498 ON THE TOBACCO PIPE MANUFACTURE, ETC. 



Rock in Devonshire, is a beautiful specimen of granite. It is 

 chemically divided into alumina, silicic acid, and mica ; the disintegra- 

 tion of these three compounds forming an earthy mass, which is 

 commonly called clay. 



The clays principally used for pipe-making and other purposes, 

 appear to take their origin from the above named granite hills of 

 Haytor, on the borders of Dartmoor, and from thence deposited in a 

 large sheet or mass at their base. Owing to floods and other causes, the 

 purer portions of the disintegrated felspar of the granite has been pro- 

 pelled onwards towards the sea, and deposited in fine channel-like and 

 continuous beds, by the flood-charged streams. This may account for 

 the different qualities of the clays, as each ribbony deposit is varied 

 from the others in its adaptation to manufacturing purposes. For 

 instance — one, a dark body, burns similarly to China clay from Corn- 

 wall ; another is a white body, and is more plastic, and is used for long 

 tobacco pipes, it would not vitrify sufficiently for pottery purposes 

 These clays are unique in themselves for the particular manufacture 

 for which they are suitable, and no deposits have yet been found of 

 identically the same nature. 



The Granite Hills at Haytor, from whence these deposits are pre- 

 sumed to arise, are in Ilsington parish, about twelve miles in a direct 

 line from Teigmnouth, passing through the neighbouring parishes of 

 Bovey Tracey, Hennock, and Teigngraie, until they reach the parish of 

 Kingsteignton, where the deposits appear to be the purest and most 

 continuous, and whence clays have been procured for manufacturing 

 purposes, for a period of at least a century. Messrs. Whiteway have 

 the largest portion of these deposits, either as owners themselves, or 

 renters of the clay property of other landowners ; and they are the 

 present representatives of a firm which has been in existence for more 

 than half a century. 



As it may not be uninteresting to some readers, we shall briefly 

 explain the nature of the three chemical divisions of this important 

 article of manufacture, and would observe that aluminum forms a 

 portion of the crust of our earth, since its oxygen compound, which is 

 termed alumina, constitutes (next to silicic acid and lime) the mass of 

 the greatest number of minerals. 



Crystalized alamina is found under the same circumstances as 

 crystalized carbon : thus the sapphire, consisting of pure alumina, 

 and distinguished by its hardness, lustre, and the variety of its 

 colours, is numbered among the precious stones, and is considered 

 next in value to the diamond. 



The aluminous portion of clay is an important material in the 

 process of dyeing, and it is this that fixes the beautiful colours in 

 our prints, muslins, and other fabrics. Alumina having an affinity 

 tor vegetable matter, forces a portion of the colour into the fibre, 

 thus making it secure and permanent. 



