15 



loped ly gallic acid, then drawn over iodide of 



mm, ami dilute nitric ;n-id, .m<l exposed to lull sunshine: 



while Near-liing tin- dark parts, the light is re-darkening the newly 



I.H ( -ipitated iodide in the lighter portions, and thus the negative 



picture is converted into a positive one. 



These processes are, as we have said, difficult to manage snc- 



ly; and the, resulting pictnres have, though more minutely 



defined, and free from many defects inherent to copies through 



paper, tin- same disadvantages as those of the Daguerreotype, 



vi/. the pnvii,, m , an- revei sed, and the copies cannot be multiplied. 



A good negative picture having been obtained and carefully set, 

 copies may lie procured on almost any kind of photographic paper. 

 Tin- following are the formulas for making the papers commonly 

 used for the purpose. The Knergiatypc paper, which is also 

 very Hliitahle, is desrrihed further on.* 



i. MH. Fox T,u. HOT'S PHOTOGRAPHIC; PAPER. Take a sheet 

 of good paper, and having dipped it for a minute or so in a solution 

 <>l common Halt, one part of saturated solution to eight parts of 

 water, ili \ it first in blotting paper, and then spontaneously. Wash 

 one of the sides, previously marked, with a solution of nitrate of 

 .silver eighty grains to OIK ounce of distilled water. Allow it to 

 dry, and it i ready for use. 



2. MR. (.'UNDEM'S PAIM u. To a solution of one drachm of 



nitrate silver, in twelve drachms of water, add strong ammonia, till 

 t h< precipitate which falls is just re-dissolved. Wash the marked 

 side of the paper over with HUH solution, then dip it in water con- 

 taining forty grains common salt to the pint; apply the nitrate of 

 silver solution as he fore, and dry carefully in Hie dark. 



:t. MR. COOPER'S PAPER. Soak Hie paper for a few minutes in 

 a boiling solution of chlorate of potash, (the strength is immaterial;) 

 dry it, and wash it on one side with a solution of nitrate of silver, 

 sixty grains to the ounce of distilled water. This paper is not 

 very sensitive, hut the image can be fixed by washing only. 



l. M. DAOUBRRB'S PAPER. Immerse the paper in hydro- 

 < hloric (muriatic) ether, which has become acid from keeping ; the 



|.,.li/.. <l. Photographic, MIK! KM. i-i.i\i" Paper, may h. Messrs. 



T. *R. WUtit*,R, Chc: M . 



