16 FERTILIZERS. 



POTASH. 



Potash is the element potassium combined with oxygen 

 " potassium oxide " it is called by the agricultural 

 chemists. Potassium itself is but a curiosity of the labora- 

 tory ; for it can be kept pure only by excluding all air, and 

 is therefore only to be found in the bottle of the chemist. 

 The name " potash " was given it because it was made in 

 iron pots from ashes. 



In Canada and other primitive countries, in clearing the 

 land, the trees having been felled, piled, and burnt, the 

 ashes are collected, mixed with about one-twentieth of 

 lime, and placed in half-barrels, with false bottoms perfo- 

 rated with holes, and covered with straw. They are 

 drenched with water ; and in an hour or two the water is 

 drawn off into shallow iron pans, and evaporated. The 

 crude potash obtained is purified by heat on the floor of a 

 furnace, where most of the sulphur and water is driven 

 off, making the pearl ash of commerce. 



Potash is a most caustic, biting alkali, dissolving and 

 decomposing all organic structures it comes in contact 

 with. It is one of the most powerful bases ; in other 

 words, it is a vigorous, unprincipled chemical thief, seizing 

 upon, and absorbing into itself, the acids it finds combined 

 with various saline compounds. Pure water could not 

 dissolve the potash as it exists in the particles of felspar 

 and mica that are found in the soil ; but, taking carbonic 

 acid from the air, it has the power of dissolving the sili-' 

 cate of potash, leaving the quartz and alumina to form the 

 clays. Caustic lime also has this power. The silica, 

 combined with the potash, preferring the lime, divorces 

 itself from the potash, and, marrying the lime, sets the 

 potash free. In the vegetable kingdom it is held by 

 plants, while in the process of growth, in a soluble state, 



