30 
BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 
A steam box was constructed of cypress, equipped with thermome¬ 
ters, dew-point apparatus, and manometer and connected with the 
main which supplies steam to the laboratory greenhouse (figs. 15 and 
16). By means of suitable reducing valves in the connecting pipes 
it was possible to control the steam pressure in the box; hence, the 
exact conditions to 
which the blocks 
were subjected could 
be readilv determ- 
ined. Steam at at¬ 
mospheric pressure 
onlv was used. 
Previous to steam¬ 
ing, the blocks were 
again weighed. 
They were then 
close piled or strip¬ 
ped in groups of 25 
in the steam box and 
steamed for differ¬ 
ent lengths of time. 
At the end of the 
steaming period, 
some of the lots were 
allowed to cool for a 
certain time and then 
reweighed. Others 
were weighed imme¬ 
diately. Xearly all 
were put in a small 
ventilated box in the 
open and allowed to 
air-dry for several 
weeks. Some, how¬ 
ever, were placed in 
a closed shed for 
four weeks, and still 
others were taken 
from the steam box, weighed, and placed directly in the tile chamber. 
Some lots were stripped; others were close piled. An interval of at 
least 3 inches was maintained between adjacent piles. 
After the preliminary seasoning mentioned above, a number of the 
blocks were returned to the tile chamber for incubation. This was 
done for the purpose of subjecting the blocks to the conditions exist¬ 
ing in box cars and poorly A^entilated warehouses during warm and 
Fig. 11.—Stacking sawed billets in an open shed. It will 
be observed that the billets at the extreme right are 
cross piled, while those in the center are close piled. 
The former method of piling insures a better ventila¬ 
tion of the stack, provided intervals of at least 1 inch 
are left between the adjacent billets of a course. In 
the case of the cross-piled billets shown here this pro¬ 
vision was not made. 
