102 ANNUAL OF SCIENTIFIC DISCOVERY. 



ter, or pulverized soapstone, or other similar equivalent granular or 

 pulverized matter, so that each article shall be completely surrounded 

 and covered by the sand or pulverized soapstone or plaster, c., and 

 imbedded in the same, and thereby sustained. When it is desired to 

 give a very smooth surface to the article, we cause it to be completely 

 surrounded with a layer of soapstone, even though sand may be 

 employed about the layer of soapstone. We sometimes use moist 

 sand or pulverized soapstone. When the articles are thus properly 

 placed in the box, we subject the sand or other material to pressure, 

 so that the box shall be solidly filled ; we then by means of a cover, 

 or sometimes by pressure, confine the sand or other material so that 

 the articles shall be at all times in contact with and pressed upon by 

 the sand or other material during the process of heating. We then 

 place the articles surrounded with and sustained by sand or pulverized 

 soapstone or other material, in an oven or heater, and subject the same 

 to a high degree of artificial heat, moist or dry heat, say from 260 to 

 300 Fah., for a period of from three to seven hours; and upon taking 

 the articles out of the sand or other material, the articles will be found 

 to be vulcanized in the same form in which they were when put into 

 the sand ; we are thus enabled to produce economically great variety 

 of objects. Among them, embossed, or indented, or plain sheets or 

 plates or masses of regular or irregular forms, convex or concave, such 

 as pieces of furniture, book covers, buttons, toys of various kinds, &c. ; 

 or we make the moulds of plaster of Paris, (best calcined), or other 

 substance, which, when dried will be porous and permit the escape of 

 gases evolved from the matter under treatment, and all contained air, 

 and thereby prevent the expansion of confined air and other gases 

 from injuring the surface of the moulded substance ; or we mould the 

 article in a mould which is to produce the figure, and pack in sand, or 

 pulverized soapstone or other like granular pulverized substance to 

 support the other surface or surfaces of the article to be produced, 

 and thus keep the face, which is to be figured in contact with the 

 partial mould of metal or plaster, or other material, and thus aiford a 

 free discharge for air and gases, whilst at the same time the moulds 

 are greatly cheapened. The moulds or outer casing may be made of 

 glass instead or iron or other metal, but we prefer the first mode of 

 procedure, as it avoids entirely the use of moulds during the process 

 of vulcanization. The sand or other pulverized or granular material, 

 having the effect thoroughly to support and retain the form previously 

 given to the article by moulding or modelling. The prepared 

 caoutchouc, gutta percha, &c., if it is to be imbedded in moistened 

 plaster should be previously varnished, and to keep the surface of 

 such articles to be thus vulcanized in sand, smooth India paper should 

 be interposed between such surface and the sand. 



STEREOTYPE MOULDS. 



At a late meeting of the Scottish Society of Arts, Mr. Wilson 

 described and exhibited the new process introduced by him to the 



