732 KEPORT— 1893. 



i.e., it seems to be a nitroquinoketopyridin ; the calcium salt of this substance 

 crystallises in beautiful yellow needles. Experiments are also in progress upon 

 the products of reduction of citrazinamide. The reduction takes the same course 

 as in the normal reduction of amides of the aromatic series, an alcohol being 

 produced. 



12. On a Nottingham Sandstone containing Barium Sulphate as a 

 Cementing Material. By Professor Frank Clowes, B.Sc. 



The author draws attention to papers presented by him to former meetings of 

 the British Association (' Brit. Assoc. Reports,' 1885, p. 1088, and 1889, p. 594), 

 These papers described sandstone extending over a large area at Bramcote and 

 Stapleford, in the immediate neighbourhood of Nottingham, in which crystalUsed 

 barium sulphate occurred in large quantity. Bramcote and Stapleford Hills and 

 the Hemlock stone were wholly composed of such stone. The largest quantity 

 found in the specimens analysed reached 50 per cent. ; complete analyses were 

 given of specimens of sandstone from different parts of this district. The sulphate 

 was in a beautifully micro-crystalline condition, and the crystals had been identified 

 and separated both lay Professor Lebour and by Mr. J. J. H. Teall. In some 

 parts of the sandstone the barium sulphate uniformly permeated the mass. In 

 other parts the sulphate occurred in streaks or network, the latter distribution 

 leading to a curious mammiUated weathering of the surface of the rock, owing to 

 removal of the uncemented grains. Occasionally the cementing material occurred 

 in nodular patches, as seen in sections of the sandstone : this led to the formation 

 of the so-called * pebble sand-beds' at the top of one of these sandstone hills. The 

 beds were the effect of weathering; the uncemented sand-grains became loose 

 sand, and disseminated amongst the loose sand were the ' pebbles,' consisting 

 of masses of sand-grains bound together by barium sulphate. The author has not 

 been able to obtain from any source evidence of the occurrence of similar sandstone 

 in any other part of this country ; he is still without direct evidence whether the 

 sulphate has been deposited as such, as in the colliery boxes of Durham, or is the 

 result of chemical change occurring between calcium sulphate in solution coming 

 into contact with barium carbonate already deposited in the sandstone. 



