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BULLETIN OF THE BUREAU OF FISHERIES. 
to the very low coefficients of distribution of its tar acids between it and the sea 
water with which it was either extracted or emulsified. This point will be consid- 
ered in detail in a later paper. 
If differences in toxicity exist among the isomeric cresols or between alpha- 
naphthol and betanaphthol, such differences are probably slight. 
TAR BASES. 
Four samples of tar-base distillates were furnished by S. R. Church of the 
Barrett Co. These fractions were obtained by the Hempel distillation of crude 
bases after extraction of the latter from a creosote oil with dilute sulphuric acid. 
The temperature limits of these distillates were, respectively, 94 to 167° C., 170 to 
210°, 210 to 250°, and 250 to 315°. Experiments were made also with a sample 
of C. P. pyridine and of synthetic quinoline (Merck) . 
The experimental results with the tar bases are given in the lower two rows of 
Figure 4. Here, as in the case of the tar acids, there is a rise in toxicity with rise in 
boiling point. The point just raised in connection with the tar acids, namely, their 
low coefficients of distribution between their creosote-oil solutions and sea water, 
applies with equal force to the tar bases. 
SOLID HYDROCARBONS OF CREOSOTE. 
Experiments were carried out using pure samples of acenaphthene, anthracene, 
naphthalene, and phenanthrene. All these are wet with difficulty by sea water, 
so the following method was used: A quantity of the hydrocarbon, sufficient to 
make a layer about 5 mm. deep in the bottom of a finger bowl, was triturated with 
some powdered gum arabic. The powder was then stirred up with a large quantity 
of sea water to wash out the gum arabic. In this way the hydrocarbons settled well. 
Twenty-five Limnoria were put into a finger bowl full of sea water in the bottom of 
which was a layer of the hydrocarbon. The animals rapidly burrowed into this 
layer. Their activity was noted at 24-hour intervals. In the least toxic of these 
preparations, that with anthracene, a small percentage of the animals survived for 
five days. In a control experiment, using talc instead of a hydrocarbon, 80 per 
cent of the animals were found to be normal after 8 days. 
Arranged in the order of diminishing toxicity, the solid hydrocarbons are 
naphthalene, phenanthrene, acenaphthene, and anthracene. With the exception 
of naphthalene, their toxicity is very low. 
SUMMARY. 
1. Fractionates of coal tar creosote diminish in toxicity with rise in boiling 
point. The same is true of the light oils — benzol, toluol, and the xylols. 
2. The tar acids and the tar bases increase in toxicity with rise in boiling point. 
3. Naphthalene, phenanthrene, acenaphthene, and anthracene diminish in 
toxicity in the order named. 
4. The results with the small borer, Limnoria, confirm the earlier findings in 
the case of the ship worm, Xylotrya. 
