496 ANNUAL EECORD OF SCIENCE AND INDUSTRY. 



divided brown hydrated peroxide of manganese. In prac- 

 tice, addition of magnesium sulphate to the solution hastens 

 the reaction. The process may be conducted as follows : 

 Dissolve equal parts of manganate of soda and crystallized 

 Epsom salt in twenty to thirty times the amount of water, at 

 about 144, and brush the planed wood with the solution. 

 The less the water employed, the darker the stain, and the 

 hotter the solution, the deeper it will penetrate. When 

 thoroughly dry, and after the operation has been repeated, 

 if necessary, the furniture is smoothed with oil, and finally 

 polished. It is well to wash it carefully with hot water be- 

 fore smoothing, to prevent the efflorescence of the sulphate 

 of soda formed. For floors the solution may be employed 

 boiling hot, and if the stain is not dark enough, a second ap- 

 plication of a less concentrated solution should be made. 

 After it is quite dry, it should be varnished with a perfectly 

 colorless oil varnish. On account of the depth of penetra- 

 tion of the stain, a fresh application will not soon be required. 

 25 C, XLIL, 331. 



GOLD VARNISH FOR METALS. 



Dr. Kaylor found picric acid and boracic acid in a gold 

 varnish for metals, which afforded a very hard and beautiful 

 surface, and he recommends a clear solution of shellac, with 

 the addition of picric acid, and about half of one per cent, 

 of boracic acid, as giving results equally good. 8 (7, XII., 

 311. 



GILDING LETTERS AND DESIGNS ON GLASS. 



According to Moser, the glass, after being thoroughly 

 cleaned with powdered chalk, is coated uniformly, by means 

 of a brush, with a hot solution formed by soaking seventy-five 

 grains of gelatin in one quart of water, and then boiling it. 

 The gold-leaf is next laid on very evenly, an operation re- 

 quiring some practice. After this coating is dry, additional 

 layers of gold-leaf are placed on it by means of the gelatin 

 solution. False leaf may also be used for the purpose. The 

 less uniform and heavy the leaf, the greater the number of 

 layers required. When the gilding appears perfectly opaque, 

 on being held up to the light, and has become quite dry, the 

 letters or designs, previously traced with the point of a needle 



