il 



100-0 



4t4tG Dr. Kane o« the Composition of certain Essential Oils. 



camphor, I am inclined to consider the high values for carbon 

 in the oils used in analyses A and C as owing in great part 

 to its presence, and to assign the analysis B as a closer ap- 

 proximation to the composition of the pure oil. With this 

 idea agrees Saussure's old* result, who from an oil of the sp. 

 gr. 0'877 obtained the composition 



Carbon = 75*50" 

 Hydrogen = 11 "07 

 Oxygen = 13-07 

 Nitrogen = 0-36_ 

 The nitrogen being now acknowledged to result from im- 

 perfections in the method employed, the tendency of which was 

 also generally to give an under-estimate for the amount of 

 hydrogen, his result is found to agree with that of analysis B ; 

 but whether from both oils being pure, or from both being 

 equally impure, I cannot undertake to say. 



Under such circumstances it is scarcely useful to attempt 

 the construction of a formula, as representing the result ob- 

 tained. Cj5 Hi4 Os = 3 Cg H4 + 2 HO, may, however, be 

 employed : 



Thus, Ci5 = 92-1 75-5 



Hi4 = 14-0 ll'S 



O2 = 16-0 13-0 



122-1 100-0 



I must not be understood as stating positively this formula 

 to represent the truth. 



Additional Remarks. — There is a peculiarity in the method 

 of ebullition of these oils which renders it very difficult to fix 

 upon a certain fixed temperature as the boiling point, but 

 rather compels us to consider the oil as boiling within a limit 

 of temperature, sometimes extending to ten degrees of Fahr- 

 enheit. Thus, in taking the boiling point of an oil in a tube, 

 a thermometer being immersed therein to some distance above 

 the bulb, the oil will enter into full ebullition apparently at 

 '355°, and the temperature of the thermometer, on continuing 

 the boiling for five or ten minutes, will gradually rise to 360° 

 or 365°, and will not then stop so completely, but that an 

 ebullition continued for five or six minytes more may pro- 

 duce a further rise of a couple of degrees. If the oil be al- 

 lowed to cool, and be then again heated, the same phseno- 

 nienon will be repeated, and so, as often as may be wished ; 

 but the most colourless oil, when thus frequently heated, gra- 

 dually becomes brown, and then there is a permanent eleva- 

 tion of the boiling point, arising from decomposition, 



