50 ON THE CONDUCTIVITY, SPECIFIC GRAVITY AND 



grammes of barium hydroxide in a copper boiler lined 

 with tin, and condensing in a block tin worm. The iirst 

 portion of about 200 cc. that came off, was always thrown 

 away. The water thus purified had at 18 C. a conductivity 

 ranging from .95 x 10~ 6 to 1.03 X 10~ 6 expressed in a Kohlrausch's 

 new unit (Ohm" 1 cm." 1 ) 



The amount of potassium chloride in a solution was deter- 

 mined volumetrically by Mohr's method. Two solutions of 

 KC1, about deci normal, were made by direct weighing of the 

 pure fused salt. These were employed in obtaining a standard 

 solution of Ag NO 3 . Weaker solutions of Ag N0 3 were 

 obtained by known dilution from this standard one. Neutral 

 potassium chromate was used as the indicator. The following 

 results will show with what accuracy this method of titration 

 could be performed : 



(1) 1 cc. solution contained , 0.02444 



(2) 1 cc. 0.02445 



(3) 1 cc. " " 0.02448 



Mean 0.024457 



Thus it seems that results which differed from the mean 

 value by about 0.1 per cent could be obtained. 



The amount of potassium sulphate in a solution was deter- 

 mined gravimetrically by precipitation w r ith barium chloride. 

 Results in this case were found to differ about 0.1 per cent from 

 the mean value, as shown in the following example : , 



(1) 1 cc. solution contained 0.05229 



(2) 1 cc. 0.05238 



(3) I cc. 0.05235 



Mean 0.05234 



The burettes and pipettes used in the above analyses were 

 calibrated by the weight of distilled water they delivered. The 

 burettes had a capacity of 50 cubic centimetres, and were gradu- 

 ated to a tenth of a cubic centimetre. By means of an Erdmann 



3 Kohlrausch u. Holborn: Leitvermogen der Elektrolyte, 1898, p. 1. 



