Page:Brinkley - Japan - Volume 8.djvu/87

 The Kudaru-yama-tsuchi is found in various places between layers of hard rock.

The first process to which the stone is subjected after quarrying is that of pulverisation. The implement employed for this purpose is of the simplest construction. It consists of a horizontal beam, to one end of which a vertical stamp is fixed, to the other a water-box. This contrivance is placed by the side of a stream, whence water is conducted into the box. The latter, filling and emptying itself, lifts and drops the stamp, which is shod with iron and works in a stone mortar containing the material to be pulverised. No other machinery is employed for the purpose, and the consequence is that such parts of the mineral as cannot be sufficiently reduced by this rude method, have to be thrown away. These rejected portions amount to as much as 40 or 50 per cent of the mass. Much of the loss is doubtless due to imperfect mechanical contrivances, but Mr. Korschelt, formerly Chemical Analyst to the Geological Survey of Japan, suggests that the minerals themselves are not homogeneous, but consist of harder and softer parts. The same expert draws attention to the important fact that, in pulverising the Arita porcelain stone, a separation of its materials is effected. Thus, though European machinery would work much more economically and efficiently than the Japanese stamper, it could not be introduced without some modification, since it would transform the whole stone into a homogeneous powder, and a porcelain of a different composition, containing more quartz, would be obtained.

The pulverised mineral is then placed in a reservoir of water, where it is allowed to settle. The most subtile particles, which naturally constitute the uppermost layer of the deposit, are used for the pâte of fine porcelain; the middle layer is reserved for the manufacture of coarser vessels, and the bottom layer is thrown away. The powder obtained by this method of decanting is carefully mixed, and afterwards transferred to pans where the moisture it contains is partly drained off and partly absorbed by a layer of sand covered with straw mats. The clay is finally made more consistent by putting it for a time on the warm ovens. It is then