The History of Salt

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Salt, fortunately for us, is a commodity remarkably easy to obtain; almost everyone knows it is in great abundance in the ocean,30 and there are inexhaustible supplies of it in the earth; it is also present in some rivers, and in no inconsiderable quantity.

We may account for this great proportion of salts by the fact that the Thames collects its water from the drainage of comparatively soft and soluble rocks; we should also remember the vast amount of refuse organic and inorganic matter which is being continually thrown into this river; and we must also call to mind that it is nothing more or less than the main sewer which receives the ordure of the modern Babylon.31

We may naturally suppose that in those rivers which flow through sparsely inhabited countries, where there is little or no traffic, the amount of saline matter would be next to nothing, and probably not a trace would be discovered. In a river like the Thames, owing to the vast quantity of its shipping, the great percentage which Mr. John Ashley has given us need not afford the least surprise. Sea-water is deficient in its proper proportion of salt at the mouths of great rivers, where the volume of fresh water displaces that which properly belongs to the sea, and therefore a river does not obtain much saline matter from that source.

Before we pass on to consider the geographical distribution of salt, we will just cursorily glance at the position it occupies in the vegetable world. It is present in all plants growing near the sea, and in variable quantities in some of those which are in or near districts where the soil is mixed with salt; though its place is taken by potash when they grow inland. Dr. Balfour writes as follows: “Soda and potash occur abundantly in plants. They are taken up with the soil in combination with acids. Those growing near the sea have a large proportion of soda in their composition, whilst those growing inland contain potash. Various species of salsola, salicornia, halimœnenum, and kochia yield soda for commercial purposes and are called halophites . The young plants, according to Göbel, furnish more soda than the old ones. There are certain species, as Armeria maritima, Cochlearia officinalis, and Plantago maritima, which are found both on the seashore and high on the mountains removed from the sea. In the former situation they contain much soda and some iodine; while in the latter, according to Dr. Dickie, potash prevails and iodine disappears.”

Soda being present in those plants growing near the sea, and potash in those which are inland, are two points well worthy of notice, and which we will now discuss. The number of vegetables which are cultivated near the coast shrink into insignificance when compared with those which grow inland; and naturally the markets are supplied with inland produce on account of a larger supply, therefore the consumption of those vegetables containing potash is in the same ratio. This being unquestionably the case, we ought, on that account alone, to use salt freely with our vegetable food in order to supply that which is absent, arising from the difference of locality and dissimilarity of the atmosphere. I shall enter fully into the relation salt bears to vegetable food while it is going through the process of digestion further on, when we come to consider the effects which food salted beforehand has upon the system when continued for any length of time, with little or no variation, which dietary is supposed to be the sole cause of the attacks of scurvy on board ship.