208 ANNUAL OF SCIENTIFIC DISCOVERY. 



ON THE PRODUCTS OF SMELTING FURNACES, AS PROOFS OF GEO- 

 LOGICAL HYPOTHESES. 



A PAPER on the above subject was read before the German Scien- 

 tific Association at Wiesbaden, by Prof. Leonhard, of Heidelberg, of 

 which the following is an abstract : " For a long period of time," 

 began the author, " no particular attention was devoted to scoriae and 

 slags, the secondary productions of all smelting works. As useless and 

 unprofitable, they were thrown aside after the metal had been extrac- 

 ted, as the miner in his shaft gets rid of all waste and unproductive 

 rock." He then showed how, until lately, the study of lavas them- 

 selves was neglected. The same was the case with scoriae and slags ; 

 they are not, as was formerly supposed, " accidental combinations of 

 several materials, nor arbitrary mixtures of earths and metallic oxides, 

 which, however occurring again and again in this or that smelting 

 produce, show nevertheless in a quantitative point of view the most 

 endless varieties. The scientific foundation of a theory of the for- 

 mation of scoriae and slags is the work of Mitscherlich. The 

 production of mineral substances by means of fire, or as the produce 

 of high furnaces by the gradual diminution of the temperature of 

 materials melted together in given proportions, or from vapors, attrac- 

 ted more and more attention. The influence of temperature on the 

 resulting substances is most important, bringing about new combina 

 tions and new conditions out of the same material. These phenomena 

 are most remarkable in the combination of iron and charcoal. 



" Space, quiet, and freedom of motion," said the author, "are the 

 most important conditions and necessary requisites for the parti- 

 cles of matter to be able to arrange themselves in regular order to 

 produce well-formed crystals ; this the chemist had taught us. All 

 products of this kind are subject to unchangeable laws. The more 

 gradual the reduction of the igneous fluid to a solid mass, the more 



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favorable are the conditions of crystallization. If proportions and 

 conditions are the same, we always see the same forms reproduced." 

 After these words the author described the process of late chemists 

 with regard to the melting and reduction of various rocks, and then rap- 

 idly noticed the numerous minerals and combinations of minerals found 

 in the scoriae and slags of smelting furnaces. " All scoriae," he added, 

 "have a similarity of substance and degree of flexibility (?) sufficient 

 to enable the metalic particles thus obtained to sink by means of their 

 greater specific gravity. Scoriae have a less specific weight than the 

 products to be gained by smelting ; the latter are pure metals, or a 

 combination of metal with charcoal, sulphur, &c. the former consist 

 entirely or chiefly of earths. We can thus understand how a cover- 

 ing of slag is formed over the melted treasure as a protection against 

 the influence of fire and of atmosphere." After mentioning some of 

 the principal minerals obtained from furnaces, and which are the 

 principal ingredients of the most extensively found rocks, he observed 

 that " in a geological point of view these products are of the greatest 

 importance. They point out how nature has ever worked in her 



