UC-NRLF T LIBRARY OF THE UNIVERSITY OF CALIFORNIA, RECEIVED BY EXCHANGE Class Electrolytic Separations Possible With a Rotating Anode JTHESIS Presented to the Faculty of the Department of Philosophy of the University of Pennsylvania, in Partial Fulfilment of the Requirements for the Degree of Doctor of Philosophy, BY DONALD S. ASHBROOK, PHILADELPHIA, PA. 1904 PHILADELPHIA THE JOHN C. WINSTON CO. 1904 Electrolytic Separations Possible With a Rotating: Anode THESIS Presented to the Faculty of the Department of Philosophy of the University of Pennsylvania, in Partial Fulfilment of the Requirements for the Degree of Doctor of Philosophy, BY DONALD S. ASHBROOK, PHILADELPHIA, PA. 1904 ^e; . PHILADELPHIA THE JOHN C. WINSTON CO. 1904 cto 5 This work was undertaken at the suggestion of Dr. Edgar F. Smith. The author takes this opportunity to thank him for his many kindnesses and personal interest during the six years in which he has been a student. INTRODUCTION. A year ago, Exner* working in this laboratory demon- strated that by using a high current density and great pressure with a rotating anode it was possible to deter- mine fourteen metals in the electrolytic manner much more rapidly than had ever been done previously The deposits were in all instances most satisfactory. These results constituted an important advance in electro- chemical analysis. The objection once put forward, that too much time was necessary in such work, was com- pletely removed. Indeed Exner's investigation has wholly revolutionized electro-analysis. However, there remained the question as to how far this procedure would lend itself to the separations of the several metals. This point became the guiding thought in the investigation here presented. The apparatus and method of procedure have been fully described and amply developed by Exner, so that they need not be again entered upon, but the separations which were successful and have value will now be described in such detail as to guide all persons who may be desirous of repeating them. * Jour. Am. Ch. Soc., Vol. XXV, p. 896. 173155 EXPERIMENTAL PART. COPPER. i. FROM ALUMINIUM. (a) In sulphuric acid solution. Dilution 125 cc., o.i cc. of sulphuric acid (Sp. G. 1.83), N.D IOO = 4-5 amperes and 14 8 volts. Time 10 minutes. Copper present 0.2696 gram, aluminium 0.2500 gram. Copper found 0.2696 gram-o.2696 gram-o.2695 gram. Like all deposits from this electrolyte they were some- what spongy but perfectly adherent. On increasing the amount of sulphuric acid to i cc. the deposit was much smoother and more uniform. (b) In nitric acid solution. Dilution 125 cc., i cc. of nitric acid (Sp. G. 1.43), N. D IOO = 3 amperes and 4-5 volts. Time 20 minutes. Copper present 0.2874 gram, aluminium 0.2500 gram. Copper found 0.2873 gram-o.2874 gram-o.2874 gram. The conditions given here were most satisfactory for copper in this electrolyte. A speed of 300-400 revolutions per minute is best. Too high a speed or less time gives a low result. (c) In phosphoric acid solution. Dilution 125 cc., 10 cc. of phosphoric acid (Sp. G. 1.085), 50 cc. of a 10% solution of Na2HPO4, N.D IOO = 5 amperes and 6 volts. Time 10 minutes. Copper present 0.2742 gram, aluminium 0.2500 gram. Copper found 0.2741 gram-o.2742 gram-o.274i gram. The conditions recorded here gave the best deposits. They were spongy in appearance but perfectly adherent and were washed with ease. On dissolving them in nitric acid and testing with an ammonium molybdate solution, a slight deposit of ammonium phospho-molybdate was (5) obtained in every case. This amount of phosphorus was so slight, however, that it would not affect the weight of the deposit materially. 2. FROM ANTIMONY. (a) In tartrate solution. Dilution 125 cc., 8 grams of tartaric acid, 25 cc. of ammonia, N.D IOO = 5 amperes and 5 volts. Time 10 minutes. Copper present 0.2742 gram, antimony 0.2500 gram. This experiment resulted in the precipitation of nearly all of the antimony with the copper. 