Owing to the introduction of tin from the Straits Settlements, where it is found in the condition of stream tin and can be easily worked, the tin mining in Cornwall, necessitating real mining and the following of lodes, has proved unremunerative and has been abandoned, and now but few mines are worked for the metal. Another cause has fatally affected Cornish mining--the fraudulent practice of the promoters of the mines. It was no uncommon practice for the "captains," when a rich lode was struck, to cover it up, and follow false lodes, till the investors in the venture lost heart and refused to advance more money, when the captains would carry on the work in the real lode, if they could raise the capital, but this they often failed to do, the mine having fallen into discredit, or the water having broken in. But if tin mining be practically dead in Cornwall, another industry has risen with leaps and bounds. It is that of the china-clay and china-stone, employed in the manufacture of porcelain, in the sizing of paper and of cotton materials, in the manufacture of alum, etc. The glazed paper so largely employed in our illustrated papers is made up largely with china-clay. Some years ago the Italian government employed this paper for its official documents, but found that after a few years under the influence of damp weather the records had dissolved into a lump of clay. [Illustration: China Clay Quarries, Porthpean] China-clay consists of decomposed felspar, quartz and white mica. In 1817 the amount shipped for manufacturing pottery was comparatively small, but of late years it has grown, and employs over 3000 persons. The china-clay is the same as the Chinese _Kaolin_; its value was discovered by a Plymouth Quaker, Mr Cookworthy, in 1745. Porcelain was introduced into Europe from the East in 1518, when it acquired the name of China. For a long time it was supposed that the kaolin or fine white clay of which it is composed, was found only in the Celestial Empire, and specimens of this brought to Europe fetched a high price. At the beginning of the eighteenth century it was discovered in Saxony in an odd way. A merchant named Schnerr, being on a journey, was struck with the whiteness of some clay near Schneeburg, and collecting some of it used it for powdering his wig. It succeeded, but had this disadvantage, that wigs dressed with this new powder were very heavy. An apothecary named Bötcher noticed the increased weight of the wig, analysed the powder, and discovered that it was identical with Chinese kaolin. He began to make Dresden China in 1709, and the process was carried on with the greatest secrecy, the exportation of the earth being forbidden under heavy penalties. In 1748 Cookworthy discovered kaolin on Tregonning Hill, more was found at Boconnoc, and Cookworthy and Thomas Pett began to make china in 1768. At present St Austell is the great seat of this industry, and the produce is shipped at Charlestown and Polmear.