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should know what is the most that is required of an inten sifier and a reducer. An ideal intensifier should fulfil these requirements: (1) It should intensify the high lights more in proportion to the half-tones, such as would be necessary in an over-exposed plate where there is plenty of detail but not enough density; (2) it should intensify the half-tones more in proportion to the high lights, as in the case of a negative slightly under-exposed, where the high-lights are about the right density, but the half-tone is weak ; (3) it should intensify all parts in equal proportion, as in the case of a negative which is too weak generally. These same remarks apply with equal weight to the ideal reducer. The ideal reducer should act in such a manner that (1) it should attack the high-lights more in proportion to the half-tones, as when a negative is under-exposed, and the high-lights are, consequently, too strong ; this would be greatly assisted when the intensifier strengthens the half-tone more than the lights, and the two could be used consecutively; (2) it should reduce the half-tone more in proportion to the high-lights, so that an over-exposed negative could be thinned down in its half-tones to give the high-lights more value; (3) it should reduce the negative in equal proportions generally, so that a negative which is so thick that printing takes too long can be thinned down generally, and printing be thus facilitated. The permanency of the negative should not in any way be affected by the treatment. With regard to the permanency of negatives after treatment with any of the known reducing formula;, I believe they are not affected in any way what ever, and that a negative which has been carefully reduced, and proper attention given to the washing, will stand as long as if it had not been reduced. But this, unfortunately, cannot be said about all the intensifiers at present in use. The experience of many of you will no doubt bring to mind the fading of many a valuable negative which had been strengthened by intensi fication. Yet here, again, I believe the fault has been due more to insufficient care in washing than to the shortcomings of the intensifier. As for the relative value of an intensified negative, Captain Abney has proved, I believe, beyond the shadow of a doubt, that the half-tones are strengthened more in proportion to the high-lights, and, therefore, there is generally less detail in the higher lights of an intensified negative than in the same negative before the treatment. I myself have often noticed the want of detail which an intensified negative gives in the resulting print in the high-lights, to what had appeared in the same negative before strengthening. It should be said, however, that I had used the same formula as Captain Abney had used. The same rule may not be applicable to other formula;. Before reducing, and especially before intensifying, the plate must be entirely freed from all traces of the fixing agent. Want of attention to this rule is almost the only cause of stains, and is also a great cause of fading. To free the plate from hypo, nothing is better than placing it in a solution of hydrogen peroxide. The method of using it is as follows. The plate is first washed under the tap, and then is placed in the following solution :— Hydrogen peroxide } drachm Water ... ... ... ... ... 25 ounces In this it remains for a few minutes, and is again washed so as to free it from the peroxide. The plate can then be intensified or reduced in the usual way. Another way of clearing the plate from hypo is also stated to be very effectual. An ounce of glacial acetic acid is added to four ounces of water. To this is added, little by little, one ounce of barium dioxide finely pow dered. When this has dissolved, the plate is soaked in it for a few minutes and then slightly washed. For the efficacy of this method I am unable to express any opinion, as I have not yet tried it, though, as far as I can see, there is no reason why it should not be as good as the peroxide of hydrogen, which chemical forms part of its composition, and it is no doubt cheaper. Personally, I use nothing but a saturated solution of alum for ridding negatives from hypo, giving each negative half an hour’s washing in several changes of water, and then placing it in the alum for about twenty minutes, afterwards letting the plate re main in running water for about ten minutes. Whilst I was writing these lines, I noticed in the Photographic Review that, according to Dr. Stolze, the alum bath should not be used until the fixing solution has been removed by washing, otherwise sulphur may be deposited on the film and cause fading. Certainly, I am aware that hyposul phite of sodium and alum decompose one another, but, as far as my own experience goes, I have never found any bad results to come from the method last described. There is one more matter I should like to mention. There seems to be a difference of opinion existing as re gards the best time to intensify a negative, some saying it is best to let the plate dry first, whilst others prefer to treat it before the film has lost its first moisture. As to the best time to intensify, if a negative partly dry and partly wet is used, where the film is wet it becomes denser than where it is dry. Therefore, to take advantage of this difference, it is best to let the plate dry if it is not required to strengthen it to the fullest extent, and to treat it before it becomes dry when the greatest intensity is required. The cause of this is owing to the difference in the porosity of the gelatine film before and after drying. When a plate has been exposed and developed, it contains a certain amount of unreduced silver bromide surrounded with gelatine, which is dissolved out from the gelatine by the fixing agent. When this is fixed out, it being a solid substance, it naturally leaves a number of pores, which finally become filled with water. When the plate is placed in the intensifying solution these pores rapidly become filled by it by exosmose action. For this reason the intensifier has greater action on the silver than if the plate was dried ; first, because the water evaporating out of the film allows the pores to become closed up, and, as they do not open again to the same extent on being placed in water the second time, the gelatine acts, to a certain degree, as a barrier to the action of the intensifier. (To be continued.) To Repair Broken Negatives.— Place the negative, gela tine side down, on a plate rather larger than the negative. Coat the edges of the fragments with warm Canada balsam ; join them together, using strong pressure. Remove the excess of balsam, then cover the negative with another plate exactly the same size, and previously coated on one side with this varnish: Sandarac ... ... ... ... 3 grammes Mastic in tears ... ... ... 3 , Sulphuric ether ... ... ... 50 ,, Benzole (pure) ... ... ... 25 ,, Lift together the three plates, turn them over, remove the large one that has served as a support, scrape off from the I gelatine side the balsam that may have exuded, then surround the two plates with strips of gummed paper. Heat slightly the fragments before joining them together. This process will yield a print upon which no trace of breaking is to be seen.— VAmateur Pholographe.
