possible to foresee all the new applica tions of nuclear physics to the future Some of these - applications, however, stand out prominently even now. Undoubtedly, during the coming years, the use of tracer isotopes will shed mucfci light upon many of the processes studied in organic chemistry, biophysics, physioLogy, and other branches of science. Where the isotope used as tracers ar-e stable, the mass spectrograph offers very good possibilities of sorting out the tagged atoms because of their difference in mass from the atoms with which they are mixecH. During the Avar, the mass spectrograph ha,s developed from a rather fussy instrument operated only by specially trained physi cists to an instrument for routine analysis in industrial companies, such as in thte oil industry. The use of C13, a stable iso tope of carbon, offers, for instance, good possibilities for tracer work with analyses carried out by the mass spectrograph. Fully as attractive as the- use of stab-le tracer isotopes is the use of radioactive isotopes of which the quantity present is determined by a measurement of the d_ecay radiation emitted. The uses of radLo-
active iodine and phosphorus in physiologica-1 studies have been emphasized. Th«e use of su.ch tracers with beta- and gamma-emission of widely differing pene trating power will stimulate the design of many highly specialized instruments for radioactive measurements. The more sensitive tile detecting instrument, the snialLer in the cmantity of the tracer iso tope which, must be initially used. Such sparimg use will be desirable, since un doubtedly during the next few years the demand for these isotopes will greatly ex ceed the supply. A sparing use is also indicated a t least in work with animals, sincer there is a n upper limit to the amount of ra-dioactivc substance which can be safeby toLerated. I t would thus seem that instruments should be designed whicrli are just as sensitive as possible without sacrificing ruggedness and con venience for use. For instance, in using C 14 , which emits only very soft beta-particles, the design of instrrument cadis for the elimination of heav^ily absorbing windows. An opti mums design would call for the insertion of Ibie sample into the measuring chamber
Agricultural Chemists Discuss Analytical Methods Λ S T A F F REPORT
JL HIS Association of Official Agricultural Chemists, seeking simplification and gen eralization of analytical methods, held its sixteenth annual meeting in Washington, D. C , Oct. 14 through 16. Forced to cancel its 1945 meeting because of Tthe transportation emergency, the 62-yerarold organization was determined to ca~rry on this year despite strike-bound Washing ton hotels. This was shown by the inter est of the 363 persons in attendance. Although founded for the purpose of bringing order to the field of fertilizer analysis, the AOAC has gradually en larged its scope until its official guide mow lists methods of analysis under 42 -different topics. In addition to fertilizers, methods of analysis are listed under such topics as vitamins, dairy products, alcoholic bever ages, insecticides, fungicides, drugs, s,nd many others. These facts were bromght out by the address of the retiring presi dent W. H. Ross, formerly of the Bur-eau of Plant Industry, Soils, and Agricultural Engineering, in which he discussed the role of fertilizers in plant growth in the last 80 years. Dr. Ross declared that more precise methods of fertilizer analysis are needed and t h a t the fertilizer-crop rela tionship should be further studied. Hampered by wartime shortages? of manpower and equipment, the associa-tion has not heen able to carry out a full pro gram of research and development, buat an. V O L U M E
2 4,
NO.
extensive pro-gram has been planned for the ensuing year designed to carry out to the= fullest trie association's aim toward mozre uniform and accurate methods of analysis. Thus very few methods were presented to the meeting for final official certification, but a large number of re ports were presented which were selected to Ibecorne the basis for future study. Exemplifying the work done in the past year was a report b y 0. W. Ford on the use of sodium acetate instead of sodium hy droxide i n trie determination of potash in fertilizers- Seventeen collaborators as sisted in obtaining experimental data, and as a result of their work it was recom-
itself either in the solid form or preferably as a gas—such as carbon dioxide or carbon monoxide. Such a sample may be intro duced directly into a Geiger counter, which offers some technical difficulties, or it may be introduced into an ionization chamber and the small resulting current measured. The development during the war of a very sensitive and very stable electrometer for measuring such currents offers considerable hope a t the present for the latter method. In conclusion, it would seem well to emphasize the constant need in the future for monitoring instruments for personnel protection wherever radioactive materials are used. Bearing in mind the radiation intensities produced by such instruments as the newest cyclotrons and the hetatron, one stands aghast a t the possibilities of radiation damage to personnel by even a few moments of careless operation. The use of even relatively small quantities of radioactive material presents hazards to the workers involved. Hence, such use is justified only when every adequate pro tection to the health of the individuals is. assured.
mended that the study be continued. Cit ing the confusion caused among the col laborators by the phrase "80% alcohol", Mr. Ford suggested that solvent concen trations be expressed as either per cent by volume or per cent by weight in future methods of analysis. Another phase of the association's work was illustrated bjr the study made by E. F . Fleck of the Department of Agriculture on methods for the determination of the para-para isomer of DDT. Six new meth ods were recommended for further work, including an hydrolyzable chlorine method and a total chlorine method. In all, over 130 reports and papers covering almost all the topics within the association's scope were presented at the three-day meeting. Selected to lead the organization for the coming year was J. O. Clarke of the Food and Drug Administration. Other officers elected were G. H. Marsh of the Alabama State Laboratory as vice president and Henry A. Lepper, FDA,secretary-treasurer.
W, IT. lioss, retiring presiflent, Henry A. Lepper, Faod and Drug Adminislrat,iott-9 secretary-treasurer, and J. O. Clarke, newly elected president
21 . N O V E M B E R
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1946
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