OLEOEESIN PRODUCTION. 21 



trees from the double area at the end of the season was more pro- 

 nounced than that of the year before. 



The yields from the double area presented in Tables 5 and 6 show- 

 that a higher total quantity of gum was obtained by this method 

 than by either the standard or the narrow chipping. From Table 6 

 it is also apparent that under the careful narrow " pulling " prac- 

 ticed in 1917 there was a marked gain over 1916 in yield, with refer- 

 ence to amount of face used. A slightly higher relative proportion 

 of turpentine, as compared with rosin, was obtained by this method 

 in both 1916 and 1917. It is questionable, however, whether the 

 extra yield obtained is sufficient to justify the cost of the extra chip- 

 ping, especially since the microscopic investigations showed that 

 the responses of the trees on the double area, as expressed in the 

 reduction of wood formation (Tables 2 and 3) and in the somewhat 

 more belated and less abundant formation of resiniferous tissue, 

 particularly in the spring of 1916, were less satisfactory than the 

 responses obtained with the other methods of turpentining. Yet if 

 a case occurs in which timber can be turpentined only for a short 

 period (one or two years) before it is cut, this method might deserve 

 consideration, especially if practiced only during the height of the 

 producing season. 



NARROW CHIPPING. 



Narrow chipping was practiced on about 6,000 faces at Columbia, 

 Miss., for a period of two years. The results obtained gave infor- 

 mation worthy of careful consideration and further test, since they 

 indicated a means of securing a high sustained yield for a consider- 

 able number of years with a comparatively small reduction in the 

 vitality of the trees turpentined. The streak specified was of the 

 same dimensions (one-half inch deep and one-fourth inch high) as 

 that used on the double area, but it was cut only once each week. 

 The type of forest was the same as that turpentined by the standard 

 and double methods. Figures 5 and 6 show the results obtained from 

 the monthly observations on the five trees selected for 1916 and 1917, 

 respectively. Tables 2, 3, and 4 show the results of observations on 

 larger numbers of specimens obtained at the end of the season each 

 year. 



Yields from narrow chipping. — The summarized yield data for 

 KtHl and for 1917 are given in Tables 5 and 6. During the second 

 year of operation the narrow crop produced within 4 per cent of the 

 total yield of the standard erop, all hough during 1916, the first year 

 of th<- operation, it had fallen 18 per cent below. With the narrow 

 method, however, the n-iial second year reduction in yield was prac- 

 tically eliminated; whereas about L5 per cent reduction occurred in 



the standard and doiihle when (lie yield of the second ye,ir was com- 

 pared with that of the first. 



