ANKERITE VEINS @F ‘LONDONDERRY—LOUIS. 51 
| if ee: Jeane 
Tnsoluble Siliceous Matter .... .. 0.43 0.47 0.25 
GIO AT DONAECS eistdie se syeecees ot wee bO8 0.59 3.14 
Ferrous cee Gute aie Beene, 67.96 69.20 68.47 
MeMPAMOUS S|) hats oes sd es es03 Si, Weel 1.37 2.08 
PTI pes i cia se b's os Be eel eS i 28.73 26.02 
MERINO 6 fetus cc, sc ca wwe L's 0.08 
| 99.48 1100.44 | 99.96 
The average composition, exclusive of insoluble matter, as de- 
vived from several analyses, is :— 
@alere Carbonater ns cas bowen c. 1.92 
Ferrous AL 2 gla Se Rate Re 68.15 
Man raMme@uses op scam a acis -- ich are 1.87 
ONTOS Tage a Me Aer ey on cxe' ys oe 28.06 
100.00 
Evidently, the Manganous and Calcic Carbonates :are onhy 
accidentally present, the main constituents being :—~ 
Perrous’ Carbonate... 4.005.2. O02 
Macnesic % Seat eve eS 
100.00 
The formula that most nearly corresponds to this composition 
is 5 Fe Cos + 38 Mg Co, The per centage composition required 
by this formula is :— 
Ferrous Carbonate ........ - 69.72 
Magnesic Bi es Dan Dt. 30.28 
100.00 
‘This may also be written for the sake of comparison :— 
Carbonic Anhydride.......... 42.30 
BetrousrOxides; 2. 2).4.. edie 43.28 
Mipmiesia, sca zrtae dierent axe 14.42 
100.00 
