300 
The N.Z. Journal of Science and Technology. 
[Sept. 
DEPARTMENTAL REPORTS. 
Fireproofing and Antiseptic Treatment of New Zealand 
Timbers.* 
( Continued from page 246.) 
By C S. Hicks, M.Sc., A.I.C., F.C.S., New Zealand National 
Research Scholar. 
PART II. 
Effects of Temperature-changes in Wood under Treatment. 
Materials used in Seasoning Experiments. 
Discussion of Results. 
Effect of Treatment on Strength. 
Leaching of Zinc Chloride. 
Appendix. 
Note on New Zealand Beeches (commonly called “ Birches ”), 
by E. Phillips Turner. 
/ 
EFFECTS OF TEMPERATURE-CHANGES IN WOOD UNDER TREATMENT. 
Following the lines of investigation laid down by L. M. Hunt in the 
United States Forest Products Laboratory, Wisconsin, investigation was 
made into the rate of penetration of heat into the centre of timbers under 
investigation, during either preliminary steaming or steam-seasoning. The 
essential feature of seasoning by steam is that the wood shall be heated 
right through to the temperature of the steam-bath, the subsequent vacuum 
then hastening the removal of moisture by the consequent lowering of the 
boiling-point. It is clear that unless the stick is heated to the centre the 
vacuum will fail to remove all the moisture, entailing loss of efficiency ; 
in the same way, excess heating achieves no further object in so far as 
moisture-removal is concerned, and might even do harm, apart from 
inefficiency. Again, the object of the vacuum is to hasten the evaporation 
of the contained moisture. With this rapid vaporization loss of heat 
results, and any further holding of the vacuum past the point where no 
more heat-units are lost by the wood results in economic loss. 
The object of these experiments then, is to ascertain — (1) Time 
required to enable temperature of stick to attain a maximum under the 
conditions ; (2) time required for removal of the maximum amount of 
moisture under the conditions of the test. 
The methods adopted in carrying out these experiments differ from 
those of the United States Forest Service in some of the practical details, 
but the results agree so closely that the possibility of wrong conclusions 
seems remote. 
Apparatus .—The pressure cylinder described in the tests on impreg¬ 
nation was used, the only difference being that the thermometer was 
* Abbreviated from report presented to the Chairman, Research Scholarship Board, 
Otago University, on the 21st January, 1917, and printed by direction of the Board 
-of Science and Art. 
