ANALYSES OF SLAG. 



701 



Analyses XXV^-XXIX. — Analyses of Leadville slag. 



Analyses Nos. XXV and XXVI, made by Dr. M. ^V^. lies, are of Grant's old slags 

 of the singulo-silicate type. 



Analysis Xo. XX\'II, made by Dr. M. W. lies, is of a slag now made at the 

 Grant smelter. It belongs to the acid type. 



Analysis No. XXVIII, made by Dr. M. W. lies, is that of a slag of the singulo- 

 silicate type, made at Messrs. Billing & Eilers's smelter, with pure arragonite instead 

 of dolomite. It is remarkable for its large percentage of lime. 



Analysis Xo. XXIX is of a slag of the singulo-silicate type, made at the California 

 works, and analyzed by Mr. J. E. Hardman. 



From the preceding figures it will be seen that the composition of slag.s is well 

 understood in Leadville, although some obscure points, such as their magnetic prop- 

 erties and the state in which sulphur exists in them, need elucidation, and although 

 some metals always present in slags, such as zinc, and substances such as phosphoric 

 and titanic acids, are not reported. 



Special researches on slags made in the laboratory of the Survey The word slag seems 



appropriate to designate the strange products which flow from the blast furnaces 

 during the process of lead smelting. These products are sometimes masses of large 

 intersected crystals, brittle, with a vitreous luster; sometimes fine-grained tough masses, 

 with a dull fracture, but always dark colored and opaque. On the other hand, the 

 word scoriie ought to be adopted for translucent or transpareat slags. Scorite are 

 accidentally formed in the blast furnaces, having been found by the writer in the 

 cavities of iron sows. There is no doubt that they are regularly formed during the 

 process of smelting, but are soon transformed into slag, so that only slag flows from 

 the furnaces. 



A rough qualitative examination was made of the scoriae found intimately mixed 

 with iron sows; the color was that of pure blende; they were translucent — almost 

 transparent — contained no sulphur, and consisted almost exclusively of .silicate of 

 protoxide of iron and manganese, with traces only of lime and magnesia. This acci- 

 dental product, which probably no one else has ever perceived in Leadville, affords ^ 

 means of studying the nature of the reactions which take place iu the blast furnace, 

 and which such accidents alone can reveal. 



