Answers to Correspondentsby@scientificamerican

Answers to Correspondents

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Mixing Metals.—All the hard gray American charcoal iron, of which car wheels and all such work are made, requires more heat and a longer time to melt than soft iron, especially Scotch pig, which is the most fluid and the easiest to melt of any iron. Consequently, unless the melter exercises good judgment in charging, the Scotch pig will melt and run off before the car-wheel iron is melted. If G. H. P. be particular in the quality and strength of his iron, he will make better results by using soft American charcoal pig, with old car-wheel iron. It will make stronger castings, mix better, and melt more uniformly; but he should always recollect in charging his furnace that soft iron will melt before hard in the same position, in the cupola. I also think he had better use a larger proportion of soft pig, as every time cast iron is melted it becomes harder, so much so that iron which can be filed and turned with ease, when re-cast will often be found too hard to work.—J. T., of N. Y. Hardening Tallow.—If E. H. H. will use one pound of alum for every five pounds of tallow, his candles will be as hard and white as wax. The alum must be dissolved in water, then put in the tallow, and stirred until they are both melted together, and run in molds.—F. O. H.

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