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J. Robertson Knowles, M.D.
JAMA. 1941;116(21):2394. doi:10.1001/jama.1941.62820210002007a.
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Any one who has occasion to examine urines, and especially a person who heats Benedict solution over a Bunsen burner or an alcohol lamp, knows how easy it is to have the solution boil up and, with considerable force, go all over the wall or surrounding objects.

For that reason I have devised a guard for a test tube which is simple, can be easily made, is inexpensive and gives perfect protection.

The guard, as may be seen in the accompanying illustration, is made of an ordinary large light teaspoon, by means of a pair of tin clippers. The handle is cut off from the spoon, which leaves the bowl of the spoon together with 1½ inches of the stem. The bowl of the spoon is then bent down, with the concave surface facing downward. The stem of the spoon is then soldered to a tin spring, which can be


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