INVESTIGATION'S INTO KESINS. 341 



It has been shown that the heartwood grows poorer from l/< toward the pith of the tree. It 

 will therefore follow from what has been said in the preceding paragraph that ., will also grow 



smaller from l/ to the pith. The yield of volatile oil from a constant quantity of turpentine 

 can be expressed in a general way by a graphic illustration similar to that which expresses the 

 yield of total oleoresin from different parts of the disk. 



T 



It is difficult to explain satisfactorily this decrease of ,,. The two parts of the radial sec- 

 tions that have been the longest exposed to air are lx and the last li. The question naturally 

 arises. May not the decrease of ,, be due to a greater evaporation of volatile hydrocarbons from 



these two ends; Hut this can hardly be so. No. 53, II, 4/t was analyzed at intervals of two 

 months and furnished the following data: 



I, Sept. 28. 



H,O=11.23 

 T =1.30 

 R =7.96 



II, Nov. 27. 



7.24 

 1.34 

 8.12 



Calculated for wood free from moisture: 



Sufficient experimental data are lacking to prove conclusively that the volatile hydrocarbons 

 do not evaporate to any extent from the heartwood except from freshly cut surfaces of it. 



Relation between different flixkx of the name tree. There is no constant relation between the 

 different disks of the same tree so far as the amount of oleoresiu is concerned. Although the 

 disks do vary from each other, the variation can not be connected with gravitation, by virtue of 

 which the lower disks would contain a larger amount of turpentine than the upper ones; for dif- 

 ferent trees vary from each other considerably in this respect, the variation being apparent in 

 both bled and unblcd trees. If a, I, < stand for the amounts of oleoresin in disks denoted by 

 lloman numerals, the relative magnitudes being represented by the letters in the alphabetic order, 

 then the results of analysis can be condensed in the following table for the trees denoted in Arabic 

 numbers : 



It is evident that no constant relation as to amounts of oleoresin exists between the disks of 

 the same tree. 



Comparison of tree .7;' icith ;'>.'!. These two trees were both supposed to have been sound, 

 healthy trees at the time of felling, and yet they differ from each other as much as two trees could 

 ditl'er. The heartwood of one is very rich in turpentine; that of the other contains comparatively 

 very small quantities only a trace. How to explain the difference! Previous to felling they had 

 both been tapped for four consecutive years; consequently both must have contained considerable 

 amounts of turpentine. Since- the last tapping they stood for five years side by side, both exposed 

 to the same inHuences. This great difference can not be traced directly to tapping, for the latter, 

 it maybe assumed, would have affected both treesequally. Thecauseof theditterence between 53 and 

 5li ought to be looked for, rather, in the condition of the two trees before tapping. In connection 

 with this it would be interesting to know how much turpentine each tree had yielded when tapped. 



Comparison of free* <;<> <nul (11. There is a decided difference between the two trees. The high- 

 est numbers in 00 are O.S4 per cent for volatile hydrocarbons and 5.35 for rosin, while in <1 0.75 



