Note 224 — A CYCLOPÆDIA OF PRACTICAL RECEIPTS, PROCESSES, AND COLLATERAL INFORMATION (continued 16)

The ‘strength’ varies with the colour and quality of the rags. From 2 to 4 lbs. per cwt. of rags is a common proportion; but for dyed and printed rags as much as 7 or even 8 lbs. per cwt. are often employed. It is better, however, to prolong the process with a weaker solution, than to hasten it by using the chloride in excess. Large rectangular cisterns of wood, or of slate, are commonly employed as the bleach-vessels. Cisterns of wood, or brick-work lined with gutta percha or with asphalto-bitumen, are employed in some paper-mills, and answer admirably.