On the Composition of tlie 



was dissolved, and then dried at 212° until it ceased to lose in 

 weight. 



5. Determination of Gum, Pectin, and Salts insoluble in Alcohol; 

 —The solution separated from the casein was evaporated on the 

 water-bath to a thickish syrup, which was treated with strong 

 alcohol to throw down pectin and gum. The gum, pectin, and 

 salts insoluble in alcohol thus precipitated were boiled repeatedly 

 with alcohol in order to remove any traces of adhering sugar. 

 When washed quite clean with alcohol, the residue was trans- 

 ferred into a weighed porcelain crucible, dried at 212 F., and 

 weighed. On burning, gum and pectin were dissipated, and 

 the salts insoluble in alcohol vv^ere left behind, which, being 

 deducted from the weight of the impure gum and pectin, gave 

 the proportion of pure gum and pectin. 



. 6. Determination of Sugar. — The alcoholic liquids obtained 

 in determining the gum and pectin were introduced into a retort, 

 and the alcohol distilled off in the water-bath. The residue in 

 the retort was transferred into a porcelain crucible, and, after 

 perfect evaporation on the water-bath, dried at 230° F., until it 

 ceased to lose in weight. The drying process of the sugar is 

 exceedingly tedious, as it takes a long time to expel the water 

 completely from the sugar. 



The sugar thus obtained contains a considerable proportion of 

 inorganic salts, soluble in alcohol. The weight of the latter vv^as 

 determined by exposing the impure sugar to a strong heat, at 

 which the organic part was destroyed, and the inorganic matters 

 were left behind in the form of a white ash. The weight of 

 the ash deducted from that of the impure sugar gave the pro- 

 portion of pure sugar. 



7. Determination of Fatty Matters. — In order to ascertain the 

 proportion of oil or fatty matters contained in carrots and parsnips 

 100 grains of the dried roots were repeatedly ^digested with 

 ether, which readily dissolves all fatty matters. The ethereal solu- 

 tions were passed through a filter, upon which the powdered sub- 

 stance, now exhausted with ether, was washed with this solvent 

 in order to remove all traces of adhering fat. By distillation in 

 a retort the greater part of the ether of the ethereal extracts was 

 obtained back again. The residue in the retort, evaporated to 

 dryness, was found to contain some sugar, which had been dis- 

 solved with the oil by the alcohol usually contained in ether. 

 The oil was separated from this sugar by digestion with a small 

 quantity of anhydrous ether, free from alcohol. On evaporation 

 of the ether the oil was left behind quite pure, and its weight 

 determined. It is essential to examine carefully the residue 

 which is left on evaporation of the first ethereal liquids, for 



