Secrets of Wise Men: Chemists and Great Physicians

Break up the glue and soak in the water for a few hours, then heat by water-bath until melted. Next add the glycerine and heat together for some time to evaporate part of the water, and then strain into the pan, which should be placed perfectly level and filled about two-thirds full; skim with a card to free from bubbles, and set away to cool. An improvement consists in adding one ounce of carbonate of barium to the fluid while warm. The composition should be made somewhat softer for winter use than for summer, which can be done by adding a little larger proportion of glycerine. Another way to make the composition is to soak over night in cold water best gelatine or glue 1 part, and the excess of water poured off. The glue is then warmed in a water-bath with the addition of from 10 to 12 parts of glycerine, to which may be added 4 to 6 parts of finely ground heavy spar, and one part dextrine thoroughly mixed by constant stirring. (In summer less glycerine.) The letter or sketch to be duplicated is written on a sheet of paper with ink specially prepared for the purpose. For the original it is best to use smooth, well-sized writing paper, allowing the ink to dry without using a blotter. After writing the original place it face downward on the pad, and rub it gently with the hand to insure contact at every point. Let it remain from two to six minutes, according to the number of copies you wish to print. In cold weather it should be left longer, as it requires more time for the composition to absorb the ink. Remove the original carefully, and a reversed impression will be observed on the pad. To take off copies lay dry sheets of paper on the reversed impression, press gently, and remove quickly. When you have taken all the copies you require wash the ink from the surface at once with a sponge and plenty of lukewarm water; never use hot water. The surface of the composition will allow considerable rubbing without fear of tearing it, if not done roughly and carelessly. Be sure your sponge is free from sand and grit, and also avoid scratching with the finger nails. Always wash the surface with a sponge before using, and dry with a newspaper. In cold weather if the composition feels chilled it will not absorb the ink properly, and the copies will be faint unless it be carefully warmed to a moderate temperature. Attention to these details will produce the most gratifying results.