94 W. P. Headden — Products found in an old Pkirnace. 



The crystals from the slag were contaminated with metallic 

 tin, but I feared to continue the treatment of the mass with 

 ferric chloride until the whole of the tin should be removed, 

 lest the sulphide of tin should be attacked. The analysis of 

 these crystals, soluble in hydrochloric acid, gave : — 



Per cent. 



Sn .- -.. 80-413 



Fe - - - 2-905 



S -.- 17-134 



100-452 

 Basing my calculation on the percentage of sulphur found, I 

 make the amount of free tin present 22*91 percent; deducting 

 this and calculating the rest to one hundred, I obtained : — 



Per cent. Atomic Equivalent. Atomic Ratio. 



Sn 74-006 62-80) 



Fe._ 3-769 6-78 f 69 53 1 °° 



S 22-225 69-43 69'43 l'OO 



100-000 



Both analyses lead to the formula SnS, with a small part of 

 the tin replaced by iron. In the first analysis this replacement 

 amounts to 3/22, in the second to 3/28 of the tin. 



Iron Arsenide. — This compound was found associated with 

 stannous sulphide in two specimens, in one of them it formed 

 the principal part of the specimen ; in the other it formed only a 

 thin layer between the slag and the stannous sulphide, and 

 occurred sparingly throughout the mass of crystals; it also 

 formed the major part of a third specimen. 



It was freed from the stannous sulphide by boiling with con- 

 centrated hydrochloric acid and subsequently with potassium 

 hydrate. It has a dark steel-gray color. The specific gravity 

 was found to be 7*6500 at 16° C, but this becomes 7:9414 when 

 correction is made for the presence of 1'76 per cent, of sand, 

 specific gravity 2*6. The crystal form is orthorhombic. Most 

 of the crystals show only two forms — 110 and 101 — but some 

 of them show the additional form, 100, and in one or two 

 cases I observed the presence of a brachydome. The analysis 

 of these crystals resulted as follows : 



Per cent. Atomic Equivalent. Atomic Ratio. 



Sand 1-760 



As 53-224 70-9 ) 



S 0-536 1-7 [ 74-9 1-00 



Sn 2-847 2-3), 



Fe 38-304 68'4 



Co 3-640 6-2 



Ni _ Trace 



Cu Trace 



74-6 1-00 



100-311 



