Editors' Column
established in 1874. The first professor of chemistry A. Velkov appointed in 1875, and a laboratory of chemistry opened in 1876."
MOLECULAR MOVEMENT STUDIED BY LASER
Two scientists from the Akron University's Institute of Polymer Science have reported at the national meeting of the Society of Rheology (St. Paul, Minn., Oct. 1922) the development of a laser device for measuring molecular movement. Coherent red light from a sixfoot laser tube is passed through a solution of polymer macromolecules, whereupon a Doppler shift occurs that is detected by a photoelectric cell. Circuitry developed by the researchers, Dr. J. E. Frederick and Thomas F. Reed, filters noise and separates and records various frequencies and their harmonies. The laser tube for the apparatus is mounted on a one-ton concrete slab supported by steel " I " beams, and the entire system of laser tube, glass vessel for sample, and photocell are supported on heavy springs to absorb vibrations above 10 Hz. We are encouraged to remark that although the implementation •of laser devices in 'analytical and associated instrumentation has been slow, there are a t least encouraging signs that progress is being made, however deliberate the pace continues.
No sacrifice in response or efficiency. Choose a Sargent combination pH electrode by size alone.
Both of these Sargent combination pH electrodes cover the entire pH range from 0 to 14 pH. Both offer fast, linear r e s p o n s e even in highly acid solutions. Response to alkali ions is insignificant below pH 12.5 (at higher pH, response is low and stable). Both electrodes achieve high efficiency, with a millivcIt/pH response close to the Nernst coefficient. And you get this kind of performance over a range of 0 to 80°C. These electrodes also feature all-glass, shock-resistant construction. No rubber or plastic to contaminate samples. No pockets to trap solutions or hamper cleaning. Stainless-steel caps provide sure, strong clamping. What's the différence, then, between these two combination pH electrodes? Size alone. For samples as small as Vz ml or those in extremely confined volumes, choose the miniature electrode (priced at $42.00). Otherwise, your best choice is the standardsize ($40.00). Both come with connecting cable and plugs to fit all popular pH meters. Call your Sargent man or write to us for a closer look at these combination pH electrodes or for data on our complete line of glass and reference electrodes.
NEW MASS SPECTROMETER
A new mass spectrometer which weighs less than 2 oz, using three mesh electrodes has been developed by General Electric. Ions in gases are sorted according to their masses in the three-dimensional quadrupole electric field inside the electrodes, and a electron multiplier device is used to measure the number of trapped ions. Further information will appear in a later issue.
SARGENT-WELCH Scientific instruments, apparatus, chemicals. Sargent-Welch Scientific Company 7300 N. Under Ave.; Skokie, Illinois 60076 Chicago/Anaheim/Birmingham/Cincinnati Cleveland/Dallas/Denver/Detroit Springfield, N.J./Toronto/Montreal/Vancouver
Circle No. B5 on Readers' Service Card
ANALYTICAL CHEMISTRY, VOL. 4 1 , NO. 14, DECEMBER 1969
·
71 A
