SODA AND AMMONIA, 
15 
SODA. 
Both potash and soda are bases for organic and mineral acids, in which combination 
they are connected with the growth and development of plants. The tubers of potatoes 
require both potash and soda, and, when grown in a suitable soil, they form a valuable 
food : if, however, they vegetate in the open air, a poisonous alkali is formed from the 
elements of the tuber, in which there exist mere traces of potash and soda. 
The great source of soda is sea water and saline springs, where it is in combination with 
chlorine. It is also found in mineral bodies, in the same relations as those of potash : 
hence soils may be supplied with soda by the decomposition of slates, shales and clays. 
It will be observed, on consulting the analyses, that soda is in less proportion in soils, 
rocks, and in the ash of plants, than potash. Plants growing in sea water and near brine 
springs, as at Salina and Syracuse, contain soda. The Salsola kali is common about the 
salt-pans and fields moist with chloride of sodium. It here finds its proper food, and is as 
flourishing as upon the shores of the Atlantic. 
In rocks the percentage of soda is sometimes as high as 11*48, as in albite, a common 
variety of felspar; in mica, it is only from 3 to 5. Notwithstanding the apparent small 
percentage of soda in rocks and soils, we see that it has accumulated in immense quantities 
in some locations, as in the rock salt of Cheshire in England, Cracow in Poland, &c. 
The sea, however, forms the great reservoir. 
It is maintained by many that potash and soda may replace each other, in case of an 
absence of either ; that marine plants which naturally require soda, if cultivated far inland, 
take the vegetable alkali in place of the mineral. This, however, is a forced state ; and 
the probability is, that in these cases the plant in a few years would cease to vegetate. 
AMMONIA, VOLATILE ALKALI, HARTSHORN. 
Ammonia, like pctash and soda, is an original constituent of the globe ; but unlike those 
alkalies, it is constantly produced and destroyed by the affinity of the elements which 
compose it. Nitrogen and hydrogen being its elements, may unite whenever they exist 
in a complex substance, when that substance is decomposed. It is exhaled from animal 
and some vegetable matters in the process of decay, during which it is probably formed 
by the union of its elements, but in which it did not exist as ammonia when the decay 
began. 
Ammonia is also exhaled from the deep interior of the earth. Its salts condense in 
and upon the fissures of the rocks near volcanic vents. Its vapor rises from the lagoons 
of Tuscany, in company with boracic acid. This fact, however, does not prove that it 
exists in masses and reservoirs in the interior of the earth : it may be formed in its bowels, 
by the decomposition of water and other bodies in which nitrogen is an element. 
The importance which ammonia takes in the processes of agriculture, arises from the 
