1891.] [Warwick. 



I. INFLUENCE OF DILUTION UPON THE PRECIPITATION OF CADMIUM. 



Cadmium Cadmium TT o Frpp M T - OH gas per 



taken. deposited. ee acid. Time. minute. 



Grams. Grams. c.c. c.c. Hours. c.c. 



(1) .0994 .... 100 none 1.75 



(2) .0497 .... " " 



(3) .0994 .... " .5 I 



(4) " .0218 "51 



(5) .0497 .0109 " f 



(6) .0248 .0053 " f 



(7) .0124 .0026 " f 



(8) .0062 .0011 " T 5 ? 



In (1) and (2) no free acid was added, and in (3) only .5 c.c. was pres- 

 ent ; all three were failures. The amount of acid was then increased to 

 5 c.c., and the experiment repeated, all the other conditions remaining 

 the same. The deposit was adherent and compact. The poles were 3.16 

 cm. apart, and had an area of (2.85 cm. X 3.8 cm.) x 2. 



II. INFLUENCE OF TEMPERATURE UPON THE PRECIPITATION OF 



CADMIUM. 



(2) was very spongy and was covered with, a white gelatinous deposit 

 resembling cadmium hydrate. The amount of cadmium was then dimin- 

 ished more than half, while the amount of formic acid present was in- 

 creased to 25 c.c. (5) and (6) were somewhat spongy but adherent. The 

 increase was (2QO-40O) .0022 grams, (40O-6QO) .0100 grams, (6QO-80) .0047 

 grams. The amount of metal deposited increased with rise of temperature, 

 being greatest at 80, but the greatest ratio of increase was at 60, being 

 almost five times greater than at 40, and more than twice as great as at 

 80. These results were so different from those obtained with copper 

 that a second series of determinations was made, in which the amount of 

 cadmium in the solution was reduced still more in order to insure a com- 

 pact deposit at the higher temperatures. The results which, were in close 

 accord with those above are as follows : 



Cadmium Cadmium TT ,-. -p - -, OH gas per Temperature in 



taken. deposited. minute. degrees Cent. 



Grams. Grams. c.c. c.c. c.c. 



(1) .0198 .0022 135 15 1.25 2(P 



(2) " .0031 " " " 400 



(3) " .0078 " " " 600 



(4) " .0102 " " " 800 



