482 THE POPULAR SCIENCE MONTHLY. 



Indium resists oxidation up to a temperature somewhat beyond its 

 melting-point, but at much higher temperature it oxidizes freely ; and at 

 a red heat it takes fire in the air, burning with a characteristic blue 

 flame and abundant brownish smoke. It is readily attacked by nitric 

 acid, and by strong sulphuric and muriatic acids. In diluted sulphuric 

 and muriatic acids, however, it dissolves but slowly, with evolution of 

 hydrogen. Oxide of indium is a pale-yellow powder, becoming darker 

 when heated, and dissolving in acids with evolution of heat. The 

 hydrated oxide is thrown down from indium-solutions by ammonia, as 

 a white, gelatinous, alumina-like precipitate, drying up into a horny 

 mass. The sulphide is thrown down by sulphuretted hydrogen as an 

 orange-yellow precipitate, insoluble in acetic but soluble in mineral 

 acids. The hydrate and sulphide of indium, in their relations to fixed 

 alkali solutions more particularly, seem to manifest a feebly-marked 

 acidulous character. Chloride of indium, obtained by combustion of 

 the metal in chlorine gas, occurs as a white micaceous sublimate, and 

 is volatile at a red heat, without previous fusion. The chloride itself 

 undergoes decomposition when heated in free air, and the solution of 

 the chloride upon brisk evaporation, with formation in both cases of 

 an oxichloride. 



* 



THE CAUSES OF PHYSICAL DEGENEKACY. 



By A. K. GAKDNEE, M.D. 



"TTTTIETHER the human race is degenerating, and, if so, by what 

 VV causes, are questions of much speculative interest to scientific 

 thinkers, and of much practical interest to each father and mother in 

 the community. The subject is complicated by many conditions. 

 Physical health and vigor, and mental strength and power, are to a 

 great degree a matter of hereditary transmission, over which the indi- 

 vidual has no control. Yet, taking our natures as they are, we can ren- 

 ovate, reinvigorate, and advance them by attentive study of and con- 

 formity to the laws upon which health and vigor are based. I pro- 

 pose in the present article briefly to glance at the chief physical 

 agencies air, exercise, clothing, food, and rest and at some of the 

 mental and moral influences, by the bad or good employment of which 

 the physical stock is deteriorated or improved. 



Air. Probably the inhabitants of the globe generally were never 

 so thoroughly sheltered as at present. The house keeps off rain, dew, 

 and the moistures from evaporation certainly very desirable but it 

 also to a greater or less degree modifies the temperature and the qual- 

 ity of the air that we breathe. 



Theoretically, air is admitted to be an agent conducive to life ; prac- 



