252 Gooch and Beyer — Use of the Filtering Crucible. 



Obviously this process of electrolytic analysis is fairly 

 rapid, easily executed, and accurate ; but the desirability of 

 quickly removing the liquid from the deposit after stopping 

 the current is evident. 



Second Process. 

 In Table II are given results obtained as in the preceding 

 process excepting the single point that the liquid was drawn 

 off while the current was still running. In these experiments 

 the filtration was effected by removing the cooler, taking off 

 the caj3 and band from the crucible, and quickly swinging into 

 place the filtration apparatus shown at the right in figure 2. 

 The liquid was then drawn through the crucible and replaced 

 by wash water until the current ceased to flow because there 

 was no electrolyte to carry it. The apparatus was washed 

 with water and finally with alcohol, and the crucible and con- 

 tents were dried for periods of ten minutes at 100°-110°, to 

 constant weight. 



Table II. 



Second Process : Electrolysis and nitration without interruption of the 



current. 

 Vol. Theory 



CuS0 4 .5H 2 of H 2 S0 4 for Copper 



taken liquid (1 : 1) Current Time copper found Error 



grm. cm 3 , cm 3 , amp. volt. niin. grm. grm. grm. 



(1) 0-5030 50 5 | 4 I 7 ] 30 °' 1281 O' 12 ? 8 ! —0-0003 



(2) 0-5008 50 5 j 4 1 ^ "1 40 °' 1275 O' 12 ' 75 ! O'OOOO 



(3) 0-5024 50 5 j 4 j 7 j 40 °* 1280 0'1277f —0-0003 



(4) 0-5014 50 5 I 4 {7 j 40 °" 1277 0*1276* -0-0001 



(5) 0-5018 50 5 I 4 I ° j 40 V' 12 * 8 O' 12 ' 78 * 0-0000 



* No copper in filtrate or in washings. •)• Trace of copper in filtrate. 



J Trace of copper in washings. 



These results are plainly excellent. 



Third Process. 



When a deposit is so loosely adherent as to be moved by 

 the liquid it may be compacted upon the filtering felt by keep- 

 ing the liquid in process of filtration and constant motion 

 through the cell to the receiver. The adjustment of appara- 

 tus for this purpose is shown in figure 3. Here the electro- 

 lytic cell rests in the crucible holder fitted to a separating 

 funnel used as a receiver and connected into the vacuum 



