408 G. J. Brush on the Chemical Composition of Clintonite. 
In the quantitative analyses, the decomposition was effected by 
fusion with carbonate of soda; the alkalies were determined by 
Smith’s method with carbonate of lime; the separation of zirco- 
nia and iron was made by the presence of tartaric acid in an 
ammoniacal solution, and the iron was precipitated by sulphid of 
ammonium, A particular examination was made to prove the 
purity of all the precipitates obtained. The following are the 
results of two analyses: 
Oxygen. 2. Oxygen. 


BE 
Silica, ‘ ; . 20°24 10°74* 20°13 10°69 
Alumina, . : s+. 89-18 18°29 88°68 18:07 
Peroxyd of Iron, Pee Se: 098} 1947 3-48 1°04 } 19°29 
Zirconia, . z Pe | 0-20 0°68 0718 
am 13°69 3°89 35 3°80 
agnesia, . 20°84 8°34 21°65 8°66 5 
Soda, 114 a Te ay 029 ( 127 
0-29 3 029 00 
Water, 1-04 092 05 0-98 
100°39 100°45 
Only one determination was made of the alkalies. A third in- 
complete analysis gave, Silica 19°73, oxyd of iron and zirconia 
4-15, lime 13-43, magnesia 20-81, water 1-09. 
great difference between the above analyses and those of 
Clemson and Richardson is in the amount of water. To deter- 
mine this point the powdered mineral was dried over sulphuric 
acid and then very powerfully heated by a blast-lamp; in four 
experiments but a trifle over 1 per ct. was lost. 
' ‘The analyses do not give a satisfactory formula, the oxygen 
ratios are: 
i R R 
No. 1, 10°74 19°47 12°55 
No. 2, 10°69 19°29- 12°78 
The relation between # and & is 3:2 or 6: 4, and the most sim- 
ple ratio is 3: 6 : 4, but the silica is in excess and the real ratio is 
nearer 3h :6:4. If in Clemson’s analysis the 5 pr. ct. of iron 
be considered to be peroxyd (5-0 Fe=4'5 ¥e), we have the ratios 
i # R 
9-02 18-92 13°76 
which seems to render it probable that the true ratio for the min- 
eral is 3:6:4, from which may be deduced the formula 
RSi+ Re A, 
The European species Xanthophyllite and Disterrite are Very 
nearly related to Clintonite ; in all physical characters except color 
they are identical with it. Their chemical composition as give? 
by Meitzendorf and v. Kobell is: 
* Atomic weight of silicium = 21°3. 
