coal is dear this will probably be found a valuable improvement; but with some descriptions of coal it is impracticable, and in all cases the labour will be considerably increased.

eighteen inches' diameter, and widening gradually upwards (in the shape of an inverted cone, with the apex cut off) to about one half or one third of the whole depth, and then the remainder carried up perfectly cylindrical to the top, the diameter of the cylinder being about one third of the whole depth."

"In fixing on a place to build such a kiln, the side of a hill, near the rock to be burnt into lime, is always preferred: the workmen begin by excavating a large hole in the place where it is to be erected, of sufficient dimensions to bury the back part of it in the ground. In building up the kiln, there are two walls carried up; the space betwixt them is filled with small rubble, to keep in the heat, and next to the inner wall the kiln has a lining, about a foot or half a yard in width, of a slaty gritstone that will stand heat well: when the lining wants repairs or renewing, the wall behind it keeps the rest of the materials from falling in. A kiln, built according to the plan hereunto annexed, would cost about 251."-Cond.

ART. VII. On Melon Compost, and on the Influence of Soil on the Flowers of Hydrangea hortensis. By W. R. Y.

I HAVE always used the compost to which the Dutch so strictly adhere; viz. one third strong hazel loam, one third scouring of ditches, and one third rotten dung, exposing the mixture two years to the influence of the summer and winter, to evaporate what noxious qualities may lurk in the earths; for it is well known, that in proportion to the degree of salt of iron, it will be proportionably sterile. I had often observed the leaves of my melons turn yellow; occasionally plants died for which I could not account: I suspected iron, as it pervades our district, to be the cause; but as the magnet would not take up any of the compost, my attention was diverted from that point. Similar results, in future seasons, again called my attention to it, and I added lime to correct the sulphate of iron, if any; but I lost my whole crop, I fancied, by the application of the lime. As during winter a red oxide filtered from the compost heap, I again felt certain of the presence of iron. I submitted the compost to the test of burning, and having by that means got rid of the superabundant carbon, the magnet immediately detected the iron. I changed my soil, and have never since lost any melon plants. The experiment proves, that the old test of the loadstone may

be defeated by the presence of other inherent matter; for though it was inactive over the cold soil, it acted in full force upon the soil, when, by roasting, it had discharged its gas.

Hydrangea hortensis. While a profitable experiment resulted on the one hand, a great amusement occurred on the other, with some green-house plants. I mixed the compost fresh from the ditch, with water, and found a precipitation of iron: I used the soil and water to a hydrangea, a cutting from the common pink variety, and it so altered the colour to purple, as to form a new plant. I applied the same to the Cánna índica, and some other scarlet and blue plants, but obtained no apparent change of colour. I have always considered the brilliancy of colour to depend upon the air-bubbles under the epidermis of the petals, and was much surprised at not having effected a change in the Canna, though the colour will change under strong rays of solar light. Pink and purple flowers may be more sensible of the influence of the gas, being secondary colours, than the red and blue, which are primary.

This district is upon freestone; the adjoining is limestone : upon the line of junction are the wild flowers indigenous to both soils, and it is wonderful to see the brilliancy of the colour of them upon the latter, in comparison of the former.

I do not know whether or not the above experiments are new to you or your readers; if new, they may afford security to operative melon growers, and amusement to florists. The subject is very interesting to myself and some other botanical friends here. I am no chemist, but if your correspondents cau elicit any information from that science, I think they will add much to your valuable work.

Sheffield, May, 1826.

W. R. Y.

There is a fine opening in horticulture for any chemist of leisure, and practical acquaintance with the various operations of garden culture and management, to exert and distinguish himself. The good and the evil of pulverising soils, and exposing them to the atmosphere, and to different descriptions of weather, remains to be determined, no less than to be explained. It may excite surprise in some gardeners to be told that ridging of garden soil, in order to expose it more completely to the influence of either frost or sun, is frequently more injurious than useful; but we believe the assertion is consistent with facts, and with the experience of accurate observers. If bad qualities are exhaled, or oxidised by the aeration of soils, may not good qualities also escape or undergo

a change for the worse? Compression is, for certain soils, more valuable than expansion, and the effect may sometimes depend on mechanical, and sometimes on chemical, or other reasons. If Mr. Grisenthwaite, of Wells, has paid as much attention to horticulture as he seems to have done to agriculture, he is capable of throwing much light on this department of our art; and should he by any means see this, we invite him to become a correspondent. Even the speculations of such a man will be most interesting to many readers, and may prove truly valuable in the end, by leading practical men to study chemistry, to institute scientific experiments, and to acquire habits of accurate observation. One must have some favourite theory or hypothesis to establish or support as a motive to begin with, otherwise experiment would not be pursued with sufficient enthusiasm. Whatever becomes of the hypothesis, the facts remain, and are so much in addition to the previous stock of knowledge. - Cond.

ART. VIII. On the Culture of the Mushroom in Hot-house Sheds. By Mr. THOMAS FORREST, C.M.H.S. Gardener 'to W. L. Hughes, Esq. M. P., at Kinmel Park, near Abergeley, Denbighshire.

BEHIND the hot-houses here I have sheds, and along the back wall I grow the mushroom with very great success. All practical gardeners are well aware of the rapid decay of wooden shelves used for that purpose, owing to the very great steam that arises from the dung of a mushroom bed. I therefore build along the back wall of the shed, 'a thin wall of brick, four feet distant from it, which will make a bed four feet wide, and about eighteen inches or two feet high in front, and will afford plenty of mushrooms. [Cast-iron shelves are found to answer extremely well; one at the Earl of Grosvenor's, Eaton Hall, has given every satisfaction.] My mode of filling the brick beds is as follows: I lay on the bottom six inches of faggots, or any old wood that may be of little use, in case the dung be wet (for we are not able at all times to have things as they ought to be), to drain off any improper moisture that might be in the dung; I then fill the bed, within three inches of the top, with old linings of hot-beds, not too much exhausted; beating it down, at the same time, as firm as possible. I then take and lay on the top four or five inches of good horse-droppings, beating it well down also. The bed

may be then spawned, which obviates all that fear about the bed getting overheated which is so common among gardeners. A bed of this kind will keep a good moderate heat thrice the length of time another will, made wholly of new dung: consequently it will bear three times as long. Besides there are other advantages arising from this mode; you can make three beds for one, and with the same quantity of new dung. There are many small families, who have only two or three horses, which makes it difficult to have mushrooms, all owing to the mistaken notion, that the bed must be wholly composed of new droppings; because, by the time a sufficient quantity of these droppings are collected, one half of them has become useless. I am, Sir, &c.

Kinmel Park, February 8. 1826.

THOMAS FORREST.

ART. IX. Description of a Mode of growing Mushrooms on the Floor of a Green-house, as practised in the Neighbourhood of Vienna. By Mon. NAPOLEON BAUMAN, Junior, of Bollwiller, on the Upper Rhine.

Dear Sir,

DURING a stay of eleven months at Vienna, in 1825 and 1826, I had an

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