. Journal. ium thiocyanate are dissolvedin of water at a temperature of 45°—50° C, and the is immediately cooled; *5 of concentratedhydrochloric acid are added, and the slight reddish colourimc to the presence of ferric sails is discharged by theaddition of a trace of zinc dust ; the indicator becomesred after a few hours by absorption of air; it can bedecolorised again by more zinc dust, but its dolicacybecomes impaired after it has been decolorised severaltimes. For the determination of sugars the authors profer tou c t lie Fehlings solution in the undiluted form. Ten
. Journal. ium thiocyanate are dissolvedin of water at a temperature of 45°—50° C, and the is immediately cooled; *5 of concentratedhydrochloric acid are added, and the slight reddish colourimc to the presence of ferric sails is discharged by theaddition of a trace of zinc dust ; the indicator becomesred after a few hours by absorption of air; it can bedecolorised again by more zinc dust, but its dolicacybecomes impaired after it has been decolorised severaltimes. For the determination of sugars the authors profer tou c t lie Fehlings solution in the undiluted form. Ten freshly-mixed Fehlings solution are raised to the boilingpoint in a flask and the sugar solution, the concentrationof which should be so adjusted that 20—30 correspondto 10 of Fehling, is run into the boiling liquid in smallamounts, the mixture being boiled after each the end of the titration, drops of the liquid arewithdrawn by means of a glass rod and rapidly brought in. jiic. which is closed at one end, has a lengthinn., and an internal diameter of 15 mm. Ati i nil is a rubber stopper, and through this pass:. lain tube f. 250 mm. long and (i mm. in diameter ;i nke k through which the products of corn-to the absorption apparatus; (3) a stouti wire (No. 18, B & S gauge), which extends from orcelain tube c is joined outside the combustion us of rubber tubing to a branched glass tube. one branch d the oxygen or air for the combustion ml through g a piece of stout platinum wire passes ends to h. A thinner platinum wire (No. 29 1 75 m. and weighing about 25 grins., is joined platinum wire at h ; it passes through the i tube and returns on the outside of this as a coil the other platinum wire at j. roll of copper wire gauze 60 mm. long, and the next the closed end as shown. out a combustion, the boat with substance is tube, and the absorption apparatus fixed on. it of oxygen is admitted, and the electric ii the platinum coil is closed. The curren
Size: 2980px × 839px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectchemist, bookyear1882
