PEODUCING SODA PULP FROM ASPEN. 
11 
to the charging temperature and run into the digester, and the cook- 
ing operation was begun by permitting live steam to enter at the 
bottom. 
During the cooking, observations were made at 15-minute intervals 
of (1) digester temperature, (2) digester pressure, (3) steam pressure 
at digester inlet, and (4) room temperature. The volume of liquor 
in the digester was also observed, but at hourly intervals. These 
observations were recorded, and a graphic "log of cook" was made 
at the same time, an example of winch is shown in figure 3. If at 
any time the digester temperatures and pressures as observed on the 
thermometer and pressure gauge did not agree when compared by 
means of pressure-temperature tables for saturated steam, the excess 
of pressure was relieved ; such a condition occurred as a rule only dur- 
