Professor Orenville A. J. Cole— On Flame- Re action. 103 



Atlas. It is a very important work, namely, the Geology of 

 the County of York, in four sheets. This is one of the finest 

 of Smith's works. It is full of admirably worked out details. 

 In the West Riding, the outcrops of the chief of the grit-beds 

 are represented on the map with their relations to the coal-seams, 

 and a fine vertical section of them is given ; and in the north-east of 

 the county. Smith clearly defines the estuarine strata of the Lower 

 Oolites as follows : " Sand Rock and Grit Freestone of the Moors, 

 lying over the Alum Shale" (Upper Lias), " and, in Scarborough 

 Castle Hill, under the Oolite or Calcareous Freestone. A thin coal 

 in the cliffs is worked on the Moors at Danby and other places." In 

 this work we see the fruits of Smith's residence at Scarborough, 

 which commenced in the year 1820. 



The maps of Part V of the Atlas (Leicester, Nottingham, Hun- 

 tingdon, and Rutland) were printed in 1821, but the part, according 

 to Phillips, did not make its appearance till 1822. Two years later 

 Part VI, with the Maps of Northumberland, Cumbei'land, Durham, 

 and Westmoreland, was issued, and this was the end of this very 

 important undertaking, though Phillips informs us that "other parts 

 to complete this work were left in a state of forwardness." With 

 the exception of a little " Synopsis of Geological Phenomena," 

 a single folio sheet printed at Oxford in 1832 at the Meeting of the 

 British Association, the Geological Atlas of England and Wales was 

 the last of William Smith's published works. It is perhaps not 

 generally known that the plates of Smith's Atlas seem to have 

 been acquired from Gary by the well-known map-publishei's Messrs. 

 Crutchley, and the sixpenny County Maps for many years issued by 

 that firm contain the lines and legends of William Smith's maps. 



In attempting to solve various questions that have arisen in 

 connection with the history of these early geological maps of 

 the British Islands, I have received much valuable assistance from 

 Mr. F. W. Rudler, F.G.S., the Curator and Librarian of the Jermyu 

 Street Museum. And to the same gentleman the Department of 

 Science and Art is indebted for the gift of a number of maps which 

 have proved to be of great value in making more complete the series 

 exhibited in the Science Museum. 



II. — On the Flame-Reaction of Potassium in Silicates. 



By Grenville A. J. Cole, M.R.I.A., F.G.S., 

 Professor of Geology in the Royal College of Science for Ireland. 



WHEN recently examining a series of igneous rocks for the 

 Geological Survey of the United Kingdom, I required a ready 

 method for the determination of potassium in the felspars, whether 

 they occurred as porphyritic crystals or as microlites in the ground- 

 mass. The ordinarjf flame-reaction has always been recognized as 

 unsatisfactory in the presence of sodium, and the use of blue glass 

 has been long recommended, of a sufficient thickness to cut off 

 a sodium flame, the potassium flame then coming through alone. 



