272 Flora — Estimation of Cadmium taken as the Sulphate. 





Cd. 







Cur't 









Cd. 







taken. 



NaOH. 



KCN. 



read = 



N.D 100 . 



E.M.F. 



Time. 



found. 



Error. 



No. 



grin. 



grin. 



grm. 



amp. 



amp. 



vts. 



min. 



grm. 



grm. 



1. 



0-1491 



1-5 



0-5 



2-5 



7-5 



8 



35 



0-1498 



+ 0-0007 



2. 



0-1491 



1-0 



0-5 



2-5-4-5 



7-5-13-5 



8 



30 



0-1490 



—o-oooi 



3. 



0-1223 



1-5 



1-0 



2-5 



' 75 



8 



35 



0-1225 



+ 0-0002 



IV. In Solutions containing Pyrophosphates. 



Brand* has recommended the use of a solution containing 

 sodium pyrophosphate for the electrolytic estimation of metals, 

 among others, cadmium : and the fitness of this solution for 

 use with the rotating cathode was now studied. In each case 

 the cadmium was precipitated with the indicated amount of 

 sodium pyrophosphate, the precipitate dissolved iu an excess 

 of ammonium hydroxide (series A), phosphoric acid of 1*7 

 specific gravity (series B), sulphuric acid (series C), or hydro- 

 chloric acid (series D), and subjected to the action of the 

 current. The volume of the solution was 60 cm \ 



While fairly accurate results may be obtained, the method 

 is neither so accurate as those previously described, nor are the 

 conditions so flexible. Particular care must be used to avoid 

 too large a current, as a spongy deposit may result. The 

 following were the results obtained : 











Seeies A. 













Cd. 













Cd. 







taken. Na 4 P 2 





Cur't = N.D 100 . 



E.M.F. 



Time. 



fd. 



Error. 



No. 



grm. 



grm. 



NH 4 OH. 



amp. amp. 



vts. 



min. 



grm. 



grm. 



1. 



0-1491 



0-5 



15 6m3 (l:4) 



1-0-1-5 3-0-4-5 



8 



15 



0-1498 



+ 0-0007 



2. 



0-1491 



0-5 



excess. 



04 1-2 



8 



15 



0-1489 



— 0-0002 



3. 



0-1864 



0-5 



15 cm3 (cone.) 



H 3 P0 4 



(l-7sp.gr.) 



0-7 2-1 

 Series B. 



8 



15 



0-1869 



+ 0-0005 



4. 



0-1491 



1-0 



1 -o cm3 . 



1-0 3 



8 



30 



0-1496 



+ 0005 



5. 



0-1864 



1-0 



1-0 " 



1-0-1-5 3-0-4-5 



8 



30 



0-185 7 



— 0-0006 



6. 



0-1491 



1-0 



1-0 " 

 H 2 S0 4 . 



1-0 3-0 

 Series C. 



8 



30 



1493 



+ 0-0002 



7. 



0-1491 



1-0 



'2 cm3 (l :4) ' 



2-0-2-5 2-0-7-5 



8 



30 



0-1501 



+ 0-0010 



8. 



0-1864 



0-5 



excess. 

 HC1. 



1-0-2-0 3-0-6-0 

 Series D. 



8 



35 



0-1862 



— 0-0002 



9. 



0-1491 



0-5 



sit. excess. 



1-0 3-0 



8 



37 



0-1499 



+ 0-0008 



10. 



0-1491 



0-5 



u a 



1-0 3-0 



8 



36 



0-1486 



-0-0005 



* Z. anal. Ch. xxviii, 581 (1889). 



