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 winte...