ON PHOTO- MICROGRAPHY. 195 



Here again an excess or deficit of three or four 

 drops is of no consequence. This solution is then 

 to be poured into the beaker, into which also the 

 " pyro " solution from the tray is to be poured, and 

 the mixture is then returned to the tray in an even 

 wave, and kept gently rocking. For a few seconds 

 nothing will be visible, and for that time it is quite 

 as well to shade the plate from the light, then, if 

 the exposure has been correct, gradually the highest 

 lights will appear and get deeper and deeper, and 

 detail will begin to appear in the lightest half 

 tones. If all is going well, the plate may be left 

 at this stage while an additional 50 drops of B 

 are measured out and poured into the beaker. 

 Again the solution from the tray is to be returned 

 to the beaker, and again the mixture poured back 

 and the tray kept rocking. 



By this time the picture should be full of detail, 

 and more light will be required, and may be safely 

 used. This is a most important time, and great 

 judgment is required to know when to stop the 

 development. In the feeble light employed, it will 

 seem as if the picture is blackening all over and 

 disappearing, but really, if properly exposed, it is 

 only gaining density. The judgment will be assisted 

 by removing the plate from the tray, and holding it 

 up before the light ; the amount of density can then 

 be better seen. If judged insufficient, the plate is 

 returned to the tray and rocked a few seconds 

 longer. If the exposure has been properly timed, 

 the whole development will occupy about two and a 

 half or three minutes from the first application of 

 the B solution. When at last the proper moment 

 arrives, the plate is to be removed from the tray, 



