METHOD OF BLEACHING PAPER. 126 



that, fur example, a ream of the fize denominated raifm 

 fhould weigh only four or five kilograms, that is to fay, about 

 one-third of the weight of common paper of the fame form. 

 The manufacturer makes choice either of new rags already of 

 a fine white, or of unbleached rags. 



In the cafe of the white rags, it is fufficient to pafs them Treatment of 

 under the firft cylinder, then to give them a bath of the the ra S s » &c * 

 bleaching liquor, and afterwards a bath of fulphuric acid, as 

 we fhall proceed to direct, after which they are patted under 

 the finiining cylinder for feven or eight hours, and, laftly, 

 conveyed to the working trough to be made into fheets of 

 paper. 



Rags, which have never been bleached, may be treated by 

 either of the following proceffes, that is to fay, the firft, 

 which prefer ves the utmoft degree of toughnefs to the paper, 

 but is likewife the moif expenfive, confifts in decompofing 

 the rag, and afterwards applying the method of Citizen 

 Berthollet for bleaching piece goods ; namely, fubjecling it to 

 three or four lixiviations, and afterwards alternately to lixi- 

 viations, baths of the bleaching liquor, and baths of fulphuric 

 acid. The weight of the raw unbleached material is dimi- 

 nished from 50 to 45 per cent, in thefe operations. 



This method was the firfl which we ufed for the affignat Great advantage 

 paper; but we foon perceived that we might omit moft of of fufterin S thc 

 the lixiviations and baths of the bleaching fluid, and ftill pre- t h e fpontaneous 

 ferve as /much toughnefs as the paper required. Nothing change of rotting 

 further was neceffary for this purpofe than to fufFer the rag to ^^ 

 undergo a degree of fermentation more or Jefs advanced, by 

 leaving it to rot. In this operation the colouring matter un- 

 dergoes a flow combuftion, and pafTes to a kind of faponaceous 

 fiate, and is carried off by the water, by wafhing the rags in 

 the velfel of the firft cylinder. 



One fingle lixiviation, two baths of the bleaching liquor, The bleaching Is 

 and one of fulphuric acid, are then fufficient to bleach com- ^ eat y acl ,tat " 

 pletely the raw rags or cordage. This is the fecond method. 

 We were not, at that time, acquainted with the economical 

 procefs of Citizen Cbaptal in the operations of lixiviation. 

 This will, no doubt, be ufed ; but the effect of rotting, 

 carefully conducted, will always he found very advanta- 

 geous. 



La/tly, 



