62 ELEMENTARY PHOTO-MICROGRAPHY. 



ried too far. As development is very rapid, the 

 exposure must be correct to 1 get good results. 

 After a few trials it will not be found at all difficult 

 to determine when to stop printing. The develop- 

 ing bath, which should not be below 60 F., is 

 made up of : 



Neutral potassium oxalate ... i ounce. 



Oxalic acid (saturated solution) 



i part to 20 parts of developer. 



Water ... ... ... ... 10 ounces. 



This is a stock solution, and may be bottled for 

 future use. The paper is floated on the bath face 

 downwards, turned quickly over and development 

 watched. A black and white image will rapidly ap- 

 pear, and when sufficient depth of tone is obtained 

 the print may be removed to a bath composed of : 



Water ... ... ... 10 ounces. 



Hydrochloric acid i ^ drams. 



Any of the lemon colour left will here be cleared 

 away, and black and white tones only remain. 

 After five minutes in this bath the prints are trans- 

 ferred to a similar but rather more dilute bath for 

 ten minutes ; then to three baths of clean water for 

 ten minutes each, into the second of which a few 

 grains of sodium carbonate have been added to 

 neutralise any acid left in the prints. 



Wollf's " indelible railway pencil " is excellent for 

 any retouching with either bromide or platinotype 

 prints. Photo-micrographs kept in a special album 

 having only one print on a page show to better 

 advantage than when mixed with others of a mis- 

 cellaneous kind. 



