Mercury, an oxide of, changes in sun-shine, 5.

applied in daguerreotype, 42,249.

—— bichloride, its whitening pro-perty, 269.

—— photographic properties of,60

Metallic silver revived from the chlo-ride, 126.

Michellotti on life of germs, 6.

Milk, serum of, 282.

——— sugar of, its use, 231.

Morichini on magnetism induced bysolar rays, 5.

Moser, M., on the determination ofimages in darkness, 150.

, sur la formation des imagesdaguerriennes, 165.

Muller's process, as used in India ,236.

Muriatic acid, 130.

Muriates, various kinds employed,129.

Muriated papers, 207.

Natural colours, production of, 172.

Negative collodion changed to posi-tive, 269.

paper on wax paper, 231.

photographs, 195.

Newton, Sir Isaac, on spectrum, 117.

Niepce de St.-Victor introduced albu-men, 103.

produces coloured photo~graphs, 174.

on albumen, 276.

Niepce, Isidore, pension to, 35.

——; M., his discovery of helio-

graphy, 12.Nitrate of silver, 205.

Organic matter increases the sensi-bility of silver salts, 127,, use of, in calotype, 227.

Papaver orientale, photographic use ofJuice of, 68.

Paper , calotype , to prepare, 27.

———, irregular imbibition of, 129.

———, selection of photographic,187.

———, talbotype, prepared for camera,220.

Paper , to prepare with albumen, 286.

Patent, calotype, specification, 26,

Petit notices influence of light oncrystallisation, 4.

Phillips, Mr. Reuben, on fixing pho-tographs, 214.

Phosphate of silver, 132.

Phosphorescence exalted by blue rays,10.

Phosphorus, photographic use of, 35.Photogenic drawing by H. Fox Tal­ bot , 19.Photographic agents, hydriodic saltsas, 288.camera, Herschel on, 201.——— registration, 153.Photographometer, description of,57

———, Claudet’s, 149.

Photographs, invisible, 217,

———, negative, 195.

———, positive, 195.

———, on glass plates, 100.

Picture , Talbotype , fixing of, 222.Plants, influence of light on, observed,

Plate bender, 242.

Platinum, chloride of, 290.

Polishing daguerreotype plate, 241.

— silver plate, 86.

Patent right, photographic, 303.

Ponton’s, Mr., photographic process,72.

Poppy, red, photographic use of juice,71.

Porcelain tablets, pictures on, 29.

Porta Baptista invents the camera,198.

Portraits from the life, 301.

Portraiture by daguerreotype, 104.

Positive collodion formed from nega-

tive, 269.

——— photograph, 195.

———, by one process, 88, 288,

———, from etchings, 283.

Potash, bichromate of, photographic

use of, 72.

———, chlorate of, 130.

Potassium, ferrosesquicyanuret, as aphotographic agent, 52.

, ferrocyanide of, its use as aphotographic agent, 83,

—, fluoride of, 282.

Practice of photography, 185.

Precious stones, influence of sun’s

rays on, 3,