salt which the sea has left in the bowels of the earth. When obtained from the sea, the sea water is evaporated, and contains from 16 to 1,800 grains of salt to the gallon of water. But the sea in former times has formed bays, and those bays have been gradually silted up, and the sea has retired from the bay, and the bay now becomes a lake, and this lake is a salt lake. We have many such salt lakes; they are numerous in the Crimea. The Dead Sea is a great salt lake. You will see by this diagram how these changes take place.

If the lake thus cut off from the sea receives but little fresh water from rain or rivers, the water will go

that it is said a human body will not sink in it. Such lakes eventually get dried up, leaving the salt at the bottom, which gets covered up by some insoluble material; the whole goes again under the sea, and, rising as dry ground, we dig into the earth and find the lake becomes a salt-mine. Such mines are found in the new red sandstone of Cheshire, on the continent of Europe, and other parts of the world. The salt obtained in these districts is frequently in a state of solution, and is pumped from wells which are called "Brine Springs."

Now, not only do animals that live in the sea require salt, but we find that all animals require it. We find, for instance, in the great salt lakes and salt bogs of Kentucky, that there is a certain district there which is salt, called the Big Bone Lick, from the existence in it of the bones of gigantic animals who have died there. These animals, that lived in America before man, were attracted by the salt, and in seeking it there have perished in the swamp, and left their great bones behind them. Now, not only do these large animals require salt, but

man requires it. It is so

necessary to him, that to tax his salt is one of the surest sources of income to a government.

A part of the

British revenue in India is still raised on salt.

Now, the question comes as to how this salt acts upon the system? The quantities of the various saline matters entering into the composition of a human body weighing eleven stone, I have calculated is as follows:

1. Phosphate of Lime, forming the principal lbs. part of the earthy matter of the bones

Oz. grs.

5

13

0

The quantity of salt contained is not much, but still it is more than any other mineral constituent of the human body, except phosphate and carbonate of lime. When we take these away, we have only left about ten ounces more of these ashes, or mineral matters, and of these ten ounces, the chloride of sodium, or salt, is three ounces and three quarters. Now the question is, where this salt exists. If you take the muscles or the nerves of animals, you do not find that they contain salt; but if you take the blood of animals, you will find that it contains salt. I do not wish to produce upon your minds any disagreeable reflection, but those of you who have tasted your own blood, must recollect that it tastes salt, and we find three drachms of salt in a gallon of human blood, and that is the quantity nearly in all animals. It is not found in the muscles, in the nerves, or in the bones, or other tissues, but it exists only in

bodies formed, amongst which the crystals of salt will be most prominent.

Now, it may be asked, of what good is the salt? You may be sure that it does good. There are some people

who are foolish enough to believe that man has been wrong in all ages, and that salt has done harm. A medical man wrote a book to show that salt was the forbidden fruit that was eaten in the garden of Eden. He died not very long ago, and as I understand, a victim to his folly. There are some people who have no hesitation in rejecting the practices of their fellowcreatures-there are some who insist upon living upon vegetables—and I saw a book the other day, written by a person who said he never knew what health was until he lived entirely on animal diet.

Let us, then, inquire a little into the probable uses of salt in our system.

If we take a vessel, and divide it into two parts by an animal membrane such as exists in our own body, and then put salt and

water on one side, and spring water on the other side, so that they may both stand at the same level, in the course of time we shall find that the spring

water will go down, and

Fig. 4.

the salt water will rise up and flow over.

The pure water in fact passes through the membrane, but the salt water will not. Now, this is precisely the relation of the blood to the membranes of the stomach. It is a solution of salt; and if we place in our stomachs pure water, it will pass through the membranes of the stomach just in the same way that it passes through the membrane in the vessel. This, then, appears to be one of the important functions performed

by salt. It facilitates the absorption of water into the system. This will also account for the thirst produced by taking excessive quantities of salt, or salted food of any kind.

Another action of salt to which some physiologists have attached importance is, that it supplies to the system a certain quantity of chlorine which is necessary to the perfection of some of the vital processes. Thus during digestion a fluid is thrown out from the stomach, called gastric juice. This fluid contains free hydrochloric acid, and the chlorine of this compound could be only furnished by the salt taken with the food.

Then salt appears to facilitate certain changes in the system which are beneficial to health, which are difficult to explain exactly. The nature of these changes is indicated by such an experiment as the following: A number of oxen were taken by a great French chemist and experimentalist; he fed one set of them with salt, and another set of the same weight without salt. For a short time there appeared no difference; but at the end of a month the cattle that had the salt were sleek and well favoured, while the others had rough coats, and looked less comfortable, and so it went on for two years; and at the end of that time there was no doubt that the healthier animals were those which had the salt. There seemed to be some improvement in the quality of the blood going on by the action of the salt. The practice of placing pieces of rock-salt in meadows for horses, cows, and sheep to lick, is quite common in this country. It is also well known that marshes which have been overflowed by salt water give an improved appearance to the stock which grazes in them.