ART. VII. On the Application of the Ammoniacal Liquor of Coal Gas to the Destruction of Insects and Vermin. By ROBERT MALLET, Esq.

Sir,

I HAVE much pleasure in complying with your request (Vol. VII. p. 558.), by furnishing such details concerning this particular use of ammoniacal liquor, as, I imagine, will be sufficient for every intelligent gardener. Ammonia is present in the ammoniacal liquor, partly pure or caustic; but, in a larger quantity, in the states of sulphate and carbonate of ammonia; and I find the following to be one of the best modes of finding exactly the entire quantity of pure ammonia contained in a given quantity of the liquor:

Place 300 or 400 grains of the liquor in a small retort; apply a gentle heat, and collect whatever pure ammonia is present over mercury, and observe its quantity. Dilute the fluid with an equal weight of distilled water; and carefully drop in either muriate of lime or of barytes, until it ceases to occasion any further precipitate. Then filter and wash the precipitate with pure water, add the washings to the clear liquor, and evaporate the whole to dryness in a previously weighed flask, applying the heat carefully, towards the end of the evaporation, lest the muriate of ammonia be sublimed. Let the flask and contents be again weighed; subtract the former from the latter weight; and the difference will be the weight of the muriate of ammonia produced by the sulphuric and carbonic acids, which formed the sulphate and carbonate of ammonia, quitting their base and uniting with that of the muriate of barytes or lime, and the muriatic acid of the latter uniting with the ammonia of the former salts. The weight of muriate of ammonia being known, the quantity of pure ammonia may be easily estimated, every 100 parts of the former containing 31.95 of the latter.

I give this at length, to enable any gardener, who is competent (and what gardener can pretend to understand his business who is not a tolerable chemist?), to repeat the process; which it will be well to do before using the liquor, as that obtained from different gas-works contains varying quantities of ammonia.

Those, however, who are unable to determine the quantity of ammonia for themselves, may rely safely enough on the result of my experiments; viz., 1 ft. of ammoniacal gas will be produced from 11023 grains of ammoniacal liquor, at a mean temperature and pressure of the atmosphere. There is no gardener, I should hope, at the present day, who cannot find the

cubical contents of a horticultural house; so that the quantity of liquor necessary to fill one fifth or any other portion of the contents of a house, at a mean temperature and pressure, is thus easily known. But all houses are not at a mean temperature; viz., 60° Fahr.: it may, therefore, be necessary to make a correction in the volume of gas for temperature. The following rule may, therefore, be used to estimate what would be the volume of any portion of gas, if brought to the temperature of 60° Fahr.:-Divide the whole quantity of gas by 480: the quotient will show the amount of its expansion or contraction for each degree of Fahrenheit's thermometer. Multiply this by the number of degrees which the gas exceeds or falls below 60°. If the temperature of the gas be above 60°, subtract the product from, or if below 60°, add it to, the absolute quantity of gas: and the remainder in the first case, or sum in the second, will be the answer.

As perfect accuracy in determining the quantity of gas is not necessary, there never can be need of any correction for pressure.

All this may possibly, to some, appear to have more of craft than utility in it: to which I say, first, if a thing is worth doing at all, it is worth doing rightly; and, next, if it serves no other purpose, it will be a good exercise of thought, &c., to young gardeners. Now, as to the mode of producing and applying the gas. Those who can, ought to have a vessel proper for the purpose, made of tin, a section of which is here represented. (fig. 126.)

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127

In this figure, a is a cylindrical vessel of tin, about 15 in. in diameter, and 6 in. deep; b is a channel, formed by an external concentric cylinder of tin, about 2 in. deep, and half an

inch from the internal one. when the lid (c) is put on, its edge goes down into the water, and forms an air-tight joint or valve. The gas passes off by the tube (d), likewise made of tin, which should have two bends at right angles (fig. 127.), in separate pieces, to permit its motion in all directions.

