12 BULLETIN 322, U. S, DEPARTMENT OF AGRICULTURE. 



Chemical reduction was effected in a steel, rotary pulp boiler, 6 

 feet long by 4 feet in diameter, which was supplied with a ther- 

 mometer well, pressure gauge, and pipes for relief and direct steam 

 inflow. 



Bleach No. 193. — A charge of 277 pounds (242 pounds, bone-dry 

 weight) was treated with 15 per cent of burned lime (36.1 pounds) 

 and 100 gallons of water, the lime being slaked in part of the water 

 before being added. Direct steam was admitted, so as to bring the 

 charge up to 118° C, or 50 pounds steam pressure, in 1 hour; then 

 regulated so as to maintain this pressure for 10 hours, after which 

 the pressure was relieved and the contents removed. This stock was 

 followed down with a fairly light roll and washed for 3 hours in a 

 400-pound beater, at which point the stock was removed, drained, 

 pressed, weighed, and sampled for moisture content. From these 

 data the yield was found to be 64.6 per cent of the sieved straw, or 

 48.7 per cent of the original bone-dry straw. 



Bleach No. 194- — This bleach was made in the same manner as No. 

 193 and beaten and washed 3 hours, after which the stock from No. 

 193 was added to it in the beater. The combined stocks were beaten 

 a total of 19 hours, the last 7 of which were fairly hard, the washer 

 being used the first 4 hours. The long bast fibers were very strong 

 and not easily reduced; likewise, the woody portion did not com- 

 plete^ reduce to the separated individual fibers, but remained as 

 more or less fine shives, or cell aggregates. The washer used in this 

 work was 60-mesh, while a much coarser, possibly 20 or 25 mesh, 

 would have removed many more of the shives and given a far better 

 product. This unsized and unscreened stock was pumped to the stuff 

 .chest and run over a 30-inch Fourdrinier paper machine, in conjunc- 

 tion with a Jordan type of refiner. The stock acted well On the ma- 

 chine wire, was strong after the second press rolls, did not cockle on 

 the driers, but became very brittle on drying, doubtless due to the 

 large amount of woody shives present. It was apparent that more 

 wood must be removed from the finished product. This could be ac- 

 complished by removing it from the straw before treatment, or by 

 more severe chemical treatment, or by a harder beating and washing. 

 Another test was made on the same lot of straw, which gave a sieving 

 loss of 35 per cent of the original straw. 



Other bleaches. — Three bleaches, Nos. 202, 203, and 204, were made, 

 similar to bleach No. 193, using 14.7 per cent of lime and treating 

 10 hours at 160° C, equivalent to 60 pounds steam pressure. 



The stock from bleach No. 202 was beaten and washed eight hours 

 an a 400-pound beater, following the roll down fairly hard. At this 

 point the stock was removed and weighed, giving a yield of 63.8 

 per cent of the sieved straw, or 41.5 per cent of the original bone-dry 

 straw. 



