A Convenient Device for Dispensing Solid Samples in Teaching Laboratories We have sought a quick, inexpensive, and convenient device for dispensing solid samples to large numbers of students. The ideal dispensing device should (1) minimize waste by controlling the size of the sample; (2) eliminate contamination; (3) permit facile changes in the size of the dispensed sample; (4) require little or no maintenance; and (5) be sufficient,ly simple in o p e r a h n that no instroctian in its use is required. The PAX "Soap Saver" (G. H. Paxwood Mfg. Co., St. Louis, Ma.), one of a variety of devices found in public washrooms, most nearly satisfies these requirements. I t is available in corrosion resistant chromium plate from McMaster-Carr, P. 0. Box 43.55,Chicago, Ill. 60680, under catalog number 277952, among other suppliers, for less than $15. The PAX dispenser is adjustable to deliver ~lsefulsynthetic quantities of most crystalline or powdered reagents. A conical crusher incorporated in the dispensing mechanism breaks up lumps, improving the reproducibility of the sample size. Several of the dispensers are mounted on the laboratory walls. The hopper will hold about 2 lb of sodium chloride. The volume of the delivery is adjusted to correspond t o a slight excess of the reagent which the student accurately reweighs. Most students are familiar with the dispensers; virtually no instruction in their use has been required. Students, realizing that the d i i penser provides very nearly the correct quantity of the needed reagent, are reluctant to take twice or three t,imes the needed amount. I n use, the reagent dispensers should be clearly labeled as such; student5 are likely to wash their hands with the contents. G ~ o n o l :11. Bnos.\~r:n G ~ o n o sT. BIXNKI.:
ILLINOIS INSTITUTE OF TECHNOLOGY ILLINOIS 60616 CHICAGO,
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Journal o f Chemical Education
