[Footnote: Read lately before the Manchester Literary and Philosophical Society]

By THOMAS KAY, President of the Stockport Natural History Society.

The author called attention to the absence of research in this direction, and how man, endowed to overcome every physical disability which encompassed him on land, was powerless to live on the wide ocean, although it is teeming with life.

The water for experiment was taken from the English Channel, about fifty miles southwest of the Eddystone Lighthouse, and it was found to correspond closely with the analysis of the Atlantic published by Roscoe, viz.: Total solids 35.976, of which the total chlorides, are 32.730, representing 19.868 of chlorine.

The waters of the Irish Sea and the English Channel nearer to the German Ocean, from their neighborhood to great rivers, are weaker than the above.

Schweitzer's analysis of the waters of the English Channel, near Brighton, was taken as representing the composition of the sea, and is here given:

 Sodium chloride 27.059

Potassium " 0.766

Magnesium " 3.666

" bromide 0.029

" sulphate 2.296

Calcium " 1.406

" carbonate 0.033

Iodine and ammoniacal salts traces

Water 964.795

________

1000.000 

The chlorides in the--

 Irish Sea are about 30 per mille.

English Channel are about 31 "

Beyond the Eddystone are 32 " 

As the requirement for a potable sea water does not arise except in mid-ocean, the proportion of 32 per mille must be taken as the basis of calculation.

This represents as near 20 per mille of chlorine as possible.

From the analysis shown it will be perceived that the chlorides of sodium and magnesium are in great preponderance.

It is to the former of these that the baneful effects of sea water when drunk are to be ascribed, for chloride of sodium or common salt produces thirst probably by its styptic action on the salivary glands, and scurvy by its deleterious action on the blood when taken in excess.

Sodium chloride being the principal noxious element in sea water, and soda in combination with a vegetable or organic acid, such as citric acid, tartaric acid, or malic acid, being innocuous, the conclusion is that the element of evil to be avoided is chlorine.

After describing various experiments, and calling attention to the power of earthy matters in abstracting salts from solutions by which he hoped the process would be perfected, an imperial pint of water from beyond the Eddystone was shown mixed with 960 grains of citrate of silver and 4 grains of the free citric acid.

Each part of the chlorides requires three parts by weight of the silver citrate to throw down the chlorine, thus:

3NaCl + AgCHO = Na3.CHO+3AgCl.

The silver chloride formed a dense insoluble precipitate, and the supernatant fluid was decanted and filtered through a rubber tube and handed round as a beverage.

It contained in each fluid ounce by calculation about:

 18 grains of citrate of soda.

1-1/2 " " magnesia.

1/2 " " potash.

1 " sulphate of magnesia.

1/2 " " lime.

1/5 " citric acid. 

with less than half a grain of undecomposed chlorides.

To analyze this liquid therapeutically, it may be broadly stated that salts of potash are diuretic, salts of magnesia aperient, and salts of soda neutral, except in excessive doses, or in combination with acids of varying medicinal action; thus, soda in nitric acid, nitrate of soda, is a diuretic, following the law of nitrates as nitrate of potash, a most powerful diuretic, nitrous ether, etc.; while soda in combination with sulphuric acid as sulphate of soda is aperient, following the law of sulphates, which increase aperient action, as in sulphate of magnesia, etc.

Thus it would seem that soda holds the scales evenly between potash and magnesia in this medical sense, and that it is weighed, so to speak, on either side by the kind of mineral acid with which it may be combined.

With non-poisonous vegetable acids, and these slightly in excess, there is not such an effect produced.

Sodium is an important constituent of the human body, and citric acid, from its carbon, almost a food. Although no one would advocate saline drinks in excess, yet, under especial circumstances, the solution of it in the form of citrate can hardly be hurtful when used to moisten the throat and tongue, for it will never be used under circumstances where it can be taken in large quantities.

In the converted sea water the bulk of the solids is composed of inert citrate of soda. There is a little citrate of potash, which is a feeble diuretic; a little citrate and sulphate of magnesia, a slight aperient, corrected, however, by the constipatory half grain of sulphate of lime; so that the whole practically is inoperative.

The combination of these salts in nature's proportions would seem to indicate that they must be the best for administration in those ailments to which their use would be beneficial.

Citrate of silver is an almost insoluble salt, and requires to be kept from the light, air, and organic matter, it being very easily decomposed.

A stoppered bottle covered with India-rubber was exhibited as indicating a suitable preserver of the salt, as it affords protection against light, air, and breakage. As one ounce of silver citrate will convert half a pint of sea water into a drinkable fluid, and a man can keep alive upon it a day, then seven ounces of it will keep him a week, and so on, it may not unreasonably be hoped, in proportion.

It is proposed to pack the silver citrate in hermetically sealed rubber covered bottles or tubes, to be inserted under the canisters or thwarts of the life-boats in ocean-going vessels, and this can be done at a simple interest on the first outlay, without any loss by depreciation, as it will always be worth its cost, and be invaluable in case of need.