Soda
A substance composed of the alkaline metal Sodium, combined with Oxygen, together with a certain amount of water, called Water of Hydration. Sodium is one of the most widely-diffused elements; and its numerous compounds are almost all readily soluble in water. It is very difficult to get entirely clear of the element, even in the chemical laboratory, and it is impossible to do so in soils; hence, plants are constantly supplied with it in solution from the soil, and it is found in the ashes of all plants. Experimental cultivation of plants from which it is, to the utmost, withheld, proves that it is not indispensable to any plant; though it has been asserted that Wheat, Oats, and Barley require an appreciable trace of Sodium to allow them to form perfect seeds. It has also been stated, as a result of experimental cultivation, that Sodium may, in part, functionally replace Potassium in plants; but there seems reason to believe that Sodium produces very little, if any, effect on the health of plants, though indispensable in the nourishment of animals, including man.