. Analysis of milk and milk products. other openings, one for theadmission of a tube through which a slow current of illum-inating gas or hydrogen may be transmitted in order tomaintain a non-oxidizing atmosphere ; the other for a tubefor the escape of steam and ammonium hydroxid. The gas connection may be omitted if, as suggested byStokes, the tubes through which the vapors escape be joinedwith an empty WoolfFs bottle connected by a tube to a ves-sel containing cold water. The flask containing the coppersolution may be placed upon a whitewashed iron plate inorder to show the tint of the solut
. Analysis of milk and milk products. other openings, one for theadmission of a tube through which a slow current of illum-inating gas or hydrogen may be transmitted in order tomaintain a non-oxidizing atmosphere ; the other for a tubefor the escape of steam and ammonium hydroxid. The gas connection may be omitted if, as suggested byStokes, the tubes through which the vapors escape be joinedwith an empty WoolfFs bottle connected by a tube to a ves-sel containing cold water. The flask containing the coppersolution may be placed upon a whitewashed iron plate inorder to show the tint of the solution more clearly. From 25 to 40 c. c. of the copper solution, accuratelymeasured, are placed in the flask, a few fragments of pum-ice dropped in, the tubes and buret adjusted, and the solu- CONDENSED MILK. tion brought to boiling. The liquid containing the lactoseis added in small portions. Since the oxidizing actionoccurs more slowly than with glucose, the additions must beat greater intervals. The process is finished as soon as the. From Allens Chemistry of Urine. liquid is colorless. When common coal gas flows into the flask, a brick-red film of cuprous acetylid is formed on the surface of the liquid from the acetylene present in the gas. It is necessary to verify the correctness of the copper 70 MILK PRODUCTS. solution and this may be done by means of known weightsof pure lactose and sucrose, the latter being first invertedby the citric acid as described. Allen has recently {Analyst, 1895, P- I27) stated thatthe Gerrard-Allen method—titration with cupric cyanid—promises to be the most satisfactory volumetric method forglucose and that it may answer also for other sugars. It isdescribed in full in Pharmaceutical Journal for April 20,1895, also in the Chem. of Urine, above cited, p. 74. The following method is based on the difference in polari-metric reading before and after action of invertase. About30 grams of the sample are accurately weighed in a 100c. c. flask, dilut
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