266 ANNUAL OF SCIENTIFIC DISCOVEEY. 



crush the substances which enter into the composition of the paste, and form 

 a homogeneous mass. Double-bottomed cauldrons, equally heated by steam, 

 receive the matter, which, according to circumstances, may be heated dry or 

 in hot water. When paste is made it is put into molds and compressed, in 

 order to produce the objects required. These molds are composed of gutta- 

 percha, containing a twentieth part of caoutchouc ; this process of molding 

 affords results hitherto unknown. Each mold should be bound with iron. 

 This paste may also be composed chemically. In this case the gutta-percha, 

 caoutchouc, and pitch, are dissolved in the sulphuret of carbon. When the 

 solution is complete and the combination well effected, the solution is purified, 

 the sulphuret of carbon is drawn off, and a mass is obtained which may be 

 heated dry in close vessels. If it be desired to make pipes, boot-soles, straps, 

 etc., add to the above substances, held in solution in the sulphuret of carbon, 

 carded cotton, all the portions of which are penetrated or exactly coated with 

 the material. It is then purified, as in the former ease, and a mass is ob- 

 tained which is heated dry and passed under rollers. Under other circum- 

 stances, and according to known processes, the cotton is replaced by 

 linen, canvas, silk, wool, or any other textile substance. The paste, thus 

 prepared, may be colored by adding one or more of the oxyds indicated. 

 When it is desired to render paper or stuffs impermeable, the caoutchouc and 

 the gutta-percha must be separately dissolved in sulphuret of carbon, in the 

 proportion of 8 of gutta-percha to 100 of sulphuret of carbon, well purified. 

 The solution is left to rest during 8 days, and the white of eggs is added to it. 

 When the impure matters are deposited, it is poured forth to obtain an almost 

 colorless liquid. Paper or stuff may be then steeped in this liquid, and drawn 

 from it by passing the fabric between cleansing rollers, which equalizes the 

 layer of the matter. These stuffs become fit for all impermeable clothing. 

 The paper, rendered impermeable, is suitable for photography ; it is a substi- 

 tute for parchment ; and it serves for the preservation of valuable papers, to 

 prevent their falsification, erasures, and the action of chemical agents. As 

 to the applications of the paste, they are innumerable ; they comprise a com- 

 plete molding material, either for objects of art or utility ; and in many cases 

 may replace leather, pasteboard, plaster, carvings in wood, etc. The objects 

 may be bronzed, gilt, or silvered. 



Wood's Artificial Stone. A patent has been recently granted to John 

 "Wood, of Brooklyn, N. Y., for an artificial stone, prepared hi the following 

 manner : The proportions are fifteen parts clean sand, five parts calcined 

 plaster, and four parts animal blood. When first mixed, the composition is 

 about the consistency of stiff mortar, and the most fragile plaster mold is 

 sufficient for its retention during the few hours necessary to the perfection of 

 its form. 



The chemical action of this mixture has been described by Professor Mapes, 

 as follows: The potash of the blood dissolves a portion of the sand, and 

 diffuses it throughout the mass as silicate of potash, the element to which all 

 material analogous to this owes its adhesive properties. The albumen of the 

 blood becoming thoroughly commingled by manipulation, is coagulated by the 

 silicate of potash, and rendered insoluble thus forming locks holding all the 



