Welch GENERAL PURPOSE ELECTRIC STIRRER
the ANALYST'S I column l
L.T. Hallett, Editor
INDUCTION TYPE MOTOR
Watt-Type Governor Stabilizes Speed
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I ''HE three-day International Ozone -* Conference, held in Chicago in Novem ber, permitted a thorough presentation of the preparation, properties, reactions, uses, and analysis of ozone. Highlights of the half-day analytical session appear in the News Section. Much attention is being given to ozone and other trace materials in the air in pollution studies. The methods of analy sis, developed so far for traces of ozone, fall into four categories: 1. ible) 2. from 3. 4.
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Optical (ultraviolet, infra-red, vis Chemical—e.g., liberation of iodine potassium iodide Cracking of rubber Effect on plants
There is fair agreement among the vari ous methods, b u t it seems no one is yet ready to agree that any method is entirely satisfactory. The optical methods are rather specific, while the chemical meth ods, which depend on oxidation, can be in serious error, if not carefully controlled. The potassium iodide procedure seems to be the one favored at present and has been subject to elaborate b u t successful in strumentation for automatic and continu ous analysis both in this country and abroad. I t comes as no surprise to analysts that the preparation of a pure standard of ozone is difficult. When preparing a standard of trace amounts, the difficulties are multiplied. This general problem of preparing standards of trace amounts is a major one, which is understood generally by the few scientists whose work forces them to cope with the difficulties. Our old familiar problem of sampling arises in the analysis of the air for ozone where the vagaries of air currents, tem peratures, and air pressure changes make it difficult to obtain accurate values. Such variations are negligible above 30,000 feet, but this level does not always meet the needs of the smog analyst whose main problems are closer to earth. The ozone conference papers will even tually be published by the ACS in the Advances in Chemistry Series. Analysis Defined Frederick C. Strong, associate professor of chemistry a t Stevens Institute of Tech nology, wrote us some time ago about the general definition of analysis, and indi cated that the title of the journal is too restrictive. We are inclined to agree with Professor Strong. At the time the title
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THERMO ELECTRIC MANUFACTURING CO. 4 7 8 HUFF ST., DUBUQUE, I O W A For further information, circle number 47 A-2 on Readers' Service Card, page 73 A V O L 2 9 , N O . 1 , JANUARY 1 9 5 7
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