6 On the Composition of the 



inorganic salts, soluble in alcohol. The weight of the latter was 

 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 

 clryness, 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 

 commercial ether always contains some water and alcohol, 

 which both dissolve a certain portion of sugar from the root. 

 Unless care, therefore, is taken to extract the impure oil with 

 ether perfectly free from alcohol and water, the oil contained in 

 roots and other vegetable productions, furnishing sugar on 

 analysis, will be estimated too high. Inattention to this point, 

 perhaps, accounts for the great variations which are observable 

 in the determinations made by different persons of the quantities 

 of fat contained in the various articles of food. 



8. Determination of the whole Amount of Protein Compounds or 

 flesh-forming Constituents. As a check upon the direct deter- 

 mination of casein and the indirect determination of insoluble 

 protein compounds, the whole amount of flesh-forming consti- 

 tuents in the carrot and parsnip was ascertained by the indirect 

 method of combustion. 



About 18 to 20 grains of the dried substance were 

 burned with soda-lime. The amount of nitrogen obtained ac- 

 cording to the method of Will and Varrentrapp, being multi- 

 plied by 61, gave the proportion of protein compounds in the 

 roots. 



9. Determination of Ammoniacal Salts. Having found that 

 the juices of many plants contained sometimes considerable 

 quantities of ammoniacal salts, which necessarily must render 

 the determination of the flesh-forming constituents in plants in- 



