LOW-POWER WORK 35 



effect upon it. It is always well to leave negatives in the "hypo" a few. minutes — 

 say five— after they appear to be " done," as there are good grounds for belief that 

 they keep better in the future if such a plan be adopted. 



As regards drying the final negative, we have had so much trouble caused by 

 inequalities in the film, produced by irregularities in the drying, that some time ago 

 we gave much attention to the subject, and seeing that now hardly any trouble in 

 that direction arises, we venture to simply state how it may be avoided. 



The negative is placed glass side downwards on a cloth and a fine handkerchief is 

 gently and neatly laid over the gelatine side. It is smoothly and firmly pressed with 

 the hand for two or three seconds, which allows the fabric of the handkerchief to 

 absorb all the superficial moisture. On raising the handkerchief it will be found that 

 the gelatine shows distinct marks of the fabric. This is not of the slightest con- 

 sequence, for it absolutely and entirely dries out of all existence. 



The back must now be carefully wiped — one source of trouble arises entirely from 

 drops of water accumulating there, thus causing an unequal distribution of 

 temperature in the whole plate. A ring of slightly melted gelatine will often be the 

 result, which it is needless to say spoils the picture. This is especially the case when 

 the negative is dried on a hot water tank. 



Having superficially dried the plate in this manner, all that is necessary is to 

 separate it from others at least by an inch, for if this be not done what is left of the 

 moisture in the gelatine film of one plate will condense on the back of the other, and 

 this condensation in due course will collect into drops, producing the same effect as if 

 the back of the negative had not been wiped. 



With respect to developing the enlargements to which we have referred, a few 

 words must now be said. Oxalate of potash is by far the best developer for large 

 work, as it is much cheaper. It must be very concentrated and mixed with the iron 

 solution just before use in a manner and in proportions fully set forth with each paper 

 that is upon the market. 



Of these there are several brands ; the one which we have used for single enlarge- 

 ments even up to three feet in length from J-plate negatives, is the rough Ilford 

 Rapid ; but for fine work such as the reproduction of prints from negatives, where 

 fine details exist, like that in diatoms or bacteria, the paper is not suitable ; " Nikko 

 Paper" is the variety to employ for this purpose, but to that we shall refer a little 

 later on. 



