186 METHODS IN PLANT HISTOLOGY 



Land's Tropical Developer for negatives and lantern slides. — 



Hydrochinon 8 g. 



Metol 3g. 



Sodium sulphite (dry) 30 g. 



(60 g. if crystals are used) 

 Sodium carbonate (dry) 30 g. 



(90 g. if crystals are used) 



Potassium bromide 2 g. 



Water 1,000 c.c. 



This formula will develop an underexposed plate when the usual 

 developers fail. With this developer, the image flashes into sight with 

 surprising suddenness, but do not become startled and remove the 

 slide too soon, lest you fail to secure details. In the tropics, where it is 

 often impossible to get reasonably cool water, this developer is a boon 

 to the scientist who cannot wait until he gets into a favorable place for 

 developing. 



Process Developer for negatives, films, la7itern slides, and paper. — 



A 



■., . ■ Apothecaries'- 



Metnc Avoirdupois 



Water 500 c.c. ( 16 oz.) 



Hydrochinon 22 g. (176 gr.) 



Sulphuric acid 2 c.c. ( 30 gr.) 



Sodium sulphite 15 g. ( § oz.) 



B 



Water 500 c.c. (16 oz.) 



Sodium carbonate log. ( | oz.) 



Potassium carbonate 45 g. ( U oz.) 



Potassium bromide 4 g. (32 gr.) 



Sodium sulphite 45 g. ( U oz.) 



With a process plate, a process film, or a "red-label" Cramer lan- 

 tern-shde plate, or similar plate by other makers, this developer is 

 ideal for maps, graphs, typewritten tables, and similar subjects. In 

 making copy for the negative, use smooth, pure white paper and dead 

 black ink. The wretched lantern slides, seen so often at scientific meet- 

 ings, result from using the same plates and developers which are used 

 for landscapes. 