3. FROM ARSENIC. (a) In ammoniacal solution. Dilution 125 cc., 25 cc. of ammonia, 2.5 grams of ammonium nitrate, N.D IOO = 5 amperes and 7 volts. Time 15 minutes. Copper present 0.2742 gram, arsenic o. 2 500 gram. Cop- per found 0.2740 gram-o.274i gram-o.274i gram. The deposit was dark in color, smooth and adherent. (b) In nitric acid solution. The conditions were the same as were used in the separation of copper from aluminium. Copper present 0.2742 gram, arsenic o. 2 500 gram. Cop- per found .2741 gram-.2742 gram-.2742 gram. 4. FROM CADMIUM. (a) In nitric acid solution. The same conditions were used as in the separation of copper from aluminium. Copper present 0.2742 gram, cadmium 0.2500 gram. Copper found 0.2742 gram-o.2742 gram-o.2742 gram. 5. FROM CHROMIUM. (a) In sulphuric acid solution. The same conditions were used as in the separation of copper from aluminium. Copper present 0.2890 gram, chromium 0.2500 gram. Copper found 0.2890 gram-o.289i gram-o.289o gram. Better deposits were obtained by starting the current at 3 amperes and raising gradually to 5 amperes. (6) In nitric acid solution. The same conditions were used as in the separation of copper from aluminium. Copper present 0.2874 gram, chromium 0.2500 gram. Copper found 0.2874 gram-o.2875 gram-o.2874 gram. If the current was allowed to run above 3 amperes the deposit weighed too high. A blank was run with chro- mium alone under the same conditions, which gave 0.0022 gram of a metal showing all the tests for chromium. (c) In phosphoric acid solution. The same conditions were used as in the separation of copper from aluminium. Copper present 0.2742 gram, chromium 0.2500 gram. Copper found 0.2742 gram-o.274o gram-o.2742 gram. Slight traces of phosphorus were found in the deposits. 6. FROM COBALT. (a) In nitric acid solution. The same conditions w^ere observed as in the separation of copper from aluminium. Copper present 0.2874 gram, cobalt 0.2500 gram. Cop- per found 0.2875 gram-o.2874 gram-o.2874 gram. Cobalt was partially deposited in sulphuric acid and phosphoric acid electrolvte. 7. FROM IRON. (a) In sulphuric acid solution. The same conditions were used as in the separation of copper from aluminium. Copper present 0.2696 gram, iron 0.2500 gram. Copper found 0.2694 gram-o.2695 gram-o.2696 gram-o.2696 gram-o.2695 gram. (6) In nitric acid solution. The same conditions were observed as in the separation of copper from aluminium. Copper present 0.2874 gram, iron 0.2500 gram. Copper found 0.2873 gram-o.2875 gram-o.2874 gram. (c) In phosphoric acid solution. The same conditions were used as in the separation of copper from aluminium. 8 Copper present 0.2742 gram, iron o.2Soc gram. Copper found 0.2743 gram-o.274i gram-o.2742 gram, with 8 amperes in 5 minutes. Cu = 0.2741 gram. Slight traces of phosphorus were found in these deposits. 8. FROM LEAD. (a) In nitric acid solution. The results were low. Lead seems to hold back the last traces of copper. 9. FROM MAGNESIUM. (a) In sulphuric acid solution. The same conditions were used as in the separation of copper from aluminium. Copper present 0.2696 gram, magnesium 0.2500 gram. Copper found 0.2696 gram-o.2696 gram-o.2695 gram. (b) In nitric acid solution. The same conditions were used as in the separation of copper and aluminium. Copper present 0.2874 gram, magnesium 0.2500 gram. Copper found 0.2874 gram-o.2874 gram-o.2875 gram. If the current was allowed to run too high a white de- posit was obtained which dissolved in sulphuric acid without effervescence. A neutral solution of Mg. (NC>3)2 acidified with one drop of nitric acid and electrolyzed with a current 2-3 amperes and 15 volts for 20 minutes gave a white coating weighing 0.0334 gram. (b) In phosphoric acid solution. The same conditions were used as in the separation of copper from aluminium. Copper present 0.2742 gram, magnesium 0.2500 gram.. Copper found 0.2742 gram-o.274o gram-o.2742 gram. 10. FROM MANGANESE. (a) In sulphuric acid solution. The same conditions were used as in the separation of copper from aluminium. Copper present 0.2890 gram, manganese 0.2500 gram. Copper found 0.2890 gram-o.289i gram-o.289o gram. (b) In nitric acid solution. The same conditions were observed as in the separation of copper from aluminium. Copper present 0.2874 gram, manganese 0.2500 gram. Copper found 0.2872 gram-o.2874 gram-o.2874 gram. Only a part of the manganese was deposited as peroxide on the anode, but no floating particles were observed in the liquid. 