8 



BULLETIN 322, IT. S. DEPARTMENT OF AGRICULTURE. 



perature has been reached this degree is maintained constantly for 

 the required number of hours, after which the burners are removed 

 and the boiler cooled in about half an hour by means of a small 

 stream of water applied to the boiler shell. The resulting stock, on 

 removal from the boiler and after remaining unwashed over night, 

 is well washed with water, pressed into a uniform cake, weighed, and 

 a sample drawn for a moisture determination, from which data the 

 yield of total stock is determined. 



The stock after bleaching shows the bark more or less complete^ 

 resolved and the bast very loosely held in the structure. The inside 

 woody portion appears practically unchanged, but in reality it has 



Fig. 1. — Experimental 10-pound beater, supplied with washer. 



suffered a chemical and physical change whereby the structure is 

 mechanically weakened. 



ISext, the stock is " beaten " in an experimental 10-pound beater 

 (fig. 1), which consists of a trough in which the stock is caused to 

 circulate and pass between a bedplate of coarse knives or bars and a. 

 series of similar knives set in the periphery of an iron roll making 

 about 150 revolutions per minute. The distance between the two 

 sets of knives can be regulated and altered to any degree, according 

 to the effect desired. This action causes the bleached stock gradually 

 to be disintegrated into its ultimate cells, the bark being reduced 

 to bast cells and the small connecting cells of the structure and the 