This is filled with water; and

Into this vessel the previously determined quantity of ammoniacal liquor is to be put; and about half a pound of quicklime, in small pieces, for every quart of liquor, is to be added. The cover is then put on, and the tube inserted into some convenient opening in the lower part of the house, taking care that no plants are very close to the aperture.

In this way, which I find a great improvement upon the plan of evaporating the fluid, the gas is abundantly disengaged; the slacking of the lime produces sufficient heat, without the application of fuel; and the ammonia is in a caustic

state.

Those who cannot procure this apparatus will probably not be able to get the liquor either; but should they get

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the liquor, a small still, or even a watering-pot, placed within the house in this position (fig.128.), may be substituted.

Ammoniacal liquor may be used with safety for washing dirty pines, and the wood and buds of vines; to kill the red spider early in their season of appearing. Plants in pots, when very dirty, may even be dipped into it, diluted with an equal quantity of water; and soon after dipped into, or syringed with, pure water, to wash it and the dead insects off. A single very filthy plant, with close hard leaves, such as a Pandanus, a Bonapártea, &c., may be covered with an inverted barrel, and the gas applied to it alone, the plant being previously and subsequently syringed.

In every kind of house, it is well to syringe gently before applying the gas, as the water absorbs some of the gas, and it thus acts more powerfully; but, in every case, the house should be syringed afterwards.

In very humid houses, rather more of the gas than one fifth of the volume should be applied; the quantity, however, will in general be best found by the observation of the intelligent

gardener. Diluted ammoniacal liquor, where it can be procured abundantly and at a reasonable rate, is a powerful and excellent manure; and, like salt, possesses the valuable property of clearing the ground from all insects and worms.

I am, Sir, yours, &c.

94. Capel Street, Dublin, Nov. 7. 1881.

ROBERT MALLET.

ART. VIII. Design for a Gardener's House, adapted for being connected with the West Wall of a Kitchen-Garden.

In pursuance of our plan of giving eight designs for gardeners' houses, especially calculated for the four sides and four corners of kitchen-garden walls, we present figs. 129. and 130.,

before we describe which, we shall introduce a few remarks, which have been sent us on the subject by our architectural friend who first suggested the idea of publishing them. "The gardeners' houses which I visited in Scotland are either lean-tos generally behind the hot-houses, and consequently exposed to the north winds, and precluded from all sunshine, except during a few weeks in summer; or they are detached houses, generally lodges to gates, or placed in conspicuous situations in the grounds as ornamental objects. Now, the first class I consider as discreditable in point of humanity, and the other equally so in point of architecture. Would any human being voluntarily submit to live on the ground, under a shed exposed to the north, and excluded from every ray of light or sun from the south? Surely, no master entitled to the appellation of humane would wish a servant to remain in such a dwelling, if the evils attendant on it were pointed out to him. I have been particularly requested not to mention

names where the gardeners live in sheds, and therefore I shall not do so; but I am not under the same restraint with respect to the ornamental lodges, and therefore I shall just refer to one, all show on the exterior, without either accommodation or convenient arrangement within, as a specimen of the discreditable in architecture; it is the gardener's house at Eglinton Castle, and I mention it the more readily, because I have no idea who was the architect." The design before us contains, on the ground floor, a kitchen, a; parlour, b; back kitchen, c; and office, d. The chamber floor contains three good bed-rooms, e; and a seed-room, f. There are two closets, g and h.

ART. IX. Design for a Gardener's House, serving, at the same time, as a Watchtower for the Fruit Walls of a Garden in the Neighbourhood of a large City. By T. A.

THE following design, by one of our most eminent London architects, was sent us for our Encyclopædia of Cottage, Farm, and Villa Architecture, as the gardener's house of an elegant suburban villa, the plan of which accompanied it. Both are such perfect models of their kind, and display so much in so little, and at such moderate cost, that we cannot resist the