. Journal. be (this is easilydone by a small pump or aspirator attached to thethree-way cock <?) till all theairhasbeen displaced by thegas, when c and d are turned, so as to shut off the gas inB from the air outside, as well as from communica-tion with A. Water is then poured into A, and byturning c can be gradually admitted into B, so as toabsorb the soluble constituents. When the absorp-tion is completed, the residual volume of gas is readoff, the difference between this and the originalvolume (lOOcc, since B holds exactly lOOcc. whenfull) directly giving the percentage of soluble gases.
. Journal. be (this is easilydone by a small pump or aspirator attached to thethree-way cock <?) till all theairhasbeen displaced by thegas, when c and d are turned, so as to shut off the gas inB from the air outside, as well as from communica-tion with A. Water is then poured into A, and byturning c can be gradually admitted into B, so as toabsorb the soluble constituents. When the absorp-tion is completed, the residual volume of gas is readoff, the difference between this and the originalvolume (lOOcc, since B holds exactly lOOcc. whenfull) directly giving the percentage of soluble gases. So much for the modes of measurements by meansof Hempels gas burette, and we have next to considerthe apparatus employed for the subsequent treatmentof the sample—viz., the absorption of its respectiveconstituents. Hempel used for this purpose twoapparatus, which he terms the simpleand the compoundabsorption pipette. The simple absorption pipette(Fig. 3) essentially consists of two glass bulbs a and b,. connected by means of the bent glass tube d.( The Fig. also contains a small third bulb c,which, however, is not strictly required ; most of thesimple absorption pipettes, in fact, only consist of thetwo bulbs a and 6.) The lower bulb b is connected witha capillary U-tnbe u, fixed on a white porcelain platemm . the whole apparatus is mounted on a suitablewooden stand. The absorbing agent is introducedinto 6, which must lie completely filled with the solu-tion, whilst the second bulb a remains nearly slight modification of the simple pipette is shownin Fig. 4. It is intended for the use of solid re-agentssuch as phosphorus, and merely differs from theordinary burette just described, by that the secondbulb 6 is made more of cylindrical shape, and has anopening at the bottom Is communicating with an aperture / in the stand, through which the solidi. aunt can be introduced. The apparatus shown inthe Fig. represents such a pipette filled with a solu-tion of KHO and con
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectchemist, bookyear1882
