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ART. VII.-A description of a new Sand-Bath with Water-Bath and Distilling Apparatus attached, erected in the Yale Analytical Laboratory; by Prof. JOHN P. NORTON.

THIS Sand-Bath was constructed and brought into active employment during the last term in Yale College. Its operation, with that of all its connected parts, has proved so entirely satisfactory, that it has been thought worthy of a notice in this place. There is nothing particularly novel in any one feature, but the combination of conveniences is such as I have never seen equalled, even in the best European laboratories.

The idea of uniting with the advantages of the sand-bath, those of the water-bath and distilling apparatus, and of accomplishing the working of the whole by means of a single fire, is one that I had before entertained. I long hesitated to attempt its realization, because no model existed; my success in the experiment has however been so complete, that it seems a favor to the chemists of the country, to give such a description as shall enable those who have occasion to build, to adopt an arrangement which possesses the recommendations of efficiency, compactness, and economy of fuel, while at the same time it may be considered almost self-acting.

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The accompanying plans and elevations, in figures 1 to 3, will I ink with some short comments, sufficiently explain the construc

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tion and connection of the several parts. They are all drawn accurately to a scale, so that measurements may be taken. No. 1 is the ground plan. In this plan, a is the furnace. The position of this furnace may also be seen at a in the front elevation, fig. 2. The sand-bath as represented here and in fig. 3, is similar to one put up in the New York Free Academy by Prof. Wolcott Gibbs; from that one this and several others have been copied. The original however, and all of the other copies were simply sand baths. The lower windows slide up. weights being included in the corner pillars; the heat of the fire passes through the bed plate b b, fig. 2, heating the sand which lies upon its upper surface All noxious fumes are conveyed away by the ventilator e, fig. 2, which opens into a chimney flue and may be closed or opened at pleasure by the chain d. It is then to this sand bath by Prof. Gibbs, that I have made the additions now to be described.

The furnace a, is an iron pot, lined inside with fire brick as usual, except e e, fig. 1, where is inserted a water-back of large size. This communicates by the pipe f, with the water bath g. There are two of these pipes, one above, and one below, as shown at ƒƒ, in fig 2, through the open door. The front elevation of the water bath, which is of copper in all its parts, is shown at g, in fig. 2. Each of the doors seen on the front, opeus into a separate compartment. The depth of these compartments is shown by the sections hhh, in fig. 1. At i, fig. 2, is a larger compartment, for receiving articles of considerable size.

Atj is a glass tube to show the height of water in the water bath, and at k, a cock placed so low that all of the water contained may be drawn off, thus removing any small quantity of sediment which occasionally accumulates. These two parts are seen more clearly at j and k, in fig. 3.

The furnace is fed through a door at l A moderate fire is sufficient to establish a brisk circulation through the pipes ff, and causes the water to boil violently in the water bath, keeping it always fully up to 212° F. The steam formed escapes through the pipe m, fig. 1, also shown at m m, figs. 2 aud 3. ` At n, figs. 2 and 3, is a coupling connecting the copper pipe m, with a block tin pipe o, figs. 2 and 3, and worm p, fig. 1. This worm is cou tained in the condenser q, figs. 2 and 3. The distilled water thus produced, escapes at r, figs. 2 and 3, and runs into the receiver The condenser stands on a shelf over a sink beneath. 8, t, figs. 1, 2, and 3, at the farther end of which is a force pump u, figs. 1 and 3. A pipe v, figs 1 and 3, runs from the top of this pump into the condenser. The pump delivers cold water into the sink in the common way, but by closing the cock at w, fig. 3, will throw its stream into the condenser. This water when warm is drawn off at the cock x, figs. 1, 2, and 3. The pipe

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from this cock seen at y, fig. 1, rises to within an inch or two of the top of the condenser, so that the warm water is drawn off first. By this arrangement the very great convenience is obtained of a constant supply of hot water, delivered into the sink for washing.

