'234 Effects of Heat and Solvents on Films of Metal [June 4, 



DESCRIPTION OF PLATES 1113. 

 (The numeration of the figures is continued from those in foregoing paper.) 



PLATE 11. 



Fig. 13. Gold leaf annealed by heating on glass. 

 Transmitted light with green screen. 

 Objective 12 mm. Apo. N.A. 0'65. 

 Magnification x 440. 



Pig. 14. Gold paint on glass annealed by heating. 

 Light and objective as in fig. 13. 

 Magnification x 440. 



Figs. 15 to 18. Gold film, phosphorus reduced annealed by hoating on glass. 

 Transmitted light with green screen. 

 Objective 12 mm. Apo. N.A. 65. 



Fig. 15. The thickest part of the film. Fig. 16. A thinner part. 



Fig. 17. A still thinner part. Fig. 18. The thinnest part. The dark 

 patches were deep green, and the light patches pale pink by transmitted 

 light. 



PLATE 12. 



Fig. 19. Gold plate planished and polished. 



Normally reflected light, green screen. 



Objective 3 mm. Oil immersion. Apo. N.A. 1'4. 



Magnification x 1500. 



fig. 20. The same after heating for 10 minutes to 700 800. 

 Surface broken up into films by escaping gas. 



Fig. 21. The same after further heating for 1 hour. 

 Surface subsiding after escape of gas. 



Fig. 22. The same, after further heating for 2 hours. 

 Surface further subsided. 



Fig. 23. Gold plate, another specimen, heated for 1 hour. 

 Surface subsiding after escape of gas. 

 Lighting and objective as in figs. 1922. 

 Magnification x 1500 (enlarged from 775). 



Fig. 24. The same after further heating for 1 hour. 



The surface has subsided and has assumed an appearance of viscous flow. 



PLATE 13. 



Fig. 25. Gold plate. A gpot amalgamated with mercury, which was then driven 

 off by a gentle heat. The dark part was most affected by the treat- 

 - ment, and the light part least. 



Normally reflected light, green screen. 



Objective 12 mm. Apo. N.A. 0'65. Magnification x 250. 



Fig. 26. The light part of the same more highly magnified. 

 Objective 3 mm. Oil immersion. Apo. N.A* 1*4. 

 Magnification x 775. 



Fig. 27. The dark part of the same more highly magnified. 

 Objective as in fig. 26. Magnification x 775. 



