If this salt be mixed, and merely rubbed together with sulphur, phosphorus, charcoal, or indeed any other combustible, it explodes strongly. [Footnote *: According to Sir H. Davy’s new views, just explained, oxy-muriat of potash is a compound of chlorine with oxyd of potassium.] CAROLINE. Like gun-powder, I suppose, it is suddenly converted into elastic fluids? MRS. B. Yes; but with this remarkable difference, that no increase of temperature, any further than is produced by gentle friction, is required in this instance. Can you tell me what gases are generated by the detonation of this salt with charcoal? EMILY. Let me consider . . . . . The oxy-muriatic acid parts with its excess of oxygen to the charcoal, by which means it is converted into muriatic acid gas; whilst the charcoal, being burnt by the oxygen, is changed to carbonic acid gas. --What becomes of the potash I cannot tell. MRS. B. That is a fixed product which remains in the vessel. CAROLINE. But since the potash does not enter into the new combinations, I do not understand of what use it is in this operation. Would not the oxy-muriatic acid and the charcoal produce the same effect without it? MRS. B. No; because there would not be that very great concentration of oxygen which the combination with the potash produces, as I have just explained. I mean to show you this experiment, but I would advise you not to repeat it alone; for if care be not taken to mix only very small quantities at a time, the detonation will be extremely violent, and may be attended with dangerous effects. You see I mix an exceedingly small quantity of the salt with a little powdered charcoal, in this Wedgwood mortar, and rub them together with the pestle-- CAROLINE. Heavens! How can such a loud explosion be produced by so small a quantity of matter? MRS. B. You must consider that an extremely small quantity of solid substance may produce a very great volume of gases; and it is the sudden evolution of these which occasions the sound. EMILY. Would not oxy-muriat of potash make stronger gunpowder than nitrat of potash? MRS. B. Yes; but the preparation, as well as the use of this salt, is attended with so much danger, that it is never employed for that purpose. CAROLINE. There is no cause to regret it, I think; for the common gunpowder is quite sufficiently destructive. MRS. B. I can show you a very curious experiment with this salt; but it must again be on condition that you will never attempt to repeat it by yourselves. I throw a small piece of phosphorus into this glass of water; then a little oxy-muriat of potash; and, lastly, I pour in (by means of this funnel, so as to bring it in contact with the two other ingredients at the bottom of the glass) a small quantity of sulphuric acid-- CAROLINE. This is, indeed, a beautiful experiment! The phosphorus takes fire and burns from the bottom of the water. EMILY.