Dec. 17. 1853.] 



NOTES AND QUERIES. 



599 



hy means of the glass rod, or by floating, as 

 before, and then the glass rod. But if floating is 

 resorted to, then a larger quantity must be pre- 

 pared. As soon as it is applied the paper should 

 be blotted ofi" by means of blotting-paper (which 

 should never be used more than once in this way, 

 although preserved for other purposes), and put 

 into the dark frames for use.* It is not requisite 

 that the paper should be perfectly dry. This ex- 

 citing should be conducted by a very feeble light ; 

 the paper is much more sensitive than is generally 

 supposed ; in fact, it is then in a state to print 

 from by the aid of gas or the light of a common 

 lamp, and very agreeable positives are so produced 

 by this negative mode of printing. 



I would advise the aceto-nitrate of silver and 

 the solution of gallic acid to be kept in two bottles 

 with wooden cases differing in their shape, so that 

 they may not be mistaken when operating in com- 

 parative darkness. A 5 of an ounce of gallic acid 

 put into sucih a 3-ounce bottle, and quite filled up 

 with distilled water as often as any is used, will 

 serve a very long time. 



I would also recommend that the paper should be 

 excited upon themorningof the day upon which it is 

 intended to be used ; no doubt the longer it is 

 kept, the less active and less certain it becomes. I 

 have, however, used it successfully eight days after 

 excitement, and have a good negative produced at 

 that length of time. The general medium time of 

 exposure required is five minutes. In the ne- 

 gatives exhibited, the time has varied from three 

 minutes to eight, the latter being when the day 

 was very dull. 



The pictures should be developed by equal 

 quantities of the aceto-nitrate of silver and the 

 saturated solution of gallic acid, which are to be 

 mixed and immediately applied to the exposed 

 surface. This may be done several hours after the 

 pictures have been removed from the camera. 

 Care should be taken that the back of the pic- 

 ture does not become wetted, as this is apt to 

 produce a stain which may spoil the printing of 

 the positive. 



If upon the removal of the paper from the dark 

 frame, the picture is very apparent, by first ap- 

 plying a little gallic acid, and immediately after- 

 wards the mixed solutions, less likelihood is in- 

 cui-red of staining the negative, which will be 

 more evenly and intensely developed. If a 

 browning take place, a few drops of strong acetic 

 acid will generally check it. 



Should the picture be very tardy, either from 



* It is very requisite that the glasses of the frames 

 should be thoroughly cleansed before the excited papers 

 are put into them. Although not perceptible to the 

 eye, there is often left on the glass (if this precaution is 

 not used) a decomposing influence which afterwards 

 shows itself by stains upon the negative. 



an insufiielent exposure, want of light, or other 

 cause, a few drops of a solution of pyrogallic acid, 

 made with 3 grains to the ounce of water, and a 

 drachm of acetic acid, will act very beneficially. 

 It sometimes gives an unpleasant redness upon 

 the surface, but produces great intensity upon 

 looking through it. Until the pyrogallic solution 

 was added, there was scarcely anything visible 

 upon the specimen exhibited, the failure having 

 in the first instance happened from the badness of 

 the iodized paper. 



As soon as the picture is sufficiently developed 

 it should be placed in water, which should be 

 changed once or twice ; after soaking for a short 

 time, say half an hour, it may be pinned up and 

 dried, or it may at once be placed in a solution 

 almost saturated, or quite so, of hyposulphite of 

 soda, remaining there no longer than is needful 

 for the entire removal of the iodide, which is 

 known by the disappearance of the yellow colour. 



When travelling it is often desirable to avoid 

 using the hyposulphite, for many reasons (besides 

 that of getting rid of extra chemicals), and it may 

 be relied on that negatives will keep even under 

 exposure to light for a very long time. I have 

 kept some myself for several weeks, and I believe 

 Mr. Rosling has kept them for some months. 



The hyposulphite, lastly, should be effectually 

 removed from the negative by soaking in water, 

 which should be frequently changed. 



Some prefer to use the hypo, quite hot, or even 

 boiling, as thereby the size of the paper is re- 

 moved, allowing of its being afterwards readily 

 waxed.* I have always found that pouring a 

 little boiling water upon the paper effectually 

 accomplishes the object ; some negatives will 

 readily wax even when the size is not removed. 

 A box iron very hot is best for the purpose ; but 

 the most important thing to attend to is that the 

 paper should be perfectly dry, and it should there- 

 fore be passed between blotting-paper and well 

 ironed before the wax is applied. Negatives will 

 even attract moisture from the atmosphere, and 

 therefore this process should at all times be re- 

 sorted to immediately before the application of the 

 wax. 



Some photographers prefer, instead of using 

 wax, to apply a solution of Canada balsam in 

 spirits of turpentine. This certainly adds much 

 to the transparency of the negative ; and, in some 

 instances, may be very desirable. Even in so 

 simple a thing as white wax, there is much va- 



* If boiling water is carefully poured in the nega- 

 tive in a porcelain dish, it will frequently remove ft 

 f;reat deal of colouring matter, thereby rendering the 

 negative still more translucent. It is astonishing how 

 much colouring matter a negative so treated will give 

 out, even when to the eye It appears so clean as not to 

 require it. 



