CONTENTS. 



Page. 



Purpose of the investigation 5 



Arizona experiments on western yellow pine 5 



Description of experimental areas 5 



W^eather conditions 7 



Method of conducting experiments 8 



Yields 9 



Comparison of yields of dip in Arizona and Florida 9 



Comparison of yields of scrape in Arizona and Florida 10 



Comparison of yields of dip and scrape from black jack and yellow pine. 11 



Composition of dip 11 



Condition of tapped trees 12 



Evaporation from cups 13 



Special problems investigated 13 



Comparison of yields from north and south faces 14 



Comparison of dip from high and low faces 14 



Effect of temperature on weekly flow 15 



Ptate of flow during week .■ 15 



California experiments on western yellow pine 16 



Description of area and method of experiment 16 



Weather conditions 17 



Yields : 17 



Composition of dip and scrape 18 



Evaporation from cups 18 



Colorado experiments on pinon 18 



Description of area and method of experiment 18 



Weather conditions 19 



Yield 19 



Composition of dip 20 



Colorado experiments on western yellow pine 20 



Description of experimental areas 20 



Yields 21 



Summary of results 21 



Problems which confront commercial development 22 



3 



