266 H. S. S 



wmmers. 



I. Dacite, ^ miles south-west of Cherokees. 



II. Dacite, 50 yards south of Braemar House Stable. 



III. Dacite, Willimigongoiig Creek, Upper Macedon. 



IV. Granodiorite, near Braemar House. 

 V. Dacite, 1 mile west of Heskct. 



VI. Granodiorite, near old Sawmill, Hesket. 



VII. Granodiorite, Porphyry, Barringo Cl'eek. 



For reasons given above these analyses were recalculated to 100 

 per cent, with the water omitted, and all the iron reckoned as 

 ferrous oxide. These recalculated analyses are given in Table 

 II., arranged in order of increasing silica percentage: — 



TABLE II. 



I. II. III. IV. V. VI. VII. 



Total - 100.00 100.00 100.00 100.00 100.00 100.00 100.00 



I. Dacite, J mile south-west of Cherokees. 



II. Dacite, Willimigongong Creek, Upper Macedon. 



III. Dacite, 50 yards south of Braemar House Stable. 



IV. Granodiorite, near Braemar House. 

 V. Dacite, 1 mile west of Hesket. 



VI. Granodiorite, near old Sawmill, Hesket. 

 VII. Granodiorite porphyry, Barringo Creek. 



It will be seen that the only difference in the order of the analyses 

 in the two tables is that the Braemar Hou.se and the Willimigongong 

 Creek dacites change places. 



As already pointed out, thei'e is a very marked difference in 

 the shape of the graphs in the two variation diagrams plotted from 

 the original and the recalculated analyses respectively. In the 

 second diagram the relationship of the different types to one another 

 agrees with Haiker"s " linear "variation " as the percentage of each 

 oxide is a linear function of tlic silica }ierrcntage. 



One interesting point was noted in regard to the ret-alculated 

 analyses of these dacite and granodioriti\ viz., that the sum of the 

 molecular ratios was approximately a const ant figure. The nuile- 

 cular ratios of these rocks are triven in Tal)le 111. : — 



