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BULLETIN 1037, U. S. DEPARTMENT OF AGEICULTUEE. 



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 readily determ- 

 ined. Steam at at- 

 mospheric pressure 

 only 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- 

 diatel3\ Xearly all 

 were put in a small 

 ventilated box in tlie 

 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 ventilated 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. 



