THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 



31 



The toxicity of water-gas tar products is highly variable, miich 

 more so than commercial coal-tar products. By decreasing the 

 specific gravity the toxicity rapidly increased. The writers do not 

 wish it to be inferred, however, that this necessarily means that 

 water-gas tar and coal-tar products will prove equally efficient under 

 service conditions. The present results are merely suggestive. 



The fractionization of coal-tar creosote gives some interesting data. 

 In the case of Forties annosus the three lower fractions proved con- 

 siderably more toxic than the creosote itself. In the case of F. 

 pinicola the four lower fractions were included. In the former case 

 Fraction II gave the best results and in the latter the greater toxicity 

 fell to Fractions III and IV. This indicates that the middle fractions 

 are the most efficient, but to what group of substances the greater 

 toxicity is due we are not yet prepared to state. The work of other 

 investigators with naphthalene, which is one of the principal con- 

 stituents of Fraction II, would seem at least to militate against this 

 substance. 



The high-boiling carbolineums, which approach Fraction IV in 

 their physical and chemical properties, likewise approach it in their 

 toxic properties. 



While the higher boiling constituents proved to be less toxic than 

 the lower boiling ones, their greater permanence in wood under 

 service conditions may at least partially offset the lessened toxic 

 efficiency. 



The poor showing made by copperized oil against both fungi indi- 

 cates that adding small amounts of copper in this form to low-toxic 

 petroleum or vegetable oils will produce a mixture of doubtful 

 fungicidal value. 



TOXICITY TO FUNGI OF CERTAIN OF THE MORE IMPORTANT PRE- 

 SERVATIVES. 



In order to bring together in convenient form for comparison the 

 results secured by various investigators in the use of certain impor- 

 tant preservative substances, as well as those originating in our own 

 laboratory upon the preservatives mentioned, Table IV has been 

 prepared, indicating the salient features of such tests. 



In making comparisons, the sources of error as well as the degree 

 of refinement which the figures represent, should be fully considered. 



Table IV. — Toxicity of various preservatives to certain wood-destroying and other fungi. 



Toxic substance. 



Organism. 



Toxic point. 



Culture 

 medium. 



Duration of 



test. 



Investigator. 



A.— INORGANIC COM- 

 POUNDS. 



Ammonium chromate 



[(NH 4 ) 2 Cr0J. 

 Ammonium fluorid 



Coniophora cerebella. 

 do 



Per cent. 

 Under 1 



Under 0.1... 



Agar 



...do 



8 to 10 days. 

 do 



Falck. 

 Do. 



[NH 4 F], meutral. 







