88 ELEMENTARY PHOTO-MICROGRAPHY. 



To this are added 



Sodium sulphite . . . . i dram. 



Acetic acid . . . . . . 6 drams. 



Alum . . . . . . i dram. 



Dissolved in ij ounces of water. 



The prints are kept moving a few moments, 

 and afterwards allowed to remain fifteen minutes. 

 An hour's washing in running water, or in eight 

 changes of water, as before described, completes 

 the process. A thorough washing should be given. 

 The above bath keeps clean much longer than a 

 simple hypo and water bath, and can be used 

 time after time. 



Platinotype printing is at once the simplest, 

 most permanent, and most effective of all pro- 

 cesses. Good negatives yield prints equal in beauty 

 to a fine steel engraving, with rich gradations of 

 tone very pleasing to behold. The whole process 

 can be completed on a bright day in a little over 

 an hour, though on dark days the printing is slow. 

 Moisture is the chief preventive of successful work ; 

 therefore paper, wood frames, and place of exposure 

 must be dry. 



The platinotype paper itself is supplied in 

 sealed tins, twenty-four sheets, quality A A, 

 4i*3in., for 1/6, from which it should be re- 

 moved for preservation to a special tin tube having 

 a false bottom, under which calcium chloride is 

 kept to absorb any moisture, and the joints of this 



