The sulphur is not (properly speaking) a necessary ingredient in gunpowder, since nitre and charcoal alone, well mixed, will explode; but the use of the sulphur seems to be to diffuse the fire instantaneously through the whole mass of powder. But, if the following experiments are correct, it should seem that the advantage gained by using sulphur in increasing the force of explosion only applies to small charges; but in quantities of a few ounces, the explosive, or at least the _projecting_ force of powder without sulphur, is full as great as with sulphur. The following are a few out of many trials made at the Royal Manufactory at Essonne, near Paris, in the year 1756, to determine the best proportions of all the ingredients. Of powder made with nitre and charcoal alone, 16 of nitre and 4 of charcoal was the strongest, and gave a power of 9 in the eprouvette. With all three ingredients, 16 of nitre, 4 of charcoal, and 1 of sulphur, raised the eprouvette to 15, and both a less and a greater quantity of sulphur produced a smaller effect. Then diminishing the charcoal, a powder of 16 of nitre, 3 of charcoal, and 1 of sulphur gave a power of 17 in the eprouvette, which was the highest produced by any mixture. This last was also tried in the mortar-eprouvette against the common proof powder, and was found to maintain a small superiority. The powder made without sulphur in the proportions above indicated was also tried in the mortar-eprouvette, and with the following singular result: when the charge was only two ounces it projected a sixty pound copper ball 213 feet, and the strongest powder with sulphur projected it 249 feet; but in a charge of three ounces, the former projected the ball 475 feet and the latter only 472 feet; and on the other hand the great inferiority of force in the smaller eprouvette of the powder without sulphur has been just noticed. It is a fact, known from time immemorial, that by the combustion of bodies caloric is generated, or chemically speaking, is given out in a free state; but the cause was not known until the anti-phlogistic theory of chemistry was established, which abolished as untenable the old doctrine of phlogiston; The quantity of caloric, which passes from a latent to a free state in combustion, as combustion is nothing more than the phenomena occasioned by this transition, is variable; and depends therefore on the substances burnt, and the nature of what is denominated the supporter of combustion.