8 
BULLETIN 322, U. 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 completely 
resolved and the bast very loosely held in the structure. The inside 
wood} 7 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. 
Next, 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 distintegrated into its ultimate cells, the bark being reduced 
to bast cells and the small connecting cells of the structure and the 
