etc. It was too early for his assertions with regard to atomic weights to be verified, but it is surprising how nearly accurate his system was.
Döbereiner, between the years 1820 and 1830, made some remarkable discoveries with platinum. He heated the double chloride of platinum and ammonium to a glow and obtained what he called platinum sponge. He found that this light, porous substance, when slightly warmed and placed in contact with alcohol, becomes red hot, and that if it is set in a mixture of hydrogen and oxygen, it grows hot without the application of heat from without. He drove hydrogen against a piece of the platinum sponge surrounded by atmospheric air, and found that the platinum was heated and the hydrogen ignited by the process. He found also that metallic platinum, in contact with hydrogen gas, causes it to unite with oxygen to form water. These experiments excited attention and admiration throughout the chemical world. The great Swede Berzelius termed his discoveries "the most brilliant of the generation," and the most celebrated of Döbereiner's pupils, Runge, the discoverer of aniline, ranked his master as "the most famous of living chemists."
We have said that a great deal of Döbereiner's work has industrial importance. He saw how to derive acetic acid from alcohol, and he was able to hasten the process of vinegar formation by the help of powdered platinum. He applied his discovery of the ignition of hydrogen by contact with platinum sponge, to the construction of an instrument called the "Döbereiner igniter," which enjoyed great popularity until it was superseded by friction matches. But this quality of platinum is still utilized in gas tips and in the manufacture of sulphuric acid.
Döbereiner experimented with the possibilities of coal-gas for illuminating purposes, obtaining his gas by the action of steam on coal at a very high temperature; and he was the first to discover the usefulness of the mixture of hydrogen and carbonic oxide called "water-gas." There has been some discussion on this point, but a letter of Goethe's dated December 5, 1819, proves that Döbereiner had studied the mixture seven years before a process for the production of water-gas was patented in England.
The poet and the chemist were faithful correspondents, and we have sixty-five letters of Goethe to Döbereiner and five of those written by the chemist in return, which prove that they were on very intimate terms. The two would spend entire days together in the laboratory at Jena, and other days together in Weimar, where Goethe maintained a laboratory especially equipped for his friend's use. We have a poem of Goethe's dedicated to the scientist on the occasion of the latter's birthday, and we find again and again that the chemist's patron tried to
