Ordinary casts taken in plaster vary somewhat, owing to the shrinkage of the plaster; but it has hitherto not been possible to regulate this so as to produce any desired change and yet preserve the proportions. Hoeger, of Gmuend, has, however, recently devised an ingenious method for making copies in any material, either reduced or enlarged, without distortion.
The original is first surrounded with a case or frame of sheet metal or other suitable material, and a negative cast is taken with some elastic material, if there are undercuts; the inventor uses agar-agar. The usual negative or mould having been obtained as usual, he prepares a gelatine mass resembling the hektograph mass, by soaking the gelatine first, then melting it and adding enough of any inorganic powdered substance to give it some stability. This is poured into the mould, which is previously moistened with glycerine to prevent adhesion. When cold, the gelatine cast is taken from the mould, and is, of course, the same size as the original. If the copy is to be reduced, this gelatine cast is put in strong alcohol and left entirely covered with it. It then begins to shrink and contract with the greatest uniformity.

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