A treatise on the theory of solution including the phenomena of electrolysis . to make the instrumentavailable for different solvents, whichfreeze at different temperatures. The method of using Beckmannsapparatus is as follows. A weighedquantity of the pure solvent is intro-duced into A, and its freezing point determined by placing in Csome mixture whose temperature is just below the point to bereached. The tube A is then removed, and the solvent weighed quantity of the substance to be dissolved is intro-duced through the side tube D, and the tube replaced. It isbetter to cool it slig
A treatise on the theory of solution including the phenomena of electrolysis . to make the instrumentavailable for different solvents, whichfreeze at different temperatures. The method of using Beckmannsapparatus is as follows. A weighedquantity of the pure solvent is intro-duced into A, and its freezing point determined by placing in Csome mixture whose temperature is just below the point to bereached. The tube A is then removed, and the solvent weighed quantity of the substance to be dissolved is intro-duced through the side tube D, and the tube replaced. It isbetter to cool it slightly below the temperature at which it willfinally stand. This can be done if it be kept quite at undercooled liquid is then stirred by means of the platinumwire, when small crystals of ice form. The temperature rises toa certain point, and then keeps stationary, but will again beginto sink if we go on freezing the solution; for as the solvent isfrozen out, the remaining solution gets stronger, and so hasa lower freezing point. The highest of these temperatures is. Fig. 45. 156 SOLUTION AND ELECTROLYSIS [CH. VI therefore the one giving the freezing point of the solution, theconcentration being corrected for the volume of ice formed. An immense number of observations have been made withone of the many forms of this apparatus. Some of Eaoultsresults are given below. They represent what he calls themolecular depression, that is the lowering which would be pro-duced by one gram-molecule of the substance in 100 grams ofthe solvent. The numbers are calculated from observations onsolutions of much less concentration than this, on the assump-tion that the law of proportionality is still applicable. Solutions in Acetic t Hoffs formula gives 38-8. Methyl iodide 38-8 Butyric acid 37-3 Chloroform 38-6 Benzoic „ 43-0 Carbon disulphide 38-4 Water 33-0 Ethylene chloride 40-0 diethyl alcohol 35-7 Nitrobenzene 41-0 Ethyl 36-4 Ether 39-4 Amyl 39-4 Chloral 39-2 Gl3cerine 36-2
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