WRY BIBBS SING. 



541 



Tvater, and not an abandoned lagoon of the Red Sea. By chemical 

 and spectral analysis, it contains neither iodine nor silver, nor lithine, 

 while all those substances are found in the Arabian Gulf, a body whose 

 waters differ from those of the oceans only by their greater density 

 consequent on the strong evaporation to which they are subjected. 



The determination of the air dissolved in the ocean is attended 

 with many difficulties. We can only indicate a few prominent prin- 

 ciples. This air has not the same composition as the air we breathe, 

 although ic differs but little in that respect from the air held in springs 

 and rivers. Oxygen, which forms only a fifth of the atmospheric air, 

 being more soluble in water than nitrogen, constitutes about one third 

 of the air which is expelled from water by boiling. The volume of 

 gas absorbable by water diminishes as the temperature rises. Cold 

 water is richer in air than warm. Moreover, the law of decrease being 

 regular for nitrogen, while it is less simple for oxygen, the relative 

 proportions of the two elements are variable in waters of different 

 temperatures. According to Mr. Tornoe, there is a little more oxy- 

 gen at the surface than theory calls for, while in the zones where ani- 

 mal life is largely developed there is a slight deficiency. The pres- 

 ence of sunlight, or the cutting of it off by clouds, has no important 

 effect ; and the same may be said of the enormous pressures to which 

 deep-sea waters are subjected. But little carbonic acid occurs dissolved 

 in a free state, although that gas is very abundant in combination. 

 Mr. Tornoe, who has given this subject careful attention, thinks the 

 older chemists collected carbonic-acid products of the decomposition 

 of carbonates or bicarbonates at the boiling-point He finds an alka- 

 line reaction in sea-water, which he attributes to a small quantity of 

 free salts of soda. Mr. Hamberg, a Swedish chemist, who has recently 

 studied the waters of the Greenland seas, agrees with Mr. Schloesing 

 that marine water contains neutral carbonates, bicarbonates, and slight 

 traces of free carbonic acid, and that temperature and atmospheric press- 

 ure have a complex influence on both the uncombined gas and that 

 which is united to bases. — Translated for the Popular Science Monthly 

 from the Hevue des Deux Mondes. 



WHY BIEDS SING. 



By Db, B. PLACZEK. 



I HAVE long been an interested observer of bird-life. The situa- 

 tion of my house and garden, on the terrace-slopes of the Spiel- 

 berg, affords me favorable opportunities for studying the habits of the 

 feathered tribes. They build their nests in my garden, and lend them- 

 selves with great docility to the purposes of the friendly spectator of 

 their movements. At one time the nest of a hedge-sparrow {Sylvia 



