332 ON THE FORMATION OP 



the position of this village it is more than probable that a 

 Roman camp stood on the high commanding gronnd now occu- 

 pied by the houses. The Roman way, which went from the 

 Watling Street at Bewcley to Bewick, so carefully investigated 

 by Mr. M'Laughlan, lies about half a mile to the west. At 

 Black Heddon there are the remains of three or four camps. 



XXVII. — Theory of the Formation of Sulphur in Volcanic Countries. 

 By Robert C. Clapham. 



I PURPOSE in this paper to illustrate the theory of the forma- 

 tion of sulphur in volcanic countries, by the decomposition of 

 gypsum (sulphate of lime) by specimens from Spain, Sicily, and 

 the Grecian Islands. 



Within the last few months, samples of what is called " sulphur 

 stone" have been sent to this country, which may probably 

 lead to the importation of sulphur from entirely new sources. 

 The samples were brought under the notice of the writer and 

 other parties. One of these samples consisted of — 



Sulphur 24-0 



Gypsum 62 2 



Sand, &c 6*0 



Water 7-0 



99-2 

 Another sample consisted of — 



Sulphur 22-3 



Carbonate of Lime 6o'4 



Gypsum 5-2 



Sand, &c 2-3 



Water 6-0 



99-2 



In all countries where sulphur is found it exists near to, or 

 is surrounded by, rocks of Gypsum ; in many cases this Gypsum 



