NATUKAL PHILOSOPHY. 175 



The principal colors obtained by this wonderful process are red, yellow, 

 purple, blue, white and green. To produce a pale blue design on a white 

 ground, or white on a deep blue, they employ solutions of citrate or tartrato 

 of iron, and ferrocyanide of potassium. The cloth is afterward plunged into 

 a solution of sulphuric acid. Brown or chamois shades are obtained with a 

 solution of bichromate of potash. The salt which impregnates the portions on 

 which the light has not reacted, being removed by washing, these portions 

 remain white, or are decomposed by salts of lead, to form a yellow chromate 

 of that metal. By combining the two processes, and employing in addition 

 madder, campeachy, etc., an infinite variety of shades may be obtained. 



The exposure to the light varies from two to twenty minutes, according to 

 the method employed, and the pattern used. Numerous experiments have 

 shown that the light of a short winter day has all the power necessary very 

 beautiful specimens have been produced as late as four hi the afternoon in the 

 month of January. 



IMPKOVE3IENTS IX PHOTOGRAPHY. 



Photographic Impressions of Flowers. Regnault, in a late sitting of the Acad- 

 emy at Paris, presented, in the name of A. Braun, of Dornoch, an album of 

 actinic impressions of flowers, which were remarkable for their harmony and the 

 chasteness of their model. Braun has proposed to form a collection of studies, 

 intended for artists who use flowers as elements of decoration, whether in 

 calico or wall-paper printing, or on porcelain, etc. He has attached groups 

 of branches and flowers, so as to produce the most interesting effects in an ar- 

 tistic point of view. Those presented to the Academy, although a hundred in 

 number, were only a small portion of what he had executed, all perfectly 

 successful. Humphrey's Journal. 



Application of Photography to Porcelain. M. Camarsac has recently pub- 

 lished a plan for the " transformation of photographs into indelible pictures, 

 colored and fixed." It appears to resemble the usual operations of paint- 

 ing on porcelain, though he also proposes to work on glass and enamel. 

 The paper of the positive is consumed in the heat of & muffle (an enameler's 

 oven), leaving the photograph on the porcelain, glass, or metal. These are 

 colored with enamel colors, and burned in. He operates on white or colored 

 bases. On the dark bases, the lights are formed by the reduced silver deposit, 

 which obtains a great brilliancy from the fire. On porcelain, white enamel, 

 and transparent glass, the blacks are formed by the metallic deposit, which he 

 afterward treats with the salts of tin, the salts of gold, and of chrome. An- 

 other method he proposes, is to cover the porcelain, glass, or enamel, with a 

 sensitive resin, and, by means of a negative, to print a positive thereon, on 

 which he works with enamel colors, *to supply the place of the sensitive var- 

 nish, which is to be destroyed by the heat of the muffle. Liverpool Photo- 

 graphic Journal. 



Lunar Photographs. At a recent meeting of the Astronomical Society of 

 London, Mr. Hartnup presented actinic maps of the moon, taken on collodion. 

 The original impressions were one inch and a third in diameter, while those 



