Subnntted by: Roger Whcaton, Michigan State University, East Lansing Phecked by: Gordon Anderson, Fairview Junior High School, St. Paul, Minnesota
PREPARATION
may 116%hastcned by stirring. The xater sohble dyc does not color the carbon tetrachloride, and the oil boluble dye does not color the mater Iodine crystals placed on the surface of the water move to the center and dissolvr in the rarbon tetrarhloride.
Yrovide petri d~shes,dist~lledwater, ear1)on tetrachloride, water and oil soluble dyes, and iodine crystals, IXl the petri dish to a depth of I/#-inch nith vatcr and add sufficient carbon tetrachloride to form a rirrular pool in the center of the dish. The ~ a t e shot r Id flax to the outside exposing the nppcr surface of the rarbon tetrachloride 1%hich will be loxer than the m-atrr surfare.
REMARKS
DEMONSTRATION
Add a very small quantity of a dye to the natc,~and 011wve solution and diff~sion If desir(~d,the p~oress
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A Compact Light Box S t d m t t t d by. man
Robert Barnard, Montana State College, Boze-
The light box described here is suitable for use in uw classroom box include: minimum size t o accept containers up t o 2 liter capcity, light weight, and even low intensity lighting from the hotton~or behind the containers. This is mzde pos8iblc by u ~ i n g a single 25 watt fluorescent light and curved polished aluminum reflectors. Ilemovable masks allow unused portions of the box to he darkened or make etkctive backgrounds (each mask is reversible, dark on one side and light colorcd on the other). We are present,ly using disposable masks made of cardboard which comes in the color8 mentioned and making cut-out,s in these niaslcs to accon~modatevarious sizcd flasks. The minimum ma.m between the horizontal and vert,ical glass panels is important to achieve the elfect of even lighting a t this portion oi a conVainer,
I n practice we light from beneath colored reactions such as 20-25 in "Tested Demonst,rations." Back light in^ is effective u1.m ) ~ r e c i ~ i t ~. , ~r ~c liwm~ W~. ~I ~ ~ ; I I C < I \\". V \ , N m, t , . I L!, ,&,Iv:,w? * * ( tlsv lwl w e T , , d~~t n . ~ i wt1.v n., 4 ~ i w l i v d
