in the Compounds of Zine and Antimony. 235 
that no one after reading Rieffel’s paper can doubt that the com- 
pounds of copper and tin vary in composition like those of zinc 
and antimony. 
2. ‘The mineral Discrasite, a compound of silver and antimony, 
crystallizes in trimetric prisms, of which Jon J=119° 59’.* The 
analyses given below are copied from Dana’s System of Mineral- 
ogy, changing slightly the order. 
Sb Ags = Antimony 28-5 Silver, 71-5=100. Sb Ags = Anti- 
mony 23, Silver 77=100. 
1. Andreasberg (foliated granular), Antimony 24-25 Silver 75:25=99.5, Abich. 
2. Wolfach (coarse granular z: 24 4 6=100, Klaproth. 
3. Andreasberg (foliated granular), % 23 nef SAA A Femme ASU 
: * * “ “ 29 “ —718=100, Vauquelin. 
5. Wolfach (fine granular), - 16 “ 84==100, Alaproth. 
It needs no comment on these results to show that Discrasite 
is homceomorphous with Sb Zns, and varies like it in compo- 
sition. 
4. It is stated by Staedeler$ that crystals of the compound of 
grape sugar and common salt can be obtained containing for 
every equivalent of grape sugar one or two equivalents of chlorid 
of sodium and also of intermediate composition. He states more- 
Over that “Calloud, who first observed that the grape sugar of 
honey combined with chlorid of sodium, found that the amount 
of the latter varied between 8-3 and 25 per cent.” Staedeler re- 
fers the variation in composition to a mixture of the compound 
of one with the compound of two equivalents of chorid of sodi- 
um which he assumes to be isomorphous. He adds that it may 
be caused by “enclosed crystals of chlorid of sodiam althongh 
the eye could not distinguish any heterogeneous constituents. 
_ All the above compounds are examples of weak chemical affin- 
ity accompanied by large variations in composition without any 
* Dana’s System of Mineralogy, 4th ed., vol. ii, p. 35. 
+ Poggendorff’s , 115. 
American Journ. of Science, vol. xix, p. 355. 
i Chemical Gazette, vol, xiii, p.44. 
