808 JOURNAI, 01? FORESTRY 



classification is justified. It would seem to correspond more nearly 

 with the numerical data to class Port Orford cedar, western red cedar, 

 lodgepole pine, and red fir oils as "good" flotation agents and the other 

 three as "fair." There seems to be nothing in the numerical data to 

 show that Port Orford cedar is better than the other oils, and western 

 red cedar is clearly better than larch, although it is not classified as 

 such in the conclusion. Several oils are included in the flotation tests 

 of which there is no description in the first part on the production of 

 the oils. This is confusing as well as is the use of terms like "creo- 

 sote" without further description of how the material was prepared. 

 The writers apparently were in ignorance of the fact that "pine oil" is 

 the well known and well recognized trade name lor a heavy oil con- 

 tained in comparatively large quantity in the wood of very resinous 

 longleaf pine. The use of the term "pine oil" to describe the total oil 

 obtained by the destructive distillation of western yellow pine is there- 

 fore confusing. Another example of lack of information on wood dis- 

 tillation is shown in the statement that the type of retort used in the 

 experimental work is extensively used in commercial plants through- 

 out the Southern States. As a matter of fact, this type of retort in 

 which the distillation is accomplished by means of the circulation of 

 hot oil through a coil of pipe inside the retort has never been used in 

 a commercial plant. The conclusions of the reviewer would be that 

 the yields of total oil from the woods distilled were disappointing in 

 comparison with the yields obtained by commercial distillation plants 

 using longleaf pine, while the flotation values of the oils were sur- 

 prisingly high. L. F. H. 



The Availability of Western Wood Oils for Flotation Concentration. By J. W. 

 Cook, Henry Schmitz, and Louis A. Grant, University of Idaho, Volume XVI, 

 No. 134. 



Experiments in November, 1930, in the forests 

 Caterpillar of Haguenau (Bas-Rhin) with a small, 35 horse 



Tractors power caterpillar tractor weighing 660 pounds 



in Forest showed that it can climb without effort slopes 



Exploitation of 35 to 40 per cent and can cross swamps, 

 ditches, and small streams. It maneuvers rap- 

 idly in pole stands and does little or no damage to the soil, but is de- 

 structive to seedlings in areas under regeneration. The tractor is able 

 to haul easily three pine logs with a total volume of more than 140 



