Electrical Conductance in Absolute Ethyl Alcohol. 



107 



salts of N/50 dilution were made up in this same manner at the begin- 

 ning of our work, but this dilution was omitted later as unnecessary. 

 Let us notice a few of the necessary steps in the titrations. All 

 such were made in 70 c.c. solution (50 c.c. water, 10 c.c. acid, and 

 approximately 10 c.c. ethylate). The carbon-dioxide-free air was 

 allowed to bubble through the solution for 2 minutes before titration. 

 It was found that the presence of some alcohol retarded the end-point 

 and a number of titrations were made throughout the year to enable 

 us to correct for this. We found as a result of our work : 



70 c.c. water and c.c. alcohol required 0.03 c.c. to produce color. 

 60 c.c. water and 10 c.c. alcohol required 0.04 c.c. 

 50 c.c. water and 20 c.c. alcohol required 0.05 c.c. 



Therefore it was necessary to apply this correction, as our accuracy 

 in titration was made to check to 0.02 c.c. 



After calculating the amounts necessary, 100 c.c. N/100 salt solution 

 in absolute alcohol at 25 was prepared, placed in a 150 c.c. glass- 

 stoppered Erlenmeyer flask, and sealed with rubber cement until the 

 conductances were to be determined. It was possible to make up 

 three or four different mother solutions of various organic salts in one 

 day, another day being devoted to the dilution down to weaker con- 

 centrations, measurement of the conductances, and calculation of results 

 for each salt. These last three operations on a single salt at various 

 dilutions we have designated as a "run." 



It is deemed advisable at this point to introduce an example of the 

 Calculations upon which a single salt was prepared as described above : 



Acid orthonitrobenzoic, CvHsC^N. Strength of standard HC1, 0.10027. 



I. Standardization of the Ethylate. 

 10.005 c.c. HCl used in each titration. 



Ethylate burette. 



II. Standardization of the Organic Acid. 

 10.005 c.c. acid used in each titration. 



Ethylate burette. 



Mean 8.08 less 0.04 correction = 8.04 



c.c. ethylate. 



10.005 : 8.04 : : x : 0.10027 

 x =0.1248 normality of the ethylate. 

 To make 100 c.c. N/100 salt solution 



requires 8.015 c.c. 



Mean 8.04 less 0.04 correction = 8.00 



c.c. ethylate. 



8.04 : 8.00 : : 0.10027 : x 

 a; = 0.09977 normality of organic acid. 

 To make 100 c.c. N/100 salt solution 



requires 10.02 c.c. plus 0.01 c.c.; 



excess equals 10.03 c.c. 



