OF PYRITES AND GYPSUM. 327 



historian of Cornvvall, though of course with scarcely any know- 

 ledge of chemical geology, was acute enough to see this, for he 

 remarks : " There is good reason to believe that mundics are 

 perpetually forming," and then, after giving instances, he goes on 

 to observe that " The mineral principles are always active and 

 forming new concretions." 



It was seen, in an earlier part of this address, that gypsum is 

 often formed by the reaction of decomposed pyrites on calcareous 

 matter ; it is now seen that, conversely, pyrites may be formed 

 from the reaction of decomposed gypsum on ferruginous 

 solutions. Nothing surely can better illustrate the intimate 

 relationship between these two minerals, or explain why they are 

 often found associated in the clays of Essex. 



Allow me, in conclusion, to congratulate the Essex Field 

 Club on the attention whicii is at present being given to the 

 arrangement of the mineralogical collection in its Museum at 

 Stratford. My friend, Mr. T. W. Reader, is good enough to 

 sacrifice much time in co-operating with Mr. W. Cole in over- 

 hauling this department of, the museum. Let us hope that 

 before the revolving year brings round another Annual Meeting 

 we shall see, as a result of Mr. Reader's valuable labours, all our 

 specimens of minerals and rocks not only accurately determined 

 and scientifically classified, but well displayed and neatly labelled 

 in the cases of our Museum. It is true that from what we have 

 seen this evening we can hardly expect the local minerals to 

 make a brave show, and in order to gain a comprehensive view 

 of the natural history of the mineral kingdom it is necessary to 

 travel outside our county. The mineral collection of this Insti- 

 tution is therefore a general collection ; and when properly 

 exhibited it will be found to include some of the most beautiful, 

 the most instructive, and the most marvellous objects in the 

 whole realm of Natural History. 



Note referred to on page 310.— Dr. Philemon Holland the translator of 

 Pliny, was an Essex man, having been born at Chelmsford in 1552. His 

 industry in translating the classics led to his being styled " translator general of 

 his age." Pope refers to the " groaning shelves " weighed down by his ponder- 

 ous folios. 



