, and would form a very interesting subject for research.