L. TECHNOLOGY. 497 



up and down, making a smooth, even, and very thin surface. 

 Allow this to dry, after which it is to be flowed with a solu- 

 tion of albumen made with the white of one egg and sixteen 

 ounces of water. When dry it may be coated with a sec- 

 ond albumen solution. Take white of one egg, water four 

 ounces, chloride of ammonia forty grains; beat the whole to 

 a thick froth, allow to subside, then decant or filter through 

 a fine sponge placed in a glass funnel. Pour a sufficient 

 quantity on one corner of the block to cover it when spread 

 around with the edge of a strip of glass. Let the surplus 

 solution drain back into the bottle, and dry the film by a gen- 

 tle heat. Now take of ether one ounce, alcohol one ounce, 

 gun-cotton eight grains, nitrate of silver thirty grains, dis- 

 solved in as small a quantity of water as possible, and al- 

 lowed to settle for a few days protected from the light. Flow 

 the block of wood with this solution in the dark room, and 

 dry by gentle heat. It is now ready for exposure under the 

 negative. A porcelain printing-frame, or any other suitable 

 method, may be used to print it. After printing dissolve off 

 the film with ether and alcohol, assisted by rubbing gently 

 with a soft sponge. The picture can now be toned and fixed 

 in the ordinary way, or fixed and toned at one operation by 

 the hypo and gold bath. After being allowed to dry it is 

 ready for the engraver. 8 A, August, 1870, 146. 



FIXING PENCIL OR CRAYON DRAWINGS. 



A convenient method of fixing pencil or crayon drawings 

 consists jn moistening the opposite side of the sheet with a 

 solution of bleached shellac in alcohol, care being taken not 

 to have the solution either too concentrated or too thin, but 

 such as will flow readily on the paper, making it transparent 

 when moist, and leaving no spots behind on evaporation. In 

 this way the drawings will, it is said, become permanently 

 fixed, and may afterward be painted in w x ater-colors so as to 

 ju'oduce a very excellent effect. 13 C\ August 11, 1870, 1140. 



COPYING PICTURES BY COLLODION. 



According to Mr. Kleffel, if a glass plate be coated with 

 collodion in the ordinary manner, and, after the liquid has set, 

 a piece of printed paper be pressed lightly upon the surface 

 by the hand, a very exact reproduction of the letters or fig- 



