72 BACON. 



DISCUSSION OF ANALYTICAL KESULTS. 



Several regularities will at once be noted. The ester number of first- 

 grade oils is usually 100 or more, whereas that of second grade but 

 rarely rises above 80; the refractive index of the former class is usually 



OAO 



low, being but rarely over N^ = 1.4900, whereas that of the latter ap- 

 proaches 1.5000. This difference is due to the larger content of sesqui- 

 terpenes and resins in second-grade oils, cadinene having a refractive 



30° 

 index N^^ =1.5060. The optical rotation of first-grade oils is much 



lower than that of the second grade, it being but rarely over — 45° and 

 usually varying from —32° to — 45°, that of the second grade being 

 around — 60° and over. This difference is also caused by the high 

 content of the latter in sesquiterpenes. A few provincial oils have a low 

 optical rotation together with a low ester number, and such oils are in 

 general very poor, they are also apt to have a very low specific gravity." 

 The results all go to show that an oil with a low refractive index, low 

 optical rotations, and high ester number is almost certain to be good, 

 while high refractive index, high optical rotation, and low ester number 

 indicate a second-grade oil. 



No especial regularities have been noted in the specific gravities of 

 the various oils, save that if an oil has a high specific gravity and high 

 ester content (ester number above 110) it may follow that it may also 

 have a higher refractive index, and oils with all these constants are very 

 superior. (See Table II, number 23.) 



Manila buyers of provincial oils are often anxious to ascertain the 

 quantity of flowers used by the distiller in obtaining the oil offered, so 

 that they may judge as to its quality. A nimiber of experiuients were 

 made on the distillation of ylang-ylang oil in vacuo to obtain data on 

 this point and to ascertain whether it might be jDOSsible to rectify a 

 lower grade of 'oil by such a procedure. 



One hundred cubic centimeters of first-quality oil were placed in a 200 cubic 

 centimeter, liigli-necked flask, the distance from the surface of the oil to the exit 

 tube being 16.5 centimeters; a slow, regular distillation was made from a metal 

 bath the temperature of which was kept 15° to 20° liotter than that of the dis- 

 tilling vapor; the total time consumed in the distillation being one hour and 

 twenty-five minutes. 



30° 

 The original oil 'gave the following constants: Specific gravity, — - =0.927; 



A— = — 44.4; n5— = — 1.4883; ester number=117.8. 



Fraction number I. — Fifty-two cubic centimeters at 13 millimeters pressure, 

 passing over between 73° and 100°, temperature of metal bath up to 120°. 



° Cf . Table III, numbers 4, 9, 16, 21. 27. 35, all of which numbers were known 

 to represent very poor oils. 



