Artifact no.: CSTM 1978.0006
Source: CN Rail, Montreal

pH is a measure of the acidity or alkalinity of a substance. The Beckman pH meter, model G, introduced in 1937, was the first compact, self-contained portable device of its kind. It did not have to be assembled and the electronics required only minimal adjustment before it could be used. Obtaining a reading was relatively simple and fast. Once the “null balance meter” was adjusted to read zero, the user could simply read the pH value from the pH dial. Its sealed glass electrode was an improvement over the one in common use at that time.

Their sensitivity of the Beckman model G, is comparable to modern instruments which use a sealed glass combination electrode, rather than separate glass and reference electrodes. Modern pH meters also benefit from elimination of vacuum tubes, miniaturization, and the introduction of battery power. The Chemical Heritage Foundation has indentified this pH meter among its finalists for the top 50 commercial chemical laboratory instruments that changed the world in the 20th century.