As the well water at New Haven contains a considerable amount of solid matter, which soon encrusts the interior of vessels in which it is steadily boiled, rain water only is used in the waterbath. The supply is kept up through the pipe z, as shown in figs. 1, 2 and 3, running under the floor. Its whole course may be traced by these three figures. It rises into the box A, figs. 1, and 3, in which the water stands on a level with the upper part of the glass guage tube, show at j in fig. 3. Upon the surface floats a large hollow copper ball, B, fig. 1. As soon as the formation of steam and its consequent passing off into the condenser commences in the water bath, the surface of course lowers, and a corresponding lowering occurs in the box A. The copper ball, B, sinks with the water, and gradually opens a valve at C, fig. 1. This admits a stream of water from an elevated cistern, which flows in just fast enough to supply that which passes off from the water bath as steam.

This arrangement is only novel in its present application, being I believe quite common in some of our cities for regulating the flow of water into cisterns. It works admirably in the present case, and seldom if ever requires any attention. If the fire is very hot, so much steam is occasionally generated, that it is not condensed with sufficient rapidity; a partial flow of hot water back into the box A, has several times occurred under these circumstances, but has never been sufficient to overflow. This difficulty might be avoided by enlarging the conducting pipe m, and the worm p, or by reducing the size of the water-back e, e, fig. 1. The space D, fig. 1, is a large dry hot oven, where quite a high heat is obtained. This is also shown at D, the door being taken. off. In this oven a shelf is placed, perforated with holes for the insertion of funnels, tubes, &c. It is in constant use for drying, and is found to be of very great service in all cases where rapid drying is desirable, and a precise temperature is not required. The small door at E, fig. 2, is another means of access to this

oven.

The water-bath is set in the brick work, but may be taken out and reset without disturbing the rest of the apparatus, in fact every part is accessible. The couplings to the pipes ff, may be reached through the door F; those to the supply pipe z, at G, fig. 3, those to the escape pipe, m, by taking out a brick at H, fig. 3. In order to obtain ready access to the interior of the furnace pot a, there is a large moveable circular plate immediately above; its circumference is shown by the dotted line at I, I, in fig. 1.

The supply of water from the cistern to the box A, is cut off by a stop-cock at the cistern, and the water may be entirely drawn off from the box, by a small cock at J, under the floor.

It will be perceived that this arrangement is compact and simple. There is no part liable to get out of order, or that once out of order, cannot be easily reached for the purpose of repairs.

By means of one fire, and that not large, we heat the sand-bath sufficiently, maintain a large water bath constantly at 212° F., make from ten to fifteen gallons of perfectly pure water per day, heat a large drying oven, and keep a constant supply of hot water over the sink for washing. Everything takes care of itself excepting the fire, and the occasional pumping of cold water into the condenser. I am unable, after two months of experience, to suggest any important improvement in these arrangements, and feel confident that any one who should put up a similar apparatus would not be disappointed.

Prof. Porter of Brown University is partially copying after this model for his new laboratory in that institution.

I must here express my obligations to Mr. Culver, of the firm of Culver & Cory, New York. His practical skill enabled me to overcome several difficulties which at first appeared quite formidable. Nearly all of the iron and copper work was done in the shop of Messrs. Culver & Cory, and in so substantial and satisfactory a manner, that I can safely recommend them to all who may contemplate putting up anything of the kind I have described. Having the patterns and the experience, they can work cheaper and better than those who have never done any such business. The iron work is all japanned. The glass should be set with a putty made of boiled linseed oil, as that will harden under the heat to which it is exposed; the common putty made with fish oil remains soft, and the glass is constantly liable to get out of place.

ART. VIII-On Microscopes and Microscopy.

PROF. J. D. DANA-Dear Sir:-I much regret not being able to communicate to you, before now, some facts on microscopes in answer to the inquiries made. But many circumstances have prevented me, and although this may come at rather a late hour, yet I trust it will prove acceptable since the facts relate to a subject possessing at this time more than ordinary interest.

You are aware that lately I have been somewhat in "the microscopic way," and I think that you will learn most from me, by allowing me to go over that portion of the ground that bears on my personal experience.

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