12 



WESTERN PINES AS A SOUKCE OF NAVAL STORES. 



Considering the pure dip, free from water and chips, there is little 

 variation in the proportions of rosin and turpentine. The average of 

 all the samples, 77.9 per cent rosin and 22.1 per cent turpentine, is 

 practically the same as that of a number of samples of dip from south- 

 ern yellow pine. The proportion of water and chips in the Arizona 

 dip is considerably lower than hi samples of dip collected from tur- 

 pentine operations in the Southeast. This is to be expected, because 

 in the Southeast the chipping is done as piecework, and the chipper 

 in his hurry frequently neglects to place a guard over the cups, even 

 when he is required to use a guard, which is but seldom. The com- 

 paratively few cups hung in Arizona enabled the work to be carefully 

 supervised. Table 7 indicates a slightly higher proportion of turpen- 

 tine during the beginning and latter part of the season than in the 

 summer months. There is practically no difference in the propor- 

 tions of rosin and turpentine in gum from black jack and yellow pine. 



TABLE 7. Results of laboratory analyses on samples of dip from western yellow pine, 



Arizona. 



CONDITION OF TAPPED TREES. 



At the time the cups were hung, the trees were examined at the 

 butt to determine if they were infested with boring beetles. Very few 

 of the trees showed signs of insect attack, but, because of the thick, 

 rough bark the examination told but little, since the evidences of 

 beetle infestation are not noticeable except in severe cases. At the 



