Encyclopedia of Chemical Reactions
To the Editor: The Encyclopedia of Chemical Reactions, first proposed in 1933 [See J. CHEM.EDUC.,10, 614 (1933)] is now on the road to publication. When it finally reaches the publication stage, much credit must be given to the editors of this JOURNAL. Dr. Reinmuth accepted for publication my first article on the E. C. R., and as a result of this I was brought in contact with nearly a dozen chemists who have either assisted with the abstracting of chemical reactions or given me material aid and encouragement for the project. I also wish to acknowledge my indebtedness to the present editorial staff for publishing my letter in the September, 1940, number of the JOURNAL, which was instrumental in finding a publisher for the E. C. R. as well as another abstractor. The work has now taken on new life. The Chemical Publishing Company, Inc., of New York City, has agreed to publish the Encyclopedia of Chemical Reactions, and authorizes me to say that anyone wishing to join our list of abstractors, will, for a small contribution of his time, receive permanent recognition on the Board of Editors, besides the satisfaction of having helped in compiling a much needed work. One of the abstractors calls i t "an indispensable reference work." Abstracting assignments are still available for most of the German, French, and Japanese journals, and some of the English. Most of the American journals have been covered. Any chemist wishing to become represented on the editorial board of this Encyclopedia should communicate with me, the temporary editor-in-chief. C. A. JACOBSON
Symbols o r Abbreviations?
To the Editor: Many science teachers are annoyed, and students are often confused, by the great difference in usage with regard to the shortened designations for many of the common units which are such an essential part of scientific thinking. Herewith are a few examples taken from current scientific journals or texts: For centimeter(s): cm., cm, cms., Cm., Cms. For cubic centimeter(s): cc., c.c., cmz, c cm., c.cm. For gram(s): g., gm.,gms., g, gs. Would it not be apropos for the JOURNAL OF CHEMICAL EDUCATION to conduct a campaign among science teachers to point out that much of the confusion in connection with the shortened forms in referring to the fundamental units would disappear if scientists as a group would come to appreciate to a greater extent two facts: (1) that the various designations for the units
are symbols, not abbreviutions; and that ( 2 ) teachers should consistently use the symbols as recommended by some body or organization whose standing as a scientific body is unquestioned. In this country, this would logically be the National Bureau of Standards. As custodian of the customary English and metric systems of measurements in the United States, the National Bureau of Standards has made specific recommendations as to the spelling and ~ymbols~of all the commonly used units. Scientific workers as a class might well familiarize themselves with the principles back of the recommendations of the Bureau of Standards : (1) The period is not used in the shortened designation for a unit, thus making it a symbol, not an abbreviation. The only common exception to this rule is where the shortened form is an English word. For example, to avoid possible confusion with the word in, the designation in. is used for the word inch. (2) The exponents "2" and "3" are used to signify "square" and "cubic" instead of the abbreviations "sq." and "cu." This does away with the designation cc. for cma and sq. cm. for cm2. (3) The same symbol is used "for both singular and plural." (4) Small letters are used for all shortened designations, except in the case of A for Angstrom. These principles conform to the recommendations of the International Committee on Weights and Meas..-.,"re. As illustrative of the application of these principles, the following examples can be cited: Unil
Symbol
centimeter enbie centimeter dedmeter foot kilogram millimeter gmm
cm cmx dm ft kg mm
s
Unit milliliter inch micron millimioon milligram pound Square =entimeter
Symbol ml in. I I
m(l ms lb Em.
Strictly speaking, the cubic centimeter and milliliter are not identical because the liter is not exactly a cubic
decimeter. "The liter is a secondary or derived unit of capacity equal to the volume occupied by the mass of one kilogram of pure water a t 4'C." Actually, one liter is equal to 1.000027 cubic decimeters. Hence, the milliliter is larger than the cubic centimeter by 0.000027 cm3. While for all practical purposes this is a negligibly small quantity, nevertheless all volumetric glassware is graduated in liters and milliliters, and chemists as a group should recognize that the designation milliliter is preferable to cubic centimeter as a unit of capacity. C. E. RONNEBERG
1 "Proces-verbaux des seances de 1879," Cornit6 International des Poids et Mesures. 1880, Vol. IV, p. 41.
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