MECHANICS AND USEFUL ARTS. 97 



rubbing the composition on the stone, the Paris blue and the ox- 

 alic acid having been mixed before with water in the above-given 

 proportions. A solution of soda in water is sufficient to thor- 

 oughly cleanse the type." 



PAINTS AND VARNISHES. 



Aniline Black Varnish. — An aniline black varnish, of recent 

 Parisian production, is the following: In a litre of alcohol 12 

 grammes of aniline blue, 3 grammes of fuchsine, and 8 grammes 

 of naphthaline yellow, are dissolved. The whole is dissolved 

 by agitation in less than 12 hours. One application renders a 

 white object ebony black; the varnish can be filtered, and will 

 never deposit ■ afterwards. The 3 colors are not destroyed, 

 for each can be separated ' by analysis with the characteristic 

 properties. 



Black Varnish for Iron Woi^ks. — Dr. Lunge distils gas tar until 

 nearly all the volatile products are got rid of, the residual pitch 

 being then dissolved either in the heavier oils, or, if a quick-drying 

 varnish is required, in the light oils or naphtha. The advantage 

 of varnish so prepared over the original tar is, that by the above 

 process we get rid of the ammonia, water, carbolic acid, and 

 other constituents that give to tar its disagreeable odor, and make 

 it so long in drvino-. 



Preserving Polished Steel from Rust. — It is said that nothing is 

 equal to pure paraffine for preserving the polished surface of iron 

 and steel from oxidation. The paraffine should be warmed, 

 rubbed on, and then wiped oft' with a woollen rag. It will not 

 change the color, whether bright or blue, and will protect the 

 surface better than any varnish. 



Silicate Paint for Stoves and Ovens. — Black-lead certainly has 

 its recommendations, but it can hardly be said to be ornamental, 

 while it entails an immense amount of labor on servants. In 

 Germany, where a stove and sort of kitchen range is continually 

 to be found in the common sitting-room of a respectable family, 

 the unsightliness seems to have been felt, and a suggestion has 

 been made to do away with the black-lead, and paint the stoves 

 and ovens. Oil paint, of course, cannot be employed, but water- 

 glass (silicate of potash), colored with pigment to match the 

 paint of the apartment, is the material recommended. Before 

 this is applied the iron must be thoroughly cleaned from grease, 

 and all rust-spots must be rubbed oft" with a scratch brush. Two 

 or three coats of the paint may then be put on and allowed to dry, 

 after which the fire may be lighted without fear of injury to the 

 color, which may, indeed, be heated to redness. Grease or milk 

 spilt over the paint has no eftect upon it, and it may be kept clean 

 by washing with soap and water. Dutch-ovens and like utensils 

 may also be coated with the same materials, and the labor spent 

 in polishing be saved. A good coating of the paint, the author 

 says, will last a year or two. 



To make Paint adhere to Zinc. — Dr. Bottger claims to have 

 9 



