486 THE CHEMISTRY OF CREATION. 



to the analysis of sea-water will show that in 

 its composition are to be found all those elements 

 which are present in the sea- weed. 



The saline and mineral ingredients forming 

 the food of marine plants must by no means be 

 considered as simply accidentally present, or 

 present merely by imbibition, as they would be 

 in a cotton wick plunged into sea-water. They 

 are absorbed into the plant by the powers of 

 vital chemistry, and are as important to its 

 well-being as the alkaline and earthy matters 

 present in land-plants are to them. This is 

 remarkably illustrated in the case of the 

 element iodine. The chemist can only detect 

 minute traces of iodine in sea-water, yet he 

 extracts it from sea-weed, though it is only 

 present in the proportion of one grain in one 

 million grains of sea-water. Were it not, in 

 fact, for this faculty possessed by sea-weed, 

 and wisely made essential to its growth, man 

 would be deprived of one of the most useful 

 of medicinal substances, in the element thus 

 extracted. All the iodine of commerce is ob- 

 tained from the fused ashes of the sea-weed. 

 Bromine also is chiefly known to us as one of 

 the minute products of a chemical operation to 

 which kelp is subjected. Both the elements 

 thus abstracted from the water for the use of 

 man by the sea- weeds could not otherwise have 



