To the Editor: Professor Fisher's table in his Letter to the Editor (p. 259 of May, 1957 issue) is essentially the same as one given by Bunn ("Chemical Crystallography," Oxford, 1946, p. 52) which perhaps, in the interest of those who prefer information served up highly condensed, should have been specifically cited by Mysels. Furthermore, Professor Fisher rightly concludes that on morphological grounds alone, there is no suitable or satisfactory terminology for crystal classes. If, on the other hand, as is done by the International Union of Crystallography, structure is used as the basis of classification, then crystals with one threefold axis are all trigonal and those with a sixfold axis are hexagonal, the term rhombohedra1 being used for trigonal structures with rhombohedral lattices, the others being simple trigonal, much the same as a cubic crystal may be either simple, body centered, or face centered.
T o the Editor: As a reader of the JOURN.~L, and as a scientist, permit me to protest your publishing in the February issue the article by Henry M. Leicester, "Recent Methods for the Prevention of Dental Caries." I thought that it was the rigid practice of editors of scientifi magazines to have articles reviewed by qualified experts. If this had been done in this case, you would have found that a number of dental, medical, and water distribution experts insist that: (1) dental caries is not significantly decreased by the ingestion of fluoride; (2) objectionable mottling of the teeth does occur a t the proposed concentration of 1 p.p.m.; (3) there is no adequate evidence that life-long ingestion of fluoride a t this low level is completely harmless; (4) there is no moral or legal justification for the compulsory medication of the whole population for the alleged protection of a few against a non-communicable disease; (5) the water distribution systems should not be tampered with for a purpose which has nothing to do with the distribution of pure water. The proper places to discuss this controversial issue are the dental societies, as regards efficacy, the medical societies, as regards safety, and the public at large, as regards the method of offering fluoride to those want it. But please let us concern ourselves here with chemical education, and not with one-sided presentations of dubious issues.
GEORGE CALIMG.LERT HOBART AND WILLIAM SMITH COLLEGES GENEVA,NEW YORK
JOURNAL OF CHEMICAL EDUCATION
