Your most affectionate
and obliged humble Servant,
Wm. Borlase.
X. Experiments on applying the Rev. Dr. Hales's Method of distilling Salt-water to the Steam-Engine. By Keane Fitzgerald, Esq; F.R.S.
Read Feb. 17, 1757.
ON reading Dr. Hale's account of purifying salt-water, by blowing showers of air thro', it occurred to me, that something of the kind might be applied with advantage to the steam or fire-engine, by increasing the quantity of steam, and consequently diminishing the quantity of fuel otherwise necessary.
As the strength of steam raised from boiling water is always in a fluctuating state, and, by the best experiments hitherto made, has never been found above ⅒ stronger, or weaker, than air; I was in doubt, whether steam, produced by this method, would be sufficiently strong for the purpose of the steam-engine.
I made an experiment first on a small boiler, about 12 inches diameter, made in the shape of those commonly used in steam-engines, with a funnel at the top, of about 1 inch diameter, for the steam to pass thro'; the aperture of which was covered with a thin plate, fixt at one end with a hinge, and a small leaden weight to slide on the other, in the nature of a steel-yard, to mark the strength or quantity of the steam. A tin pipe made for this purpose, with several small holes towards the end, passed from a small pair of bellows, through the upper part of the boiler, to within about an inch of the bottom. The boiler was half filled with water, which covered the holes in the pipe about six inches. From the best observation I was capable of making with this machine, by blowing air thro' the boiling water, it produced about ⅙ more steam than was produced by the same fire without blowing air thro'.
I then applied a machine of this kind to the engine at the York-buildings water-works, the boiler of which is 15 feet diameter. This is a patent-boiler, a section and plan of which is annexed. It has a double concave, with a kind of door-way or passage from one to the other, in order to let the flame pass, as it were, thro' and round the water; by which means there is no-where above nine inches of water to be heated thro', tho' the boiler is so large; and which, by three years experience, has been found to require ¼ less fuel, than any other fire-engine of equal bigness.
Philos. Trans. Vol. L. Tab. I p. 54.
