70 CHEMISTRY, GEOLOGY 



Saline substances are often more advanta- 

 geously employed, as manures, in a mixed state, 

 than separately. A mixture of nitrate and sul- 

 phate of soda has been found to produce a much 

 more beneficial result than the same weight of 

 either of them would have effected ; and a mix- 

 ture of common salt and gypsum will do more 

 good to a crop of beans than an equal weight of 

 either of the articles separately applied. 



Kelp is the ashes of sea- weeds ; they contain 

 an oxide of sodium, or soda. When attainable 

 in large quantities, they are a valuable manure 

 as a top-dressing to grass lands ; and, mixed 

 with common manure, it is of great advantage to 

 crops of turnips and potatoes. 



Wood-ashes contain potash, a combination of 

 oxygen with potassium. They are usefully 

 applied to grass lands, destroying the mosses 

 which impede the growth of the grass, and ren- 

 dering it much more thrifty and luxuriant. 

 They produce the same effect upon young grain 

 and potatoes. Mixed with bones, rape-dust, 



Questions. Are salts best applied mixed, or alone? 

 What is kelp ? Of what composed ? For what is it valuable 

 as a manure ? Of what do wood-ashes consist ? What is 

 their effect upon the land ? 



