. Official and provisional methods of analysis. r the potash bulb. Many analysts preferto replace the bulb F and attached calcium chlorid tube by two U-tubes filled with siftedsoda lime. When the second tube shows a material increase in weight it is placed first,and the first tube refilled and placed in the second position. 169 170 METHODS OF ANALYSIS. dioxid is to be absorbed and attach them to the apparatus. In case two Liebigbulbs are employed, one for potassium hydroxid and the other for sulphuricacid to absorb the moisture given up by the potassium hydroxid solution, weighthem separately.
. Official and provisional methods of analysis. r the potash bulb. Many analysts preferto replace the bulb F and attached calcium chlorid tube by two U-tubes filled with siftedsoda lime. When the second tube shows a material increase in weight it is placed first,and the first tube refilled and placed in the second position. 169 170 METHODS OF ANALYSIS. dioxid is to be absorbed and attach them to the apparatus. In case two Liebigbulbs are employed, one for potassium hydroxid and the other for sulphuricacid to absorb the moisture given up by the potassium hydroxid solution, weighthem separately. If two soda-lime tubes are employed it will be found advan-tageous to weigh them separately and fill the first tube anew when the secondtube begins to increase in weight materially. Nearly fill tube B with hydro-chloric acid (sp. gr. ) and place the guard tube C in position. Then startthe aspirator at such a rate that the air passes through the Liebig bulb at aboutthe rate of two bubbles per second. Open the stopper of the funnel and allow. KSCHOLtai Fig. 9.—Knorrs apparatus for the determination of carbon dioxid ; A, distilling flask fittedto condenser by a ground-glass stopper. B, Reservoir containing acid. C, Soda-limetube fitted to acid reservoir by a ground-glass stopper. D, Condenser. E, Liebig bulbfilled with sulphuric acid. F, Liebig bulb with a solution of potassium hydroxid forthe absorption of carbon dioxid and followed by a calcium-chlorid tube. An additionalguard tube filled with soda lime should follow the tube F, though not shown in the cut. the acid to run slowly into the flask, care being taken that the evolution of gasshall be so gradual as not to materially increase the current through the Liebigbulb. After all the acid has been introduced continue the aspiration and grad-ually heat the contents of the flask to boiling, the bulb in tube B being the flask is being heated the aspirator tube may be removed, althoughmany analysts prefer when us
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