396 Flora — Estimation of Cadmium taken as the Chloride. 



It will, be seen from these results that it is better to use a 

 somewhat smaller quantity of formaldehyde than was used 

 with the cadmium sulphate ; the current potential should not 

 exceed 8 volts ; w'hile the solution should be rather dilute 

 (60 cm3 ). 



These cautions are of even greater importance when acet- 

 aldehyde is used, if satisfactory results are to be obtained, as 

 the following results show : 



Series C. — Acetaldehyde (95$). 

 Aldehd. Tot. 



Cd. (95$) Cur't = N.D 100 . E.M.F. Time. vol. Cd. fd. Error. 

 No. grm. cm 3 . amp. amp. vts. min. cm 3 , grm. grm. Notes. 



( not all 

 1.0-1324 2-0 0-2-0-7 0*6-2'l 7*8 30 60 0-1311 —0-0013 ■] out 



( sit. spgy 

 2. 0*1324 1-5 0-2-0-75 0*6-2-25 7*8 30 60 0'1346 + 0*0022 spongy 



( spongy, 

 3.0-1324 0-5 0-2-1-0 0'6-3'0 7'8 65 60 0*1307 —0*00 17 •] not all 



( out 

 4. 0-1324 1-0 0-1-0-75 0*3-2-25 8-0 35 60 0-1328 —0*0001 fair 



VIII. In Solutions containing Formates and Tartrates. 



Like cadmium sulphate, so also cadmium chloride gave nega- 

 tive results when * solutions containing in addition potassium 

 formate in the presence of formic acid were subjected to 

 electrolysis. Moreover, when no formate was added, but 

 formic acid alone, the results were still unsatisfactory. To 

 solutions containing 0*1324 grm. of cadmium in the form of 

 the chloride was added l*5 cm3 of formic acid, the whole diluted 

 to 50 cm3 , and electrolysis conducted under potentials of 7*5 and 

 11*8 volts. In each case the precipitate was spongy and non- 

 adherent, while the solution persistently held traces of cadmium, 

 even after subjecting to the current nearly two hours. 



Solutions containing tartaric acid behaved in a similar man- 

 ner. In the presence of 3 grm. of tartaric acid, under current 

 tensions of 8 and 12 volts, the precipitated metal peeled from 

 the cathode during revolution, the deposit was spongy, and 

 deposition seemed to be complete at no point of the operation. 



