468 W. P. Headden — Formation of the Alloys, e'x. 



conditions as Fe„Sn 3 which was found to be the chief alloy in 

 only one instance, i. e.. where the atomic ratio of the mixture 

 was 1 : 22 and this is singular; for in other instances where 

 the ratio was 1 : 25 and 1 : 41 respectively an alloy with a lower 

 ratio, i. e. 1*33 was obtained and, moreover, 1 : 22 is the ratio 

 given in Watts's Chemical Dictionary for a definite alloy. The 

 regulus from which I obtained this alloy and having this ratio 

 could not in any sense be considered an individual alloy. 



I have not intended to even intimate that the whole of the 

 iron in the reguluses obtained existed in the form of alloys 

 difficultly or insoluble in hydric nitrate ; for at least one alloy 

 soluble in this agent and crystallizing in long and wide but 

 thin plates was observed. 



The temperature, duration of fusion, and rate of cooling are 

 very subordinate in their influence upon the alloys formed 

 both in regard to their properties and their distribution through 

 the regulus-. 



The only alloy whose form could be definitely made out 

 was the alloy FeSn.^ which crystallizes in bright shining rhom- 

 bic prisms, being combinations of 001, 110, 010, from brownish 

 black to black in color with metallic luster. 



Another form is a six-sided often furrowed, almost always, if 

 not always hollow form. This form is very interesting but 

 not characteristic as it is common to several compounds. 



The terms iron alloy and iron bottom have been used to 

 designate a hard, gray and strongly magnetic mass forming 

 the lower part of some of the reguluses and amounting in one 

 case to rather more than one third of the same by weight. 

 My analyses of these contain two errors which being in oppo- 

 site directions about neutralize each other, only one of them, 

 however, affects the ratio of the iron to tin when these are calcu- 

 lated to one hundred, i. e. the carbon which seriously impairs 

 the value of the ratios obtained and it is no matter for surprise 

 that only one of the analyses gives even an approximate ratio ; 

 the fact that the material analyzed had to be used just as it 

 was taken from the crucible may account for this in part but 

 it is a question whether these bottoms are other than gray cast 

 iron alloyed with or containing varying quantities of tin. 

 My experiments seem to prove that their formation does not 

 depend upon the presence of a large quantity of iron, i. e. that 

 they are not products of dissociation, but that the presence of 

 carbon is absolutely necessary to their formation. 



These compounds, which I have classed with the tin com- 

 pounds despite this degree of uncertainty as to their true 

 nature, demand our attention and awaken our interest even if 

 they are related to cast iron, for they have been found to col- 

 lect other compounds still to be described. 



State School of Mines, Rapid City, S. D. 



