44 



pared witb that of untapped, one is at a loss as to what conchisious should be drawn from so few 

 analytical data. It is remarkable that the two richest trees and the poorest tree are among those 

 that had been tapped. Of the remaining 19 trees there is no difterence between the 14 tapped and 

 5 untapped. Whatever differences are found among bled trees are equally found among those that 

 have not been tapped. 



Indeed, from the study of the results of analysis the writer is of the opinion that the difi'erence 

 in untapped trees is due to the same cause as the difference in trees that have been tapped. As 

 stated on page 43, the cause of the difterence. among tapped trees can not be traced directly to 

 tapping; it ought to be looked for, rather, in the condition of the trees previous to tapping. 



The difterence between trees 52 and 53 can be explained on the following hypothesis: 53 had 

 been a rich tree fn)m early growth, and had a large amount of turpentine stored up in the heart- 

 wood ; 52 for some reason or other had very little stored away. When the two trees were subjected 

 to tapping they gave up whatever turpentine they had in the supirood and whatever they t^ould 

 produce from season to season, till at the end of four years the production became too small in 

 amount and too poor in ([uality. The trees were then abandoned. But tree Xo. .53 hail its oleo- 

 resin in the heartwood untouched, while Xo. 52 had hardly any before tapping, and for the same 

 unknown cause did not store away any in the heartwood since the tree had been abandoned. 



The explanation offered in the preceding paragraph gains still more probability when trees CO 

 and 01 are compared with each other and also with 52 and .53. The dift'eience between 1 and 2, 

 the results of average analyses, all these are very suggestive of the theory that the sap and not 

 the heart of the tree supplies the turpentine \vhen the tree is tajiped. The fact that the heartwood 

 of trees felled one year after tapping is fully as rich or as poor as that of trees felled five years after 

 tapping seems to the writer of especial signiticauce, for it shows that the richness of the heart- 

 wood in a tapped tree is independent of time of rest before felling. 



It is a well known fact that when a pine tree is cut transversely, liquid turpentine immediately 

 appears on the fresh surface of the sapwood, while the heartwood remains perfectly clear. It would 

 seem as if the turpentine iu the sap is far less viscid than that in th<', heart of a tree. It is prob- 

 able that the turpentine in the sap is richer in volatile hydrocarbons than that in the heart. [A 

 difterence of cell structure and manner of existence of oleoresiiis may also account for this ditter 

 ence iu part. — B. E. F.| 



It is generally stated that crude turjjentine as obtained on a large scale yields from 10 to 25 



T 



per cent of volatile oil. This gives p = 11.11 to 30, with an average of over 20. This average is 



T 



somewhat higher than that for the p as found for the turpentine from heartwood of the 21 trees 



analyzed. Although experimental data are wanting to show conclusively that the difi'erence in 

 the consistency of the oleoresin from sapwood and heartwood is due to a difference in the relative 

 amount of volatile oil, yet it is <[uite jn-obable that this should be the cause. The oleoresin in the 

 heartwood of trees has been produced for the most part when the heartwood was yet sa|)wood. 

 Therefore that part of turpentine which is found iu the heartwood is the (jldest in age, and con- 

 sequently has been exposed the longest to oxidizing influences of air, which gradually rei)lacethe 

 water when the sajiwood changes to heartwood. It is the same kind of oxidation and of thick- 

 ening whicli takes jdaee when crude turpentine is exposed to the air and sun, or when a fresh 



T 



cut is made in the bark of a tree. It is probably for the same reason that ^ becomes smaller as we 



approaeh the pith of the tree, because the i»arts nearest the pith are the oldest. 



It is diflicult to conceive how the thick oleoresin of the heartwood could be made to flow 

 towards the incision when a tree is tapped. It is also ditticult to explain by what means the tree 

 could change this thick turpentine into a less viscid solution in ftrder that it may flow toward the 

 wound. 



One would. iudge, a priori, from the great difference in the consistency of the turi)entine in the 

 heart and sap that only the liquid turi)entine will flow when a tree is tapped. Tapping will then 

 have little eft'ect, if any, upon the oleoresin stored \\\> in the heartwood of the tree. A tree wliosc 

 heartwood is rich in turpentine will remaiu so after tapping. 



