615 



the transport of water. It is found of every degree of fine- 

 ness, from a coarse gritty mass of decomposing pebbles, with 

 occasional large nodules of friable felspar, to that of an im- 

 palpable colourless clay, like that of Dorsetshire, known as 

 pipe-clay. This is soft, sectile, adheres to the tongue, and 

 forms a strongly adhesive and plastic mass with water, capa- 

 ble of being moulded upon the potter's wheel into the finest 

 forms. 



It bakes perfectly white, or occasionally of the slightest 

 possible rosy tint of white. 



Some of the masses of this mineral are strongly disco- 

 loured by iron and manganese, and imbedded in the finest 

 parts are occasionally found a few fragments of marine 

 shells, and bits of wood. 



By washing with abundance of water, a fine quartzose 

 sand is separable from even the finest portions of this clay. 

 This sand is white, but water separates from it a little sand 

 of a darker colour, like common sea sand of the Dublin 

 coast, and a few microscopic flakes of mica. 



A singular minute black worm is found in this clay, 

 which may be worth the attention of naturalists. 



The clay, as dug out, does not eflferversce with acid, and 

 is insoluble in them ; it yields no soluble matter to water, 

 and appears to contain no alkali in any specimens yet ex- 

 amined. 



Mr. Mallet, however, has reason to think that the less 

 fully decomposed portions of the clay may contain alkali in 

 a soluble condition, and hence render the material valuable 

 as a manure. 



Some of the finest portion of the clay, washed from the 

 sand, and dried at a temperature of 212° Fah.,was found by 

 Mr. Mallet to have the following composition. The analysis 

 having been conducted in the usual way, and with the usual 

 precautions, it does not seem necessary to detail its steps : 



VOL. II. 3 F 



