Sec. XLVIII. Of Inflammable Balls.
Count Rumford (Bibliothèque Physico-Economique, 1812) has invented a composition, which is very inflammable, and, as it is used in balls, is for that reason so called. Equal parts of clay, pitcoal, and charcoal of wood, are mixed together, (having previously reduced them to powder), and made into a consistence with water fit to roll into balls. These balls are then dried for use.
They may be rendered more inflammable, by soaking them in a strong solution of saltpetre.
Count Rumford, when he recommended the use of clay with coal, was aware, that, in the combustion of coal, a considerable part of the heat was lost; whereas, although clay is incombustible, a greater part of this heat is retained by the clay, and given out gradually.
The inflammable ball may be considered more in the character of an economical fuel than in any other.
The only inconvenience attending these balls is, that, when prepared without nitre, which must add to the expense, they do not readily inflame; and, therefore, a fire must first be kindled, before they are used.
While noticing the use of clay in this manner, we may remark, that the economical brick, as it is called, is made nearly in the same way.
Two parts of clay, separated from stones, are mixed with one part of pitcoal. After the fire is kindled, the coal burns in the same manner, and the clay bakes.
Another composition is given in the Bibliothèque Physico-Economique, for March, 1812. It is composed of potters' clay, cow dung, street dirt, saw-dust of wood, turf, horse dung, straw, and tan. Besides these, pitch, tar, oils, and other combustible substances, are occasionally used, either with the above, or mixed with pitcoal in powder.
Observations on this preparation may be seen in the work quoted, or in the Archives des Découvertes, v, p. 137.