of heating the bath, one or two of the least objectionable of which I shall describe.

1. A contrivance of some ingenuity consists in suffering the water for the supply of the bath to flow from a cistern above it, through a leaden pipe of about one inch diameter, which is conducted into the kitchen or other convenient place, where a large boiler for the supply of hot water is required; the bathpipe is immersed in this boiler, in which it makes many convolutions, and, again emerging, ascends to the bath. The operation is simply this :-the cold water passing through the convolutions of that part of the pipe which is immersed in the boiling water, receives there sufficient heat for the purpose required, and is delivered in that state by the ascending pipe into the bath, which is also supplied with cold water and waste pipes as usual. The pipe may be of lead, as far as the descending and ascending parts are concerned; but the portion forming the worm or convolutions immersed in the boiler, should be as thin as is consistent with security, in order that the water within it may receive heat without impediment; it may therefore be made of copper.

This plan is only plausible and economical where a large boiler is constantly kept at work in the lower part of the house; otherwise the trouble and expense of heating such a boiler, for the mere purpose of the bath, render it unavailable. The worm-pipe is also apt to become furred upon the outside by the deposition of the earthy impurities of the water in which it is immersed; it then becomes a bad conductor of heat, is cleansed with difficulty, and the plan is rendered ineffective, This system, however, has been adopted in some particular cases with satisfaction and success.

2. A much more simple, economical, and independent mode of heating a warm-bath by a fire placed at a distance from it is the following, which I shall describe in detail, as it is found to answer perfectly in private houses, as well as upon a more extended scale in large establishments. It is certainly open to some objections, but these are overbalanced by its preponderating advantages. A waggon-shaped boiler, holding about six gallons of water, is properly placed over a small fur

nace in any convenient and safe part of the house, the kitchen, scullery, servants'-hall, or wash-house may be used for the purpose. The bath itself, of the usual dimensions and construction, is placed where it is wanted, with a due supply of cold water from above: two pipes issue from within an inch of the bottom of the bath at its opposite extremities; one at the head of the bath about one inch, and the other at the foot an inch and one-eighth in diameter. These tubes descend to the boiler, the smaller one entering it at the bottom, and the larger one issuing from it as it were at the top.

Under these circumstan

ces, supposing the pipes and boiler every where perfectly tight, when the bath is filled the water will descend into and expel the air from the boiler, and completely fill it. Now, upon making a gentle fire under the boiler, an ascending current of warm water will necessarily pass upwards through the larger pipe issuing from its top, and cold water will descend by the pipe which enters at bottom; and in this way, by the establishment of currents, the mass of water in the bath will become heated to the desired point; or if above it, it may easily be attained by the admixture of cold water.

The annexed sectional wood-cut will, perhaps, ren der this description more in- L telligible. A is the bath. B

the level of the water in it.

L

C the descending pipe of cold water.

D

F

D the ascending

pipe of hot water. E the copper boiler with its fire

も

place. F G is the pipe admitting cold water into the bath by the opening H, when the stopcock I is open, and K closed; but when I is closed, and K open, the same pipe serves to empty the bath, the water flowing off through the general waste-pipe L, which also carries away the overflowings of the bath, through M.

The advantages of this form of bath are numerous. The shorter the pipes of communication from the bath to the boiler the better, but they may extend forty or fifty feet without any inconvenience beyond that of expense: so that there is no obstacle to the bath being near the bed-room while the boiler is on the basement story. There is but little time required for heating the bath, the water in which may, if requisite, be raised to 100° in about half an hour from the time of lighting the fire. The consumption of fuel is also trifling.

The following are the chief disadvantages attendant upon this plan, and the means of obviating them :

It is necessary, when the water has acquired its proper temperature, to draw the fire from the boiler, and not to use the bath immediately, as it will go on acquiring some heat from that of the boiler and its brickwork, so that we may become inconveniently hot in the bath. To obviate the necessity of raking the fire from under the boiler, a flue may be so constructed as to carry off the heat directly into the chimney; but this is uneconomical and not very convenient. When, therefore, I use this bath, I proceed as follows:-I heat the water in it, about an hour before it is to be used, to about 100°, and the fire below is then put out. The water will retain its temperature, or nearly so, for three or four hours, especially if the bath be shut up with a cover, so that when about to use it, I let in cold water till the temperature is lowered to the required point, and we thus avoid all the above inconveniences.

