BLEACHING WOOL.

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sulphuring with gas, because there is generated in the fabric a small quantityof sulphuric acid, which, unless removed by washing, would during the dryingtend to destroy the fibre. Woollen fabrics intended to be dyed with darkcolours are never bleached by sulphuring. Cloth intended to remain white is,after the sulphuring and washing, passed through a bath containing someindigo-carmine, in order to increase the intensity of the whites. Accordingto M. Schlumberger, skeins of woollen thread can be excellently bleached bywashing them thoroughly in a strong soap solution, at a temperature of 50°,and suspending them wet during the night in a chamber filled with sulphurousacid gas. The skeins are then dried, without being again rinsed. When thewool is intended to be dyed it is put, immediately after being taken from thesulphuring room, into a bath of dilute sulphuric acid, and next thoroughlywashed in cold water.