Rare A.L.S. 4to, 2 pages, Hotel de France, Annex: Health Rooms, Dournenez. In French, translated, with superb scientific content c. 1910-1912, the period in which he leased facilities at the Hotel, in full: "My Dear Colleague, Here are the suggestions I would make for the definitions you speak about: Electrode refers to parts of the surface of a metallic conductor which are in contact with another liquid or gaseous conductor and where by the electric current passes from the one conductor to the other. Example: the polarization of electrodes; in the decomposition of a salt, the metal moves to one of the electrodes. Electrolysis: Decomposition of a salt by the passage of an electric current, ex: the purest copper is made by electrolysis. Electrolytic: That which pertains to electrolysis. Electrolyte: A liquid capable of undergoing electrolysis. Elements: Chemistry, the old definition, if my memory is precise, is divided into two parts; in the first, one simply means by that the simple bodies which form a compound, I think that this part of the definition should be preserved as such; the formulation I have forgotten is I think preferable to all of those which come to mind. In the second part, the word element means even non-simple bodies which in combining can result in another body. The example is given: potassium and sulfuric acid are elements of potassium sulfate. This is not said anymore, or in this case it was said in using the word element in the literary sense and not in a particular scientific sense. This, this part should be deleted. In physics, it is said of various couples which are assembled to form a voltaic pile. Example: "This pile was formed from 25 Daniell elements assembled in a row," or simply: "the elements of a pile." I think there isn't room to go into this further, one can't transform the dictionary into a treatise into on physics. Please believe me, my dear colleague, in my entire devotion." Boldly signed and in excellent condition. Note: Letters and manuscripts of Henry Poincare were aggressively collected by institutions during the 1950's and 1960's to the point where today, one rarely comes to market, and letters with scientific content are almost unobtainable. Priced accordingly.
French mathematician, theoretical physicist, and philosopher of science; often described by his peers as "The Last Universalist".
Condition: Very Good