B.S. Burton—Contributions to Mineralogy. 35 
tallic copper. <A qualitative analysis of the mineral showed the 
presence of sulphur, copper, antimony, arsenic and iron. 
In the quantitative analysis the mineral was decomposed by 
the chlorine method; about one gram of it was placed in the 
bulb of an ordinary reduction tube and treated in the usual 
manner with a slow stream of chlorine gas, the volatilized pro- 
duct being made to pass through a mixture of chlorhydric and 
tartaric acids. The apparatus employed was the same as recom- 
mended by Rose with the exception that the U tube was replaced 
by a tube filled with glass fragments saturated with the acid 
mixture. The action of the chlorine was continued for nearly 
an hour, when the bulb was detached and the chlorids of copper 
and iron were dissolved in dilute chlorhydric acid, The ce a 
small insoluble residue of undecomposed mine Th 
The iron was determined in the filtrate as sesquioxyd and re- 
served for the addition of the volatile portion. From the acid 
solution containing the volatilized chlorids the sulphur was 
thrown down as sulphate of baryta, a after removal of the 
excess of baryta salt, the arsenic was separated by the ammo- 
nia-magnesia solution, core antimony was ne Pre from 
dry current of carbonic acid, ian from this the total wiisivinatt 
was calculated. The small portion of iron in the filtrate from 
_ the antimony was thrown down as tg 2 redissolved and 
converted into sesquioxyd and added to the — thea 
obtained. Two analyses ee in this mann 
Il. en 
Sulphur, 31°46 31°67 31°56 
Copper, 47°34 47°82 47°58 
enic, 17°67 17°93 17°80 
Antimony, 1°25 1°50 1°37 
n, ee ee 
~ 98°89 99°83 99°35. 
a No. 1, the insoluble residue was 2°16 pr. ct., in No. 2, 1°79 
ct, ,which amounts have been deducted from the above results. 
ratio of the equivalents of arsenic, copper and sulphur is 
1:6: 8, giving the formula 30u,S+AsS,. This is the com- 
position of Breithaupt’s Enargite as determined — ftp 
ner’s* analysis of the mineral from Pe 
called Guayacanite from Chili, analyzed and described by Field : 
* Pogg. Ann., lxrxx, 283. + This Journal, II, xxvii, 252. + 
