The Electrolytic Determination of Molybdenum.

Abstract

THE ELECTROLYTIC DETERMINATION OF nOLYBDENUM. BY LILY GAVIT KOLLOCK AND EDGAR F. SMITH. Recehed July 5. rgor ORE than twenty years ago Smith,' in describing his ex-M perience in the electrolysis of solutions of ammonium molybdate, wrote : l ' The deposition, although complete, was so very slow that this method of determination was practically of little value." During the last few months attention has again been given in this laboratory to the subject. Sodium molybdate (Na2Mo0,.2H,O) was dissolved so that 0.1302 gram of molybdenum trioxide was present in 125 cc. of solution, which was exposed for several hours to the action of a current of 0. I ampere and 4 volts. The temperature of the electrolyte was 75' C. No ~IOLYBDENUM-SULPHUR RATIO. UNIVERSITY OF PENNSYLVANIA. A COMPARISON O F THE SOLUBILITY OF ACETYLENE AND ETHYLENE.

The Mercury Cathode and its Applications.

“…There may also be mentioned the difficulties in washing and in drying the amalgam (155,170). Again, losses may occur during the washing of the amalgam (78,83) and during the drying of the amalgam (owing to the explosive evaporation of the alcohol or ether used in the process). Another error may be introduced by the solvent action of the electrolyte on the glass of the cell in basic solutions (1), although not in acidic ones (130).…”

“…The amount of mercury is governed by the use to which the cell is to be put, whether as a means of estimation or of separation. When weighing of the cell was contemplated, early workers sought to reduce the weight as much as possible and normally used 40-80 g. of mercury (1, 4,78,83,116). When the use of the cell as a means of separation became predominant, the need for conservation of weight disappeared and the amount of mercury used soared rapidly.…”

“…Bóttger recommends the addition of a small quantity of nickel amalgam before electrolysis, and of sodium acetate before breaking the current (18). It is interesting to note that it was because of the low results obtained by Price that doubts concerning the reliability of the mercury cathode first arose (132,133,134) and this resulted in careful reexamination of the procedure (83,130). Baxter and his associates used special mercury cathode cells for the determination of the atomic weight of zinc (6,9).…”

Metal Coatings

“…Molybdenum was one of the earliest additions to be used generally in the austenitic chromium-nickel steels of the so-called type (about 18% chromium and 8% nickel). Almost 20 years ago, John A. Mathews, one of the pioneers in this field, wrote (5) Molybdenum in amounts of from 2 to 4% is probably the most generally useful of all the additions to 18-8 ... it enhances general corrosion resistance against many chemicals and so far as the writer is aware never lowers it.…”