508 EXPERIMENTAL PHARMACOLOGY 



slide is now adjusted over the opening in the paper and the 

 outer edges of the paper are trimmed to fit the slide. The 

 mat is now placed on the film side of the slide and a clear 

 glass cover is laid over the mat. A paper binding strip is 

 cut into four pieces to fit the edges of the slide and are 

 moistened and stuck around the slide in such a manner as 

 to bind the two plates of glass firmly together with the mat 

 between them. After drying of the binding strips the slide 

 is ready for the lantern. 



A dilute aqueous solution of eosin may be used to stain a 

 slide a red or pinkish color. An aqueous solution of uranine 

 is used to stain slides yellow. In each case the staining is 

 done just after the slide has been finished (i. e., when thor- 

 oughly washed just after being taken out of the fixing bath). 

 If the slide has already dried it must be wet again before 

 it is placed in the staining solution. 



Pictures in books, tables printed in journals, ordinary 

 photographs of dissections or the performance of experi- 

 ments, etc., may often be used to great advantage for teach- 

 ing purposes if photographed and presented in the form 

 of lantern slides. For copying of this kind an adjustable 

 stand of which many forms have been devised (Fig. 386) 

 is needed. 



Ordinary prints are generally best made on developing 

 papers of which several varieties are on the market. It is 

 preferable to buy the prepared tubes of developer (for 

 each kind of paper) for this purpose, but it may be cheaper 

 to use a stock developer. The following is recommended 

 for ' ' Cyko ' ' paper : 



Developer. 



Avoirdupois Metric 



Pure water 40 oz. 1000 c.c. 



Metol 15 grains 1 gram 



Sodium sulphite (dried powder) 1 oz. 28 grams 



Hydnidiinon 60 grains 4 grams 



Sodium carbonate (dried powder) % oz. 21 grams 



Potassium bromide (10% solution) 40 drops 40 drops 



