268 Mr. Hunt on Light *whic7i Jias permeated coloured Media, 



riates, always keeping in view the definite proportion re- 

 quired for the quantity of the nitrate of silver used ; it vi'ill be 

 found that almost every variety of shade, from a rich dark 

 purple to a full red, and a ^e-w other tints, may be produced 

 at pleasure. 



2. The effects of light, passing through coloured glasses 

 on various papers, are singularly diversified. The following 

 are a few of the most striking results. (The glasses are, a 

 deep cobalt blue, a full laurel green, an amber yellow, and a 

 rich orange red. They are so framed that all the papers can 

 be exposed at the same time to the solar influence.) 



Colour of Glass. 



Slue. Green. 



Yellow. 



Red. 



Salt used. 



Effects produced. 



a. Chlor. of sodium. Purple. 



b. Chlor. of pctassa. Light purple. 



c. Muriate of lime. ! Rich violet. 

 Red. 



d. Muriate of iron. 



e. Mur. of peroxide 



ofiron Blue. 



/. Mur. of baryta ... Purple red. 



g. Muriate of man- 

 ganese Rich browu. 



h. Mur. of ammonia Olive brown. Palebrown.i Brown. 



Blue. 

 Sky blue. 

 Faint blue. 

 Colourless. 



Yellowish. 

 Lilac. 



Reddish. 



Violet. 

 Light violet. 

 Blue. 

 Faint red. 



Straw color, 

 Chocolate. 



Rose hue. 



Chocolate. 

 Tinted red. 

 Reddish. 

 Leaden hue. 



Yellow brown. 

 Pink. 



Yellow. 

 Dull orange. 



3. I have found but a modified action from the interference 

 of coloured fluids. In a few instances, under a solution of 

 carmine in ammonia, I have obtained the richest crimson dye; 

 but I cannot, by any means I have used, succeed in fixing 

 the colour on the paper. 



4. A paper prepared, by first washing it with a solution of 

 twelve grains of the iodide of potassium in one ounce of 

 water, and then with a solution of ten grains of the crystallized 

 nitrate of silver in the same quantity of fluid, is very sensitive. 

 When exposed beneath a solution of the ammonia-sulphate 

 of copper to sunshine, it changes to a rich light blue. Acetate 

 of copper produces a bromi. Muriate of the peroxide ofiron 

 imparts a gree?i tinge, and solutions of carmine a hro'wn red. 



5. The papery becomes red, when acted on by rays pass- 

 ing through nitrous acid gas, and is tinged ;yellotv, by the light 

 which has been subjected to the interference of chlorine and 

 its protoxide. 



6. To have as full a volume as possible of iodine and bro- 

 mine vapour, carefully closed vessels containing a small por- 

 tion of these bodies, were placed upon a plate of copper 

 warmed by water. 



The paper h was laid beneath them, and exposed to lumi- 

 nous influence. Under the bromine it was unchanged, but 



