120 SODA ESCULENT ROOTS. 



numerous combinations which it forms as alkaline salts are of the 

 greatest importance. But as an immediate product of burnt vegeta- 

 bles, and as a constituent of living ones, it has a more special relation 

 to our subject. It is alluded to in the chapter on the agriculture of 

 chemistry as an important agent in soils ; and as a staple article of 

 commerce in this country, it is highly important. Of pot and pearl- 

 ashes, the exports from the U. S. in 1830 were 8,957 tons, valued at 

 $1,105,127. The value of the product of 1840 is put down at $533,193 

 though it is thought to be increasing as our lands become cleared and 

 the trees and herbage are consumed. There is probably a greater 

 quantity exported from this country than from any other, as it can be 

 produced in great quantities only where there are extensive forests. 



Vegetables yield potash in very different proportions. In 1000 Ibs. 

 of the following vegetables, saline matter is afforded as below worm- 

 wood 748, fumitory 360, stalks of sunflower 349, beech 219, stalks of 

 wheat 198, elm 166, vine 162, fir, 132, heath 115, fern 116, oak 111. 



Grasses, leaves, the stalks of peas, beans, melons, cabbages, pota- 

 toes, artichokes and maize are very rich in this alkali. Leached ashes 

 forms an excellent manure for damp or clay soils and is used in making 

 black glass. The potash of America affords alkali 857, sulphate of 

 potassa 154, muriate do. 20; in all of which it is richer than that of 

 any other country. 



Soda exists in all plants impregnated with marine salt, and many 

 are burned for it, and some especially cultivated. For the manufac- 

 ture of soda the plants are collected when vegetation has ended, dried 

 and thrown into a pit 4 feet square, previously heated by a split wood 

 fire, and the plants gradually thrown in and the combustion continued 

 for 7 or 8 days, when a block of soda is found in the bottom which is 

 taken to market and used in glass works. From the immense quanti- 

 ty of sea-weed thrown upon our shores, we are inclined to think this 

 might be made a very profitable business in parts of this country. 

 Soda is also furnished to commerce by the decomposition of common salt, 

 converted to a sulphate by sulphuric acid, and this is decomposed in a 

 furnace, when mixed with charcoal and chalk. The most common 

 salts in plants are sulphate of potash, common salt, phosphates of lime 

 and nitrate of potash. The 4 earths obtained from plants by com- 

 bustion are silica, lime, magnesia and alumina. Dry plants afford 

 far larger portions of potash than green ones. Saussure's table of 

 the proportions afforded, as found in Chaptal, is the best guide. 



ESCULENT ROOTS. 



Roots are of different kinds, the common spindle shaped, or fusiform 

 root, shooting into the ground, with fleshy fibres and radicals branching 

 from the main stem like the beet, radish, the tree, &c. ; buttons 



