ALLUVIUM. 291 



struum, is commonly found in all waters. Hence it is obvious, that a 

 deposition of carbonate of lime from water, may be occasioned either 

 from an absorption of carbonic acid, or from the loss of that portion 

 which exists in excess. 



The only incrusting spring that occurs in Sussex, has its source in the 

 beds of limestone of the iron sand formation*. It is situated in a wood 

 at Pouncefordf, between Heathfield and Burwash. It forms an incon- 

 siderable cascade over a rock of sandstone, and pursuing a tortuous course, 

 deposits carbonate of lime on every extraneous body that Hes in its 

 channel ; converting the mosses and other vegetables within reach of its 

 waters, into masses of calcareous tufa. The specimens in my possession 

 consist of incrustations of mosses, small branches of trees, leaves, &c.: 

 some of them arc composed of a porous friable calcareous earth; and 

 others of a compact carbonate of lime of a subcrystalline structure, per- 

 fectly resembhng tlie tufaceous depositions of Derbyshire. When re- 

 cently collected, the moss on the surface was green and flourishing, and 

 had evidently continued to vegetate although the roots, &c. were com- 

 pletely imbedded in the stone. 



I have not been able to obtain ajiy of the water for analysis ; but it is 

 evidently possessed of very considerable lapidescent powers, and might 

 doubtless be applied to the same ingenious purposes as the waters of 

 Tivoli, and the baths of St. Phillip, in Tuscany:};. 



* The existence of an incrusting spring in Sussex, was first made known to me by Mr. 

 Daniel King of Lewes. 



f Pounceford is tlie name of a farm in the possession of Mr. Edward Simes ; in passing 

 from Heathfield to Burwash, it lies to the right of the road, and may readily he found by en- 

 quiring of the keeper uf the turnpike gate. 



:f At the baths of St. Phillip in Tuscany, a manufactory is estabHshed, where casts of 

 medals and bas-reliefs are formed of calcareous tufa. The water is propelled from a considei'- 

 able height into a large vessel, and being interrupted in its fall by a wooden cross, is separated 

 into a fine spray and dashed against the moulds of the medals, which are placed round the 

 sides of the vessel ; by this means excellent impressions are produced. Vide Org. Rem. Vol. i. 

 p. 363. 



The waters of the Ouse also contain a considerable proportion of calcareous earth. A 

 wooden pipe which had for several years been used for the conveyance of water from the 

 paper-mill at Lewes, had its interior coated with a very compact carbonate of lime, nearly 0'4 

 inch thick. 



P P 2 



