;>76 Barium. Sulphate as a Cementing Material of Sandstone. 



for a sulphate finding its way into the water which had been in contact 

 with the rock. But in the Nottingham district all evidence of barium 

 chloride in solution was wanting. 



The occurrence of barium chloride in water from an artesian boring 

 at Ilkeston has, however, recently been pointed out by Mr. John 

 White, and he has described the nature of the strata through which 

 the boring passed, and the results obtained by him in the chemical 

 examination of the water, in 'The Analyst' (February, 1899). The 

 Ilkeston boring has been made in the immediate neighbourhood of 

 the Bramcote and Stapleford sandstone which contains the large pro- 

 portion of barium sulphate. Since the barium chloride is found to the 

 extent of 4;0*7 parts per 100,000 in the water from this boring, and 

 seems to be a normal constituent of the water, it would appear that 

 soluble barium salts are still abundant in the district, and may there- 

 fore have given rise to the deposition of the barium sulphate in the 

 original sand beds. The crystallisation of the sulphate around the 

 sand grains would then cause it to act as a compact, insoluble 

 cementing material. 



It is worthy of note that one of the samples of water from the 

 boring contained a small amount of barium in the presence of a large 

 amount of sodium carbonate ; in this case the barium must therefore 

 itself have been present as bicarbonate. 



Water containing barium chloride to the extent of about 9 grains 

 per 100,000 has recently been found at Llangammarch in Breconshire. 

 Since the publication of my original paper on the occurrence of 

 barium sulphate in the Bramcote sandstone, I have continued my 

 examination of samples of sandstone from the basement of the pebble 

 beds of the Bunter, with the object of ascertaining whether the occur- 

 rence of barium, either as sulphate or in other forms of combination, 

 was characteristic of the sandstones of that geological period. I have 

 thus far failed to find any similar rock to that at Bramcote, and it 

 therefore seems probable that the occurrence of barium sulphate, 

 although it extends over a very extensive area at Bramcote and 

 Stapleford, must be looked upon as being due to purely local causes. 



[February 22. Mr. J. Lomas, in a letter dated 20th instant, draws 

 my attention to a paper read by him and Mr. C. C. Moore before the 

 Liverpool Geological Society, on February 8, 1898, in which the 

 authors draw attention to the occurrence of large proportions of 

 crystallised barium sulphate in triassic sandstones at Prenton and 

 Bidston. Mr. Lomas had previously mentioned the presence of the 

 sulphate in the Bidston sandstone thirteen years ago in a paper to the 

 above Society. 



In different specimens of the sandstone the percentage of the 

 silphate varied from 12*4: to 33-8 per cent. It is colourless and highly 