11. FROM NICKEL. (a) In sulphuric acid solution. No satisfactory deposits were obtained. All conditions were tried. The nickel seems to hold the copper back when they are present in equal amounts. When the copper is greatly in excess it carries the nickel down with it. (b) In nitric acid solution. See the thesis of Exner.* (c) In phosphoric acid solution. Nickel is partially deposited in this electrolyte. 12. FROM URANIUM. (a) In sulphuric acid solution. The same conditions were used as in the separation of copper from aluminium. Copper present 0.2890 gram, uranium 0.2500 gram. Copper found 0.2889 gram-o.289o gram-o.289o gram. (b) In nitric acid solution. The same conditions were observed as in the separation of copper from aluminium. Copper present 0.2742 gram, uranium 0.2500 gram. Copper found 0.2742 gram-o.274i gram-o.2742 gram. 13. FROM ZINC. (a) In sulphuric acid solution. Dilution 125 cc., i cc. of sulphuric acid (Sp. G. 1.83), N.D IOO = 3-5 amperes and 5 volts. Time 10 minutes. Copper present 0.2890 gram, zinc 0.2500 gram. Copper found 0.2890 gram 0.2889 gram-o.2889 gram-o.289o gram-o.2888 gram. The current was raised gradually. The deposits were excellent. * Jour. Am. Ch. Soc., Vol. XXV, p. 896. JO (b) In nitric acid solution. See the thesis of Exner.* (c) In phosphoric acid solution The same conditions were observed as in the separation of copper from alumin- ium. Copper present 0.2635 gram, zinc 0.2500 gram. Copper found 0.2635 gram-o.2633 gram-o.2634 gram. Slight traces of phosphorus were found in these deposits. CADMIUM. 1. FROM ALUMINIUM. (a) In sulphuric acid solution. Dilution 125 cc., i cc. of sulphuric acid (Sp. G. 1.83), N.D IOO = 5 amperes and 5 volts. Time 10 minutes. Cadmium present 0.2727 gram, aluminium 0.2500 gram. Cadmium found 0.2728 gram-o.2727 gram-o.2727 gram. The deposits were excellent, although slightly spongy, but perfectly adherent. (b) In phosphoric acid solution. Dilution 125 cc., 10 cc. of phosphoric acid (Sp. G. 1.083), 50 cc. of a 10% solution of Na2HPO4, N.D IOO = 5 amperes and 7 volts. Time 10 minutes. Cadmium present 0.3032 gram, aluminium 0.2500 gram. Cadmium found 0.3031 gram-o.3032 gram-o.3032 gram. These deposits all showed slight traces of phosphorus. 2. FROM CHROMIUM. (a) In sulphuric acid solution. A beautiful silver white crystalline deposit of cadmium was obtained, which always weighed low. (b) In phosphoric acid solution. The same conditions were observed as in the separation of cadmium from aluminium. Cadmium present 0.3600 gram, chromium 0.2500 gram. Cadmium found 0.3603 gram-o.36oo gram-o.36oo gram. * Jotir. Am. Ch. Soc., Vol. XXV, p. 896. II 3. FROM COBALT. (a) In sulphuric acid solution. Cobalt is partially precipitated in this electrolyte. (b) In phosphoric acid solution. Cobalt is partially precipitated in this electrolyte. 4. FROM IRON. (a) In sulphuric acid solution. The same conditions were used as in the separation of cadmium from alumin- ium. Cadmium present 0.3032 gram, iron 0.2500 gram. Cad- mium found 0.3031 gram-o.3032 gram-o.3032 gram. (b) In phosphoric acid solution. The same conditions were used as in the separation of cadmium from alumin- ium. Cadmium present 0.3032 gram, iron 0.2500 gram. Cad- mium found 0.3032 gram-o.3O3i gram-o.3032 gram. 5. FROM MAGNESIUM. (a) In sulphuric acid solution. The same conditions were observed as in the separation of cadmium from alu- minium. Cadmium present 0.2727 gram, magnesium 0.2500 gram. Cadmium found 0.2727 gram-o.2728 gram-o.2727 gram. (b) In phosphoric acid solution. The same conditions were used as in the separation of cadmium from alumin- ium. Cadmium