938 Transactions op the American Institute. , 



Painting Zinc. 



Dr. Bottger claims to liave overcome the difficulty of making paint 

 adhere to zinc, arising from the rapid oxydation which occurs on expo- 

 sure to air and moisture. He makes a solution of one part of chloride 

 of copper, one of nitrate of copper, and one of chloride of ammo- 

 nium in sixty-four parts of water, and one part of commercial hydro- 

 chloric acid. This solution acts as a mordant. It is spread with a 

 wide brush over the zinc, which immediately becomes of a deep, 

 black color, forming a basic chloride of zinc, and what he calls an 

 amorphous brass. The black color changes in the course of a day to 

 a gray, and upon this gray surface any oil paint will dry and give a 

 firmly-adhering coat. Summer heat and winter rain ok sleet will 

 have no effect in disturbing this coating, which affords complete pro- 

 tection to the zinc. 



CrystxVllized Tin-foil, 



In France and Germany there has been a great demand for paper 

 covered with crystallized tin-foil and coated with varnish, which is 

 used in ornamenting boxes. Puscher of Nuremberg, publishes the 

 fftllowing process for producing a crystallized surface on the foil : A 

 solution is made by dissolving two parts of chloride of tin in four 

 parts of hot water, and to this adding one part of nitric acid and two 

 parts of hydrochloric acid. Into this solution the foil is dipped and 

 left until the crystals appear, or the foil may be brushed over with 

 the liquid to effect the same purpose. As soon as the crystals appear 

 the foil must be rinsed in cold water, or its surface may be well 

 washed with a soft sponge. The crystals are small and brilliant 

 when the solution is applied to the cold tin ; but when large crystals 

 are desired it is essential to heat the foil, by spreading it on a hot 

 plate, before applying the solution. After being rinsed, the foil is 

 attached to paper and covered with a colored varnish or with gelatine. 



Blp:aciiing Flax Fiber. 

 M. Kolb, in a memoir to the French Academy of Sciences, gives 

 the results of his researches upon the bleaching of tissues, chiefly of 

 flax. He has shown that the gummy substance which adheres to 

 flax, and passing under the name of resin, gum resin, saponifiable 

 matter, &c., is nothing else than pectose. The soaking or steeping 

 of flax determines the pectic fermentation, and the pectic acid result- 

 ing remains fixed in the flax, either mechanically in this form, or 



