Page:Brinkley - Japan - Volume 7.djvu/154

RV 130 around its base to steady it, and the stoppers were removed from the ingates. The ingates, of which there were seven—four about the middle of the mould and three at the top—were fashioned in the form of small cups of fireclay, about two inches in diameter, each having three apertures half-inch in diameter opening into the channel leading into the mould.

The mould was now ready for receiving the metal. On looking into it through one of the ingates it was seen to be at a dull red heat. The bronze was then tapped into four iron ladles, each of which was held by a workman, and a small quantity of wood ashes was thrown upon its surface. The workmen then took up their positions opposite the lower ingates, and on a signal being given poured the contents of their ladles simultaneously into the mould. The quantity of metal had been very accurately estimated as it just reached about half-way up each ingate. These ingates were then closed with clay stoppers luted in with fireclay. Three of the ladles were filled again and poured in the same manner as before, but into the upper ingates, completely filling the mould. During pouring very finely powdered rice bran was thinly sprinkled on the metal as it flowed from the mouths of the ladles. The mould was allowed to stand for six hours before breaking it from off the casting. Several other smaller moulds were then filled in a similar manner, and as one ladleful of metal was sufficient to fill each, they had only one ingate and one air outlet. Whilst the bronze was being poured into them they were rather vigorously tapped with a short stick to dislodge any air bubbles which might have adhered to their sides.

For castings of very large size ladles are not used, but the bronze is run from one or more cupola furnaces, first into a receptacle lined with fireclay, and then from this through an aperture in its bottom into the mould. The outflow is regulated by means of a plug, so that a considerable depth of metal is always retained in the receptacle in order that scoriæ and oxidised scums may be prevented from entering the mould. To prevent oxidation as far as possible, the surface of the metal is kept carefully covered with a layer of charcoal or of partially carbonised straw.