REVIEWS 865 



The toxicity of these mixtures is an established fact and they are much 

 cheaper than creosote. The investigation described in this bulletin 

 gives valuable information on the absorption and penetration secured 

 with various of these mixtures as compared with results secured with 

 creosote, using yellow pine for all tests. Special laboratory apparatus 

 was used for the penetrance tests, and the impregnation tests were 

 made in a cylinder under pressure. The effect of varying time pressure 

 and temperature were also studied. 



The authors are extremely conservative in their conclusions. We 

 learn that temperatures as high as 200° F. materially aid in securing 

 satisfactory absorption of products containing a large percentage of 

 by-product coke-oven tar ; that with the use of tar alone or in mixture 

 with creosote the difficulty of injection would increase as the percent- 

 age of tar and free carbon was increased ; that mixture containing 

 low-carbon tars are preferable, and that the practice of filtering free 

 carbon, sometimes resorted to, seems to ofifer a means of improving the 

 ])enetrating properties of the preservative. 



Anything which will reduce the cost of a wood preservative without 

 impairing its efficiency is a direct aid to the industry and to the busi- 

 ness of conserving timber supplies. It is because of its bearing on these 

 questions that the bulletin is worthy of thoughtful study by foresters. 



S. W. A. 



Forests of British Columbia. By H. N. Whitford and R. D. Craig. 

 Report of Commission of Conservation, Ottawa, Canada. Committee 

 on Forests. 1918. 409 pp., 27 pi., 21 maps. 



This is a report of great value, the result of three years' work bv 

 the authors in securing personal knowledge of local conditions in each 

 district and in compiling a large amount of data, including detailed 

 estimates and reports on stands furnished by the British Columbia 

 Forest Branch, timber-owners, cruisers, surveyors, and others. The 

 area of the province is 355.855 square miles, or one-tenth larger than 

 the combined areas of Washington, Oregon, and California. The 

 forest land area of the province is placed at 149,344 square miles, as 

 compared with 117,000 sqviare miles in the Pacific Coast States, but the 

 stand of merchantable timber in the former is estimated at only 366 

 billion board feet as compared with 1.300 billion in the latter. The 

 timber on two-thirds of the forest land area of the province has been 

 totally destroyed by fire and over half of the remainder has been seri- 

 ously damaged ; 200.000 square miles of the jirovince is non-forest 



