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CHAPTER XII. *

PRACTICAL RECIPES IN CONNECTION WITH WOOLLEN YARN AND FABRICS.

Bleaching.

TN quantities of 100 lbs. The process is very simple. The scourer should■*" have care that his kettle is not hotter than 132 0 F., and that the wooldoes not lie in the bath long enough to become yellow. The goods or yarnare scoured in clean soap, as usual, and then hung up in a closed chamber orbleach-house, exposed to the vapour of sulphurous acid, produced by burningin an iron pot 6 or more pounds of brimstone. When yarn is bleached for themarket, it should be put into the sulphur-house without the soap being rinsedout, only switched out well. If the white has to be coloured, the wool shouldfirst be run through a cold bath, containing 2 lbs. of muriate of tin, 2 ozs. ofextract of indigo, 3 ozs. of cochineal paste.* Red, blue, and yellow formwhite, and the wool is naturally yellow; hence the method of treatment.Then take the wool into the sulphur-house. The fabric ought never to becoloured after sulphuring, as it will become spotted. Carpet-yarn may beafterwards run through a bath containing 5 lbs. of whiting: this somewhatneutralises the offensive odour. Care should be taken in bleaching part cottongoods when poles or slats are employed; the wood absorbs sulphuric acid, andwill rot the cotton if in contact with the cloth. The poles should be oftenwashed or planed.

Another Method of Bleaching.

In the case of a large quantity of goods for printing, it is more convenientto bleach them in large vats filled with water, charged with sulphurous acid,as follows:—

Half fill a stone pot with pine sawdust, and cover it with a wooden coverthrough which is a hole to receive a lead or glass pipe. Pour enough sulphuricacid to cover the sawdust, and insert the pipe which conducts the sulphurousacid gas into the vat of water, rendering the joint gas-tight by a luting ofclay. To prevent too much free acid going over, the gas may be passedthrough a strong solution of soda, and then to the vat. The vat, of course,should be covered. The goods are thrown into the water over-night, and whentaken out will be found sufficiently bleached.

This method, when modified, will be found advantageous in bleaching thewhites of goods coloured chrome-black, should such a process be required.

* Cochineal paste is obtained by placing 10 lbs. of Honduras cochineal in a vessel, andadding 30 lbs. of ammonia water (i7°B.), stirring the mixture well. The vessel should becovered with a cloth, and allowed to stand for a few days. The vessel is then to be immersedin boiling water, in order to evaporate the superfluous ammonia; when the evaporation iscomplete the mixture is ready to be used. The ammonia may be condensed during the evapo-ration, if employed in large quantities.