NATURAL PHILOSOPHY. 167 



and create an unconquerable uniformity. Mr. Niepce, however, is 

 able to prove by a number of very curious experiments, that, far from 

 being injurious, the influence of the white light is very useful, and 

 that it assists considerably in copying colors. 



The Hilotype. It will be remembered, that some two years since, 

 it was asserted that a discovery had been made by the Rev. Mr. Hill, 

 of Westkill, N. Y., by which the images of objects in all their natural 

 colors could be copied photographically from nature in a few seconds. 

 The failure of Mr. Hill to substantiate his assertions by the exhibition 

 of results, has caused the whole subject to be discredited, and the 

 announced discovery has generally been considered as fabulous.* 

 Within the past year, however, testimonials have been published by 

 various artists, who have seen the pictures taken by Mr. Hill, which 

 renders it certain that something has been accomplished. The course 

 pursued by Mr. Hill in relation to the discovery is a most singular 

 one, and forms a striking contrast to the open and manly conduct of 

 INI. Niepce in regard to the same subject. Mr. Hill appears to be 

 actuated by pecuniary motives, rather than by a true scientific spirit. 

 The honor of the discovery, in any event, will now undoubtedly be 

 awarded to M. Niepce. Had a different course been pursued it might 

 have belonged to Mr. Hill and his country. Editor. 



XIEPCE'S SECOXD MEMOIR ox HELIOCHROME. 



Ix the Annual of Scientific Discovery for 1852, pp. 126-131, we 

 published a memoir submitted to the French Academy by M. Niepce, 

 on the subject of Heliochrome, or the production of colored photo- 

 graphic pictures. The following is a second memoir on the same 

 subject, subsequently read to the Academy, by the same author, and 

 containing some additional details respecting his extraordinary and 

 interesting investigations. The memoir is copied from Humphries' 

 Daguerrean Journal, for which it was translated : My later experi- 

 ments have proved to me that these phenomena of coloring by light 

 only held good according to the proportion of chlorine or chloride of 

 which the baths were composed in which I prepared my silver plates. 

 It is known from the experiments of M. E. Becquerel that chlorine 

 water impresses the silver plate by a simple immersion so as to 

 render it susceptible of copying afterwards, by means of the light, the 

 colors of the solar spectrum : but there w T ill be produced one or 

 another predominant color, according to the quantity of chlorine that 

 the water serving to prepare the silver plate may contain. For 

 example, I produce the yellow ray by the feeblest quantity of chlo- 

 rine, and the red and orange by water completely saturated with 

 chlorine, or I add to some liquid chlorine a salt of copper, and even 

 perchloride of iron. The former of these substances gives much 

 liveliness to the colors, for they are very feeble when the chlorine is 

 employed alone. Many chlorides have no influence fin the silver 



* See Annual of Scientific Discovery, 1852, p 131. 

 15* 



