W. P. Headden — Products found in an old Furnace. 95 



If we reject the tin and sand, and calculate the remainder to 

 one hundred, the ratio for the arsenic and sulphur to the iron 

 and cobalt is 1:1*03, but I do not think that the tin should be 

 rejected. 



This product resembles the mineral loellingite in form, but 

 differs from it in having the formula FeAs. Leucopyrite, etc., 

 are intermediate between these two — FeAs 2 and FeAs. 



FeAs + SnS. — The next product is a molecular combination 

 of the preceding two : it occurs as black, shining plates belong- 

 ing to the monoclinic system. The forms recognized on these 

 crystals are the same as those given for the stannous sulphide. 

 The material analyzed was selected with the greatest of care 

 and, while the amount of the substance obtained was small, it 

 was free from crystals of other substances. The analysis 

 resulted as follows : 



Per cent. Atomic Equivalent. Atomic Ratio. 



Fe _. 17-949 32- 



* 



Co 2-037 3- 35 ' 5 1#06 



S 10-671 33*3 33-3 1-00 



As 27-166 36-2 36'2 1*08 



Sn 43-106 36-5 36*5 1'09 



100-929 



The atomic ratio is evidently 1:1:1:1. Following the indica- 

 tion of the other analyses, it seems that the simplest and proba- 

 bly the correct way of interpreting this ratio is by assigning 

 the formula FeAs + SnS to these crystals; the iron in the 

 iron arsenide being replaced in part, as in the preceding sam- 

 ple, by cobalt. 



An Arsenide of Tin, Sn 6 As. — One of the samples in the 

 suite was a small mass of bright, highly lustrous crystals of a 

 grayish tin- white color. They were quite brittle, six-sided 

 plates, whose form I could not satisfactorily make out. The 

 crystals have a slight bronze-yellow tarnish. Their composi- 

 tion was found to be : — 



Per cent. Atomic Equivalent. Atomic Ratio. 



Sn 90-414 7662 6*02 



As 9-441 12-72 1*00 



99-855 

 This appears to be a new alloy of tin and arsenic. It is 

 soluble in hydrochloric acid with the evolution of hydrogen 

 arsenide, and the separation of brown flakes, not further exam- 

 ined, except that they were observed to be soluble in nitric 

 acid. Ferric chloride attacked the crystals, taking tin in 

 solution and leaving a bluish black residue containing a nucleus 

 of the original crystal. It was quite impossible to free the 

 crystals from metallic tin, which could be easily recognized 

 with the aid of a magnifier, as minute globules, occurring spar- 

 ingly on the crystals. 



