Richard K. Brown Rincon High school
Tucson, Arizono
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Melting- Point Apparatus
The usual experiments in determining the melting points of various solids involve heating mineral oil, sulfuric acid, etc. These setups leave much to be de~ired,and commercial melting point apparatus may be too costly for general adoption. By spending approximately $8 for some readily available materials, and with some help from the school machine shop, a very workable instrument may be constructed. The heatimg source is a soldering imn tip which is regulated by a rheostat. An aluminum cylinder, approximately 7/8 by 31/2in., is drilled to fit over the soldering iron element. Another hole is drilled into the top of the cylinder to accommodate a thermometer.
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From one to three small holes about in. in diameter and ll/& in. long are drilled from the top of the cylinder quite close to the outside of the cylinder to hold the melting point capillary tubes. A small portion of the side of the cylinder is filed away to expose the small capillary holes. -
Parts: Rheostat, 1 5 0 0 ohms, 2 5 watts type H (Allied Order No. 31M2451; soldering iron element tip,type 5 3 6 (No. 46N582)i SPST toaale switch. CH7501-K12 (No. 3589331-&minum minibox, 3 X 4 X 5 in., CU 3005A (No. 80P3651.
NSF support was received for this project.
A glass sleeve fitted over the aluminum cylinder helps retain heat. A small wire hook may be attached to the cylinder so that it can be removed and doused in water to cool it rapidly so another determination may be quickly run.
Volume 42,
Number 8, August 1965
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433
