Make 200 good cupels, as follows: Take the box used for the purpose and fill with bone-ash, add water and mix. Use as many ounces of water as pounds of bone-ash. The right amount of water has been added when the bone-ash loses its harsh, gritty feeling, and at the same time is not pasty. A small amount of potassium carbonate (2 per cent solution) may be added to assist in cementing the bone-ash, but this is not necessary. When the bone-ash is thoroughly mixed and is of the right consistency, sift through a twenty mesh sieve and then place a sufficient amount in the mould, and hammer down firmly; two hard blows are enough; do not use anything but the wooden mallet in striking the mould. Place your cupels on a board and set away to dry.