(1) (2) (3) (4) (5)
Silica 55·08 52·87 52·054 54·75 66·70
Clay earth 23·10 23·95 — 18·82 21·01
Iron oxide 14·13 4·78 13·966 14·48 5·89
Carbonate of lime 5·22 13·80 — 5·30 3·20
Magnesia 0·75 2·35 1·850 3·38 1·26
Potash 0·79 0·89 1·852 1·55 1·02
Carbonate of sodium 0·28 0·45 0·523 0·53 0·57