RAIN, Janez Friderik (1612-late 17th. century) Praeservativum universale naturale. A natura et arte depromptum in omni morborum genere, est Lapis philosophorum. Cujus possibilitas, realitas, existentia & praeparatio, quantum licet, quodq[ue] is solus sit unicus morborum debellator Hercules. / contra Jacobum Joannem Wenceslaum Dobrzenski, de Nigro Ponte ... Lapidem philosophorum ... negantem, remonstratur editore Joanne Friderico à Rain, ad Stermoll & Radelsegch ... - Labaci : typis Joannis Baptistae Mayr, 1680. - , 83,  p,  leaf of plates (frontispiece) ; 8° (15 cm) J. F. Rain is a representative of the alchemy “scientists” from the 17th century. Around the mid 18th century, alchemy had to make way for scientifically founded chemistry, whose predecessor it was. Some of alchemy’s findings were however put to good use by other sciences, especially metallurgy and medicine. Rain was a castle lord and landowner, as well as a citizen of Ljubljana. He devoted much of his time and money to alchemy. His only printed work, Praeservativum naturale universale…, was published by the printer Mayr in Ljubljana in 1680. The front page illustration shows an allegoric celebration of mercury. The image was drawn and etched into copper by Peter Mungersdorff, as assistant in Valvasor’s paintworks in Bogenšperk (Wagensberg) Castle. Rain complains in the introduction that there is little interest in the noble art of alchemy and that many people ridicule it. The introduction is addressed to the Carniolan Provincial Estates. It is followed by a treatise on the liquid “alchaest” and on “aurum potabile”. The liquid alchaest was first mentioned by Paracelsus as an excellent medicine for all diseases of the liver. Unfortunately, he forgot to mention its composition. Alchemists later fervently tried to make the liquid that was supposed to return all substances into original matter The principal aim of Rain’s discussion was to prove that this miraculous alchaest was a kind of fluid “lapis philosophorum”. It was supposed to turn all substances into gold and to be the best medicine for all diseases. It was thought to consist of philosophical sulphur and philosophical mercury, which were not ordinary sulphur and mercury, but “spiritual” elements, which, when joined, would produce the great mysterious “magisterium”. Rain is reported to have sought mercurius philosophorum in mercury that was purified carefully and through complex procedures, and sulphur philosophorum in gold. The main section of the book strives to prove that it is possible and realistic to make lapis philosophorum. In support of his theory, Rain quotes numerous excerpts from alchemy books and various historical events; he passionately attacks the thesis of the Czech alchemist Dobrzensky, who rejected the existence and possibility of lapis philosophorum. Rain dedicated Praeservativum to the emperor Leopold, who awarded him a grant of 36 guilder as a contribution to his efforts in 1686. Rain’s second work on alchemy existed only as a single-copy manuscript; it was said to be an exceptional work of calligraphy with splendid illustrations, including figural ones. Rain dedicated it to Empress Eleonore and Emperor Leopold and delivered it in person to them. They had it transferred to the Augustine monastery to be kept there. Nowadays, the manuscript is deemed to be lost, but its title De chymia suggest that Rain may have gone beyond the phase of alchemy which strove to produce artificial gold, and that he may have become aware how useful the procedures, substances and devices were, which led to the origin of chemistry in the modern sense in the following period.