336 TEE POPULAR SCIENCE MONTHLY 



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. 



Dobereiner, between the years 1820 and 1830, made some remark- 

 able 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 Dobereiner's 

 pupils, Eunge, the discoverer of aniline, ranked his master as " the 

 most famous of living chemists." 



We have said that a great deal of Dobereiner'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 hydro- 

 gen by contact with platinum sponge, to the construction of an instru- 

 ment called the " Dobereiner 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 until it was superseded by friction matches.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 sul- 

 phuric acid. 



Dobereiner experimented with the possibilities of coal-gas for illu- 

 minating purposes, obtaining his gas by the action of steam on coal at 

 a very high temperature; and he was the first to discover the useful- 

 ness 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 Dobereiner had studied the mix- 

 ture 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 Dobereiner 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 birth- 

 day, and we find again and again that the chemist's patron tried to 



