SPEISS. 



719 



The low barometric pressure at Leadville, which is, on an average, nine inches to 

 ten inches of mercury less than that at sea level, explains in a great measure the 

 extraordinary volatilization of so many products ; but the fact that non-volatile sub- 

 stances are carried away in the state of volatile compounds, and, so to speak, repre- 

 cipitated in a non-volatile form, is abundantly proved by the fact that this smoke con- 

 tains chloro-bromo-iodides of calcium, magnesium, and aluminium, and still more by the 

 fact that it contains more tin than any other. Most surprising of all is the small per- 

 centage of oxygen and the large percentage of sulphur, as compared with the amounts 

 of both substances in flue and chamber dusts. 



SPEISS. 



The speiss formed in the blast furnaces of Leadville belongs to three types : 1. 

 The white metallic-looking speiss, in large lamellar crystals, studded all over with 

 very small, indistinct crystals. 2. The grayish sub-metallic looking speiss, in fine crys- 

 talline grains. 3. The vesicular speiss. 



It will be seen that iron sows belong also to the speiss family, being, so to speak, 

 embryonic speiss. 



A specimen of type No. 1, taken from a cake at Messrs. Billing & Eilers's smelter 

 and made from dolomitic smelting charges, contained only a few grains of metallic lead 

 and none of metallic iron. The lead grains were separated by the sieve, and the speiss 

 powder being analysed gave the composition reported in Analysis XXXVII. This 

 speiss has such a characteristic appearance that it mayte assumed that similar speiss 

 found at the other smelters possesses the same composition. 



No. XXXVIII is the analysis of a sample representing type No. 2, composed of 

 equal parts of specimens taken from different smelters, as indicated below: 



By sifting, the speiss was separated into 



Speiss powder 98.21 



Lead grains 1. 22 



Iron grains 0. 57 



Total 100.00 



The non-combined iron grains did not contain any arsenic and were very tough; 

 the lead was also very pure. The speiss powder only was analysed. 



