Vol. 57.] MOUNT GIKNAK, JUI^-AGARH. 47 



aud analcime. The molecular proportions are in some cases also 

 tabulated : — 



Iff. 16. M. II a. 116. M. III. IV. M. V. VI. M. VII, iM. 



per per per per per per per per per 



cent. cent. cent. cent. cent. cent. cent. cent. cent. 



SiOo 52-79 53-02 .3-91: 53-43 54-21 4-04 52-38 51-24 2-17 54-51 54-67 4-00 43-93 2-2.5 



AL2O3 ... 21-60 22-78 1-00 20-86 22-71 1-00 22-92 24-00 I'OO 23-20 23-12 1-00 33-25 1-00 



PegOa ... 1-96 2-61 -75 1-20 



MgO undeid -29 -^9 -33 



CaO -66 1-14 2-26 1-68 ... -37 



^'aaO) „ 11-63 12-66 K.^.- 10-66 11-61) .,., 14-30 14-05),.^^ 15-15),.,. 



g-^Q^... 1480 1556 ilJ ^..^ 2-73^"'' 2-13 1-25 f '^ -26 f^^^ 7-67 P^*^ 



H2O 8-19 8-64 2-15 7-06 7*68 1-92 7'50 8-47 2-23 8-42 8-15 2-00 



CI 



Totals 99-53 99-59 99-78 10106 



[Columns headed by tlie letter M represent the molecular proportions 

 of the oxides in the column immediately to the left.] 



No. la is the analysis of the separated portion of the Girnar 

 rock. The ' silica ' includes a small amount of insoluble extraneous 

 material. All the iron in this analysis was estimated as ferric oxide. 

 The soda includes the potash, which was not separately determined 

 on account of the small amount of material available. The water 

 was calculated by difference, and the figures given include the small 

 amount of manganese and magnesia that may have been present. 



ISTo. I 6 is the same analysis, but the chemical constituents of 

 the hornblende have been deducted, on the assumption that it has 

 the composition of barkevikite. Por this purpose the mean of the 

 analyses of specimens from Skudesundskyar and Erevig (2 & 3 

 in Dana's ' System of Mineralogy,' 6th ed., 1892) were taken.'^ 



It was assumed as an approximate hypothesis that the iron present 

 in No. I a was derived from the hornblende, aud the corresponding- 

 amount of the other constituents of the hornblende were calculated 

 on that basis. The silica and oxide of titanium were deducted 

 from the silica of No. I a, the soda and potash from the soda, and the 

 magnesia and manganese- oxide from the loss assumed to represent 

 water. The whole were then recalculated as percentages of what 

 remained. 



No. II a is the analysis, given by Hunter & Rosenbusch, of the 

 isotropic matrix of the monchiquite from Km. 36, 8anta Cruz 

 E-ailway, E,io de Janeiro. 



No. 116 is the same corrected, as described by Mr. Pirsson 

 (see p. 39).' 



No. Ill is the mean of two analyses of the analcime of the 

 ' analcite-basalt ' described by Mr. Lindgren from the Highwood 

 Mountains of Montana [9], See also [19] p. 684. 



No. IV is the analcime from the ' analcite-basalt ' described by 

 Mr. Whitman Cross from Colorado (22). In the lime, -06 of strontia 



^ Except in the case of silica and oxide of titanium, which are taken from the 

 Brevig analysis, as that alone gives them both. 



^ The molecular ratios are slightly different from those tabulated by Mr. Pirs- 

 son, as more exact atomic weights are used. 



