Flora — Estimation of Cadmium taken as the Sulphate. 275 

 Series A. — Urea, 3 grms. 





Cd. 







Cd. 







taken. 



Cur't = 



N.D 100 . Time. 



found. 



Error. 



No. 



grm. 



amp. 



amp. min. 



grm. 



grm. 



1. 



0-1019 



0-25-0-5 



0-75-1-5 35 



0-1018 



—o-oooi 



2. 



0-1223 



0'2 



0-6 35 



0-1223 



±0-0000 



3. 



0-1223 



0-25-0-5 



0-75-1-5 30 



0-1230 



+ 0-0007 







Series B.— Formalin, 2 cm3 . 







1. 



0-1019 



o-i -1-0 



0-3 -3-0 30 



0-1018 



—o-oooi 



2. 



0-1223 



0-2 -1-0 



0-6 -3-0 30 



0*1224 



+ 0-0001 



3. 



0-1223 



0-2 -1-0 

 Series C 



6 -3 30 

 !.— Acetaldehyde, 2 cm3 . 



0-1225 



+ 0-0002 



1. 



0-1019 



0-1 -0-8 



0-3 -2-4 35 



0-1022 



+ 0-0003 



2. 



0-1223 



0-1 -0-8 



0-3 -2-4 30 



0-1228 



+ 0-0005 



3. 



0-1223 



0-1 -0-8 



0-3 -2-4 30 



0-1222 



—o-oooi 



Since the conductivity of the solutions containing urea and 

 the aldehydes is comparatively low, the effect of adding elec- 

 trolytes was tried. The rate of deposition was very much 

 increased, but the precipitated metal showed such tendency 

 toward sponginess that this procedure is not to be highly 

 recommended. The following were the tests tried : 



Serier A.— Urea, 3 grms.; Time, 20 min.; E.M.F., 7*8 volts 

 0'5 amperes; N.D ]0 o, 1*5 amperes. 



No. 

 1. 

 2. 



3. 



4. 



Cd. taken. 

 grm. 



0-1019 

 0-1019 



0-1019 



0*1019 



0-1019 



Electrolyte. 

 K a SO 4 ,0-5grm. 



same 

 (H 5 SO,(l:4) 

 ( 5 drps. 



same as 3 

 (H 2 S0 4 (l:4) 

 ( 8 drps. 



Cd. found, 

 grm. 



0-1031 

 0-1031 



0*1023 



0:1027 



0-1027 



Error, 

 grm. 



+ 0-0022 

 + 0-0022 



+ 0-0004 



+ 0-0008 



+ 0-0008 



Current read, 



Notes. 

 spongy. 



u 



good ppt. 

 sit. spgy 



Series B.— Formaldehyde (formalin), 2 - 5 cm ; Time, 20 min.; E.M.F. 7*9 

 volts. Current started at 0*5 ampere and rose to 1*0 ampere at the end 

 of the process (N.D 10 o = 1 "5-3'0 amperes.) In each case the precipitate 

 was good. Ten drops of dilute sulphuric acid were added to increase 

 the conductivity of the solution. 



Cd. taken. Cd. found. Error. 



No. grm. grm. grm. 



1. 0-1019 0-1020 +0-0001 



2. 0-1019 0-1019 ±0-0000 



VIII. In Solutions containing Formates. 



The use of the solutions containing potassium formate and a 

 slight excess of formic acid has been recommended,* but I 



* Warwick, Z. anorg. Ch., i, 285 (1892); Avery and Dales, J. Am. Ch. 

 Soc. v xix, 380(1897). 



