354 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 19, 



III. Calcareous lava, with imperfectly crystallized hornblende, 

 and minute red felspar crystals ; from the valley of the White-leaved 

 Oak. 



lY. Another fragment of the same rock. The rock after being 

 finely pulverized, was digested with distilled water acidulated with 

 25 per cent, of glacial acetic acid ; and the soluble and insoluble 

 portions were separately analyzed. 

 a. The portion dissolved. 

 h. The portion undissolved. 

 C. The composition of the undissolved portion. 



Y. Lava, from a boss in a small plantation south of the Eastnor 

 Eoad; contains hornblende; the felspar is not crystallized; G=2-739. 



YI. From the interior of a loose spherical fragment of the same 

 rock. A confused mixture of hornblende and felspar indistinctly 

 crystallized, and with a little calc-spar. 



YII. Prom the same fragment, nearer the surface. 



YIII. Lava from the footpath from Fowlett's farm to the valley 

 of the White-leaved Oak, in contact with the black shales, which are 

 there bleached by it ; uncrystallized ; contains hydrated peroxide of 

 iron in vesicular cavities ; partly decomposed. 



IX. Porous ash, of a light-brown colour, east of Coal Hill. 



X. Thin bed of calcareous ash, interstratified with shale, east of 

 Coal HiU. 



XL Another thin Calcareous bed from the same place. The car- 

 bonates were dissolved out by placing the pounded rock in cold dis- 

 tilled water and adding hydrochloric acid, drop by drop, as long as 

 eifervescence continued, a. The portion dissolved, h. The residue. 

 C, The composition of the undissolved portion. 



XII. Another thin calcareous bed, from the same place. 



XIII. Grey ash, west of Coal HiU. 



XIY. Calcareous lava from a boss north-east of Eronsill Castle. 

 B. Another fragment of the same rock. 



a. The portion soluble in cold dilute hydrochloric acid. h. The 

 residue. C. The composition of the undissolved portion. 



XY. Calcareous lava, south of the British Camp, Herefordshire 

 Beacon, and south-east of the cave. a. Portion dissolved by cold 

 dilute hydrochloric acid. 6. The residue. C. Composition of the 

 undissolved portion. G = 2-701. 



As the two rocks last mentioned contain crevices and vesicular 

 cavities, which were filled by calc-spar, the proportion of carbonates 

 varies in different fragments of the same rock. In one of the small 

 bosses under Bronsill Castle, carbonate of lime fiUed a cavity formed 

 by the decomposition of a crystal of augite ; and in other cavities it 

 was associated with zeolite, which may have been formed by the de- 

 composition of labradorite. In such cases the calc-spar is clearly 

 the result of infiltration and decomposition. But in those now under 

 consideration, XIY., XY., and in the calcareous lava in the valley of 

 the White-leaved Oak, III., lY., the carbonate of Hme was dissemi- 

 nated through the entire substance of the rock, and was more abun- 

 dant in the hard unaltered parts of it than where it was decomposed. 



