Physical and Chemical Behavior of Solids. 239 



Table IV. Spring's results on the formation of Sulphides by "compression." 





No. of 





Metal 



compressions 



Kesult 1 



Mg 



6 



Gray mass, dissolves slowly in water at 

 50-60° with evolution of H 2 S. 



Zn 



3 



Block very closely resembling natural zinc 

 blende. 



Fe 



4 



Very hard homogeneous block, which could 

 be filed only with difficulty. 



Cd 



3 



Yellowish gray mass. 



Al 



5 



Incomplete. 



Bi 



2 



Perfectly homogeneous black mass. 



Pb 



_ 



Combine very easily. 



Ag 



8 



Combination very slow, mass finally homo- 

 geneous. 



Cu 



3 



Complete combination. 



Sn 



3 



Grayish-yellow mass of SnS 2 . 



Sb 



2 



Gray-black mass resembling stibnite. 



P 



_ 



Absolutely no action. 



C 



- 



Absolutely no action. 



1 In each case (excepting the two last) addition of acid to the product 

 caused an evolution of sulphureted hydrogen. 



powdered zinc and sulphur, mixed in presence of dilute hydro- 

 chloric acid, also give rise to an evolution of sulphureted 

 hydrogen." 



To these experiments the following observations may be 

 made. For the formation of some sulphide of copper, or 

 of other sulphides, it is not even necessary that the sul- 

 phur and copper be in contact. Thus Hallock* writes : 

 " I have made the sulphide at ordinary temperatures with 

 the copper and sulphur an inch apart and a wad of cotton in 

 the tube between them. It is simply the vapor of the sulphur 

 that attacks the copper. . . . The case of copper and mer- 

 curic chloride is precisely the same. The vapor of the chloride 

 will go through a whole tube past cotton wads and attack the 

 copper (or color potassium iodide)." 



Now, in Spring's experiments the compression was far from 

 uniform ; hence the process of compression was accomplished 

 by considerable grinding or kneading of the material, and so 

 produced very good contact between adjacent particles. It is, 

 moreover, highly probable that the process of reducing the 

 compressed blocks to powder by filing also promoted combina- 

 * Hallock, this Journal (3), xxxvii, 405, 1889. 



