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T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
I n the first experirnents (Xovember 8, 1919) there were used 15 in. of twisted tube, made by flattening down completely a section of three-sixteenth in. 0. d. copper tube and twisting it uniformly on a lathe. I n place of the elaborate expansion valve customary in liquefiers, various sorts of valves and orifices, the details of which are not important here, were used. Thermocouples were soldered on a t the top, middle, and bottom of the twisted tuhe, in order to gain some idea of the thermal distribution. This tube was placed in a loosely fitting test tube insulated with cotton wool. The flow of gas used was about 0.2 cu. m. (6 cu. ft.) per niin. The pressure was 220 atm. After thermal equilibrium had been reached, the temperatures of the tube a t the top, middle, and bottom were, respectively, +20", -5", and '-30" C., about what would be expected if there were no interchange. It was thought that this unfavorable result might be due to the fact that the flow outside the tube was not turbulent. Therefore the experiment was repeated, packing the space between the twisted tube and the test tube with coarse copper and aluminium powder. The temperature dropped very rapidly, and within 15 min. liquid air was observed in the bottom of the test tube, the temperature then being at the bottom - B O " , a t the middle -80", and a t the top $20" C. However, as the temperature of the outgoing gas was - 10") the eIEciency of this interchanger was only 40 per cent of theory. I n other
Vol. 14, No. 1
experiments the aluminium powder was replaced by winding a spring of copper wire, as shown in Fig. 2-C. The efficiency for a 46-em. (18411.)interchanger at 0.2 cu. m. (6 cu. ft.) per hr. was 60 per cent. Several twisted tubes in parallel were also tried, and finally Mr. Kelson constructed a complete liquid air machine (Fig. 3), using 2 m. (6 ft.) of twisted tube in the interchanger. This machine had a capacity of 3.51. per hr. liquid air, using an intake pressure of 250, an intake temperature of OD, and a free flow of air of 0.72 cu. m. (24 cu. ft.) per min., or an efficiency of about 70 per cent. Such liquefiers would seem to have a great use for laboratory purposes. Their cost is but a fraction of the usual liquefier, their size is small (the height of the can in Fig. 3 is 12 in.), and as they use only 2 m. (6 ft.) of copper tubing for the interchanger, the time necessary to run the machine before it begins to form liquid air is much reduced, i. e., 4 min. as compared with 30 min. or so for apparatus of the old type. Interchangers using the twisted tube were also employed in a successful small-scale liquid hydrogen machine. The first designs of this machine (by Rodebush and Latimer and by the author) have, however, been superseded by a very ingenious design of Dr. Latimer's, which uses also the same twisted tube interchanger, and which will shortly be described by him.
CHtANDLER M E b A L AWARD' Introductory Remarks
Chemistry is a basal science underlying the practice of so many human activities that a large proportion of those who By George B. Pegram start with a chemical training must ultimately add to their COLUMBIA UNIVERSITY, NEW YORK,N. Y. equipment other kinds of expert knowledge before qualifying It is our pleasure to be assembled this evening to hear as for their life's work. It is a pity that so few up to now have the Chandler Lecturer for the present year a gentleman who is chosen biological qualifications. Hitherto, the primary trainwidely known among chemists as a pioneer in the very rema-kable ing of most of those who have investigated biochemical problems developments of our knowledge that have been brought about has been biological or medical. Such workers have done very through the study of food accessories such as vitamines. well, but as knowledge progresses it becomes more and more I have the honor of introducing Professor Frederick Gowland netessary that at least some of the work should be done by those Hopkins, of Cambridge University, England. whose chemical knowledge is primary and not secondary. But I have referred to certain disadvantages suffered by biochemistry and you will think of one of them. It has hitherto been difficult to point clearly to a professional (as distinct from Medal Address an academic) career for the young man who thinks of devoting Newer Aspects of the Nutrition Problem himself to the subject. Only in connection with medicine has it hitherto offered professional opportunities, and medical By F. Gowland Hopkins PROFESSOR OR BIOLOGICAL CHEMISTRY, UNIVERSITY OA CAMBRIDOE, CAM- qualification is often first demanded of its votaries. This BRIDGE,ENGLAND state of affairs is rapidly altering. Medical practice can and will NUTRITIONAL STUDIES AS A BRANCHOF APPLIEDCHEMISTRY in the future be helped by workers whose training has comprised something less than a complete medical course. Biochemical The study of nutrition is most productive when it is followed knowledge, moreover, is being sought in many unexpected as a branch of applied organic chemistry. As such it doubtless quarters. The scientific representatives of a firm that manusuffers certain disadvantages. It calls for workers fully ac- factures explosives on a great scale asked me some time ago quainted with the technic of the chemical laboratory and pos- to supply them with a biochemist. At first.it seemed difficult sessed of all that is special in the chemist's mental equipment to know why; but the explanation was simple enough. There and mode of thought. Yet it calls for the application of these is, or was, some anxiety about the supply of glycerol. Fats possessions in a region which is perhaps more remote from the which used to be hydrolyzed are now being used intact in all chemist's experiences during his training than are any other of the sorts of fresh ways, and there is less glycerol as a by-product. many regions in which his science is applied. The successful Hence a desire to develop the methods by which it is produced by pursuit of biochemistry, of which science nutritional studies microorganisms, and the biochemist gets an opportunity. This form a part, calls for a second discipline. The young chemist is but one illustration. I can say with certainty that, in Great having received his primary training must be content to become Britain a t any rate, there is a demand for professional biochemnext something of a biologist; he must know enough about ists which is greatly in excess of the present supply. This I animals and plants to appraise the problems which their or- find satisfactory, for if a profession opens up we shall find it ganization presents; he must acquire a biological outlook. easier to obtain workers who during one period at least of their 1 Presented at Columbia University, New York City, April 18, 1921. career will help advance the science itself.
