Observations on the Diseases of Seamen

by Sir Gilbert Blane

Spring water is to be preferred to running or stagnated water; for, unless it is taken at the source, or near it, it is apt to be impregnated with decayed vegetable and animal substances, such as leaves, grass, wood, and dead insects. This inconvenience is greatest in a hot climate, where every thing teems with life, and where the materials of putrefaction are both more abundant and more prone to corruption. This is the most pernicious kind of impurity; for the mineral impregnations common in springs are seldom, in any degree, unwholesome, and do not tend, like the other, to make the water corrupt. At many of the West-India watering places the water is found stagnated just above high-water mark; and care should be taken to go higher up to take it where it is running.

The purest water is apt to spoil by producing a putrid glare upon the inner surface of the cask which contains it. There is a great difference in this respect between a new cask, especially if made of moist wood, and that cask which has been hardened and seasoned by age and use. Several contrivances have been proposed for preparing the vessels that hold the water; but none have been found by experience so effectual as letting them stand for some time full of sea water; and it is a great advantage of this method, that it is so easily practicable.

It is in few places we meet with water such as that of Bristol, which, in clean vessels, may be kept for any length of time. We may consider all water kept in wooden vessels as more or less liable to putrefaction; but there is a substance, which is neither rare nor costly, that effectually preserves it sweet. This is quick lime, with which every ship should be provided, in order to put a pint of it into each butt when it is filled. It has the advantage of not being injurious to health; but, on the contrary, is rather friendly to the bowels, tending to prevent and check fluxes. In the year 1779 several ships of the line arrived in the West Indies from England, and they were all afflicted with the flux, except the Stirling Castle, which was the only ship in which quick lime was put into the water. Nor does it spoil the water for any culinary purpose. Its action in preventing putrefaction consists, in part at least, in destroying vegetable and animal life. An addition of putrescent matter is produced in water by the generation of small insects; and the glare that collects on the sides of casks, and also what collects on the surface of the water, is a species of vegetation of the order called by naturalists algæ[79]. Quick lime is a poison to this species of vegetable life as well as to insects: but upon whatever principle it depends, the property of it in preserving water sweet is so well ascertained, that it is inexcusable ever to neglect the use of it.

Quick lime is equally efficacious for this purpose, whether slacked or unslacked; and though the latter form is more convenient for stowage, by having less weight and bulk, yet the other is to be preferred for the sake of safety; for if water should by chance reach the unslacked lime, a great degree of heat is thereby produced, which has been known to give occasion to the most formidable accidents.

The only other objection I know of to the use of quick lime is, that it converts the water into a lime water, rendering it thereby disagreeable to the palate and stomach: but the quantity necessary to preserve it makes but a very weak lime water; for part of the lime is precipitated by the mephitic air, or the aerial acid, as it is otherwise called, of which there is some contained in the water. The accidental exposure to the atmosphere, which also abounds with this sort of air, tends farther to lessen the acrimony of the quick lime[80].

There are other substances which have been found useful in correcting bad water. Alum and cream of tartar, as antiseptic bodies, have been employed for this purpose. Vinegar and the vegetable acid juices and fruits, such as tamarinds, may be used occasionally to take off the putrid offensive taste which may have arisen in case the use of quick lime has been neglected. In the fleet under Sir Charles Saunders, the water of the river St. Lawrence having been found to produce fluxes, this quality was removed by throwing four pounds of burnt biscuit into each cask before it was used. But there is nothing so effectual, and subject to so few inconveniences, as quick lime.

The next method to be mentioned of purifying water is filtration, which not only separates the gross impurities, but removes the putrid smell and taste. It is performed with a dripping stone, which is a convenient contrivance for officers, but cannot furnish a supply for a whole ship’s company.

When the water of wells or brooks is found loaded with mud, the following expeditious method of filtration, described by Dr. Lind, has been practised with success:—Let a quantity of clean sand or gravel be put into a barrel placed on one end, without the head, so as to fill one half or more of it, and let another barrel, with both ends knocked out, of a much smaller size, (or let it be an open cylinder of any kind) be placed erect in the middle of it, and almost filled with sand or gravel. If the impure water be poured into the small barrel or cylinder, it will rise up through the sand of both barrels, and appear pure above the sand of the large one in the interval between it and the small one.

But when water is offensive in consequence of being long kept, the most effectual and expeditious method of sweetening it is by exposing it to the air in as divided a state as possible. Boiling will not expel the putrid effluvia contained in water; but such is the attraction of air for this offensive matter, that the water need only be thoroughly exposed to it to be rendered quite sweet. This is best done by a machine invented by Mr. Osbridge, a lieutenant of the navy. It consists of a hand pump, which is inserted in a scuttle made at the top of a cask, and by means of it the water, being raised a few feet, falls through several sheets of tin pierced like cullenders, and placed horizontally in a half cylinder of the same metal. The purpose of it is to reduce the water into numberless drops, which being exposed in this form to the open air, is deprived of its offensive quality. The same method will serve to separate the superfluous quick lime in the water. It is a machine very deservedly in common use, and the working of it is a moderate and salutary exercise to men in fair weather.

The following contrivance will be found to afford a sufficient supply of sweet water to particular messes, and may be considered as an artificial and more expeditious sort of dripping stone.—Let the narrow mouth of a large funnel be filled with a bit of sponge, over which let there be a layer of clean gravel or sand covered with a piece of flannel, and over the whole another layer of sand. Muddy or offensive water being poured upon this, runs or drops out clear; and care must be taken to change the sand, sponge, &c. frequently, as they will become loaded with the impurities of the water[81].