Collodion For Hot Weather.

Ether........................................

10 ounces.

Alcohol.....................................

12 "

Bromide of Cadmium.......................

1 grain per oz.

Bromide of Ammonium........................

1 " "

Iodide of Cadmium.............................

1 1/2 " "

Iodide of Ammonium...............................

3 " "

Add to the ether and alcohol, and shake until all is dissolved, filter, and add your cotton A. reasonable amount of age helps this collodion. - Hugh O'Neil sium. It improves the keeping qualities of the collodion, but it cannot be used so soon after making it. A potassium collodion may be used a few hours after it is mixed. After weighing out the ingredients, we put the alcohol in a bottle, and add the iodide; after the latter is dissolved add the ether. The potassium must be dissolved in water, as little as possible being used, and then added to the other. A precipitate is at once formed, the bromide entering the collodion and the metal base falling to the bottom. This we filter out by means of filtering-paper, and then add sixty grains of gun-cotton to the whole. After settling a few hours, and filtration through a tuft of clean absorbent cotton, the collodion is ready for use in coating the sensitized plates.

131. If the novice is not aware of the fact, one day he will be, that photographers are an exceedingly dogmatic species. They will stickle

131. For collodion, the best chemicals should be used. Ether and alcohol equal parts. For thirty-five ounces, use

Iodide of Cadmium.....................................

135 grains.

Iodide of Potassium....................................

70 "

Bromide of Cadmium.................................

70 "

Iodide of Ammonium................................

12 "

This I use in winter; for summer it is not limpid enough, cadmium making it tend to fogginess. I have another collodion.

Alcohol................................

12 ounces.

Ether....................................

8 "

IodideIodide of Ammonium of Ammonium,.........................

5 grs. per oz.

Iodide of Cadmium.............................................

1 gr. "

Bromide of Cadmium,.........

2 grs. "

Take two parts of the first and one part of the last. This makes a combination that will work in the hottest of the season. The last collodion is fine for copies. Developer is twenty grains; solution of iron in water, acetic acid, little. - S. M. Robinson.

• The following suggestions for modifying the tendencies of collodion will be found useful, both in relation to commercial samples and to making others. For subjects having violent contrasts, and for instantaneous collodion, a large proportion of bromide may be used to secure softness and harmony. The tendency of bromides is to decrease contrasts and sere detail. When the contrasts are great, and there is a tendency to hardness and over-intensity, the amount of bromide may be increased; when want of intensity is present, the proportion of bromide may be decreased. A quarter of a grain, or less, per ounce, will secure cleanness.

Collodion yielding a thick, creamy film generally gives a vigorous, fine image. The addition of an extra grain or two of pyroxylin will often confer this quality on collodion giving a thin image, as the use of a good body of pyroxylin tends to give a dense image. When the film repels the bath, and gives a thin image, a drop or two of distilled water to the ounce will often be an improvement, if the defect proceeds from the use of anhydrous for a favorite salt, or an extra grain thereof in their collodion, with as much tenacity as Shylock did for his "pound of flesh." Some use the bromides only. Some others modify their formula "to secure more in-tensity," or "a better color," what not Often times there is reason for these modifications, and it is as well to understand them, though, since light and atmospheric changes rule the matter largely, experience is the best teacher. l32. A "slow "' collodion,and one giving Hat effects without brilliancy and roundness, is not difficult to produce, hence effort is made to secure such a mixture of the Ingredients as will enable the operator to work quickly and at the same time get the proper printing density. Perhaphs as many varieties of formula could be given as would fill this book - one or two will suffice, though a great many know that they are by no means the best. They have been found sufficient, however, to avoid the ne-cessity of procuring a "lightning" rod.

133. Among others, the veteran photographer, Mr. J, W. Black, of Boston, advocates a collodion entirely without bromides. This neces-sitatM the working of an extremely acid bath and as that is difficult, solvents. Over-iodized collodion generally produces streaks at one end of the plate, and, if the iodide be present in great excess, it leaves the film in flakes whilst in the nitrate bath. - G. Wharton Simpson.

I will give one of the quickest and finest collodions in existence:

Alcohol and Ether.............................................................................

equal parts.

Iodide of Potassium.....................

5 grains.

Bromide of Potassium.....................

2 1/2 "

Pyroxylin (to ounce of plain collodion).....................

5 to 6 grains.

Now it is the way this is made that makes the difference. Weigh out the excitant and the cotton, and put them into the ether and alcohol, and shake the bottle until the whole bath is dissolved; let it stand until it settles; then Alter, and you have it. - James (). Mkrrill.

188. With regard to the preference of the bromo-iodized collodion over the purely iodized collodion, it is found practically in the greater sensibility of the former for the reflected light of the shadows. Having stated the difference of quality of the direct and reflected light, the folllowing will be easily understood. A plate of purely iodized collodion is sensitive only for violet and violet-blue rays, purely bromized collodion is sensitive for violet-blue, and blue rays, bromo-iodized collodion is sensitive for violet, violet-blue, blue, and even green rays

The decomposition of the white light into the pure colors which nature shows in the rainbow. can be effected by a prism of glass. By photographing the rainbow-like colored spectrum, which is obtained by the prism, these remarkable facts have been stated.

It is obvious that the bromo- iodized collodion is the most susceptible to impresssion by the light of the shadowy parts, in which the violet and violet-blue rays are much and since the most lovely effects can be and are secured with the bromo-iodized collodion, there is no good reason for going into trouble for the sake of avoiding its use. Yet, as long as the collodion and the nitrate bath are used, doctors will greatly disagree on this point.

134. " Double - iodized " collodion is preferred by some manipulators. It was introduced commercially some years ago by Mr. Alfred L. Hance. of Philadelphia, and his brand is yet very popular in some sections Its preparation is about as follows: