114 EXPERIMENT STATION RECORD. 



held before tbe spectroscope will just show the presence of two absorption 

 bands. 



By multiplying by 0.0948 the degree of dilution (i. e., the figure which shows 

 how many times the pentose-coutaiuing solution after treatment is diluted with 

 alcohol) plus 1, the percentage of pentose added in the original solution can be 

 ascertained. Dextrose, levulose, and cane sugar when present have no effect 

 upon the results. 



Amyloineter, a new apparatus for calculating the starch content of pota- 

 toes, W. ViLiKovsKY and G. Stempel (Ztschr. Landw. Versuclisw. Osterr., 16 

 (1913), No. 9, pp. 893-898, figs. 2).— A description of the apparatus with which 

 it is possible to determine the starch content of potatoes with small samples. 

 The JNIaercker, Behrend, Toth, and similar methods require very large quanti- 

 ties of potatoes for a determination. 



Estimation of copper in conserves with the spectrophotometer, E. Tassilly 

 {Bill. 8oc. Cltini. France, 4. ser., 13 {1913), No. 2, pp. 72-7^; abs. in Chem. Ztg., 

 37 {1913), No. 74, Repert., p. 3^1).— From 10 to 15 gm. of the conserve under 

 examination is dried upon a water bath, ignited, and then exposed to a moderate 

 degree of heat. After digesting with from 2 to 5 cc. of sulphuric acid for three 

 hours on a water bath, this is triturated from time to time, water added, filtered, 

 and the residue washed on the filter with water. The copper in the filtrate is 

 then precipitated with sodium hyposulphite, boiled, filtered, ignited in a por- 

 celain crucible, subjected to a moderate heat, dissolved in the crucible with 1 to 

 1^ cc. of sulphuric acid and a few drops of nitric acid, and heated to remove the 

 excess of sulphuric acid. The I'esidue is then dissolved in water, and 2 cc. of 

 a solution of potassium ferrocyunid which contains 0.07 gm. of potassium 

 ferrocyanid in 1 cc. of water added, made up to 100 cc, and the copper de- 

 termined spectrophotometrically. The results are compared with those obtained 

 with a standard copper ferrocyanid solution of known strength. 



Determination of copper in copper-spraying mixtures, P. Malvezin {Ann. 

 Chim. Amilijt., 18 {1913), No. 6, p. 220; abs. in Chcm. Abs., 7 {1913), No. 19, 

 pp. 3382, 3383). — The method depends on the action of methanal sulphurous 

 acid (CH2OH2-SO3H) on an ammoniacal copper solution. The reagent is made 

 by saturating a 40 per cent solution of formaldehyde with sulphur dioxid. The 

 titer of the resulting solution is then determined with a 1 per cent solution of 

 metallic copper in an aqueous nitric acid solution. One cc. of this solution is 

 mixed in a test tube with 2 cc. of ammonium hydroxid and 1 cc. of water and 

 the reagent added until the solution becomes colorless. 



In order to determine the quantity of copper in a spray " weigh out 1 gm., 

 ignite carefully in a porcelain crucible, and dissolve in nitric acid; dilute in a 

 graduate to 20 cc. with water, filter, transfer 10 cc. to a large test tube, add 2 

 cc. ammonium hydroxid, and dilute with water to 20 cc. Filter, and to 10 cc. 

 of the filtrate add 1 cc. of ammonium hydroxid and titrate as above. The 

 method is said to be rapid and exact, being designed for the use of pharmacists 

 in preparing sprays for viticulturists. 



General method for the analysis of the ashes of body fluids. W. Mestrezat 

 {Jour. Pharm. ct Cliiiti., 7. so:, 7 {1913), No. 2, pp. 60-65; abs. in Jour. Chem. 

 Soc. [London], IO4 {1913), No. 605, II, p. 2U)-—A description of a general 

 method whereby phosphoric acid, iron, aluminum, lime, and magnesium can be 

 determined in the same sample of ash from a body fluid. Sodium and potassium 

 are estimated in a separate sample of ash. 



A new method for determining lactic acid in organic substances, A. Bellet 

 {Compt. Rend. Soc. Biol. [Paris], 74 {1913), No. 15, pp. 900-902, fig. 1; abs. in 

 Chem. Ztg., 37 {1913), No. 72, p. 725). — In this method the lactic acid is con- 



