544 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



1 



creased temperature is also required for this preparation. 

 The approved formula consists in mixing together 100 parts 

 of rubber, 45 of sulphur, and 10 of gutta-percha, with suffi- 

 cient heat to facilitate the combination. In manufacture, a 

 sufficient quantity of this mixture is placed in a mould of a 

 desired shape, and of such material as will not be affected 

 by the sulphur contained in the mass. It is then exposed to 

 heat of about 315, and a pressure of about 12 pounds to the 

 square inch, for two hours. This is done most readily by 

 placing the mould in a steam-pan, where the requisite press- 

 ure and temperature can easily be kept up. When cold, 

 the ebonite is removed from the mould, finished, and polished 

 in the usual manner. 18-4, January 8, 1875, 818. 



GLAZIXG PAPER BY PARAFFIN. 



According to Dr. Vohl, the following process for glazing 

 paper by means of paraffin is adapted to white and all del- 

 icate tints : Add 100 parts, by weight, of fine, washed, and 

 dried pure white China clay, previously heated to at least 

 the temperature of fusion of paraffin, to 24 parts of (easily 

 fusible) melted paraffin. The clay, if hot enough, will com- 

 pletely absorb the liquid paraffin. Pulverize the mass, when 

 cold, and grind in the color- mill with cold water. Add 

 from 4 to 6 per cent, of this semi-fluid mass to the color pre- 

 viously prepared, and treat the dried paper as usual. The 

 driest and dullest earth colors assume a fine glaze by this 

 process ; and for dark tints clays with a decided color may 

 be used. The paraffin mixture may also be employed with 

 advantage for glazed pasteboard, as it likewise renders it 

 less liable to be affected by moisture. 6 C,July 16, 1874, 

 265. 



POLISHING-CLOTH FOR BRASS. 



A sort of linen was exhibited at the Vienna Exposition 

 which served the purpose of cleaning and polishing brass 

 very well, and was at the same time cheap enough for gen- 

 eral use. Investigations by Dr. Keichardt indicate that the 

 effect is due to the presence of silicic acid and an alkali, and 

 that the article may be prepared by impregnating some loose 

 fabric, such as fustian, with a weak solution of water-glass, 

 and then washing it thoroughly. A not inconsiderable 



