THE SEA AND THE ATMOSPHERE. 17 



ingredients again, in the sea they would have to remain. There, 

 accumulating in its waters, thc}^ would alter the qualitj^ of tho 

 brine, injure the health of its inhabitants, retard evaporation, 

 change climates, and work endless mischief upon the fauna and 

 the flora of both sea, earth, and air. But in the oceanic machi- 

 nery all this is prevented by compensations the most beautiful, 

 and adjustments the most exquisite. As in the atmosphere tho 

 plants are charged with the office of purifying the air by elabo- 

 rating into vegetable tissue and fibre the impurities which the 

 animals are continually casting into it, so also to the mollusks, to 

 the madrepores, and insects of the sea, has been assigned the 

 office of taking out of its waters and making solid again all this 

 lixiviated matter as fast as the dripping streams and searching 

 rains discharge it into the ocean. 



47. Monuments of their industry . — As to the extent and magni- 

 tude of this endless task some idea may be formed from the 

 coral islands, the marl beds, the shell banks, the chalk cliffs, 

 and other marine deposits w^hich deck the sea shore or strew 

 the land. 



48. Anahjsis of sea-water. — Fresh water is composed of oxygen 

 and hydrogen gas in the proportion by weight of 1 to 8 ; and the 

 principal ingredients which chemists, by treating small samples 

 of sea-water in the laboratory, have found in a thousand grains, 

 are — 



Water 962.0 crains 



Chloride of Sodium 

 Chloride of Magnesium 

 Chloride of Potassium . 

 Bromide of Magnesia . 

 Sulphate of Magnesia . 

 Sulphate of Lime 

 Carbonate of Lime 

 Leaviu": a residuum of . 



27.1 „ 



5.4 „ 



0.4 „ 

 0.1 



1.2 „ 

 0.8 



0.1 „ 



2.9 „ = 1000, 



consisting of sulphuretted hydrogen gas, hydrochlorate of ammo- 

 nia, etc., etc., in various quantities and propoi-tions, according to 

 the locality of the specimen. 



49. Proi^ortion oficater to tJie mass of the earth. — If we imagine 

 the whole mass of the earth to be divided into 1786 equal paiis 

 by weight, then the weight of all the water in the sea would, ac- 

 cording to an estimate by Sir John Ilersckel, be equivalent to 

 one of such parts. Such is the quantity, and such some of the 

 qualities of that delightful fluid to which, in the laboratories and 







