RADIO USED BY JONES IN CHEMICAL RESEARCHES

This article describing the research work to be done by Professor Grinnell Jones G. '05 with his Milton Award is the fifth of a series appearing in the Crimson.

Professor Jones has received an award from the Milton Fund to aid his researches on the electrical conductivity of solutions. By the adaptation of devices from the radio he has been able to make substantial improvements in the methods of measuring the conductivity of solutions and now with the aid of R. C. Josephs 1G., and of Professor E. L. Chaffee '11, radio expert, he is building a Wheatstone Bridge for this purpose, which is expected to be the best in the world.

Audion Vacuum Tube Used

In working with solutions it is necessary to use alternating current because direct current causes chemical action at the electrodes, which would cause gross errors in the measurement. Professor Jones uses as the source of the alternating current an audion vacuum tube hooked up with capacities and inductances so that it "howls", in the vernacular of the radio fan, although in this case it might better be described as "singing" because it gives a beautiful pure note of single frequency, and can be made to give any note desired within the range of audibility.

This has proved to be an important improvement over the older and usual methods of generating current for this kind of measurement as the greater purity of the tone permits a more accurate setting of the Bridge.

Improvement in Grounding

Another improvement is the use of a two-stage audio-frequency amplifier to improve the sensitiveness of the telephone. This permits the use of much weaker currents in the Bridge itself, thereby minimizing disturbing effects due to heating and electrode reactions and increasing the range of usefulness of the apparatus. Another improvement is in the proper grounding of the set to eliminate errors due to electro-static capacity to ground.

The electrical conductivity of solutions is one of their most important properties from a practical and theoretical point of view. Some solutions, such as sugar solutions, are non-conductants of electricity, whereas most salt solutions conduct well and acid solutions the best of all and the conductivity is directly related to other properties of solutions so that accurate knowledge of conductivity is a matter of considerable scientific interest. Professor Jones is planning to make many measurements of this kind, but the improvement in the technique has made all existing standards of reference obsolete and it will first be necessary to compare a few standard solutions directly with mercury which has been adopted by scientists as the standard of reference for all measurements of electrical resistance and conductivity.

In the industrial world the conductivity of solutions is important also, being often an essential part of a manufacturing process.