This name is given to several compounds, prepared by calcination, which take fire when exposed to the air, especially when breathed upon. The following are perhaps some of the best:

1. Heat tartrate of lead in a tube of hard glass, and securely close the tube before the charred residium becomes cold. A little poured out and breathed upon takes fire. The tartrate of lead is made by dissolving separately 2 drs. of tartaric acid and 5 drs. of crystallized acetate of lead in sufficient water, mixing the solutions, and collecting, washing, and drying the precipitate.

2. Calcine tartar emetic in a similar manner, of in a closed crucible.

3. Mix 11 parts of lamp-black with 2 of powdered sulphate of potash, and heat the mixture strongly in a closely covered crucible. The product is so combustible that it can scarcely be transferred to a bottle without danger.

4. Mix 3 parts of powdered alum with 1 of flour, and calcine the mixture in a common phial coated with clay or placed in sand, till it ceases to emit a blue flame. Before it is cold, close it securely with a sound cork or glass stopper.

5. Mix neutral chromate of lead with l-6th its weight of sulphur; triturate them with water sufficient to form a paste, and make it into pellets; dry these perfectly, then heat them in a tube till the sulphur is all driven off, and secure as the last.