506 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



with a good and durable varnish, which resists bending, as 

 well as a high temperature, without cracking or coming off. 

 Very small objects, such as hooks and eyes for instance, are 

 better placed along with some coal-dust in a coffee-roasting 

 apparatus, and this turned, as is usual in the roasting of cof- 

 fee, until the objects have obtained the desired depth of color, 

 and are uniformly coated with the varnish. 16 A, January, 

 1872,110. 



FASTENING EUBBER TO METAL. 



As rubber plates and rings are now used almost exclusive- 

 ly for making connections between steam and other pipes 

 and apparatus, much annoyance is often experienced by the 

 impossibility or imperfection of an air-tight connection. This 

 is obviated entirely by employing a cement which fastens 

 alike well to the rubber and to the metal or wood. Such 

 cement is prepared by a solution of shellac in ammonia. This 

 is best made by soaking pulverized gum shellac in ten times 

 its weight of strong ammonia, when a shining mass is ob- 

 tained, which in three or four weeks will become liquid with- 

 out the use of hot water. This softens the rubber, and be- 

 comes, after volatilization of the ammonia, hard and imper- 

 meable to gases and fluids. 1 A, May 3, 1872, 213. 



PAINT AND VARNISH DEYER. 



A rapid dryer for oil paints and varnishes, it is stated, is 

 prepared by dissolving twelve parts of best shellac and four 

 parts borax in one hundred parts of water by the aid of heat. 

 This solution, after heating, is poured into bottles, and should 

 be well corked. If mixed with some oil of turpentine and 

 then added to the oil paints, it will cause them to dry very 

 rapidly. 1 A, June 21, 1872, 300. 



BORATE OF MANGANESE 



is coming into use as an oil dryer, and has attracted the 

 attention of varnish makers, but the manner in which it is 

 employed is kept a secret. It is said to be cheaper than 

 other chemicals used as dryers, and preserves the oil, does 

 not discolor, and leaves no sediment. The cost, wholesale, is 

 eighty-five cents a pound, and three quarters of a pound, 

 when properly used, it is stated, is equal to two pounds of 



