I04 Forestry Quarterly. 



One important effect of these slits is in rendering wood 

 permeable. The greater the degree of dryness the greater the 

 permeability of the wood. In green white oak it was found 

 impossible to force any air through a two-inch block though a 

 pressure of 150 pounds per square inch was brought to bear; after 

 seasoning air was readily forced through a four inch block with a 

 pressure of less than 5 pounds. In green black oak air passes 

 readily through all of the vessels but not through the other wood 

 elements. While possible to fill the vessels of certain green woods 

 with preservatives such treatment would of itself be of little or no 

 value, since the main portion of the wood structure is composed 

 of wood fibres and tracheids which as shown are impermeable 

 until seasoning splits their walls. S. J. R. 



Maple-Sap Sirup: Its Manufacture, Composition and Bffect 

 of Environment Thereon. Bulletin 134, Bureau of Chemistry, 

 U. S. Department of Agriculture. Washington, D. C. 1910. 

 Pp. no. 



This bulletin is a report on the manufacture and analysis of 

 maple-sap sirup, after an extensive investigation covering the 

 maple producing states and Canada. Analyses were made of 

 nearly 500 samples collected from representative camps and form 

 a basis for the comparison and grading of maple sirups. 



The report is replete with tables showing camp and manufac- 

 turing data, physical properties, chemical analysis, ash data, lead 

 number and malic acid value, for the different samples arranged 

 according to source. 



The studies of the factors affecting the composition of maple 

 sirup include effect of the run, of cleansing of seasonal variations, 

 and of covered and uncovered sap buckets. It appears that sirup 

 made from the last run of sap is usually darker in color, contains 

 slightly more ash and malic acid than that from the earlier or 

 middle runs. It is probable that the color of the sirup is depen- 

 dent largely upon the presence of certain bacteria which contami- 

 nate the tap holes and affect the late run sap, giving the sirup the 

 so-called "buddy" flavor. Boring new holes or reaming out the 

 old ones will result in making the late run sap clean and clear, 

 capable of producing light colored, fine flavored sirup. 



The use of milk or white of &gg in cleansing sirup affects no 



