G. J. Brush on the Chemical Composition of Clintonite. 409 
Si xl oMg Ga Fe Na Hf 
Xanthophyllite,* 16:30 43°95 1931 1326 253 O61 433 Meitzendory. 
Oxygen, 865 20538. 772 3877 056 015 3°85 
Disterrite,+ 20°00 4322 25-01 400 860 057 360 v, Kobell. 
Oxygen, 1061 2020 1000 114 108 010 320 
These differ from Clintonite in containing about 4 pr. ct. of 
water; if this be considered as replacing magnesia in the manner 
suggested by Scheerer the relation of the oxygen in the sesqui- 
oxyds and protoxyds is nearly 6: 4; but the ratio 3: 6:4 is not 
in accordance with the amount of silica obtained in the analyses. 
If the same replacement be allowed in Disterrite and the iron be 
assumed to exist as protoxyd, the oxygen ratio will be— 
Si # R 
# 16°61 : 20-20 ; 1320 
or almost exactly 3: 6: 4. 
rom these remarks it seems likely that the three species may 
all be brought under the general formula RSi+ Re Ai* = Silica 
19-19, alumina 43°54, lime 11-86, magnesia 25-41. 
Munich, August 7th, 1854. 
Nore sy J. D. Dana.—It is important to note that the’ ratio 
between the oxygen of the protoxyds and peroxyds together and 
that of the silica (the water being disregarded), is the same for 
Clintonite and Disterrite. We thus obtain— ' 
R+ Si 
1. Clintonite, . : GOS. oA see Be POS 
Gs - Fo (a S20 > 1060- =a bed 
8. Disterrite, . 2 iSO = TOS Ly oe! os OOS 
corresponding each to the ratio 3:1. This therefore appears to 
be the fundamental ratio of the species. We here take the iron 
in Disterrite as peroxyd, as published by von Kobell, which is its 
condition in Clintonite ; this gives for the oxygen of the protoxyds 
and peroxyds the ratio 11°24: 21-26. The formula (ks, 3%) Sit ex- 
presses the ratio 3: 1. ° In the Clintonite, R* is to Ras 4: 3; in 
the Disterrite nearly as 1:2. Expressing the ratio 2:3 for the 
Clintonite, this formula becomes (2k? +28)5i*. 
If we regard one-third of the peroxyd in Mr. Brush’s analysis 
as replacing silica, the oxygen ratio for R, ®, (5i) becomes 12:78: 
12-86 : 17-12, or between the bases and the rest 25-64: 17-12= 
3: 2, giving the formula on page 129 of this volume 
. gk +E ay - eee bac 
_ ® The mean from four analyses by Meitzendorf, from the 1st Supplement -of 
Rammelsberg’s Handw. Min., p. 158. 
+ Jour, fiir prakt. Chem., xii, 156. 
Sxconp Serres, Vol. XVIII, No. 54.—Nov., 1854. 52 
