— 123 — 



(Chartreuse, Benedictine liqueur, etc.). In both cases 200 cc. of 

 the liqueur are diluted with water to 300 cc, and of this mixture 

 200 cc. are distilled off, on the one hand to separate it off from the 

 sugar, and on the other to estimate the alcohol-content. 



1. Titration method with bromine liquor. Required are: 

 Y 20 th normal bromine solution (4 g. bromine to 1 liter water containing 

 40 g. potassium bromide); petroleum ether of the spec. grav. 0,680 

 previously treated with bromine and washed; further, comparative 

 solutions of oils with the same alcohol-content as the distillate of the 

 liqueur to be analysed and a definite quantity (at most 1 g. per litre) oil. 

 100 cc. of the distillate and 100 cc. of the comparative solution are 

 each placed in a graduated stoppered tube; 15 cc. of the above 

 petroleum ether and sufficient water are added to bring the alcohol- 

 content to about 2 5 Gay-Lussac; the mixture is then repeatedly 

 strongly shaken, and left standing. After adding about 20 g. common 

 salt the aqueous layer is carefully separated from the petroleum ether. 

 Every 10 cc. of the petroleum liquids are now placed in stoppered flasks 

 of 50 cc. capacity, 10 cc. water added, and titrated with the above- 

 mentioned bromine solution. In addition to this a blind test is made 

 with petroleum ether and water alone, and the result calculated. 



2. Method by gravimetric analysis: 15 cc. petroleum ether 

 boiling between 25 and 35 are used; the extraction is the same as 

 with the titrimetric process, except that as a precaution the mixture 

 is also cooled. 10 cc. of the petroleum ether extract are placed in 

 a weighed Erlenmeyer flask of 30 cc. capacity, the flask put in a 

 vacuum desiccator provided with lime and in which is placed a thermo- 

 meter graduated into 1 / 10 tli degrees; it is evacuated, and the cock closed 

 when the thermometer again indicates the original temperature. After 

 half an hour, dry air is admitted into the apparatus, and the substance 

 weighed. By multiplying the weight of the residue of the petroleum 



ether with — , and the product with 10, the quantity of oil per litre 



liqueur is found. 



Physical notes. 



On the strength of J. W. Bruhl's researches regarding the in- 

 fluence of multiple linkings on the capacity of refraction and dispersion 

 of organic bodies, the molecular refraction has frequently been employed 

 for clearing up the situation of the linkings in the molecule. In view 

 of the definite conclusions which Bruhl's figures enable us to draw 

 on the structural conditions, K. Auwers 1 ) now explains the abnorm- 

 ally high refraction and dispersion of certain bodies by a special 



x ) Berl. Berichte 39 (1906), 3753. 



