XXXV iii GENERAL SUMMARY OF SCIENTIFIC AND 



er in solution, the stronger acid seeks the stronger base, and 

 vice versa. Some desirable determinations of specific heat 

 liave been made. Mixter and Dana liave determined this 

 constant ibr silicon, zirconium, and boron, and shown that 

 these elements, like carbon, are exceptions to Dulong and 

 Petit's law of equality for atomic heats. Dewar, determining 

 the specific heat of carbon at high temperatures (2100 C, 

 etc.), does much, liowever, to confirm Weber's view that at 

 such temperatures the element should agree with the law of 

 Dulong and Petit. It is to be hoped that Dewar w^ill extend 

 his experiments to the other exceptions to this law. 



Other very important work in chemical physics has been 

 done by Dr. Draper, whose papers on actino-chemistry have 

 attracted much attention. Draper shows that, contrary to a 

 widely prevalent conception, all the rays of the solar spectrum 

 have actinic power, and can produce chemical change. This 

 rule applies to the invisible as well as to the visible portions 

 of the spectrum. In any selected case, the particular rays 

 producing the change depend upon the nature of the sub- 

 stance upon which they act. Champion and Pellet's experi- 

 ments on the vibratory motions of detonating bodies are also 

 worthy of notice. These gentlemen have investigated the 

 effects produced by tlie explosion of a variety of such sub- 

 stances upon a series of sensitive flames, and have shown that 

 essentially different sets of vibrations occur in the different 

 cases. 



In general inorganic chemistry many investigations have 

 been made. A number of the rarer metals have been re-ex- 

 amined, and several new determinations of atomic weights 

 deduced. That of yttrium has been fixed by Cleve and Iloeg- 

 lund at 59.7, and that of erbium, by the same experiment- 

 ers, at 113.7. Tlicse metals seem in many respects to belong 

 in the same group with zinc, magnesium, and cadmium. In- 

 dium has at last been definitely placed by Roessler. It forms 

 a true alum, like aluminum and iron. Liechti and Kempe 

 have described the chloride of molybdenum, and Atterberg 

 has investigated some glucinum compounds. At the present 

 rate, even though most chemists prefer to work in the field 

 of organic chemistry, we shall not have very long to wait for 

 an intelligible classification of the metals. 



During the year, ammonia has been made the subject of 