present 0.3600 gram, magnesium 0.2500 gram. Cadmium found 0.3600 gram-o.3599 gram-o.36oo gram. 6. FROM MANGANESE. (a) In sulphuric acid solution. The same conditions were used as in the separation of cadmium from alumin- ium. Cadmium present 0.2727 gram, manganese 0.2500 gram. Cadmium found 0.2725 gram-o.2727 gram-o.2727 gram. 12 (b) In phosphoric acid solution. The same conditions were used as in the separation of cadmium from alumin- ium. Cadmium present 0.3600 gram, manganese 0.2500 gram. Cadmium found 0.3600 gram-o.36oi gram-o.36oo gram. 7. FROM NICKEL. (a) In sulphuric acid solution. The same conditions were used as in the separation of cadmium from alumin- ium. Cadmium present 0.2727 gram, nickel 0.2500 gram. Cadmium found 0.2727 gram-o.2727 gram-o.2726 gram. (b) In phosphoric acid solution. The nickel was partially precipitated in this electrolyte. 8. FROM ZINC. Zinc always came down with the cadmium in sulphuric acid solution and also in phosphoric acid solution. SILVER. 1. FROM ALUMINIUM. In nitric acid solution. Dilution 125 cc., i cc. of nitric acid (Sp. G. 1.43), N.D IOO = 3 amperes and 3.5 volts. Time 15 minutes. Silver present 0.2600 gram, aluminium 0.2500 gram. Silver found 0.2600 gram-o.2599 gram-o.26oo gram. The deposits obtained in this electrolyte were very poor. The addition of ammonium nitrate helped matters but little. Great care was necessary in washing not to lose some of the deposit. 2. FROM CADMIUM. (a) In nitric acid solution. Conditions same as No. i. Silver present 0.2600 gram, cadmium 0.2500 gram. Silver found 0.2600 gram-o.2598 gram-o.26oi gram. 13 3. FROM CHROMIUM. (a) In nitric acid solution. Conditions same as No. i. Silver present 0.2600 gram, chromium 0.2500 gram. Silver found 0.2601 gram-o.2598 gram-o.26oo gram. 4. FROM COBALT. (a) In nitric acid solution. Conditions same as No. i. Silver present 0.2600 gram, cobalt 0.2500 gram. Silver found 0.2600 gram-o.2598 gram-o.26oo gram. 5. FROM IRON. (a) In nitric acid solution. Conditions same as No. i . Silver present 0.2600 gram, iron 0.2500 gram. Silver found 0.2599 gram-o.26oo gram-o.26oo gram. 6. FROM LEAD. (a) In nitric acid solution. Conditions same as No. i. Silver present 0.2600 gram, lead 0.2500 gram. Silver found 0.2596 gram-o.26oi gram-o.26oo gram. 7. FROM MAGNESIUM. (a) In nitric acid solution. Conditions same as No. i . Silver present 0.2600 gram, magnesium 0.2500 gram. Silver found 0.2599 gram-o.26oo gram-o.26oo gram. 8. FROM MANGANESE. (a) In nitric acid solution. Conditions same as No. i . Silver present 0.2600 gram, manganese 0.2500 gram. Silver found 0.2600 gram-o.26oo gram-o.2599 gram. 9. FROM NICKEL. (a) In nitric acid solution. Conditions same as No. i. Silver present 0.2600 gram, nickel 0.2500 gram. Silver found 0.2599 gram-o.2599 gram-o.26oo gram. 10. FROM ZINC. (a) In nitric acid solution. Conditions same as No. i . Silver present 0.2600 gram, zinc 0.2500 gram. Silver found 0.2601 gram-o.2598 gram-o.26oo gram. Silver was also tried in potassium cyanide solution but owing to the great number of metals deposited from this electrolyte and the high current density used with the rotating anode no success was attained. MERCURY. While mercury itself is easily determined by the rotating anode, it is almost impossible to make any separations of it from other metals, owing to the readiness with which the metal forms amalgams. Aluminium and magnesium were the only successful separations. From both of these metals the mercury was deposited in beautiful mirror-like form. Iron, chromium, nickel, cobalt, zinc, manganese and cadmium were tried in both sulphuric and nitric acid solutions without success. UNIVERSITY OF CALIFORNIA LIBRARY BERKELEY THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW Books not returned on time are subject to a fine of 50c per volume after the third day overdue, increasing to $1.00 per volume after the sixth day. Books not in demand may be renewed if application is made before expiration of loan period. 4 A0N 6 1920 50m-7,'16 /u