OF CERTAIN ORGAXiC BaSKS AND ACIDS. — CREIGHTON. 157 



A 2 o-normal soiiition of mannite and boric acid, whose 

 small negative temperature coefficient was compensated with 

 potassium chloride (0.06g. per liter of the mannite soltition), 

 was used as the electrolytic resistance. 



A diagram of the complete apparatus is shown in figure 2. 

 A and I are the accimiulator and induction coil. AV. AY'. W 

 and W" are the arms of the bridge (W and W are 5 mm. 

 in diameter, and AV" and W" are O.Smm.) ; D and B are two 

 resistances which remain constant dtiring an experiment; 

 K' and Iv" are variable condensers ; T is the telephone : X is 

 the cell for the unknown resistance ; S is a two-way switch for 

 introducing X behind W or in shunt with it. and C is a com- 

 mutator tised for making D and B eqtial. 



The resistances W. AV, AY", and AY'" were calibrated by 

 means of a known electrolytic resistance in the cell X. By 

 tising the same cell, for the acetophenone soltitions of the 

 stibstances under investigation, their resistances were readily 

 calculated from the length of resistance Y" required to give 

 a balance^. 



In order to test the accuracy of this method, the conduc- 

 tivity of a sample of ordinary distilled water, the condttctivity 

 of which was also meastired by the Xohlrausch method, was 

 determined. By the first method it was fotmd that at 15°.0 

 K = 1,23 10~"^. and by the second method, at the same teni- 

 perattire. that /c ^ 1.17 10~^. 



The acetophenone tised in the folloAving meastirements was 

 first pttrified by distillation and recrystallization. This 

 acetophenone had a specific condttctivity of « = 2.02 10'^. 



The measurements given in the following tables were all 

 made at room temperattire (16-17°). 



]. For a detailed description of the method, apparatus, etc., «ee 3Ialtby. M. E. 

 loc eit. 



Proc & Trans. X. S. Ixst. Sci.. Vol. XIII. Traxs. U 



