SCIENCE PROGRESS 



In each of these series a great contrast is observed between 

 the symbols of rocks in Classes IV. and V., and those in Classes 

 I., II., and III.; but when the salic ratios as used in Classes I., 

 II., and III. are also used for the calculation of rocks in Classes 

 IV. and V., the symbols thus obtained show a great congruity 

 with those obtained for the more salic rocks (compare symbols 

 within square brackets with those of the rocks in Classes I., 

 II., and III. preceding). For example, in the first eleven rocks of 

 Series I. it is clearly seen that, while the Classes range from 

 I. to III. (persalic to salfemic), the orders remain indicated by 

 5 (perfelic) with the exception of one which is 4' (intermediate 

 between 4 and 5); and eight of the rocks are dosodic (indicated 

 by 4 in the last figure of the symbol). The remaining two are 

 sodipotassic transitional to dosodic 3 (4), and persodic near 

 dosodic ('5). The third figure, however, varies with the Classes, 

 ranging from peralkalic (1) to docalcic (4), and illustrates ad- 

 mirably the usual increase in the anorthite molecule of the 

 felspars concomitantly with increase in the proportions of the 

 femic constituents. The last three rocks of the series fall into 

 Class IV. (dofemane), and their symbols, calculated by the 

 methods of the Quantitative Classification for rocks in Classes 

 IV. and V., are hopelessly incongruous with those of the other 

 ten. If, however, they are calculated by the methods used for 

 rocks in Classes I., II., and III.— that is, on the ratios obtaining 

 between the salic constituents— their relationships with the rest 

 of the series at once become evident. They are perfelic and 

 dosodic, and thus fall in with the magmatic character of the 

 salic portion of the series. The magmatic character of the 

 whole series is therefore well defined. With a variation from 

 persalic to dofemic there is a sympathetic variation from peral- 

 kalic to docalcic, whilst the rocks throughout the series remain 

 dominantly perfelic and dosodic. 



Similar analysis of the Series II., III., and IV. affords similar 

 results. The magmatic character of Series II. (New Caledonia) 

 is exceptional in that the rocks remain docalcic to percalcic 

 throughout, although the classes range from persalane (I.) to 

 perfemane (V.). In Series V. (Hawaii) five of the rocks in 

 dofemane (IV) give results which prove them to be the con- 

 tinuation of that part of the series which falls in Classes I., 

 II., and III. The remaining two, however, do not conform 

 to the series so far as is indicated by the magmatic symbol 



