RESULTS OF EXAMINATIONS. 11 



represents the ether number and is obtained by subtracting the acid 

 number from the saponification number. 



The methods of isolating the resin acids will be discussed under the 

 several species, since each species usually requires a different treat- 

 ment. The composition of the resin acids was checked by means of 

 their silver salts, which were obtained in the following way: A 

 weighed amount of the resin acids was dissolved in alcohol and the 

 solution was exactly neutralized with alcoholic caustic soda. The 

 sodium salt was then decomposed by adding the calculated amount 

 of silver nitrate dissolved in a small amount of water. The pre- 

 cipitate of silver salt was filtered off with a suction pump and the 

 residue washed with water, alcohol, and finally with ether. The 

 precipitate was dried at 60 for half an hour and then allowed to 

 stand a day over sulphuric acid. 



ABBREVIATIONS. 



The following abbreviations are used: 



d^o or "specific gravity"= specific gravity at 15 compared with 

 water at 15. 



or "index of refraction" = index of refraction at 15 

 = optical rotation at 20 in a 100 mm. tube. 

 [a] D = specific rotation. 



RESULTS OF EXAMINATIONS BY SPECIES. 



Pinus Ponderosa Laws (California). 

 LITERATURE. 



The oleoresin of Pinus ponderosa, or western yellow pine, evi- 

 dently has never been subjected to a careful examination. Sad tier 1 

 examined an oil coming supposedly from Pinus ponderosa. How- 

 ever, since the oil he examined had the general properties of normal 

 heptane, it must have come from either Pinus sabiniana or Pinus 

 jejfreyi, which, so far as known, are the only species that yield hep- 

 tane. Confusion between the species might readily occur, because 

 Pinus jejfreyi so closely resembles Pinus ponderosa that it is often 

 considered a variety. Wenzell 2 had examined in his laboratory a 

 sample of oleoresin from Pinus ponderosa obtained from Virginia, 

 Nev., and stated that the odor, specific gravity, and boiling point 

 corresponded with common oil of turpentine. The material exam- 

 ined in the forest products laboratory does not corroborate this 

 statement. 



i Am. Jour. Pharm., pp. 176-180, vol. 51, 1879. Pharm. Rev., pp. 165-172, vol. 18, 1900. 



