Sonne ON THE OCCURRENCE OF COBALT. 
Shortly after my examination of Dolcoath ore, I was induced 
to search for Cobalt in some of the products obtained in the pro- 
cess of tin smelting, and I came to the conclusion, that if Cobalt 
occurs associated with tin ore in any appreciable quantity, it will 
be found in the substance known to smelters as “ Hard Head”, in 
a highly concentrated form. 
I accordingly selected for examination a sample of “Hard 
Head,” which was of course formed in the ordinary way of smelt- 
ing, from ores obtained from different localities, and I found that 
Cobalt existed to the extent of 4:40 per cent. 
I am not aware that any reliable analyses of Hard Head have 
ever been published, so I am at a loss to know whether the pre- 
sence of Cobalt in this substance has been before noticed. 
I append a tolerably accurate analysis of the sample :— 
TONS shea is ee AN GM areinearete 53°80 
IN Fee Ce tay, Os ORR 18:00 
NET "CS SRS a AT SER EE a aU es 16°25 
Cobalt: (Ue, Le ci SUE PIS SEN Sa 4°40 
PuUMeste nics. sls. eeu eonase eases nae saan 3°50 
Sullohime (se 2G ee JO ore 2°50 
I gather from this, that Hard Head is essentially a Speise, 
similar in composition, except as regards the Tin and Tungsten, 
to those combinations of Arsenic with Iron, Cobalt, and Nickel, 
which are formed when ores containing the above metals are 
submitted to certain smelting operations. 
The specific gravity of the “Hard Head” is greater than Me- 
tallic Tin, which accounts for its separation into a distinct layer 
immediately on the hearth of the Furnace. I do not think the 
Tin indicated by the analysis enters at all into its composition 
chemically, but is merely imprisoned mechanically in the alloy. 
I am inclined to believe that the presence of Iron and Cobalt 
may be somewhat beneficial in the smelting of Tin Ores which 
contain much Arsenic, as they form fusible compounds with the 
Arsenic which otherwise would alloy with the Tin and deteriorate 
its quality. The sample of “Hard Head” before described contains 
no trace of Copper, although Copper was unquestionably present 
in the Tin Ore before treatment, so that this metal is not elimin- 
ated through the Hard Head, but passes entirely into the Tin. 
