SPEISS. 



719 



The low Ijarometric pressure at Leadville, wliicli is, ou 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 nonvolatile form, is abundantly proved by the fact that this smoke con- 

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

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

 centage of oxygen and the large percentage of sulj)hur, as compared with the amounts 

 of both substances in flue and chamber dusts. 



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 rejiorted in Analysis XXXVII. This 

 speiss has such a characteristic appearance that it may be 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: 



American. 



Cummiug & Finn 



Elgin 



Grant 



Ln Plata 



Little Chief 



Ohio and Missouri 



Billing &Ei!CT3 



Total number of specimens mixed for analysis 



No. of-spec- 

 imens for 

 analysis. 



By sifting, the speiss was separated into— 



Speiss powder 98. 21 



Lead graius 1-22 



Iron graius 0.57 



Total 100.00 



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

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



