ARIZONA EXPERIMENTS ON WESTERN YELLOW PINE. 15 



Table 8. — Composition of dip from 3-inch and 18-inch faces. 





3-mch faces. 



IS-inch faces. 



Date of collection. 



Rosin. 



Turpentine. 



Rosin. 



Turpentine. 



JuDe 10 



Per cent. 

 78.9 

 76.5 

 80.0 

 78.7 

 80.0 

 78.4 

 78.3 

 77.0 



Per cent. 

 21.1 

 23.5 

 20.0 

 21.3 

 20.0 

 21.6 

 21.7 

 23.0 



Per cent. 

 78.2 

 78.4 

 79.2 

 78.5 

 78.6 

 78.9 

 77.0 

 78.3 



Per cent. 

 21.8 



July 21 



21.6 

 20.8 





21.5 

 21.4 



Oct 13 



21.1 

 23.0 





21.7 



Averase 



78.5 



21.5 



78.4 



21.6 







EFFECT OF TEMPERATURE ON WEEKLY FLOW. 



Figure 3 shows the average flow per cup for the 50 trees on area 

 D for each week and the corresponding average temperature. The 



70 

 60 



SO 

 40 

 30 



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AVC. TEMP. BY WEEKS - DEG. F. 











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FLOW PER WEEK IN OUNCES 

 AVC- NORTH AND SOUTH CUPS 









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3 10 16 23 30 7 14 21 28 4 II IB 25 I 8 15 22 29 6 13 20 27 3 

 JUN. JUL. AUG. SEP. OCT. NOV. 



Fig. 3.— Relation between temperature and rate of flow of gum. 



flow increased or decreased with increase or decrease of temperature 

 with few exceptions. The effect of cool weather in checking the 

 flow is especially marked toward the end of the season. 



RATE OF FLOW DURING WEEK. 



It is well known that gum flows most rapidly just after a fresh 

 streak and that the rate of flow decreases until at the end of a week 

 it has become so slow as to necessitate rechipping. Data on the 

 variation in rate of flow were secured by weighing the north and south 

 cups on 10 trees on the third day after each chipping throughout the 

 season. The sum of the weights for each tree was compared with 



