406 Fifth Supplement to Dana’s Mineralogy. 
Crxnarar [p. 48, and IT, 1V].—Circular polarization has been observed in Cinna- 
bar by M. De=cloizeaux (Ann. d, M. xi, 261), quartz having hitherto been supposed 
to be alone among minerals in this respect. Its refraction is positive (instead of 
cng as Brewster stated), the index of — refraction being 2°854, of extras 
ordinary 3201. Its rotatory power is fifteen sine times that of quartz, It is 
remarkable, as Descloizeaux observes, that its vergadale are never ett 
Cuixocntore--See Chlorite. 
Cotumaire [p. 858, and II, 1V] —R. Hermann, in a f. pr. Chem.,, «i “a makes 
aigantica to the conclusion of Ovsten cited in our last Supplement, p. 1 
Conpurrire—See aap 
Domeyxire [p. 3 re ai ha observes (Quart. J. Chem. Soc., x, 289) that Condur- 
rite appears to Ae ‘ arsenite of copper es the formula Gushs, gi has resulted wl 
from the alteration of Domest (CuAs). The mean from nine samples of pn . 
durrite examined b A i n, gave for the ripentien of arsenic Herre soni As2 
Cu 71-15. The aa kite of great brillianey and purity from the Conkileras re 
fpiipn sihacied 1 Field ma 28-44, Cu 71:56; and another from Coquimbo, As 28-2 
Cu 71°48, corresponding 
Durrexoysite [p. 77, and T, II, IIT, IV] (Binnite of some au thors).--Von a 
tershausen has reviewed again the composition of this mineral (Pogg . ¢, 537) wit 
the following results. Analyses 1 and 2 by Nason, 3 and 4 by Uhr laub: 
Ss As Pb Ag Fe 
1. 23°54 25°14 51-48 017 0:08==100°41 
23°82 23°81 51°65 0°12 =. 99°40 
8. (G 5-074) 24659 23324 51188 0025 —= 99191 
4. (G@=5-459) 24046 23948 51397 0-024 —== 99415 
The nee — rng gives the atomic soe ne the sulphur, arsenic, om other metals, 
ant? ao the ratio gives erent ma ula, the composition a i 
ga ined 1, tat » Waltershausen’s Abie a compoun ua of PbS-+As wi 
(Arsenomelan} “tel: nebo genet Sedaiachaes ‘the ratios between which int 
analyses he has caleu 
Exiasite.—See Ueisiicunh Ores. 
Eprpore [p. 206, and II, II, 1V].—R. Hermann has re-calculated the oxygen pro- h 
portions ‘Noe the ae of epidote (J. f. pr. Chem., Ixx, 821), a and shows that the 
ratio 1:2 for the protoxyds = peroxyds is far fro ss uci fornt, whether the i ms 
taken as protoxyds or peroxyds, while in either case i is a remarkably unt th 
ratio of 1:1, between the oxygen of the sum of ses, that of the st as 
and water. In 11 anal by Hermann the oxygen rati _ #. Si, H, va 
between 1:1 2, and 1: 201: 37: or, if the iron be pe 
aeeeee 1:1-73: 2:60:02 26, and 1:255:344: 0°24 In 12 yeni wets 
ratio varies betwee 1:2°15 nd 1 hole, 
ula (3, Si (the water beng ws veeneral ined ith Ae wilica) covers the w oat 
cepting a part of the w er, in s. Hence rg Ig gen fo (tra 
lating that by Hermann, oh os Si for cilien) i is (Re, 
Je imilar a 
&- 
ad 
ey By eo are ce vat gt 1 the Mineralogy un under the genera 
(p. 15 d 183), While tiers is little doubt of the Nake ey yet it rn 
Pe estabiiton by the analyses, esa in epidote, the v ns ne penton 
:2:3 as the normal ratio, an a_i idocrase, abou 12: Se pe coe 
the species. Hermann writes the epidote formula, (RH) Si + nH, cs 
rightly # as epate R; but Re g to any natural or Cae <a se 
a the formula as i tands, implies 8 of 0 oxygen in the bases to 2 in the silica, | 
Conia ake: oath ns, —J, id 
tals occur at haart aoe near Abo, according to A. E. } 5 ue 
(Poe ci, 65) 85) along with Seapolite. Color pure black ; lustre vitreous; Str" (ig, 
G.=3-425. Form prismatic or tabular. Axes i 
