198 ON THE CHINA-STONE AND CHINA-CLAYS OF CORNWALL. 



this, the influence of the air, water, and soil, of mineral substances and 

 manures, on the growth and productions of plants, must be studied ; the 

 composition of their ashes, under different circumstances of growth and 

 product, examined ; the influence of food and other circumstances on 

 the growth of animals and of their parts, such as hair, horn, fat, &c, 

 must be investigated. These important observations on organic life 

 constitute a true art, as yet in its infancy ; and it is of a chemical 

 character, so far as it is pursued with a chemical object in view, (the 

 quantity and quality of organic product,) and by chemical agency, 

 (minute, practical analysis.) We may consider it under the several 

 heads, — of the chemical changes observed in the formation of useful pro- 

 ducts in plants and animals, including the peculiar chemical character 

 of such products ; of the influence of mineral organic manures on the 

 special products of plants, and various conditions on the products of 

 animals ; and the examination of the ashes of organized bodies, with a 

 view of supplying such as may be required for obtaining special pro- 

 ducts. These subjects are most conveniently grouped in this manner at 

 the present time ; but as the art becomes more fully developed, the 

 very different nature of plants and animals, and the different 

 influences exerted upon each domain of organic life, will cause their 

 separation. 



Philadelphia. 



ON THE CHINA-STONE AND CHINA-CLAYS OF CORNWALL. 



BY H. M. STOKER. 



The China-stone and China-clays of Cornwall, or the disintegrated 

 granites, have, of late years, assumed a no less important than interest- 

 ing feature in its history ; not only to the capitalist, from the great 

 addition the discovery of their use has made to its commercial importance; 

 to the working classes, from the necessarily co-existant increase of em- 

 ployment ; to the shipping, from the quantity annually exported ; but 

 also to the traveller, from the picturesque scenes, the preparation of 

 these articles have added to the previously existing and unexampled 

 ones offered him for contemplation in the various modes of raising and 

 rendering available the mineral wealth for which we have been so long 

 and so justly famed ; and not only to these, but to the practical chemist 

 as well, does it afford matter for speculation, inasmuch as the supply of 

 the former of these articles is so limited, as to require, in the course of 

 a very few years, some cheap and easily-available substitute, whether to 

 be supplied from this or from some other county, is a question to be 

 determined only by the conjoined efforts of the miner, the geologist, 

 and the analytical chemist. 



