94 ANALYSIS OF SEAWEEDS. 



be obtained, the farmer should embrace every oppor- 

 tunity for getting it. In England and Scotland, the 

 right of way to a beach where seaweed can be had, 

 increases the rent of a farm several shillings per acre. 

 On many parts of our own coast, too, the farmers are 

 very eager to obtain it. The ash of some seaweeds 

 analyzed by Prof. Johnston gave the following results: 



TABLE nr. 



Potash and soda, from 15 to 40 per cent. 



Lime, — 3 — 21 " 



Magnesia, — 7 — 15 " 



Common salt, — 3 — 35 " 



Phosphate of lime, ... — 3 — 10 " 



Sulphuric acid, — 14 — 31 " 



Silica, — 1 — 11 " 



This table shows that these ashes are rich in the 

 substances most needed by our crops, particularly in 

 potash, soda, sulphuric acid, and phosphoric acid. The 

 quantity of ash that they leave when dry, is larger than 

 that in straw or in hay. When freshly taken from 

 the sea, they contain a very large proportion of water. 



Seaweed is ploughed in green, or applied as com- 

 post. In either case it decays very rapidly, unless 

 extremely dry, and produces most of its effects upon 

 the first crop. Many of the seaweeds contain much 

 nitrogen ; and this, while it adds greatly to their value 

 as manures, increases the rapidity with which they 

 decompose. 



In England rape dust is largely used as a manure, 

 and with much advantage. The rape seed is pressed 

 to obtain its oil, just as linseed is, and the hard cake 

 formed by pressure sold for manure. Four or five 

 hundred weight per acre are applied as a top dressing, 

 or from 1500 to 2000 lbs. when it is ploughed in. 

 This is therefore a powerful manure, and is so portable 

 that it would be valuable in this country, could it be 



