82 PHOTO-MICROGRAPHS. 
ferrous-oxalate developer. It may be that the 
long time during which the plates remain in the 
developer has a tendency to harden the gelatine 
film and prevent frilling. 
Intensification. A moderate degree of intensifi- 
cation may be effected by means of a saturated 
solution of bichloride of mercury (corrosive subli- 
mate) and a ten-per-cent solution of strong 
ammonia. 
The plate is first flooded with the solution of 
bichloride, until, viewed from the back, the image 
appears uniformly gray; it is then thoroughly 
washed, and finally is placed in a bath containing 
the ammonia (ten per cent) until it is blackened. 
The following method of intensification is recom- 
mended by Eastman for his dry-plates : — 
“‘ Prepare saturated solutions of iodide of potas- 
sium, bichloride of mercury, and hyposulphite of 
soda. Pour the mercury into the iodide until it 
retains ared color after shaking. Now add enough 
of the hypo solution to dissolve the red precipitate, 
If the solution refuses to intensify, there is too 
much hypo in it; therefore, prepare another por- 
tion of the mercury-iodide solution, and add just 
enough to the intensifier already made to clear it 
up, instead of the hypo. This solution will keep. 
“Tf extra intensity is desired, add a few drops 
of a fifteen-grain solution of bromide of potassium 
to each ounce of developer before applying it to 
the plate.” (Eastman.) 
The dark room in which the plate is developed 
may be that in which the exposure was made, if all 
