MEDIUM-POWER PHOTO-MICEOGRAPHY 



123 



whole picture comes out slowly, clearly, and uniformly, we may nearly always rest 

 assured the exposure has been correct. On the other hand, if no picture comes for 

 some minutes, and then exceedingly faintly, we may be equally certain the opposite 

 condition of things obtains, and the exposure has been too short. Provided, first, 

 that the exposure has been correct, we then continue rocking the developer over the 

 negative, until the details, at first so bright and clear, fade into one common blackness 

 over the whole plate. At this juncture it is raised from the dish and the back of the 

 plate examined. We should expect to see the picture appearing there, not complete 

 in detail, but an outlined effect. With correct exposure this eff'ect is produced slowly^ 

 but with under-exposure very rapidly — an indication not to be overlooked. If, then, 

 it comes slowly, we let it proceed by returning the plate to the dish, until, in point of 

 fact, the picture can be moderately vvell seen on the hack although quite lost in blackness 

 when looking at the front of the negative. Those commencing photo-micrography 

 make here the frequent mistake of removing the plate too soon ; it wants much more 

 development than an ordinary one. Presuming now the image is fairly well seen on 

 the reverse side, the developer is poured off and the plate well washed under the tap. 

 Washing completed, it is placed in the fixing solution, a bath composed of hypo- 

 sulphite of soda and water. It is a convenient plan to obtain one of the large sweet 

 jars used by pastrycooks, which are provided with a solid glass stopper surrounded 

 with a band of cork, into which are placed the crystals of hyposulphite — commonly 

 called "hypo" — to about one-third part of its depth, filling up to the brim with 

 water. This is left for a few hours and forms a most convenient concentrated 

 solution. Before taking a photograph the bottle is shaken, and two parts of the 

 solution are added to one of water and put in the " fixing-bath dish. ' Into this 

 solution then we are supposed to have placed our developed and washed negative. 



Whilst this is fixing let us go back to the consideration of the plate which, we 

 will suppose, was over-exposed, lying in the developer to which we have added 

 the extra bromide. It has been soaking, we will presume, all the while. The 

 developer is rocked to and fro until we begin to find the back of the plate turning 

 slightly grey, the front of it having long ago turned black. At this juncture develop- 

 ment must be stopped and the negative washed, or it may become so dense that the 

 gas flame cannot be seen through it when taken out of the " hypo." 



Great judgment is required to know how long to let the plate soak in this highly 

 restrained developer, and it is not at all impossible the tyro will find his patience 

 very severely taxed before learning how to save a plate having received too long an 

 exposure, and it is an art to do this well in extreme cases. All negatives should 



