1916] AGRTCULTUBAL CHEMISTRY — AGROTECHNY. 13 



of the reliability of the method the test will prove the most useful single test for 

 the purity of maple products yet proposed. 



Experimental data obtained by the proposed volumetric lead method and 

 by the Canadian lead number method from 20 samples are submitted. 



The determination of cholesterol in blood, W. li. Bi-oou (Jour. Biol. Chem., 

 24 (1916), No. 3, pp. 227-2S1).— The author describes a quantitative colori- 

 metric procedure for the determination of cholesterol, based on the Liebermann- 

 Burchard color reaction. 



The method consists of slowly adding from a pipette 3 cc. of whole blood, 

 plasma, or serum to 75 cc. of alcohol-ether (3:1) mixture, contained in a 100 cc. 

 graduated flask. The contents of the flask are kept in motion to avoid clump- 

 ing of the precipitated material, and raised to boiling by immersion in a water 

 bath. The flask is then cooled to room temperature, filled to the mark with 

 the alcohol mixture, thoroughly mixed, and filtered. Ten cc. of this extract is 

 evaporated to dryness in a small beaker, care being taken to prevent over- 

 heating, and the cholesterol extracted fi'om the dry residue by boiling out 

 three or four times with small portions of chloroform and decanting into a 

 10 cc. glass-stoppered, graduated cylinder. This solution should be colorless 

 but not necessarily clear. To this, 2 cc. of acetic anhydrid and 0.1 cc. concen- 

 trated sulphuric acid are added, the solution well mixed, and then allowed 

 to set in the dark for 15 minutes. The color thus produced is compared to 

 that produced by a standard solution of cholesterol in chloroform, in a Du- 

 boscq colorimeter. The cement of the colorimeter cups must not be soluble in 

 chloroform. Plaster of Paris or ordinary glue have been found satisfactory 

 if the cups are not used for any other purpose. 



The error of the above method is from 4 to 5 per cent. Greater accuracy 

 may be obtained at the expense of more material and time. Experimental re- 

 sults obtained with the new procedure average about 20 per cent higher than 

 those obtained by the Autenrieth-Funk method." 



The volumetric estimation of total sulphur and sulphates in small quan- 

 tities of urine, J. C. Deummond (Biochem. Jour., 9 (1915), No. 4> PP- 492- 

 501). — An improved procedure of the benzidin method of Raiziss and Dubin 

 (E. S. R., 33, p. 415) for the determination of sulphur in urine and other bio- 

 logical material, in which as little as 2 cc. of sample can be used, is described. 

 The precipitated benzidin sulphate is titrated with a xuis-iiormal alkali. 



A method for the determination of alcohol in the presence of phenol, 

 J. Ehkoch (Jovr. Indus, and Emjin. Chcm., 8 (1916), No. 3, pp. 240, 241).— The 

 author has observed that, in the usual method of determining ethyl alcohol 

 In the presence of phenol by means of distillation from strongly alkaline solu- 

 tion, a trace of phenol resulting from the partial hydrolysis of the phenolate 

 is always carried over in the distillate. 



To obviate this source of error in the method proposed, any phenol that may 

 be carried over in the first distillation is precipitated with bromin, the slight 

 excess of bromin being immediately removed with normal sodium thiosulphate. 

 The precipitated tribromphenol is dissolved as the phenolate by alkali, the mix- 

 ture again distilled, and the alcohol thus determined. 



If the original phenol content is low the first distillation may be omitted. 

 If there is a great amount present two distillations are necessary, as the bulky 

 precipitate of tribromphenol makes it impossible to perceive when an excess of 

 bromin is present. 



Experimental results submitted indicate the great accuracy of the pro- 

 cedure. 



" :Miinohcu Mod. AVclinschr., GO (1913), No. 2.'5, pp. 1243-1248. 



