V ~ L 7, . No. 8
1937
CORRESPONDENCE
Thus the value of "live" exhibits were fully appreciated 130 years ago by Count Rumford and his proposals to insure that character would apply almost equally well today. Unquestionably, working models make "live" exhibits in a museum sense. Why, then, not animate synthesis exhibits by working models? The writer, intending this letter to be in the nature of constructive criticism, hastens to present a possible design for a true "live" chemical exhibit. A shadow box is equipped with many tiny flash-light bulbs arranged in such manner as to indicate structural formulas bearing atomic symbols. These lights, turned on by means of a snap switch, operate a somewhat modified sign-flashing device. The slowly turning sign-flasher first lights a series of bulbs forming the outline of the structural formula for the basic material used as a starting point in the synthesis. Connections made by the sign-flasher successively light bulbs showing the actual process of synthesis exactly as it is accomplished by means of the chemical processes through which it passes. Atoms substituted for others during the process of manufacture are indicated by lights switched off and replaced by others bearing the proper new symbol. The evolution of aspirin from carbolic acid could, by this means, be followed step by step. Very sincerely yours, ,
MUSEUMS OP THE E E A C ZARTS ~ 24 WEST4 0 m STREET NEW YORE CITY
ERNEST E. FAIRBANKS E
C. H., "A Chemical Museum Exhibit," J. CHEM.EDUC., 6. 730--2 (1) SPIERS, (Apr., 1929). (2) Complete Works of Count Rumford, Vol. IV, collected and published by the American Academy of Arts and Sciences. 1875.
Sodium Sulfide in the United States. The growth in domestic production of sodium sulfide from 24,682 tons in 1921 to 46,494 tons in 1927 has enabled the American chemical industry t o supply 90 per cent of domestic requirements of this commodity. The remainder is supplied by imports which averaged about 4500 tons in 1927-28. The increased consumption corresponding t o the above figures is attributable t o greater activities in the chief consuming industries for this commodity, including manufacture and application of sulfur colors, tanning, mining, and rayon. Since sodium sulfide is made from sulfates, c h i d y of barium and sodium, the im.partant changes which are affecting the availability of these salts on the American market must be considered in understanding the economics of the question. Among these are the establishment and growth of the American barium chemical industry, of which sodium sulfide is a co-product, the synthetic nitrogen and hydrochloric acid industries which tend to make the by-product nitre cake unnecessary-Chem. Age
