INDUSTRIES DEPENDING ON PLANT PRODUCTS I529 



3^east food a certain number of the diffusion cylinders were charged with 

 beet and each day some juice was withdrawn from them and added toge- 

 ther with nutrient salts to the apple slices in order to assist fermentation. 

 The yield of alcohol from the apples was taken as the difference between 

 the total yield and that of the added beet juice. It amounted to not quite 

 10 gallons of rectified alcohol (loC^) (rectified spirit and fusel oil) per ton 

 of apples. It should be borne in mind that the experiment was carried 

 out at the end of December 1915 and during the month of January 1916, or 

 in other words at a season when the sugar content of apples was daily 

 decreasing. 



In the case of cane sugar, a starter was prepared at the outset, using 

 a solution of beet malasses of a density of 1.055 to 1.060 and containing 2.4 

 to 2.5 gms. of acid per litre (expressed as sulphuric acid). To this, nutrient 

 salts were added at the rate of 0.5 per cent of sulphate of ammonia and 0.6 

 of phosphate of soda. The starter was inoculated with yeast obtained 

 from a grain distillery and fermentation was kept active by aeration. For 

 the experiments, large vats of about 5000 gallons capacity were used and 

 these were one third filled with starter. The cane sugar juice acidified till 

 it contained 0.7 to 0.8 gm. of acid per litre, was then run into the vats on 

 the top of the starter, the proportion of cane to beet sugar rising ver}^ gra- 

 dually from 4 :20 to 80 :20. It was found that 18.3 lbs. of cane sugar were 

 required to produce i gallon of rectified alcohol (rectified spirit and fusel 

 oil). The cane used had a polarisation value of 92. 



1118 - Refraction Constants of Various Vegetable Fats and Oils. — heim, f. in Bulletin 



de rOffice colonial, Vol. IX, No. 102-103, pp. 267-276. Melun, 1916. 



A number of vegetable fats and oils originating from the French co- 

 lonies were examined at the French Colonial Office with a view to determin- 

 ing the relationship, if any, between their refractive indices and other con- 

 stants in common use, and their chemical composition. 



The samples were ground in a mill and extracted in the cold with 

 benzine which was afterwards distilled off in a warm bath, the residue being 

 finally raised to 100" C. to drive off any remaining traces of benzine. Fats 

 or oils thus obtained were filtered before having their refractive indices 

 determined in a Fery refractometer. The results are set out in the adjoin- 

 ing table, and the writer draws the following conclusions : 



i) The determination of the index of refraction yielded a very reliable 

 means of estimating the chemical purity of any fat or oil. For instance the 

 oil of Thea sinensis gave a refractive index of 1.4707 to Tsujtmoto in Ja- 

 pan, and an index of 1.4706 in the present investigations. Other constants 

 showed far greater variation more especially those resulting from chemical 

 tests ; it would therefore appear that the measurement of physical cha- 

 racters is a much more accurate guide to the purit}^ of fats and oils than 

 is that of the chemical characters. 



2) Except in the case of Ricinodendron africanus the index of refraction 

 always varied with the iodine value. 



3) As a rule the index of refraction increased as the saponification 



