Parsnip and WJdte Belgian Carrot. 



389 



commercial etlier always contains somo water and alcoliol, 

 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 wliole 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 gi^ains 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 6t, 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- 

 accurate, I was led, therefore, to examine these roots for ammo- 

 niacal salts, and have succeeded in detecting in them small 

 quantities. The plan adopted for finding out the presence of 

 ammoniacal salts in parsnips and carrots and of ascertaining 

 their relative quantities vv'as as follows : — 



About 1500 grams of the finely grated roots w^ere digested 

 with distilled water, and washed upon a piece of fine linen as 

 long as anything was extracted by w^ater. The clear liquids 

 were immediately precipitated wdth basic acetate of lead, a 

 re-agent which separates completely all protein compounds. The 

 bulky precipitate thus produced was carefully washed on a filter 

 with distilled water, and the liquid, passed through the filter, 

 after having been slightly acidulated with sulphuric acid, vv as eva- 

 porated in a porcelain dish to a small bulk. Thus concentrated, 

 it was introduced into a retort, connected wath a convenient ap- 

 paratus containing some hydrochloric acid, and destined to 

 absorb the ammonia which is given off during the subsequent 

 distillation of the contents of the retort with soda-lime. It is 

 necessary to choose the receiving apparatus sufiiciently large to 

 contain all the liquid in the retort, as the contents of the retort 

 have to be distilled to dryness in order to obtain the last traces 



