442 Analyses of Books. [June, 



I do not see that the specimens in question prove the truth of 

 this opinion ; for much of the ice that floats in the Arctic Ocean 

 has been originally produced in rivers, or on the sea coast, and 

 it has been afterwards fed by the snow and rain water which 

 fell upon it while floating, and which would gradually assimilate 

 itself to the parent stock. Water saturated with salt freezes at 

 4°, and the sea water on our coasts freezes at about 28°; but I 

 have never been able to satisfy myself that in the act of freezing, 

 it parts with the whole of the salt which it held in solution. 

 This may, perhaps, be the case ; but it is difficult to conceive 

 how the particles of salt, which ought to be at least mechanically 

 mixed among the crystals of ice, could make their escape from 

 a very large mass of ice. 



The temperature of sea water ought to diminish gradually from 

 the surface to the bottom ; because its density constantly 

 increases as its temperature diminishes till it reaches, or evea 

 passes, the freezing point of sea water. This diminution of 

 temperature was observed by Capt. Ross and Lieut. Parry to 

 hold in Davis's Straits and in Baffin's Bay ; but it was deter- 

 mined by Lieut. Franklin and Lieut, Beechy that on the east 

 side of Greenland, and in the polar Seas, just the contrary takes 

 place, or the sea at the bottom is considerably hotter than at the 

 surface. 



As it would have been an endless task to have attempted the 

 analysis of all the specimens of sea water contained in the above 

 table. Dr. Marcet selected 16, and determined with as much 

 accuracy as possible the quantity of muriatic acid, sulphuric acid, 

 hme, and magnesia, contained in 500 grs. of the liquids, and 

 likewise the weight of salt left, when 500 grs. of each of the 

 liquids was evaporated to drj'ness. The muriatic acid was esti- 

 mated from the quantity of chloride of silver precipitated, and 

 ~ dried at a temperature sufficient to produce incipient fusion. 

 The sulphuric acid by the quantity of sulphate of barytas. 

 When loo grs. of sulphate of barytes, dried at 212°, are exposed 

 to a red heat, they are reduced to 97*2 grs. The lime was deter- " 

 mined by precipitating it by oxalate of ammonia, and drj'ingthe 

 precipitat© at the temperature of 212°. According to Dr. Mar- 

 cet, 100 grs. of such a precipitate contain 39'23 grs. of lime. 

 The magnesia was precipitated by means of phosphate of sod» 

 and carbonate of ammonia. According to Dr. Marcet, 100 grs. 

 of this precipitate contain 40 grs. of magnesia. The follovvJBg; 

 table exhibits the weight of the saline contents, and of the differ- 

 ent precipitates, from 500 grs. of the specimens of sea water 

 subjected to experiment : 



