184 



DR. E. H. CRTFFITHS AND MR. EZER GRIFFITHS ON THE 



considered. It thus appears as if there was some relation between the temperature 

 ..f the melting-points and the atomic heats. 



In rig. 'J the atomic heats at 50 C. have been plotted as onlinates, and the 

 melting-points as abscissae. 



This temperature was selected for comparison as the most reliable data given by 

 other observers have been obtained over temperature ranges including 50 C. as a 

 mean. 



P O O 



100 20O 300 



400 500 600 700 

 Melting Points. 



Fig. 9. 



800 900 1,000 IJOO 



[Determinations made by us since the communication of this paper to the Society 

 give the value of the atomic heat of sodium at 50 C. as 7 '01, in place of the value 

 7 '37 shown in the diagram, this latter number having been based on the values of 

 NORDMEYER and BERNOUiLLi between -185 C. and +20 C. (5'38), and BERNINI'S 

 at +10 C (6'83) and +128 C. (7'66).] 



APPENDIX III. 



Soldering Glass to Metal. 



The process is identical for glass, quartz and, no doubt, for porcelain. 



The end of the glass or quartz tube is painted with a solution of platinum chloride 

 in a volatile oil. (Solution is sold under the trade name of Liquid Platinum, No. 1.) 



The coating is very gently heated at first, and the temperature slowly increased, 

 until all the volatile matter has been driven off and a brilliant film of platinum 

 obtained. The higher the temperature to which the tube is raised, the better the 

 adherence of the film. The tube should glow with a dull red light, before being 



