938 



Extract from Proceedings of the Numismatic Society of London, 1837-38. 



"A Lecture, by Mr. Williams, on the mode of taking casts in sulphur, from coins, 

 medals, and Oriental cylinders, illustrated experimentally. 

 " The following is the process, as ingeniously described by Mr. Williams: — 

 " A number of slips of paper, about an inch in width, and of a length sufficient to go 

 somewhat more than once round the coin, or medal, should be first prepared ; and also 

 a number of slips of card, not quite half the width of those of paper. The coin is then, 

 to be oiled with a piece of cotton wool, dipped in sweet oil, and as much of the oil as 

 possible wiped off with another piece of wool. The edge of the coin should next be 

 placed about half way at one end of the slip of paper, and the paper rolled round it, a 

 little stiff paste being previously put upon the opposite end of the slip. This will 

 cause it to adhere firmly, and thus form a hoop round the coin, which will be suspend- 

 ed about midway by the edge, and must be retained in that situation by means of one 

 of the slips of card, bent round, and placed beneath it, within the hoop of paper. The 

 object of this arrangement is to cause the opposite sides of the mould to be as nearly as 

 possible of the same size. A little water is then to be poured into a cup, or other 

 vessel, and a sufficient quantity of the finest plaster of Paris lightly sprinkled into the 

 water, leaving sufficient of the latter to cover it. A slight effervescence will take 

 place as soon as the bubbles have ceased rising. The superabundant water is then to 

 be poured off, and the mixture stirred with a spoon. The plaster is now ready for use. 

 A thin coating of plaster is then to be laid on with a small brush, having moderately 

 stiff hairs, over the face of the coin, and the mould filled up to the rim with the spoon. 

 The use of the brush is to prevent bubbles from forming upon the surface of the coin, 

 as these would entirely spoil the mould ; and, in order to prevent the accumulation of 

 bubbles in the plaster, which is afterwards poured in, it is advisable to raise the hoop 

 with the coin and plaster in it, about an inch, and let it drop upon the table two or 

 three times. This, of course, must be done immediately after the pouring in of the 

 plaster. The whole is now to be left until the plaster is set, which will usually be in 

 about twenty minutes. 



*' When this is effected, the under side is to be turned up, the strip of card removed, 

 and any plaster that may have found its way between the edge of the coin and hoop 

 of paper cleared away. The operation of mixing and applying the plaster, must now be 

 repeated ; and in about half an hour the plaster will be sufficiently set to allow of the 

 moulds being separated from the coin. The paper must be removed, and great care 

 taken in pulling off the moulds ; as, unless they are taken off perfectly straight, they 

 will be injured, in consequence of some of the deeper parts being broken off by the 

 twisting of the mould. Should the mould not yield readily, the bottom of it may be 

 dipped into water, when it usually will very easily come off. Should this however fail, 

 heating the bottom of the mould before the fire, after having wetted it, will frequently 

 have the desired effect. These precautions are necessary, as a gentle force being suf- 

 ficient to remove the mould, some adhesion may be suspected where more than that ap- 

 pears to be required, which the methods pointed out will usually remove. Any super- 

 fluous plaster about the mould must be carefully removed, avoiding all injury to its 

 surface. 



" When these moulds are used for making a cast, the bottom must be placed in water 

 so shallow as not to cover the face of the mould. They will imbibe a considerable 



