234 PBACTICAL PHOTO-MICBOGBAPHY 



indicates the presence of dust. This is now rarely on the plate 

 when supplied by the makers, and is probably the result of dust 

 settling from the dark-slide or camera itself. Both before 

 exposure and before development the plate should be sharply 

 tapped on its edge on the dark-room bench, to dislodge any 

 dust particles attached to it. This is a better method than 

 that of using the dusting-brush, or any such appliance, as 

 these often only add to, rather than remove, the adherent 

 dust. 



With developers, as with plates, it is far better to adopt 

 one standard formula, and keep to it, mastering its peculiarities 

 and possibilities thoroughly. 



In cases of under-exposure, where development has to be 

 forced by using an excess of alkali, care should be taken to stop 

 the process before general fog appears. In any case the amount 

 of the alkali solution permissible is usually not greatly in 

 excess of the normal amount, and an increase of about ten 

 per cent, in the quantity is probably the limit. Where 

 intensification has to be effected, and the negative is somewhat 

 under-exposed and forced in developing so that fog results, the 

 latter should be removed by a weak reducing-solution before 

 intensification is attempted. Many workers, who only conduct 

 photographic operations at irregular intervals, are troubled by 

 the deterioration of their solutions. This may be dealt with 

 in one of two ways. The solutions may be made up in the 

 quantities mentioned; but instead of storing them in large 

 bottles, they may be stored in several small ones, which should 

 be tightly corked or sealed down to prevent the access of air. 

 One may then be opened and as far as possible used up as 

 required. In any case the keeping quality of solutions is 

 considerably increased by well boiling the water before making 

 up, so ensuring that there is the least possible amount of air 

 remaining in solution. An alternative method, and one that 

 is now easily available, is to use the tabloid developers made by 

 Messrs. Burroughs Wellcome & Co. Almost any developer can 

 be obtained in tabloid form, and there is the advantage that 

 only a sufficient quantity is made up at a time to deal with the 

 plates to be developed. The solutions are therefore fresh, do 

 not suffer from deterioration, and work under their best possible 

 conditions. The only point to be urged against them is the 

 time taken in dissolving the tabloids of each kind when a plate 



