108 INTRODUCTION TO GENERAL SCIENCE 



worthy of study, must be obtained from special books. The 

 references give the chemistry of photography and some of its 

 uses. 



References : 



1. 1703:373-375. Photography. 



2. 1803 : 433-434. The Camera. 



a. 1003 : 233-236. Uses of Photography in Astronomy. 



6. 1701:367-368. Photography. 



c. 1704:354-356. Photography. 



d. 1705:220-221. Photography. 



e. 1706:312-313. Photography. 

 /. 1707:391-392. Photography. 

 g. 1708:375-376. Photography, 

 fe. 1709:308-311. Photography. 

 i. 1711 : 155-158. Photography. 



j. 1713 : 156-158. Photochemistry. 



Experiment 39. Effect of Light upon a Silver Salt. 



Apparatus : Test tubes 6" X f", funnel, ring stand. 



Materials: Silver nitrate solution, 10 per cent, hydro- 

 chloric acid, 25 per cent, potassium bromide solution, 10 per 

 cent, potassium iodide solution, 10 per cent, several sheets 

 of filter paper. 



a. Take 5 c.c. of silver nitrate solution in a test tube and 

 add hydrochloric acid, drop by drop, until there is no further 

 precipitate formed. You have seen a chemical change. 

 Silver nitrate has been changed into silver chloride. Filter, 

 using the funnel, and expose the residue to direct sunlight. 

 What happens? Repeat, using potassium bromide and 

 potassium iodide solutions. Which material changes the 

 fastest in the sunlight? 



