July, 1934
COMMUNICATIONS TO THE EDITOR
1649
the electrolysis of sodium sulfate and sulfuric acid solutions produces oxygen with a greater proporl6than is present in the water electrohTELSON TIT. TAYLOR tion of 0 DEPARTMENT OF CERAMICS SANDPORD S. COLE lyzed, Lewis and Macdonald [J. Chem. Physics, PENNSYLVANIA STATECOLLEGE STATECOLLEGE, PA. 1, 341 (1933)l reported that no concentration of RECEIVED JUNE 22, 1934 01* was found when deuterium was concentrated by the electrolysis of sodium hydroxide solutions THE RELEASE OF SUPERCOOLING IN CRYOSCOPIC with nickel electrodes. Their method of analysis DETERMINATIONS may not have been sensitive enough, however, to Sir : have detected small shifts in the isotopic compoThe freezing point method of determining sition of the water. We have electrolyzed 5% molecular weights is one of our most useful pro- sodium hydroxide solutions with nickel electrodes cedures and the freezing point lowering of solution and compared the density of water produced by is of great theoretical importance. The precise burning this oxygen in purified tank hydrogen determination of a freezing point may be obtained with that of water produced by burning air in the by supercooling the liquid or solution under suit- same hydrogen. The water from the electrolytic able conditions and releasing the supercooling to oxygen proved to be 7.7 p. p. m. lighter than Camallow the system to come to equilibrium. The bridge tap water and that from the air burned in exact freezing point is determined in this way. the same hydrogen 1.1 p. p. m. heavier. Our reThe release of the supercooling without too great sults thus agree with those of Washburn, Smith supercooling has always been a difficult matter and Frandsen in indicating a small but definite but we have found that a little glass bead may be separation of the oxygen isotopes. cooled on a cake of dry ice (solid carbon dioxide) THECHEMICAL LABORATORIES OF CHARLES H. GREENE COLLEGE AND ROGERJ. VOSKUYL and then introduced into the system and so re- RADCLIFFE HARVARD UNIVERSITY leasing the slightest amount of supercooling. CAMBRIDGE, MASS. RECETVED JUNE25, 1934 Ordinary glass beads 3 mm. in diameter with 0.5 mm. bore may be wet with solvent or liquid and placed on the cake of dry ice for a few minutes and then with forceps may be transferred rapidly THE RELATIVE PROPORTIONS OF DEUTERIUM IN SOME NATURAL HYDROGEN COMPOUNDS to the supercooled liquid. At ordinary laboratory temperatures the little core of ice will not Sir : melt in thirty seconds or more, so there is ample The interesting obscrvations of Lewis [THIS time. The suitably cooled bead, quite free of ice, JOURNAL, 55, 3503 (1933) 1 upon the antigerminawill also release supercooling as it may be intro- tive property of deuterium oxide led us to invesduced into the system while a t a very low tempera- tigate the isotopic composition of the hydrogen ture. If the bead is placed in the closed end of a utilized by plants in the synthesis of organic comthin-walled tube i t may be cooled on dry ice and pounds with an expectation of finding a preferrapidly rolled into the supercooled system. We ence for protium in the biological synthesis. We have readily released liquids or solutions super- find, however, in common with others who have cooled only 0.04’ and with experience a super- reported upon parallel investigations [E. W. cooling of as little as 0.01’ is feasible. This Washburn and E. R. Smith, Science, 79, 188 should be of importance in determining the true (1934); M. Dole, THISJOURNAL, 56, 999 (1934)l since we began our work, that in some natural freezing point of dilute solutions. FRICKCHEMICAL LABORATORY DAVIDE. KENYON sources deuterium is more abundant than in ordiPRINCETON UNIVERSITY GEORGE A. HULETT nary water. PRINCETON, N. J. In our experiments “Mazola” corn oil was RECEIVED JUNE23, 1934 burned in dried air and the products of combustion passed over hot copper oxide before conTHE SEPARATION OF THE OXYGEN ISOTOPES densing the water. Natural gas from northern Sir: Pennsylvania was burned in air of such low huAlthough Washburn, Smith and Frandsen midity that any admixture of the water formed [Bur. Standards J . Res., 11, 453 (1933)] state that with ordinary water was negligible. After care-
Details of measurement and crystal structure data will be given in another publication.
