Pilot Light Modification for a UV-Lamp One of the methods employed for the visualization of spots in thin-layer or paper chromatography makes use of fluorescence. The chromatographed compounds may fluoresce or may he rendered fluorescent. Furthermore, in tlc a fluorescent indicator may be added to the adsorbent and the spots ran he located by noticing the quenching of fluorescence. A number of ultraviolet light sources for visuahation of spots by fluorescence seem to have a minor drawback, namely, the absence of a pilot light. Since these lamps are used in some kind of a dark room, and the user is warned not to look directly at the light, there is 8. tendency to forget turning off the UV-lamp. This tendency, particularly noticeable among undergraduate students, eventually leads to tube damage and necessitates frequent replacement of the light source. We have modified
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Circuit diagram. S, DPST toggle switch (ON-OFF type); P, pilot light assembly; C, main circuit of the
uv lamp; D, mounting bracket; E, body of the uv lamp.
our UV-lamp by substituting a DPST toggle switch (ON-OFF type) for the usually present SPST power switch and by including a pilot light assembly, equipped with a. suitable resistor for 105125 V ao operation (see part A of figure). Since there is often insufficient space within the UVlamp to have a major portion of the pilot lamp assembly extend inside the lamp, it can be conveniently mounted outside on a suitable bracket (see part B of figure). MITCHELL L. BORKE DUQUE~N UNIVERSITY E PITTSBURGH, PENNSYLVANIA 15219 (41) I ~ v m aH. , M. N. H.,ANDSIITH,J.S., J.Inoro. Nudeor Cham., 31, 3168 (19691. (42) Lonasr~n,G. F., A N D W A L ~ E R E., E., Trans. Faradoy SDE.,49, 228 (1953). (43) BIAACHI,U.,J . Phys. Chom., 69, 1487 (1965): BIANCXI, U..TVRTURRO, A.,ANDB*BILE, G., J . Phys. Chem.,71,3555 (1967).
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F n A N c K , E . U., Bndeououi, 27, 55 (1l)W).
N ~ a x r z ~ oJ., ~ aA ,N D RICE,S. A., J . Chem. Pbys., 36,2710 (19621. I~RAI-.D. J., p11.D. Thesis. University of London, 1965. TOMLZNSON, J. W.. Reu. P w e Appl. Chem. (Australia), 18, 187 (1968). H L ( I OR~., T.,A N D LIT0:;Tz. T. A,, J . A C O U ~ ~ ~SDC. C C IAmel., I 32, 1108 (1960): JANE, G. J., Molted Salts Handbook," Aoademio Pmss, New York, 1967.
