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This potash may be considered as one of the most exten- 

 sively diffused compounds in nature ; it is found in all rocks 

 and soils where a patch of vegetable life can exist— it is a 

 substance found abundantly in the juices of all plants, where 

 it exists in combination with vegetable acids, and undoubtedly 

 plays an important part in the formation of wood and vege- 

 table productions in general. This potash is converted prin- 

 cipally into a carbonate when vegetables are burnt, which 

 carbonate remains in the ashes mixed with the other fixed 

 constituents ; — it is, in fact, from the wood ashes of America 

 and Russia that our large demand for potash is supplied. 

 Like most other of the fixed constituents of plants, this pot- 

 ash was originally supposed to be peculiar to the vegetable 

 race, and was hence called the vegetable alkali ; — it was, in 

 fact, supposed to be an element of their own creation, and 

 chemical analysis had failed to detect its presence in soils. 

 This failure arose from the minute portions of potash which 

 exist in soils in a soluble state, and the impossibility of ren- 

 dering that soluble which existed in considerable quantity, by 

 the means then at command. This potash exists in all rocks 

 and soils in combination with silica, as an insoluble glass 

 which requires the prolonged action of carbonic acid, rains, 

 and other natural agencies to render a small portion of it 

 soluble ; it is also decomposed and rendered soluble by the 

 action of alkalies, such as lime, ammonia, &c., an instance 

 of the latter being often seen on the glass of stable windows. 

 Now you are fully aware that all substances which plants 

 extract from the soil must be dissolved in water before they 

 can be absorbed by their roots, hence this potash must become 

 soluble before it can be of the slightest service to their growth. 

 The time required to convert a given weight of this potash 

 into a soluble state, will depend entirely on the quantity ex- 

 isting in the soil, and the presence of the above agents to 

 effect its decomposition — a soil containing four tons of pot- 



