372 Walter Keeping — Neocomian Sands at Brickhill, Beds. 



of the gas from the iron be due to the fine state of division of the 

 metal operated upon ? In the case of the Texas and Tazewell irons, 

 where the yield of gas exceeded that obtained from the Lenarto and 

 Augusta Co. irons, the metal was in very small pieces, which would 

 favour a more rapid and complete evolution of the gas ; in the last- 

 mentioned instances they were en bloc. That iron may under certain 

 conditions, as when deposited by electrolysis, take up nearly two 

 hundred and fifty times its volume, has been shown by the recent re- 

 searches of Cailletet. 1 An observation recently made has a bearing 

 on this question. While analysing a specimen of silver amalgam, I 

 endeavoured to remove the mercury from a weighed fragment of the 

 mineral by heating the specimen in a hard glass tube, during more than 

 five minutes in the flame of the table blowpipe. The silver imme- 

 diately fused and remained during that time in a molten state. When 

 cold, the globule of metal was flattened into a plate, and having cut 

 it into strips, and subjected it to a second heating, I succeeded in re- 

 moving a considerable part of a per cent, of mercury from it. 



Wright's researches on the gases of meteoric irons have shown a 

 varying character in the oxygen and nitrogen lines when in the 

 presence of hydrogen, and the near coincidence of two of them with 

 prominent lines in the corona, with the possible coincidence of a 

 third line, which appears to indicate that the characteristic lines in 

 the coronal spectrum are due, not so much to the presence of otherwise 

 unknown elements, as to hydrogen, and the atmospheric gases oxygen 

 and nitrogen. 



The observations were made with a spectroscope of six prisms 

 with a repeating prism, giving the dispersion of twelve in all. 



(To be continued in our next Number.) 



VI. — On the Occurrence of Neocomian Sands with Phosphatic 

 Nodules at Brickhill, Bedfordshire. 



By "Walter Keeping, 

 (Of the Woodwardian Museum), Christ's College, Cambridge. 



IN a traverse through part of Buckinghamshire and Bedfordshire 

 last vacation, with the object of tracing the extent of the Cam- 

 bridge Greensand, I was informed of some recently opened Coprolite 

 works at Brickhill, near Bletchley. On further inquiry, they proved 

 to be the " red coprolites," a term applied by the workmen to the 

 phosphatic nodules of the Neocomian like those of Potton and Upware 

 (the Cambridge Greensand and Gault nodules being known as 

 the " black coprolites "). 



The workings are seen on a hill near Great Brickhill, which is 

 about three miles from Bletchley Junction, and the section exposed is 

 about thirty feet deep. The deposit is a rather coarse sand throughout, 

 composed of grains of quartz, lydian stone, and comminuted shells, 



1 L. Cailletet. Vlnstitut, Nouv. Ser. iii. 44. 



