1889.] 



Barium Sulphate as a Cement in Sandstone. 



365 



combed or fretted appearance, which is particularly noticeable on the 

 cap of the Hemlock Stone. In other parts, the fractured sandstone 

 shows compact blotches of sand cemented by the sulphate, with inter- 

 vening loose and darker portions ; the stone at the upper part of 

 Bramcote Hill is of this character, and after prolonged weathering it 

 has been converted into what has been called the pebble bed ; this is 

 a loose sand bed inclosing rounded pebble-like masses of sand grains 

 bound together by the sulphate; these are usually about the size and 

 shape of a hazel-nut. 



Quantitative Composition. — As this, sandstone appears to be unique 

 in composition amongst the sandstones of this country, quantitative 

 analyses were made of the portions which contained the largest 

 proportion of barium sulphate. They yielded the following 

 results : — 





Hemlock Stone. 



Stapleford Hill. 



Bramcote Hill. 



Top. 

 1 



Near 

 base. 



2 



Top. 

 3 



Base. 

 4 



"Peb- 

 bles " 

 at top. 



5 



Middle 

 height. 



6 



Loss at 100° C. moisture . . 

 Loss by ignition (organic 



BaO 



so 3 



Alkalis, &c. (by difference) . 



0-21 



0-87 

 6-41 

 30 -23 



0- oo 



13 

 16-39 

 44-46 



1- 30 



0- 24 



2-13 

 4-84 

 21-89 



1- 68 

 1-08 



12-09 

 54'5-S 

 1 53 



o-ii 



36 

 3 53 

 30-81 

 0-02 

 10 

 16-58 

 47-36 

 113 



0-20 



0-39 

 4-46 

 32-80 



o-oo 

 o-oo 



17 14 

 43-77 

 1 -24 



0-18 



0-93 

 5-10 

 18-52 



o-oo 

 o-oo 



10-14 

 62-59 

 2-54 



05 



0-72 



4-45 

 33 -30 



o-oo 

 o-oo 



17-42 

 41 -47 

 2-59 





46-03 



33 33 



46-92 



49-95 



28-20 



50 06 



Weathering . — It would be inferred from the composition of this 

 sandstone, that it would suffer loss only with extreme slowness by 

 weathering, owing to the very slight solubility under ordinary condi- 

 tions of the barium sulphate. Experiments were made to confirm 

 this supposition by treating finely powdered specimens of Nos. 1 

 and 2, the analyses of which have been given above, with hot dilute 

 hydrochloric acid for some considerable time. Analyses of the solid 

 matter dissolved by the acid gave the following results : — 



