370 Hyndman and Bonne y — Analysis of SpheruHtes. 



Oxygen ratio — 



Si0 3 



l!i., ()., and oxides resembling it .. 



Ab0 3 



Fe 2 3 



CuO 



FeO 



CaO 



MgO 



K,0 



Na 2 



EO : E 2 3 : Si 2 7-06 : 570 



The matrix, on fusion with mixed alkaline carbonates, gave a 

 bright blue-green mass, and this dissolved to a yellow liquid on 

 solution in dilute hydrochloric acid. The percentage of iron in the 

 matrix appears to be high, and cannot be correct unless iron came in 

 as an impurity in the materials, or was added for colouring purposes. 

 The copper, which practically remains in the glass, has been un- 

 doubtedly added for this reason. The general processes of analysis 

 and the method of determination of the alkali metals were carried 

 on in the same manner as in the former analyses. 



It is not easy to interpret the bulk-analysis of the spherulite, and 

 we must bear in mind the possibility that, as it is an artificial 

 product, the constituent minerals may not correspond with an)' that 

 occur in nature. Comparing with the analysis of the original 

 granite, it is evident that some lime, potash, and a considerable 

 quantity of soda must have been added in some form or other. 

 A rough calculation, however, indicates that if the potash were 

 present as orthoclase, and some of the soda as albite, this would use 

 up the alumina and about seven-tenths of the silica ; the remainder 

 of this, with the rest of the soda, the lime, magnesia, and iron 

 protoxide, might form a mineral allied to the soda pyroxenes. 



The silica percentage of the granite glass is comparable with that 

 in the intermediate rocks, in which Lagario l has shown that the 

 matrix tends to become a mixture of quartz and orthoclase. The 

 analysis given above does not agree with this, as the matrix has 

 less silica and more soda than the glass, but corresponds fairly 

 well with one of Dumas' quoted by Professor Bonney in his 

 presidential address 2 ; but the ratios of the oxides are very different. 



Crystallized part. Vitreous part. 



S1O2 68-20 64-70 



AI2O3 4 90 3-50 



CaO 12-00 12-00 



Na 2 14-90 19-80 



Oxygen ratio — 

 Si0 2 

 A1 2 3 

 CaO 



Na 2 



RO : R263 : Si0 2 8-54 : 159 : 34 50 7'27 : 2-2 : 3637 



