TESTS OF WOOD PRESERVATIVES. ie: 
3 months the temperature of ignition was considerably raised, due 
probably ‘to the evaporation of the more volatile constituents. The. 
loss in weight from burning treated wood seasoned for 3 months was 
also usually less than in the specimens ‘burned shortly after 
impregnation. 
In general, wood treated with oils ignited at lower temperatures than 
wood treated with water-soluble preservatives. The temperature of 
ignition in both cases was lower than that of untreated wood.’ 
Furthermore, wood treated with oils showed in general greater loss 
in weight after combustion than wood treated with the water-soluble 
salts. Itshould be noted, however, that the amount of wood actually 
burned may have been. less than, in the case of the salts. 
Untreated wood and wood treated with oils (exception, Timber- 
asphalt) burned freely, and in general had to be extinguished after a 
three-minute period, while wood treated with water-soluble salts 
(exception, cresol calctum) burned slowly and became extinguished 
in less than three minutes. 
TOXIC EFFICIENCY OF THE PRESERVATIVE IN INHIBITING FUNGOUS GROWTH. 
Table 5? contains the results of the tests thus far completed on 
toxicity. The following conclusions on the toxicity of the various 
preservatives should not be considered as absolutely final, because of 
errors peculiar to the Petri-dish method. 
The products obtained from the high-boiling constituents of coal- 
tar creosote, for example, the carbolineums and high-boiling creosote 
fractions, were much less toxic than the coal-tar creosote or the low- 
boiling fractions. The products with the greater toxic properties are 
those having the lower specific gravities and lower boiling points. 
The same was true to an exaggerated degree in the water-gas-tar 
creosotes, the 1.012 oil being about as toxic as.coal-tar creosote, 
while the 1.07 oil was only slightly toxic. 
The hardwood tar and Spirittine (from yellow pine) were less than 
half as toxic as coal-tar creosote. Wood tar from Douglas fir and 
Preservol were about equal to coal-tar creosote in toxicity. Beech- 
wood creosote was more than twice as toxic as coal-tar creosote. 
Of the water-soluble salts tested sodium fluoride was the most 
highly toxic, being from one and one-half to two times as toxic as 
coal-tar creosote. Zinc chioride was slightly more toxic to Fomes 
annosus, but far less toxic to Homes pinicola than coal-tar creosote. 
Cresol calcium was also very highly toxic, being from two to four 
1 Wood dipped in a 50 per cent sodium silicate solution ignited at a temperature of 448° C., and its weight 
was reduced 17 per cent, although burning immediately ceased when the sample was dropped in the lower 
chamber of the inflammability apparatus. 
* This table was published in the Jour. Ind. and Eng. Chem., Feb., 1914, by C. J. Humphrey and Ruth 
Fleming, who conducted the tests. They are included here because they are an important factor in deter- 
mining the value of these preservatives. 
