Seignette’s Salts.
(Soda Tartarata, Sodii potassio-tartras, Rochelle salts, Sel de Seignette, Sal polychrestum Seignette.)
Peter Seignette was an apothecary at Rochelle in the later half of the seventeenth century. He had at least a local scientific reputation, and a paper of his describing certain remarkable natural products of his locality was printed in the “Transactions” of the Academy of Sciences of Paris. A little before 1672 Seignette was making some soluble tartar (tartrate of potash), and inadvertently used carbonate of soda with the cream of tartar instead of carbonate of potash. At that time the distinction between the fixed alkalies had not been discovered. The product was a salt different from that which he had expected, and Seignette was ready to believe that he had made a valuable discovery. He ascertained that his new salt had laxative properties, he called it Sal Polychrestum, and advertised it by means of prospectuses, or handbills. From one of these it appears that he sold it at “20 sols la prise,” say 10d. for a dose. Each dose was sold in an envelope on which appeared the design of a goose. One of the prospectuses states that Seignette’s salt was sold in Paris by Lemery, but another refers customers to the “Messieurs Seignette, at present at Paris, lodging on the Quay de le Megisserie.”
Peter Seignette died in 1716, and his son continued to sell the powder. Many attempts to analyse it were made by pharmacists, but it remained a secret until 1731 in which year both Boulduc and Geoffroi, both noted pharmaciens of Paris, solved the problem. Boulduc’s paper on the subject was published in the Memoirs of the Academy of Sciences, Paris, and Geoffroi sent his account to Sir Hans Sloane of London and it was published in the “Philosophical Transactions,” (436, p. 37).
Sal Polychrestum (salt of many virtues) was a name which had been adopted a few years before Seignette made his, by Christopher Glaser, apothecary to Louis XIV. and the Duke of Orleans. Seignette’s salt pushed Glaser’s out of popularity to some extent, so that the latter is generally designated Sal Polychrestum Glaseri in the old books. Glaser made his preparation by mixing nitre and sulphur in equal proportions, then putting the mixture, a spoonful at a time, into a red-hot crucible. The powder would deflagrate, and the next spoonful was not to be added until the flame of the first had gone out. The mixture was kept in fusion for four or five hours, and after cooling was dissolved, the solution filtered and evaporated to dryness. Sulphate of potash with perhaps a little free sulphur was produced, and this has long represented Glaser’s Sal Polychrestum or Sal de Duobus, as it was also called.
Seignette’s salt was first admitted into the London Pharmacopœia of 1788 under the name of Natron Tartarizatum which was altered in 1809 to Soda Tartarizata.