14 
BULLETIN 1485, U. S. DEPARTMENT OF AGRICULTURE 
bone-dry weight of the pulp was ascertained, and thereby the yield. 
The pulp was then passed through a diaphragm screen and the 
screenings were dried and weighed. Samples of the pulp were 
Fig. 5.— Digester used for alkaline cooks since 1916 (front elevation) 
saved for bleach tests; the rest was treated in the beater to produce 
the desired quality of waterleaf paper and was run over the machine. 
Standard strength tests were made on the papers obtained. 
Bleaching tests were made by treating various samples of equal 
weight with quantities of bleach ranging from 5 to 40 per cent of 
