564 



NATURE 



\_April 15, 1880 



Of still greater importance than the discovery of arsen- 

 iuretted hydrogen was Scheele's discovery of sulphur- 

 etted hydrogen. Long before, indeed, it had been 

 observed that when sulphides were decomposed an 

 ill-smelling gas was given off which blackened silver 

 (Boyle, 1663), was combustible, poisonous, and capable of 

 being absorbed by water, to which it communicated its 

 taste and smell (Rouelle and Meyer, 1754-1774), but no 

 further examination of the nature of the gas had been 

 carried out, and it was generally considered to be impure 

 hydrogen. In 1777 Scheele isolated this gas, also a 

 previously quite unknown fluid compound of sulphur and 

 hydrogen, and gave a correct statement of their com- 

 position. The formerly neglected ill-smelling gas now 

 became the subject of comprehensive researches by 

 Bergman, Kirwan, Berthollet, &c. Its chemistry was 

 completely cleared up, and it became an indispensable 

 assistant in every laboratory and nearly every chemical 

 manufactory. 



At various Saxon and Bohemian mines there are found 

 along with tin ore two kinds of minerals, whose weight 

 early attracted the attention of the miners, and which, see- 

 ing no metal could be smelted from them, were considered 

 a- ''wild " ores of tin. We find them described in detail 

 for the first time in the Mineralogies of Wallerius and 

 Cronstedt, and Cronstedt expressly states that they do 

 contain tin as a proper constituent. One of these minerals, 

 which was afterwards called scheclite, but at first by 

 Swedish mineralogists tungsten, was found about 1770 in 

 small nodules in the Bispberg mines in Dalecarlia, and 

 was in consequence examined by Scheele. He imme- 

 diately discovered that this mineral, which had been 

 previously examined without success by so many chemists, 

 was a compound of lime with a new metallic acid. 



Bergman supposed that the chemist had here not only 

 to do with a new acid, but also with the acid of a new 

 metal, a supposition which was immediately confirmed by 

 the Spanish chemists, the brothers Don Fausto ' and Don 

 Juan Jose d'Elhuyar. This metal is now called by 

 different names — wolfram by Swedes and Germans, 

 scheele and tungstene by the English and French. The 

 List name is derived from tungsten, that given by the 

 miners at Bispberg to the mineral from which the acid 

 was first produced— a derivation perhaps difficult enough 

 for a philologist to clear up in case it comes in question to 

 determine the root of the Frenchman's acid tungstiquc. 



The paper "On the Constituents of Tungsten" was 

 published in 1781. In 1778 and 1779 Scheele inserted 

 in the Transactions of the Academy " Researches on the 

 Blacklead Molybckena'' and "Researches on the Black- 

 lead Plumbago," of which one paper enriched science 

 with a new simple substance, molybdenum, and the other 

 taught us the true chemical nature of a mineral long used 

 and unsuccessfully examined by many chemists. Both 

 these researches have been of immense importance for 

 the metallurgy of iron, the former through the splendid 

 reaction (discovered by L. Svanberg and H. Struve in 

 1848) which phosphoric acid gives with molybdic acid, 

 and which forms an indispensable means for every 

 metallurgist for discovering the least trace of phosphorus 

 in iron, the latter by the discovery that graphite enters 

 as a constituent into various sorts of iron. Some lines on 

 this point in Scheele's paper suggested the investigations 

 of Bergman, Rinman, Monge, Berthollet, Guyton de 

 Morveau, and others on the chemical difference between 

 pig iron, bar iron, and steel, which alone rendered possible 

 the development of the iron industry to the advanced 

 position which it occupies in this era of steam-engines and 

 railways. 



Scheele further enriched our knowledge of the mineral 



' Don Fausto afterwards became Minister of State in Spain. The two 

 brothers studied chemistry fur a lime under Bergman at Upsala, and visited 

 Scheele at Koping. These two distinguished Spaniards' account of this 

 visit is the only information we now possess regarding Scheele's laboratory 

 and home life at Koping. 



acids by his discovery of nitrous acid and his examina- 

 tion of the products of the decomposition of nitric acid. 

 It is said that an observation connected with this subject 

 first led to his intimate acquaintance with Bergman, and 

 his last scientific communication relates to this subject, 

 inasmuch as shortly before his death he informed Wilcke 

 by letter that nitric acid under the action of sunlight 

 gives off combustible gas. 



Want of space compels me to pass over many less con- 

 siderable, but nevertheless often very important communi- 

 cations by Scheele. I have yet, however, to give account 

 of his two greatest and most important labours. 



The first of them was published in the Transactions of 

 the Swedish Academy of Sciences for 1774, under the 

 modest title,"On Brunsten,or Magnesia, and its Properties." 

 Brunsten (black oxide of manganese) and various allied 

 species of minerals are first mentioned in the fourteenth 

 century by Albertus Magnus under the name of "mag- 

 nesia," but they had long before that time been employed 

 in the arts. Afterwards we find those minerals often 

 referred to by mineralogists and chemists, and many 

 unsuccessful attempts were made to ascertain their 

 composition. 



Soon after his coming to Upsala Scheele undertook, at 

 the suggestion of Bergman, to try his strength on this 

 difficult substance. Scheele showed at first that brunsten 

 contained a peculiar base combined with a substance 

 which had a strong affinity for combustible bodies. The 

 properties of the new base were carefully investigated, 

 also its relations to a large number of reagents. From 

 these researches Scheele drew the conclusion that we had 

 here to do with a metallic oxide — a view which was soon 

 after confirmed by Gahn through direct reduction with 

 charcoal. Chemistry was thus enriched with a new metal, 

 manganese, which has long been very extensively used in 

 the arts, among other applications in the manufacture of 

 Bessemer iron. Scheele observed further that a solution 

 of black oxide of manganese in muriatic or nitric acid 

 when sulphuric acid was added gave a scanty white 

 precipitate. It is distinctive of Scheele's chemical re- 

 searches that he never neglected to investigate the cause 

 of even the most inconsiderable occurrences in the course 

 of the work, and man)' of his most important discoveries 

 originated just from the attention he bestowed upon 

 circumstances which would probably have escaped the 

 notice of other chemists. The inconsiderable white 

 precipitate led to the knowledge of a new earth, baryta, 

 which soon after was found by Gahn in a mineral of very 

 common occurrence, heavy spar. The salts of baryta are 

 now indispensable in every laboratory as the means of 

 discovering and separating sulphuric acid, and extensive 

 branches of industry are grounded on the multitudinous 

 applications which have long ago been found for this 

 earth. 



When black oxide of manganese was treated with 

 muriatic acid Scheele observed that the dark brown 

 solution, obtained by cold dissolving, when heated gives 

 off a strongly-smelling gas, which from its colour was 

 afterwards named chlorine. This was the third simple 

 substance to whose discovery the examination of black 

 oxide of manganese gave occasion. It is scarcely possible 

 completely to sketch the enormous influence which the 

 discovery of chlorine exerted on the development of 

 inorganic, but perhaps still more of organic chemistry ; 

 and on all the branches of human knowledge and human 

 industry which in anyway arc related to chemical science. 

 As a single instance it may be observed that at that time 

 there was no other method known of bleaching cotton 

 cloth than by exposing it for a length of time to the 

 action of sunlight. Every cotton-spinning or weaving 

 manufactory therefore required extensive meadows for 

 bleaching its wares. But land is dear in England, and 

 on this account the branch of industry in question was 

 about to migrate from that country, where in the middle 



