206 EXPERIMENT STATION RECORD. [Vol. 37 



For the analysis of such soluble sulphites as anhydrous sodium sulphite the 

 solution of the solid salt directly in an excess of an iodiu solution containing 

 sufficient hydrochloric acid and the determination of the excess iodin with 

 thiosulphate is recommended. This procedure eliminates several sources of 

 error, due to oxidation of the salt by agents other than the iodin solution. 



The separation and estimation of butyric acid in biological products, I, 

 I. K. Phelps and H. E. Palmer {Jour. Biol. Chem., 29 {1917), No. 2, pp. 199- 

 205). — A method for the separation of butyric acid from formic and acetic 

 acids by treating their barium salts with an excess of quinin sulphate, extract- 

 ing the quinin butyrate with carbon tetrachlorid, crystallizing, weighing, and 

 identifying it by its melting point is described. 



A table showing the melting point and approximate solubility In carbon 

 tetrachlorid of the quinin salts of formic, acetic, propionic, butyric, and sul- 

 phuric acids is submitted. The solubilities of the propionate and butyrate are 

 so nearly the same that only a partial separation can be effected. The differ- 

 ence in the solubilities of the formate and propionate is, however, so much 

 greater that their separation is effecteil easily. 



Thiobarbituric acid as a qualitative reagent for ketohexose, G. P. Plai- 

 BANCE (Jour. Biol. Chcm., 29 {1911), No. 2, pp. 201, 20S).— The author, at the 

 Iowa Experiment Station, recommends the use of thiobarbituric acid as a test 

 for ketohexoses as follows : 



The sample to be tested is treated in a test tube with sufficient hydrochloric 

 acid and water to bring the acid concentration to 12 per cent. Tlie mixture is 

 then heated to boiling, cooled under the tap, and a few drops of thiobarbituric 

 acid solution (in 12 per cent hydrochloric acid) aiUled. If a ketohexose was 

 originally pre.sent an oraiige-coloreil precipitate forms on standing; if only 

 aldoses were present the solution may become yellow but no precipitate results. 

 It is indicated that barbituric acid can not W u.><ed in place of the thiobarbituric 

 acid, as the condensation product is nnich more soluble. 



Nitrogen in amino form as determined by formol titration, in relation to 

 some other factors measuring quality in wheat flour, C. O. Swanson and 

 E. L. Tague {Jotir. Amer. Chcm. Soc, S9 {1917), No. S, pp. 4S2-491, figs. 5).— 

 The authors, at the Kansas Exi>eriment Station, have shown " that a compara- 

 tively large amount of nitrogen in amino form, as determined by the metho<l 

 of precipitation with phosphotungstlc acid, is an indication of certain undesir- 

 able qualities in flour. The.so qualties in sound flour are of the same kind aa 

 those denoted by ash and acidity. Nitrogen in atnino form, ns nieiusured by 

 formol titration, is valuable together with the determination of ash and acidity 

 in measuring quality in flour." 



It is indicated, however, that titrable nitrogen is more uniformly distributed 

 in the wheat kernel than are the materials which determine the amount of ash 

 and acidity. In clear and low-grade flours, therefore, as comparetl with patent 

 and straight tlours made from the same wheat, the lncrea.se in tltrnble nitrogen 

 Is not proportional to the increase in ash or acidity. 



Data relative to the ash, acidity, formol titration, and total nitrogen in 10-gm. 

 samples of mill streams, commercial patent flours, commercial straight tlours, 

 commercial clear flours, and commercial low-grade flours are submitted. They 

 ■how that the lower grades of flour, such as the clear and low-grade, made from 

 sound wheat, do not contain nitrogenous substances measured by formol titra- 

 tion in as large a proportion as ash and acidity. 



See also previous notes ( E. S. R., 30, p. 555 ; 33, p. 160. ) 



The amino-acid nitrogen content of the blood of various species, J. C. 

 Bock {Jour. Biol. Chan., 29 {1911), No. 2, pp. i9i-i98).— Tabulated analytical 

 data of the amino-acid nitrogen per 100 cc. of ox, calf, sheep, pig, cat, dog. 



