The German _Verein zur Bedförderung des Gewerbefleisses_ offers the
following, among other prizes, for essays on technical subjects: One
thousand marks _(£50)_ for a comparative examination of the various
methods hitherto used for determination of the hardness of metals, with
an exposition of their sources of error and limits of accuracy. It is
stated, as a reason for offering the prize, that the methods for making
the required tests are but yet little developed, and that no thorough
comparison has yet been made of the various methods. The hardness of
metals and alloys being a very important factor in several processes, a
really good method of determination is highly desirable. Three thousand
marks (£150) for the best essay on the resistance to pressure of iron
work in buildings, at increased temperatures. It appears that after a
certain fire in a manufactory at Berlin, the police authorities issued
notices concerning the use of cast-iron columns in high buildings, and
that these notices encountered great opposition in many quarters, as it
was considered that neither practice nor theory had yet shown any proof
that cast iron is less trustworthy than wrought iron in cases of fire.
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A brilliant black varnish for iron, stone, or wood can be made by
thoroughly incorporating ivory black with common shellac varnish. The
mixture should be laid on very thin. But ordinary coal tar varnish will
serve the same purpose in most cases quite as well, and it is not nearly
so expensive.
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