474 Forestry Quarterly. 



data secured by various methods to analytical examination. 5. 

 Mutual advancement of theory and experience. 



Under the last heading the dependence of hardness to specific 

 weight forms a special feature of the discussion, in which the 

 result appears that the hardness of specifically heavier woods in- 

 creases more rapidly than their specific dry weight, when the 

 pressure is applied with not too acute bodies. 



In the resume the author states that a comparison of hardness 

 in wood on the basis of equal area, or equal indentation depth, or 

 a combination of the two, or on the basis of equal surface of 

 punches, which have different form, is theoretically not ad- 

 missible; the most suitable basis for comparison is the volume 

 equality of the punches. 



He develops the conception of "form pressure" as the most suit- 

 able expression of the hardness measure of the compression tests, 

 conceptions which can only be discussed with the use of form- 

 ulae. 



Untersuchung des Begriffs der Holzh'drte. Centralblatt f. d. g. Forst- 

 wesen. August, September, 1909. Pp. 348-387. 



From the Austrian Experiment Station Dr. 



Nezv Lorenz reports a new wood preservative 



Wood which overcomes the objections to the salts 



Preservative. soluble in water (hence easily leached out), 



and to the expense when using efficient tar 



oils, the phenols of which are also leached. This new, effective 



and cheap preservative is arsenate of copper, which is absolutely 



insoluble in water. The preparation is made by dissolving 5.5 



pounds of copperas with 16.5 pounds of ammonia of 25%NH3 



(sp. gr. .91) and water, to make 50 gallons. To this is added 



50 gallons of arsenious acid, 2.2 pounds dissolved in 5.5 pounds 



of the same ammonia and diluted with water. 



After being filtered to get rid of some carbonate of copper and 

 other impurities, the dark blue ammoniacal solution of arsenite 

 of copper (C11HASO3) is ready for use. 



According to the dryness of the wood from 25 to 40 per cent, 

 of the wood volume is taken up. The ammonia evaporates and 

 the blue green color of the impregnated wood changes to gray 

 green which remains constant (the arsenate of copper). A beech 

 tie impregnated with this liquid will contain from one-half to 



