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 first 
portion of about 200 ce. that came off, was always thrown 
away. The water thus purified had at 18° C. a conductivity 
ranging from .95 x 10-® to 1.03 x 107° expressed in *Kohlrausch’s 
new unit (Ohm7! em.—!) 
The amount of potassium chloride in a solution was deter- 
mined volumetrically by Mohr’s method. Two solutions of 
KCl, about deci-normal, were made by direct weighing of the 
pure fused salt. These were employed in obtaining a standard 
solution of Ag NO,. Weaker solutions of Ag NO, 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 ce. solution contained....., 0.02444 
@) lace: 2s ct wen.» O102445 
(G) aebace: Y icsene OO2446 
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 with 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 ce. solution contained...... 0.05229 
(2) lsc: a : wovtee OOSZaS 
(3) ice: ‘ sate O05235 
Mean .2 ae 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 
1 Kohlrausch u. Holborn: Leitvermégen der Elektrolyte, 1898, p. 1. 
