i 
| 
| 
i 
] 
1888, ] 177 [Hunt. 
ite and laurite, and as pyrrhotite, chalcopyrite and millerite ; but arsenids 
‘such as smaltite, leucopyrite and niccolite ; antimonids like breithauptite, 
horsfordite and dyscrasite ; sulpharsenids like arsenopyrite and cobaltite ; 
sulphantimonids like ullmannite ; and sulphobismuthids like grunauite. 
In this same suborder, for reasons already given, belong the metals and 
alloys, including metallic arsenic, antimony and bismuth, and also the 
metallic forms of selenium and of phosphorus. 
In the second suborder the metals are not represented by any known 
species, but by the non-metallic forms of selenium and phosphorus, and 
by the various modifications of sulphur. This suborder includes, more- 
over, simple sulphids like sphalerite, wurtzite, greenockite, hauerite, old- 
hamite, cinnabar and realgar ; sulpharsenids like proustite and tennantite ; 
and sulphantimonids like pyrargyrite and miargyrite. The opacity and lus- 
tre of the compound species of the first suborder, and their occasionally sec- 
tile character, connect them closely with the typical metals. On the other 
hand, the transparency, the absence of metallic lustre and aspect from the 
species of the second suborder recall the physical characters of oxyds like 
zincite, cuprite and senarmontite, with which they are connected through 
the oxysulphids, voltzite and kermesite. It is to recall these resemblances 
to the sparry Oxydates that we have called this suborder, Spatometallinea. 
It is worthy of note that not only the elements selenium and phosphorus, 
but the sulphids of mercury and of antimony are found in two distinct 
specific forms, and belong to both of these suborders; and there seems 
some reason to believe that under the head of fahlerz or gray copper may 
be included, besides the species belonging to the Spatometallines, others 
which pertain to the Metallometallines. 
8. In proceeding to divide into tribes and genera the various groups of 
species indicated in the preceding review of the order of Metallata, we are 
guided alike by the composition, as shown by chemical analysis, and by 
the physical characters of hardness and condensation. The latter, as 
indicated by the value of 2, calculated for the elemental unit as already 
defined (§ 8), is the reciprocal of the coefficient of condensation. This 
value will be seen to diminish with the increase of hardness of the species, 
as represented by degrees given on the scale of Mohs, in which the hard- 
ness == E100, 4552 10:0; 
In fixing the value of p for those metals which like iron and chromium, 
like copper, mercury, gold, tin, palladium and platinum, yield two dis- 
tinct chlorids, we have in all cases taken the amount of metal which, in 
the ferrous, chromous, cuprous, aurous, stannous, palladous and platinous 
compounds, is combined with one portion (85.5 parts) of chlorine. A simi- 
lar rule, as already shown (§ 3), is applied in the case of arsenic, antimony 
and bismuth, This unit-weight of the metal = p, when divided by d— 
the specific gravity, water = 1.000—gives the value of v. 
(1.) The metals and their alloys, which we include in the tribé of the 
Metalloidex, present, unlike the other tribes of the order, wide differences 
