206 Proceedings of the Royal Society of Victoria. 



•927, and if on mixture the shrinkage is negligible, as in the case 

 of most mixed liquids, then the density d of the mixture is given 

 by 



P\ + P-2 A , A n\ 

 1 - ^1 + Z ^ ^' 



\i p^ + ^^ is 100, then A = 100 '^ ^ (2); 



j^ _ j^ 

 d^ d. 



so that from the density d it is possible to calculate the percentage 

 by weight p-^ of the Terpene. Of course as a mean value •855 is 

 adopted for density of Terpene, while the actual densities range 

 from -848 to -862; this formula should not be applied to mixtures 

 containing only a small proportion of Cineol. If the Terpene 

 present is known, then in the above formula its density must be 

 taken as d-^^ ; the mean value -855 being used only when the 

 nature of the Terpene is unknown. 



To vei'ify the applicability of the above formula to mixtures of 

 Terpenes and Cineol the following mixtures were made and their 

 densities determined for comparison with those calculated by the 

 formula above. 



Mixture I. — Equal volumes of turpentine with d-^ = -866 at 

 15°C. and Cineol ^2 = '9213 at 15°, density of mixture -8936 at 

 15°, calculated value -8936 ; the agreement being absolute it 

 follows that formula (2) would give absolutely the percentage of 

 Terpene and Cineol actually mixed. 



Mixture II. — Three vols, of turpentine ^i = -866 and one vol. 

 of oil No. 34. dc^— "9081 at 15°, density of mixture found d?= "877 

 at 15°, calculated by (1) -879 : conversely using (2) to calculate 

 first the percentage of the two ingredients by weight, we get 26-2 

 Eucalyptus-Oil and 7 3 '8 of turpentine, which corresponds to one 

 volume of oil to 2*8 of turpentine instead of the 1 to 3 by 

 experiment. 



These two experiments show that given an oil consists of 

 only a Terpene and Cineol the proportions of these can be 

 obtained with a certain amount of accuracy by a single deter- 

 mination of the density of the oil, and if the density of the 

 Terpene present is known, then the formula will allow its amount 

 to be determined with fair accuracy by a single determination of 

 the density of the oil. 



