contrasts. It is well to remember that more contrast may always be secured by adding more bichromate of potash to the sensitizer.

The gelatine size for these tissues may be that with chrome alum, usually recommended for carbon supports, or, what is probably better, the following: Water, 15 ounces; gelatine, 75 grains; alum, 45 grains; methylated spirit, 31⁄2 ounces. There will of course be troubles. There will occasionally be unaccountable spots and markings, but when such occur, and careful filtering, shaking of solutions, and smooth coating does not remedy matters, it is best to throw the mixture away and begin over again. The cheapness of the ingredients renders one able to do so with a fairly clear conscience. a fresh lot of diluted developer will be the remedy.

Often

In laying in the stock of chemicals, special care should be taken to secure the ferric oxalate in right condition. None of the other chemicals display any crankiness, but the ferric oxalate calls for close watching. If right when bought, it will remain in good condition with ordinary care for months, or even years, but if wrong, it will get more degenerate with every day. It should come in glistening brownish-green scales, which show no tendency to mat together, or to cling to the sides of the bottle. Mallinkrodt puts up the right article, if one can only obtain it fresh-a feat not always easily achieved outside of the large cities.

Having once obtained the supply of chemicals, at a total cost of about a dollar and a half, one has the materials for a great many messes of sensitizer and developer, and endless fascinating possibilities for home experiment.

INCE dry-plates are in use intensifiers, like developers, have appeared in bewildering numbers. Which is the best for all-around purposes?

The writer has tried about all intensifiers or intensifying methods that have become prominent since the appearance of dry plates and seemed worth trying and, after many experiments, decided years ago on using a certain method of intensification which, at least for his own purposes, he considers the best for negatives, lantern slides and bromide papers.

Some intensifiers give more intensification than one OCcasionally knows what to do with; others exagerate the contrasts to an unpleasant degree. Some require a most careful manipulation, and a little oversight results in failure and spoiling of the negative, slide or bromide paper. Some give but

little intensification, and a repetition of the process improves matters little or not at all. Some methods of intensification can be used but once, and if the result is unsatisfactory, there is nothing else to be done but to be content. After the use of some intensifiers, reduction, if desirable, is out of question. Some intensifiers are inclined to stain the film or spoil it later. Some intensifications are not stable but change in the course of time, usually for the worse. Some intensifiers may do for negatives but not for lantern slides or bromide papers. Some methods of intensification require more time and patience than average human beings have at their disposal, and some are so filthy and nauseous that they should be used only in back yards where filth and stench would be less objectionable than in a room.

An all-around good method of intensification ought to have the following qualifications: It ought to be cleanly enough for average civilized people and easy enough so as not to rile one's good humor. It ought not to include too dangerous poisons. It ought to give a fair, proportional and certain amount of permanent intensification. It ought to leave the film clean and clear. It ought to be possible to repeat the process as often as necessary, and to reduce the intensity, if desirable. An allaround good method of intensification should be applicable not only to negatives but also to lantern slides and bromide papers.

After various experiments the writer has found about everyone of the generally recommended intensifiers wanting in some one or other of the qualifications just mentioned. The one method of intensification which comes nearest up to the ideal of the writer is that advocated by Chapman Jones, were it not for the practical difficulties attending it. Mr. Jones says in his "Introduction to the Science and Practice of Photography," page 201, London, 1895: "The only method of intensification that is theoretically and practically simple, that gives an image of known and stable composition with a substantial but not too great an increase of density, that may be repeated any number of times upon the same negative so that any density may be obtained in the end and that can be depended upon in every desirable way, consists in the application of ferrous oxalate to the image bleached by mercuric chloride."