i 



18i W. J. Taylor on Rock Guano, 



The appearance of tlie bodj of the two rocks is also much alike, 

 but in the specimens Avhich I have seen from El Eoque the ex- 

 terior crust is ver}^ different ; it is rarely more than a slight coat- 

 ing ; in some places it has a slight appearance of the enamel, 

 when examined with a pocket lens ; the surflice is very irregular, 

 often containing cavities which are lined with the same white 

 coating. It was impossible to obtain sufficient of this for analy- 

 sis : the analysis of the black portion of the rock was as follows : 



1-8636 grms. loss by ign 



1-4C09 " 0-32'74 grms, BaO, SOa gave sulpTiuric acid, T-70 " 



" 1-0066 " CaO,C02 " lime, 38-67 



U 



u 



ii 



u a 



"" 0-1118 " 2MgO,P05 " magnesia, 2-75 



" 0-0116 " insoluble 0-78 



0-0058 " FesOs&AhOa « iron and alumina, 0-40 



a 





a u 



1-1680 « 0-7936 « CaO,C03 « lime, 38-12 " 



« 0-0879 « 2MgO,P05 « magnesia, 2-70 " 



0-7383 " 2MgO,P05 " phosphoric acid, 40-49 " 



Organic matter and water, 10-22 per cent. 

 Sulphuric acid, V"70 " " Oxygen ratio, 4-61 



Lime, 38*67 " " " " 10-09 



Magnesia, 2*75 " « « " 1'09 



Phosphoric acid, 40-49 " « " " 25-93 



Alumina and sesquloxyd ^ ^ . „ 



of iron, ^ 



Insoluble, ' ' 0*78 



4'61 oxygen in sulphuric acid require 1-54 oxygen in lime; 

 there remains tlierefore 8'55 oxygen in lime which stands with 

 the oxygen of phosphoric acid 25-93, in the ratio 1 : 3, showing 

 that the phosphate in this specimen consists principally of 

 3CaO,P05. 



A specimen containing no organic matter was 



grated 



was very porous, and evidently had been acted upon by some 

 causes which were gradually removing all its components except 

 the silica. In appearance it was largely a sandstone, as the 

 analysis showed. The most compact portion of the specimen 

 was selected, which was readily pulverized ; the results of the 

 analysis differ from all the other specimens. The following are 

 the results : 



(XL) 



1-2910 grams, insoluble silica O-G'722 grams. 52-07 p. c. 



" 0-0085 CaO, CO2 gave lime, 0-37 " 



« « 0-0206 2MgO « magnesia, 0-57 " 



O-8806 « 0-1073 loss by ignition" water, 12-17 " 



0*8806 « insoluble 0'4600 grams. " silica, 52-27 " 



sulphuric acid, trace. 



