This cannot be safely done with a light that does not affect the solar spectrum; but it can be done with plenty of light of the right kind. Suit your development to your subject - your cartridge to your gun and your game. - Andrew Pringle.

Water,..........................................

100 parts.

Pure Sulphate of Iron,.....................

6 "

Acetic Acid,.....................

6 "

Alcohol,.....................

5 "

Add in the dish 55 c.c. (one fluid ounce seven fluid drachms) of the following solution, which does not change, and consequently can be prepared beforehand:

Water,..........................................

1000 parts.

Neutral Oxalate of Potash,.....................

300 "

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

1 part.

[The neutral oxalate of potash solution may he also obtained by melting with the aid of heat in a litre (one quart) of ordinary water, 200 grammes (6 ounces Troy 3 drachms) carbonate of potash, and 157 grammes (5 ounces Troy) of oxalic acid. Absolute neutrality is not necessary. The solution made and filtered, always add one gramme (15 grains) of bromide of ammonium]

Now plunge the plate into this mixture without waiting. If the plate is long, it should pass through ordinary water. Gently rock the dish;

332. I attribute the majority of failures in the gelatin process to over-exposure. The pyro and ammonia is so rapid in its action, and if prolonged over a considerable time by the addition of a little more ammonia, pyro or bromide, the film is liable to stain, which lowers the brilliancy of the resulting print. Now, with the ferrous oxalate the case is different. Prolonged development has no effect on the shadows, which remain bright if the development extend over a very long period. It is always better to err on the side of overexposure, for by careful manipulation a good negative can be secured, while it is almost impossible to get a satisfactory result from under-exposure. The plan I recommend is to have a series of ordinary dipping-baths. No. 1 to contain one part of a saturated solution of protosulphate of iron, mixed with three parts of saturated solution of oxalate of potash; No. 2, one part to six; No. 3, one part to twelve; and No. 4, one part to twelve, with three grains of bromide of potassium to each ounce of solution. To commence: Put the exposed plate in No. 3. If the development appears to be going on satisfactorily, it may be completed in that solution; should it appear too slowly put it in No. 2, and, if then not fast enough, into No. 1, where it may remain until properly developed. If the exposure be correct, the time ought not to exceed five minutes. If there be plenty of detail but a want of density, put it into No. 4, and allow it to remain there until sufficiently dense. If it show up too rapidly in thirty seconds the high - lights should show themselves, and In three minutes the cliche should be developed. In all cases the action of the developer should be allowed to continue until all the details are very ap-parent, which it is easy to see by reflection, the image showing itself white on a black ground; and until you have obtained the desired intensity, which yon will always recognize by transparency, provided the emulsion is not thicker than it ought to be, do not fear to prolong the development

D beyond the point at which it appears to be sufficient, especially if the coating of emulsion is thick. The same developer may be used to develop two or three plates, hut it should be renewed for a fourth; now wash with care, and place the plate in a ten per cent, hyposulphite hath, in which it is allowed to remain double the time necessary for its complete clearing or fixing. It is necessary to change the hyposulphite bath as soon as it acquires a too decided yellow tint, as, if care be not taken, this tint may show itself on the negative. It is for this reason that it is better to have the hyposulphite hath in a porcelain dish, in which it is easier to perceive any change of color. On taking the plate from the when in No. 8 put it into No. 4, and finish in that bath, unless it appears to be coming out too slowly, when wash the plate, and put it into Nos. 8, 2, or 1 to get the proper detail. These solutions can be repeatedly used if decanted after use into bottles kept full to the cork; or may be allowed to remain in the baths if covered with paraffine, benzoline, chloroform, or ether. In that case the plate must be made wet before immersing in the developer. I am presuming that over - exposure is the rule; under-exposure requires a fifth bath, containing the old ferrous - oxalate developer, composed of an excess of oxalate of iron dissolved in a hot saturated solution of oxalate of potash, or, failing a supply of oxalate of iron, dissolve protosulphate of iron in a boiling saturated solution of oxalate of potash. These solutions decompose more rapidly than the mixed saturated solutions, hence the necessity of covering them as soon as mixed with paraffine. To sum up: The advantages are - cleanliness, development in the light of an ordinary dark-room, leisure in watching the process of development, no after-intensification, absence of stain, which facilitates printing, and brilliant prints resembling ordinary wet-plate work. - F. York.

Try the iron development as given in our directions. It is so simple and easy to manage that anybody of common sense can work it successfully, and does away with the many bottles and continued measuring of the developing solutions, which take so much time and attention with the alkaline development. The iron is more economical and works fully as quick, and the negatives obtained thereby resemble very much the ordinary collodion plate. Furthermore, there are no fumes of ammonia created in the dark-room, which are so injurious to the silver bath. If a negative developed by iron is treated with a cold mixture of eight parts water and one part sulphuric acid after mixing and washing, it will be much improved in clearness. Negatives developed by pyro have sometimes a yellow color which makes them print slowly; this can be readily removed by pouring on water containing twelve drops of nitric acid per ounce. Our method is as follows: Oxalate: fixing - bath wash carefully, and instead of setting it aside to dry, as you are in the habit of doing with a wet-collodion plate, place it to soak in a bucket of ordinary water. When the day's work is done, remove the plates from the tub, and in daylight examine them well, one after another. If the exposure has been good, and the development well done, almost all of them will be right, and you will have nothing further to do with them. If some require strengthening, place them successively in the two baths indicated by Dr. Monckhoven for this purpose, care being taken to wash them carefully between each bath. The whiter the film becomes in the first, the greater the strength acquired in the second. If the desired result is not obtained in the first trial, you may without injury, after washing, repeat the operation.