TECHNICON CONTROLS, INC.
1
the EDITOR'S column L.T. Hallett, Editor ΓΓΗΕ INTERNATIONAL COMMITTEE on Weights and Measures has recommended general worldwide use of a Helium-3 temperature scale derived by Los Alamos Scientific Laboratory scientists. The new scale, "Helium-3 Vapor Pressure Scale of Temperatures," measures temperature in the realm of 0.25° to 3.32° above Absolute Zero Kelvin. The recommendation was an- nounced by Dr. A. V. Astin, Di- rector of the U. S. Bureau of Stand- ards and a member of the Interna- tional Committee. Action was taken at an October meeting in Paris of the Advisory Committee on Thermometry, at which time Dr. Thomas R. Roberts, physicist in the Los Alamos Cryogenics Group, ex- plained the new scale. For more than a decade there was international disagreement over scales set up using the isotope Helium-4. Finally, in 1958 agree- ment on a Helium-4 scale was reached. However, Helium-4 can- not be used for accurate measure- ments at temperatures below 2.2° K. without the use of very complicated apparatus and procedures. The va- por pressure becomes so small it is difficult to measure and the liquid becomes a "super-fluid." In this state the "liquid" will actually crawl uj) the walls of any container. Helium-3 with a higher vapor pressure does not become super- fluid. At 3.32° K., the vapor pres- sure is 3,670,000 times greater than at 0.25° K., permitting very sensi- tive measurements in this range. The new scale involves use of an intricate equation by which tem- peratures can be determined to a few ten-thousandths of a degree. Comparative measurements made with the Helium-4 scale show the new one to be several tenths of a A Student Experiment for Measuring The Half Life of Thoron (Rn ) Welch EMANATION ELECTROSCOPE Student plots radioactivity decay curve and computes half life to within two seconds Adapted from an apparatus originally developed for use at Harvard University by Profes- sors K. T. Bainbridge, Gerold Hollon, and J. C. Street. Radioactive source included No. 619. No. 619 Each, $60.00 Recommended Accessories STOP WATCH, 1/5 second. ELECTRIC STOP CLOCK. No. 823A. Each, $17.75 No. 824L. Each, $39.50 THE WELCH SCIENTIFIC COMPANY ESTABLISHED 1880 1515 Sedgwick Street, Dept. A - 1 , Chicago 10, Illinois, U.S.A. Manufacturers of Scientific Instruments and Laboratory Apparatus AUTOMATIC KARL FISCHER MOISTURE * D P R M : Κ Λ ϊ Ι Ο Ν The Karl Fischer method is now run on Technicon Auto Analyzer... Continuous / Automatic. Appli- cable wherever Karl Fischer reagent is used. In the plant... Auto Analyzer monitors and continu- ously controls moisture in process streams. In the laboratory... Auto Analyzer provides up to 40 determinations an hour automatically. Technicon® AuloAnalyzer® measures many other substances as well. Send for your free methodology literature kit KF2. T E C H N I C O N C O N T R O L S , INC. RESEARCH PARK · C H A U Ν C Ε Υ, Ν . Y. Circle No. 144 on Readers' Service Card VOL 34, NO. 13, DECEMBER 1962 · 7 9 A and Microscope Ionization Chamber Electrostatic Charger, Filter, Radioactive Source, and Emanation Pump.
Transcript of TECHNICON CONTROLS, INC.
the EDITOR'S
column L.T. H a l l e t t , E d i t o r
Γ Γ Η Ε INTERNATIONAL COMMITTEE on Weights and Measures has
recommended general worldwide use of a Helium-3 temperature scale derived by Los Alamos Scientific Laboratory scientists. The new scale, "Helium-3 Vapor Pressure Scale of Temperatures," measures temperature in the realm of 0.25° to 3.32° above Absolute Zero Kelvin.
The recommendation was announced by Dr. A. V. Astin, Director of the U. S. Bureau of Standards and a member of the International Committee. Action was taken at an October meeting in Paris of the Advisory Committee on Thermometry, at which time Dr. Thomas R. Roberts, physicist in the Los Alamos Cryogenics Group, explained the new scale.
For more than a decade there was international disagreement over scales set up using the isotope Helium-4. Finally, in 1958 agreement on a Helium-4 scale was reached. However, Helium-4 cannot be used for accurate measurements at temperatures below 2.2° K. without the use of very complicated apparatus and procedures. The vapor pressure becomes so small it is difficult to measure and the liquid becomes a "super-fluid." In this state the "liquid" will actually crawl uj) the walls of any container.
Helium-3 with a higher vapor pressure does not become super-fluid. At 3.32° K., the vapor pressure is 3,670,000 times greater than at 0.25° K., permitting very sensitive measurements in this range.
The new scale involves use of an intricate equation by which temperatures can be determined to a few ten-thousandths of a degree. Comparative measurements made with the Helium-4 scale show the new one to be several tenths of a
A Student Experiment for Measuring The Half Life of Thoron (Rn )
Welch EMANATION ELECTROSCOPE
Student plots radioactivity decay curve and computes half life to within two seconds
Adapted from an apparatus originally developed for use at Harvard University by Professors K. T. Bainbridge, Gerold Hollon, and J. C. Street.
Radioactive source included
No. 619.
No. 619
Each, $60.00 Recommended Accessories
STOP WATCH, 1/5 second. ELECTRIC STOP CLOCK.
No. 823A. Each, $17.75 No. 824L. Each, $39.50
THE WELCH SCIENTIFIC COMPANY ESTABLISHED 1880
1515 Sedgwick Street, Dept. A - 1 , Chicago 10, Illinois, U.S.A. Manufacturers of Scientific Instruments and Laboratory Apparatus
AUTOMATIC KARL FISCHER MOISTURE
*
D P R M : Κ Λ ϊ Ι Ο Ν The Karl Fischer method is now run on Technicon Auto Analyzer... Continuous / Automatic. Applicable wherever Karl Fischer reagent is used. In the plant... Auto Analyzer monitors and continuously controls moisture in process streams. In the laboratory... Auto Analyzer provides up to 40 determinations an hour automatically.
Technicon® AuloAnalyzer® measures many other substances as well. Send for your free methodology literature kit KF2.
T E C H N I C O N C O N T R O L S , I N C . R E S E A R C H P A R K · C H A U Ν C Ε Υ, Ν . Y.
Circle No. 144 on Readers' Service Card
VOL 34, NO. 13, DECEMBER 1962 · 7 9 A
and
Microscope
Ionization Chamber
Electrostatic Charger, Filter, Radioactive
Source, and Emanation Pump.
