Translated extract of a letter, from Antoine Deidier [to the Royal Society], dated at Marseilles An account of the origins of: a) natural sulphur from the sulphur works at Pozzuoli near Naples b) sal ammoniac (ammonium chloride), in particular, recounting letters from Father Sicard, about its preparation in Egypt c) minerals acids of vitriol d) saltpetre (potassium nitrate) e) alum Deidier sent this account which had not yet been published Original letter, which now no longer exists, was in French 1735