156 REPORT — 1844. 



again separates these substances from the water of the ocean, and deposits it in 

 an insoluble state in the beds, which are precipitated on the shores, and at 

 the bottom of the deep seas. In fact, similar instances of solution and preci- 

 pitation have long been known and studied by geologists, and have become 

 extensive means of explaining geological changes. Innumerable springs carry 

 vast quantities of carbonate of lime to the sea, while all rivers contain more 

 or less sulphate of lime ; yet the analysis of sea-water shows only small traces 

 of lime, but then we observe that the animals of shells and corals everywhere 

 are busily employed in extracting this lime from the water, and that they 

 ultimately deposit it in the form of solid beds of limestone. The reason 

 why so little lime is found dissolved in sea-water, is exactly the same as that 

 which explains why so small a quantity of carbonic acid occurs in the atmo- 

 sphere ; although causes which are constantly operating are always supplying 

 it with this substance, which is absolutely necessary for vegetable life. Plants 

 deprive the atmosphere as fast of its carbonic acid, as subterranean heat, com- 

 bustion and animal life produce it. In like manner, the lower animals extract 

 the lime as quickly from sea-water, as rivers and submarine springs provide 

 it, and there must necessarily be a similar cause constantly depriving sea-water 

 of its potash and sulphuric acid, which so many and constantly acting decom- 

 positions ultimately convey to the ocean. 



Marine vegetation has, in a geological point of view, but little attracted 

 the attention of philosophers, and while land plants play a necessary part in 

 every geological system, the whole vegetation of the ocean has been left a 

 blank, except as far as fucoidal forms have been an object of contemplation 

 for those geologists who principally occupy themselves with fossil plants. Not- 

 withstanding this neglect, the quantity of vegetable substances annually formed 

 by fucoidal plants is enormously great ; and what is very material, the quantity 

 of mineral substances, in the form of ashes, exceeds very much that which 

 land plants contain, and thus sea-weeds, on account of such mineral contents, 

 must necessarily have a decided influence upon the formation and changes 

 of beds. For this reason I deemed it necessary to analyse the ashes of fuco- 

 idal plants, chosen among the different families of that class, and from very 

 different parts of the globe; which plants I owe to the kindness of my friends 

 Professor Schouw, Dr. Vahl and M. Liebmann. The analysis was carried on 

 in the following way. 



The dried sea- weed was weighed, calcined, and the ashes weighed ; though 

 the quantity of ashes thus obtained is not very correct, owing partly to a quantity 

 of carbonaceous matter which inclosed by the salts had escaped combustion, 

 and thus showed the quantity of ashes to be greater than it was in reality. In 

 other instances, the quantity appeared a little less than it ought to be on account 

 of some carbonic acid, which had been expelled from the carbonate of lime and 

 of magnesia ; now and then a small quantity of the sulphates had been reduced 

 to sulphurets, and thus likewise occasioned a loss. All these causes of trifling 

 errors do not, however, affect the general result of the analyses. For to ascer- 

 tain the constituent parts of the ashes, they were extracted by water as long 

 as anything was dissolvable ; and from this solution, after it had been made 

 acid by nitric acid, or in some cases by muriatic acid, the sulphuric acid was 

 separated by a salt of barytes, and when the sulphate of barytes had been 

 separated, the excess of barytes was again thrown down by sulphuric acid. 

 The lime was then precipitated by ammonia and oxalate of ammonia, and 

 the magnesia (if any was present) precipitated by a solution of pure barytes. 

 The precipitate, which consisted of sulphate and carbonate of barytes and of 

 magnesia, was treated with sulphuric acid, and the solution which contained 