Another disadvantage of this bath arises from too fierce a fire having been made under the boiler, so as to occasion the water to boil within it, which ought always to be carefully avoided. In that case, the steam rising to the upper part of the boiler, and into the pipe D, condenses there, and occasions violent concussions, the noise of which often alarms the whole house, and leads to apprehensions of an explosion,

In

which, however, is very unlikely to occur; but the concussions thus produced injure the pipes, and may render them leaky: so that in regard to these, and all other baths, &c. we may remark, that the pipes should pass up and down in such parts of the house as will not be injured if some leaking takes place; and under the bath itself should be a sufficiently large leaden tray with a waste-pipe, to receive and carry off any accidental drippings, which might injure the ceilings of the rooms below. all newly-built houses, two or three flues should be left in proper places for the passage of ascending and descending water-pipes; and these flues should, in some way, receive at their lower part a little warm air in winter, to prevent the pipes freezing: the same attention should also be paid to the situation of the cisterns of water in houses, which should be kept within the house, and always supplied with a very ample waste-pipe, to prevent the danger of overflow. Cisterns thus properly placed, and carefully constructed, should be supplied from the water-mains by pipes kept underground till they enter the house, and not carried across the area, or immediately under the pavement, where they are liable to freeze.

3. Baths are sometimes heated by steam, which has several advantages: it may either be condensed directly into the water of the bath; or, if the bath be of copper or tinned iron, it may be conducted into a casing upon its outside, usually called a jacket; in the latter case there must be a proper vent for the condensed water, and for the escape of air and waste steam. Steam is also sometimes passed through a serpentine pipe, placed at the bottom of the bath; but none of these methods are to be recommended for adoption in private houses, and are only advisable in hospitals, or establishments where steamboilers are worked for other purposes than the mere heating of baths. A description of the different modes of employing steam as a means of heating masses of water for baths and other uses, would lead me into too wide a field of discussion for the present paper, which, therefore, I shall here conclude.

C.

70

A Manual of Chemistry, chiefly for the Use of Pupils of Mechanics' Institutions. By Andrew Fyfe, M.D., F.R.S.E., &c. Edinburgh, 1826.

THIS little book scarcely deserves the name which the author has conferred upon it, it is not a handful, but a mere pinch of chemistry; and though it may answer very well as a textbook for his course of lectures, cannot be commended as a work of reference, or as holding out any temptations to the general scientific reader. It is, moreover, disfigured by a set of villainous wood cuts, to which the doctor, however, seems passionately attached; for he repeats the same block several successive times, where mere reference to it would have been sufficient. Thus, at page 15, is a most clumsy representation of a furnace, with a tube passing through it, for the decomposition of vapours; and this ugly thing is reiterated at pages 109, 121, 129, 141, 165 (without the retort, but the same cut), and lastly, at page 197: and an equally unintelligible portrait of a retort and gas-receiver occurs at pages 5, 14, 17, 122, 151. This, in a little book of 300 pages, is too bad.

But Dr. Fyfe's information is not always correct, especially upon points of importance and interest to those whom his Manual immediately addresses. Hops, for instance, are described as the seed-pods of a plant much cultivated in England; and at page 244, we are told that the brewing porter is carried on in the same way as that of ale and beer, with this difference, that the malt is prepared in a peculiar way. "It has been already said, that that used for ale is dried by the application of a slight heat. In making malt for porter, a much higher temperature is applied, by which it is slightly burned, so that the wort got from it has a dark colour, and a peculiar bitter taste." We believe few porter-brewers would grow rich if they thus employed slightly-burned malt. But lastly, Dr. Fyfe says, that "gin, or Hollands, is always prepared by the Dutch :" this may possibly do for an Edinburgh audience, especially after the elaborate account of "whiskey" which precedes the above quotation; our London mechanics, however, know better; few of them, as we apprehend, being unacquainted with the merits of Hodges' full proof.

Upon the whole, however, though there are many marks of haste, and some of carelessness, visible in this compilation, we are ready to admit that it is not ill adapted for a text