LETTER XLVL 



REMARKS ON LEAVES CONTAINED IN NODULES. ...IMPRESSIONS 

 X)F THE SAME SIDE OF THE LEAF ON EACH NODULE.... AC- 

 COUNTED FOR BY JUSSIEU, SCHULTZ, &C.... EXPLANATION PRO- 

 POSED. 



I AM thoroughly aware of the circumstance to which our friend 

 Winton alludes. He desires you to inform me, that he will never 

 believe the impressions on the two halves, of the nodule he has sent 

 me, are the impressions of a real leaf, until I can inform him if, by 

 involving a guinea in plaster of Paris, I could obtain two impres-> 

 sions of the king's head, without any impression of the reverse. 

 The circumstance to which he refers has puzzled some of our most 

 eminent lithologists. 



An instance of the erroneous opinions which have prevailed re- 

 specting these subjects will be found in the remarks of our coun- 

 tryman, Dr. Leigh*. " In the rocks in these parts are only found 

 Polypody, Wall Rue, Scolopendrium, or leaves of thorns; doubt- 

 less other leaves, as well as these, would have occurred to our ob- 

 servation, had these been deposited here by Noah's deluge. My 

 sentiment of the whole is this, that as it is observable in chymistry 

 that the salts of some plants will divaricate themselves into the 

 figures of the plants, that these representations of plants in rocks 

 are nothing but different concretions of saline, bituminous, and 

 terrene particles." 



* The Natural History of Lancashire, Cheshire, &c. by Charles Leigh, M.D. 1700, p.99. 



