834 .
INDUSTRIAL A N D ENGINEERING CHEMISTRY
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Vol. 14, No. 10
the three Huoresoent bulbs. The lamp-starters project through the switch box and can he replaoed without opening the box. A cord from the switch box leads directly to a 110-volt alternatr ing current outlet. Dimensions and construction details'are not included here because they are not rigidly fixed but depend on materials a t hand in the laboratory and shop. The following electrical equipment is necessary: 3 G . E. Msrda (F)Euoreacent T-5Ismps. 6 watts. daylight, 0.625-inch diameter. 9-inch length $0.90 eaah 3 G. E. Euoreseent lamp ballasts. catalog No. 58GSC0 0.79 eaoh 3 G. E. fluoroeseent lamp-atsrter FS-5. for use with ballast 0.37 each 3 pair8 of Buoresoent lamp sockets. G. E. type T-5 0.54 pair
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I.~I~I>"uI"ry
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U I I V W I I Y U
The lamp is relatively inexpensive compared with other good microscope lamps, and its only disadvantage seems to be inadequate intensity of light for high-magnification photomicroscopy. The illustrations show how compactly the lamp
USEWITH BINOCULAR MICROSCOPE
tor. The brass tube also dlows the reHector t o he -partly rotated
Acknowledgment Appreciation is expressed to R. D. Spencer, undermechanic in the shop, who did the constrnction work.
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position dong the rod. Cible f c o i the reflector enters switch box, M (Figure 3), which also houses the three ballasts.and attached lamp-starters, N , necessary for i n d i ~ d u doperation of
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This report represents the reeults of cooperstive work between the Bureau of I":.."" 1,":1^_1 L('^L^^ 7", ^I T.L-.!. ..,'L,lD L. -,.:~~.--!. ~e Y..llrY uIIllcii " ~ ~ ~ , ~ - = ,", ,~ ~,," uvlverslry o1 _lYa,
Alabama. Publiahed by permiasion of the Director, ~~~e~~ of ~ i " ~ .
A Heating Device for hcrobealrers, r 1;xsks, and Centrifuge Tubes C. R. NOLLER Department of Chemistry, Stanford University, Calif.
of small beakers, Erlenmeyer flasks, and 'I centrifuge tubes for the purpose of causing solution of a compound or evaporation of a solvent is often attended by
solution with water or be insufficiently hot. An ordinary hot plate does not give adequate contact with centrifuge tubes. For beakers and flasks the hot plate is almost never a t the inconvenience and annoyance. If a free flame is used, the desired temuerature, which results in too slow a rate of beating solvent may catch fire, while steam may contaminate the if it is too low or vi0lent bumping if the plate is too hot. The device illustrated has been in use in t he author's laboratory for several years and h as proved very satisfactory. Wells are 5we,h d & d m bmss b/orX b'ored in a brass block to accommodate the c7mm. O.,Z.) I I s m . Standard sizes of small centrifuge tubes. 6.3r.n 0-v-l I ).sIF1. Z.fnrn.Cr-n*J x 3,ec-,. 1'0 this is bolted a copper tray which carries I b n m . ( 0 - 8 7 I Q.'*. ,nun. c y f e r S h ,3.amm.o=7 x + . O r , " . a foot to prevent tipping. For use the block and tray are placed on a 6-inch hot plate. TVhen temperature equilibrium between the ot plate, tray, and air is reached, one has a P /s cm. radual change in temperature from the block to the end of the tray, and beakers or NLm. Hasks need only be shifted from front to back to have the contents boil, simmer, or just keep warm. If metals other than brass and copper axe used or the dimensions are changed, it may be necessary to alter the length of the tray or the thickness of the __ 6cm. metal sheet in order to get the desired temperature change from front to back. The brass blockmay, of course, be wrapped with resistance wire and heated electrically, but Q.smm. the author prefers the simpler device. ~ n w neaug
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