952 



SCIENCE 



[N. a Vol. XXXIX. No. 1017 



tose and lactose. A copper reduction is then run 

 on an aliquot of the solution and the amount of 

 copper reduced by 1 gm. of the sample is calcu- 

 lated. From this value and the combined polari- 

 zation of the maltose and lactose the percentages 

 of these sugars are calculated by a formula. 



The analyses of some commercial infant foods 

 by this method are given. 



The Determination of Tannin in Tea: H. C. 



Fuller. 



The powdered tea is first extracted with pe- 

 troleum ether, vehieh is discarded, and then per- 

 colated with 50 per cent, alcohol. The alcoholic 

 solution is precipitated with an excess of lead ace- 

 tate solution and the whole made up to a definite 

 volume. An aliquot of this is then talien and the 

 excess of lead precipitated with hydrogen in the 

 presence of sodium hydroxide, the lead sulphide 

 being filtered into a tared Gooch, washed and 

 dried over sulphuric acid. A blank is run at the 

 same time and the difference in lead figures is a 

 measure of the lead taken up by the tannin. 



A Eapid Method for the Determination of Sodvum 



Chloride in Butter and its Substitutes: T. M. 



Rector. 



The salt is determined by titration with silver 

 nitrate with chromate indicator, in a water solu- 

 tion of a weighed sample of butter in the presence 

 of the butter fat. Some results are given to show 

 that the butter fat does not interfere with the ac- 

 curacy of the method. 

 A Mapid Method for the Determination of Un- 



saponifiaile Matter in Fats and Oils: T. M. 



Eector. 



The sample is saponified in the usual manner 

 and the alcoholic soap solution dUuted to an alco- 

 hol content of 55 per cent. The solution is then 

 extracted with light petroleum spirit, the solvent 

 evaporated, and the residue dried in vacuo and 

 weighed. 



Freedom from emulsification is claimed for this 

 method. 

 The Determination of Caffein in Coffee and Tea: 



H. C. Fuller. 



The sample is ground so that it will pass 

 through a 60-mesh sieve and a weighed amount 

 boiled with dilute hydrochloric acid; the decoc- 

 tion filtered and the extracting process repeated 

 three times with boiling water. From the filtrate 

 the caffein is removed with chloroform, after 

 rendering alkaline with ammonia, and after re- 

 covering the solvent the crude cafEein is dissolved 

 in acid and precipitated with iodide, and finally 



recovered from the iodide precipitate by treat- 

 ment with sulphite and shaking out with chloro- 

 form. 



The Official Method for Determining Crude-fiber as 

 Applied to Cottonseed Meal: Chas. K. Francis. 



The Arsenates of Lead: H. V. Tartar and E. H. 



Robinson. 



Methods have been developed for the prepara- 

 tion of pure lead hydrogen arsenate and lead pyro- 

 arsenate. All attempts to prepare lead ortho-ar- 

 senate have failed. A new basic lead arsenate has 

 been prepared. The authors believe that lead 

 ortho-arsenate is not a constituent of the ordinary 

 commercial salts used as insecticides. The sub- 

 stance present which has been thought to be the 

 ortho-arsenate is in reality the basic lead arsenate 

 mentioned above. The specific gravity of pure 

 lead hydrogen arsenate is 5.786 and of the basic 

 arsenate is 7.10. Analytical methods have been 

 worked out for the quantitative estimation of lead 

 hydrogen arsenate in the presence of the basic 

 arsenate. This paper will soon be presented in 

 full for publication in the Journal of the Ameri- 

 can Chemical Society. 



The Changes Produced by the Wrapping of Bread: 

 H. E. Bishop. 



The Determination of Lecithin-phosphorus in Mac- 

 aroni and Farinaceous Articles: H. C. Fuller. 

 The macaroni is thoroughly softened with hot 

 water, the mass treated with a large excess of 

 alcohol, the liquid filtered and the solid substance 

 treated with further portions of alcohol; the com- 

 bined alcoholic solutions are evaporated and the 

 residue extracted with ether, which dissolves the 

 lecithin. Phosphoric acid is determined in the 

 latter by ignition of calcium acetate and finishing 

 in the usual way with ammonium molybdate and 

 magnesium mixture. 



Lobster Oil: H. S. Bailey and L. B. Burnett. 



In the cooking of lobsters preparatory to can- 

 ning there is always a layer of oil collected upon 

 the top of the kettles. For a number of years it 

 has been the custom of the packers to skim off 

 this oil and sell it to the dealers in fish oil who 

 doubtless mixed it in with their low-grade prod- 

 ucts. Through the kindness of Dr. W. D. Bige- 

 low we were able last year to obtain a sample of 

 this lobster oil. It is a bright orange red in color 

 and has a characteristic fishy odor and taste. A 

 search of the literature failed to reveal any men- 

 tion of this oU, although Konigi states that the 



1 Chem. Nahr-u-Genussm., Vol. II., p. 493. 



