THE BEGINNINGS OF PHOTOGRAPHY. 351 



from this and from the title of her book that she had an idea of the 

 g-raphic application of reducing- solutions of silver and gold upon silk. 

 It is surprising, therefore, to lind that she does not seem to have 

 thought of making patterns on her silken tissues by using stencils. 

 She refers to Doctor I^ewis's experiments, alread}^ noticed, and could 

 have got the idea from his account of Schulze's experiment. There 

 is, however, no mention of it, and she, like her predecessors, treated 

 the question of the reduction of metallic salts or solutions bv light 

 almost entirel}^ from its chemical side. Though at fault as regards 

 her ideas of the nature of light, she made a great many very interest- 

 ing experiments on the reduction of gold and silver b}^ chemical proc- 

 esses, as well as I)}" the action of light on pieces of silk treated with 

 solutions of chloride of gold or nitrate of silver. She found that light 

 had little or no action on them when they were carefully dried before 

 exposure, while if the}^ were moistened with water, the metal was very 

 easil}^ reduced. She concluded, therefore, that the presence of water 

 was necessary to effect the reduction, as it also was in the case of other 

 reducing- agents she tried, including h3^drogen gas, phosphorus, sul- 

 phur, and some of its volatile compounds, charcoal, acids, etc. The 

 favoring effect of moisture in the case of the reduction of gold and 

 silver by light, had, as we have alread}" seen, been noticed bv Du Fay 

 and Lewis, but not investigated as it was by Mrs. Fulhame. 



The account of her experiments with light is in the eighth chapter 

 of her book (p. 142), headed '"Reduction of Metals b}" Light." She 

 first shows by experiments with strips of silk treated with solutions of 

 nitro-muriate of gold and nitrate of silver, dried and suspended over 

 water and kept in darkness for three months, that water alone has not 

 the power of reducing metals at the ordinary temperature of the air. 

 She then describes a series of parallel experiments with strips of silk 

 treated with solutions of the same salts; (3 and 7) dried in the air and 

 suspended in a window exposed to the sun for about three months, 

 both showing considerable darkening and partial reduction, stronger 

 with the silver than the gold; (-1 and 8) dried and suspended in cr^'stal 

 phials over dry carbonate of potash, the phials being sealed with wax 

 and exposed to the sun as before, both strips showing onlv a very 

 slight reduction on the exposed side of the silk; (5 and 10) the slips 

 after being dipped in the solutions of gold and silver were placed upon 

 china plates and exposed to the sun, ))eing kept wet with water during 

 the exposure. In the case of the gold thi^ color soon changed to purple 

 and after an hour the silk was covered witii a coating of bright reduced 

 gold. With siher the silk also soon darkened and in four hours had 

 accjuired a blackish-gray color, l)ut further exposure was required to 

 show particles of silver on the undei- side of the silk; (O and 11) the 

 slips were dipped in alcoholic solutions of the gold and silver salts and 



