Chemistry and Physics. 465 



compared their behavior with that of arsenic, silver and cadmium 

 and their compounds and finds that the atomic weight of indium 

 is near that of silver (108), and not similar to that of arsenic (75). 

 This method supplies an interesting and novel means of confirm- 

 ing atomic weights. — C. B., cxxxii, 772. h. l. w. 



6. The Presence of Platinum upon an Egyptian Hieroglyphic 

 Inscription. — In examining a metallic specimen covered with 

 hieroglyphic characters, found at Thebes and probably belonging 

 to a period corresponding to the seventh century of our era, Bek- 

 thelot has found a small thin piece of hammered metal used in 

 forming one of the characters, which, from its resistance to sol- 

 vents and the nature of the solution obtained, was evidently an 

 alloy of platinum with the closely related metals, such as is fre- 

 quently found native. It is Berthelot's opinion that the Egyp- 

 tians must have distinguished the difference between this sub- 

 stance and silver if it was often encountered, but it remains for 

 future investigation to show whether they often used platinum or 

 not. He is not aware that platinum has ever been found in 

 Egypt or in other parts of Africa or in Arabia. — C. JR., xxxii, 

 732. h. l. w. 



7. A Generalization from Trouton's Law. — An empirical rela- 

 tion between heat of vaporization, measured at the normal boil- 

 ing point, and the absolute temperature of the boiling point of 

 substances, was observed by Trouton in 1844. This is expressed 

 by the formula, 



and it was found that K varies from 20 to 26. 



In 1887 Le Chatelier observed that the dissociable metallo- 



ammonia compounds yield for — values (27*8, 28-7, 29*1) which 



are near the preceding ; Q being the heat of fixation of the 

 ammonia gas, and T' the absolute temperature at which the com- 

 pound has a tension of 760 mm . Le Chatelier showed further that 



if one calculate ^ for the following dissociable compounds, 



Pd 2 H, CaC0 3 , Ir0 2 , C 3 N 3 , Ca(OH) 2 , which disengage gases other 

 than ammonia, the values 23, 23*4, 24*3, 27*8 and 27'8 are 

 obtained, which are almost identical with the preceding. Le 

 Chatelier drew the conclusion that the equation 



T ,- T , 



is a consequence of the laws of chemical equilibrium. 



Recent investigations show that the higher values, in the neigh- 

 borhood of 24 to 26, furnished by Trouton's relation, are given 

 by liquids that have condensed molecules, while the non-polymer- 

 ized, normal liquids give very constant values which are near 21 



or 22. On the other hand, the quotient ^ gives a value that is 



