48 
BULLETIN 1037, U. 
DEPARTMENT OF AGRICULTURE. 
terval of at least H inches was maintained between adjacent groups. 
In the tile chamber the blocks were subjected to a temperature aver- 
aging S0 = F. and a relative humidity varying from 85 to 100 per cent. 
At the end of three to four weeks all blocks were carefully examined. 
The following observations were made at that time : 
Xone of the preservatives was entirely effective in controlling 
mold when used in concentrations of 1 per cent. 
Blocks dipped in sodium carbonate, sodium bicarbonate, sodium 
fluoric!, sodium biffuorid, ammonium fluorid, magnesium silicofluorid, 
zinc silicofluorid. and bleaching powder became badly molded. 
Potassium (alum), potassium chlorate, and copper sulphate seemed 
to stimulate all or certain species of the fungi used. The last seemed 
to incite the growth of Aspergillus niger in particular. 
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Fig. 22. — Diagram illustrating the method of loading used by one of the large wheel fac- 
tories and recommended by the wood-stock committee in connection with vehicle stock. 
Borax was effective in controlling the sap-stain fungus (Cerato- 
stomeUa sp.). Though it did not entirely prevent the growth of mold, 
the amount of mold that did develop was very slight in comparison 
with that on the blocks treated with the other preservative solutions. 
Under these circumstances it compared favorably with 1 per cent 
mercuric ehlorid. 
The addition of the hygroscopic substances — sodium ehlorid, cal- 
cium ehlorid. and glycerin — to the solutions of the preservatives 
apparently did not increase their efficiency. 
Of the organic compounds and mixtures tested here, creosote in 
kerosene gave the best results, while mykantin stood second. The 
latter, however, stained the wood yellow, a property which would 
prohibit its use for many purposes. 
