Daylight running lamp

Figure 6. Data on the direct exposure of filter paper (FP) and bleached pulp (BP) summarizing the results in terms of the percentage of links broken versus footcandle hours of exposure to "daylight" fluorescent lamps. Each set of symbols signifies a different experimental run the shaded data points refer to the present results shown in Figures 3 and 5.

Purification of anthracene. Dissolve 0-3 g. of crude anthracene (usually yellowish in colour) in 160-200 ml. of hexane, and pass the solution through a column of activated alumina (1 6-2 X 8-10 cm.). Develop the chromatogram with 100 ml. of hexane. Examine the column in the light of an ultra-violet lamp. A narrow, deep blue fluorescent zone (due to carbazole, m.p. 238°) will be seen near the top of the column. Immediately below this there is a yellow, non-fluorescent zone, due to naphthacene (m.p. 337°). The anthracene forms a broad, blue-violet fluorescent zone in the lower part of the column. Continue the development with hexane until fluorescent material commences to pass into the filtrate. Reject the first runnings which contain soluble impurities and yield a paraffin-hte substance upon evaporation. Now elute the column with hexane-benzene (1 1) until the yellow zone reaches the bottom region of the column. Upon concentration of the filtrate, pure anthracene, m.p. 216-216°, which is fluorescent in daylight, is obtained. The experiment may be repeated several times in order to obtain a moderate quantity of material. 

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