the name of sulphur-iron, and which is 

 much the same to appearance as the latter 

 part of the Welsh specimen. I analysed 

 this and found it to contain more siliceous 

 earth than plumbago, besides a good deal 

 of iron, not so much in the state of plum- 

 bago but what it would dissolve in acids. 



I suppose it must be the yellow lime- 

 stone about Bridport in which Dr Bl. 

 told you we found chert. How far it de- 

 serves that name I can not say, but to 

 the best of my remembrance it was of a 

 much coarser grain, and had not at all the 

 appearance of flint ; but my memory is 

 too imperfect for me to attempt to de- 

 scribe it to you. As the circumstances 

 relating to it are rather remarkable, I will 

 mention what we saw of it last year. 



On descending the chalk hills between 

 Dorchester and Bridport, by the time 

 we got about ^ way to the bottom, we 

 came to the yellow limestone, which 

 seemed separated from the Chalk only by 

 a stratum of clay of no great thickness. 

 60 



