REVIEWS 229 



principles of kiln-drying, the construction and operation of the water- 

 spray humidity-regulated dry kiln, and a discussion of the methods and 

 practices to be followed in handling various woods, especially refractory 

 ones. The author points out that the present drying practices at lumber 

 manufacturing and woodworking plants vary enormously, there being 

 no standard even for given species and given types of kilns. The re- 

 sults, therefore, on the whole have been reasonably satisfactory only 

 with woods which because of their simple physical structure lend them- 

 selves readily to crude methods. 



There is a vast amount of information in the book that is extremely 

 valuable to any one interested in seasoning lumber by artificial means, 

 whether lumberman, scientist, engineer, or forester. If the principles 

 laid down by the author were followed by sawmill men generally, 

 whether handling softwoods or hardwoods, a vast saving in lumber 

 values would follow, because there is no phase of lumber manufacture 

 which is conducted on so unscientific a basis as the artificial seasoning 

 of lumber. 



The author, who is the leading authority in the United States on 

 lumber seasoning, has devoted the major portion of his time in recent 

 years to the study of this problem, and as a nation we owe much to him. 

 since the results of his work will be one of the vital factors which will 

 enable the allies to control the aerial operations over the European 

 battlefields — an essential to an allied victory. We may, therefore, re- 

 gard this volume as one of the most valuable contributions to our tech- 

 nical literature that has yet appeared. 



R. C. B. 



Tannin Content of Pacific Coast Trees. H. K. Benson and F. M. 

 Jones. Jour. Ind. and Eng. Chemistry, December, 1917. Vp. 1096- 

 1098. 



In a study of the tannin content of western tree species made at the 

 chemical engineering laboratories of the University of Washington, it 

 was found that the tannin content of a sample of Douglas-fir slabwood 

 increased after storing for one year from 5.92 per cent to 7.5 per cent, 

 or an increase of 1.6 per cent, while the total solids increased 0.9 per 

 cent and the non-tannins decreased 0.9 per cent. Western larch bark 

 gave a surprisingly high yield of tannin, 10.6 per cent, as did western 

 yellow-pine bark, with a yield of 10.9 per cent. Western hemlock bark 

 yielded 10.93 P^'" ^'^nt of tannins, which is less than has been reported 

 by other investigators and practical tanners. The bark of a number of 



