GLASSY FIR. 



119 



sharp saw through several of the blocks of wood, cutting 

 both through the glass v area and the roughened area. These 



glUOO* «iv,a «ix« w^~ *-~- 



4J <_> V "— 



sections were so made that the point at which the cut was 



more 



glassy surface. In all cases the surface was rough over 

 its entire extent, irrespective of whether it was an isolated 



h 



In order still further to see whether the smooth appear- 

 ance of the wood was due to freezing, several pieces of 

 loblolly pine (Pinus taeda) were boiled for several hours 

 in water so as to thoroughly water-soak them. The pieces 



specially wide-ringed trees. After the 

 soaking, the pieces were laid out of doors, and were al- 

 lowed to freeze thoroughly. The thermometer during the 

 particular night when they were exposed was below zero. 



om 



The following morning the pieces were sawed half way 



through while in the frozen condition, the section being 



made about an inch from the outer surface. An ordinary 



cross-cut saw was used for the purpose. The pieces were 



then brought into the laboratory, where they were allowed 



to thaw out completely. After some 10 hours the section 



which had been partially sawed off in the frozen condition 



was completely cut off. In other words, one-half of the 



section was sawed while in the frozen condition, and the 



other half after the wood had thawed out. On plate 21 



a photograph of one of the sections is reproduced. The 



part on the upper side of the figure was the portion 



sawed while the wood was frozen; the lower half, after 



the wood had thawed out. It will be noted that there is a 



marked line of demarcation between the two parts, the 



frozen part being smooth, the other half showing the 



rough surface usually found when a pithy wood of this 



character is cut with a cross-cut saw. 



Similar tests were made with red fir and white spruce , 

 and in all cases the peculiar glassy appearance was obtained 

 in the frozen portion of the wood. 



