s>-„.. 
s 
I 
ON THE CULTIVATION OF VANDA. 
|1 
of iron dissolved in carbonic acid, or iron salts, meet with crenic or apocrenic acids, present in all culti- 
vated soils, ochrey deposits, the result of the union of these acids with oxide of iron, are always produced. 
Iron and Sulphur unite in several proportions with each other. One of these combinations, iron 
pyrites, a brass-coloured metallic substance, frequently crystallized in regular cubes, accompanies coal, 
many clay slates, and other rocks, and is consequently found occasionally in arable soils. Iron 
pyrites, heated strongly, gives off sulphurous fumes, arising from the combustion of part of the sulphur 
of the pyrites. The injurious, disagreeable, sulphurous smell some kinds of coal disengage in the 
grate, when lighted, results from the presence of iron pyrites in the coal. Small quantities of iron- 
pyrites in soils exercise no injurious effects on vegetation ; large quantities, on the contrary, may 
render a soil totally barren. In the presence of organic matter, water and air, iron pyrites is subject 
to a rapid decomposition ; in consequence of which a highly obnoxious gas, sulphuretted hydrogen, 
and a salt, sulphate of protoxide of iron, are formed ; both products, though unprejudicial in small 
quantities, act decidedly injurious on vegetation, when present in the soil in quantity. 
Sulphate of Iron, which in most cases is produced from iron-pyrites, is a compound of sulphuric 
acid, with protoxide of iron, and is more generally known under the name of green vitriol. Sul- 
phate of iron and the substance from which it is formed, iron pyrites, occur together in some soils. 
Such soils are always unproductive, and not unfrequeutly completely barren. Some time ago a 
striking example came under my notice, which is well calculated to serve as an illustration of the 
services which chemistry is capable of rendering to the gardener. A sample of a soil from Lancaster 
was sent to me for examination by a gentleman, who described to me the land from which it was 
taken, as of the very worst description, which absolutely refused to grow anything. Peas and other 
seeds rotted when sown in that part of the garden from which the sample was taken, and it was 
naturally suspected that some injurious substance was present in the soil. On examination I soon 
discovered the cause of barrenness, which, I have no doubt, must be ascribed in a great measure to 
a quantity of sulphate of iron, or green vitriol, amounting to no less than six per cent, of the whole 
weight of the soil. Iron pyrites was also present in large quantities, and thus a source for the 
formation of green vitriol was afforded. Many failures in medicine and horticulture can be traced 
to the mistaken causes of sickness and sterility. In this case, however, one of the chief causes of 
barrenness, no doubt, resulted from an unusual large proportion of sulphate of iron ; and no difficulty, 
therefore, remained of pointing out the remedy to prevent the noxious effects of this salt. Lime added 
to its solution combines with its sulphuric acid, forming gypsum, a fertilizing ingredient of farm-yard 
manure, and the oxide of iron of the green vitriol is left behind in an insoluble state. We possess, there- 
fore, in quicklime, chalk, limestones, and all sorts of marl, a ready means for sweetening such soils, 
which arc generally sour, and are able to remove in this manner the primary cause of infertility. 
ON the cultivation of vajstda. 
By Mr. T. Appleby, op the Pine-Apple Nursery, London. 
5|JO genus of orchids is more deserving of culture than the Vandas, whose noble evergreen foliage. 
ill line vigorous habit, handsome even when not in flower; and, above all, truly splendid and 
highly fragrant blossoms render them worthy of being in every collection. 
These tine plants, being all natives of the wanner parts of the East Indies, require the same 
treatment in regard to heat, moisture at the root, moisture in the atmosphere of the house, the 
material in which to grow them, and in their seasons of growth, flowering, and rest. This 
similarity of culture renders their treatment uniform and easy. There are. besides, several other 
genera of these singularly interesting plants, from similar climates, that flourish satisfactorily if 
subjected to the same treatment ; and they are now so numerous, that it is almost necessary to place 
them in a house devoted to them alone, which structure may very appropriately be named the Indian 
House, in contradistinction to another devoted to the culture of Orchidea?, from the more temperate 
climate of Southern America. In the countries from which the Vandas and similar genera 
brought, the heat at certain seasons is excessive, especially in the lower parts where these plants pre 
located. It is found necessary, in some degree, to imitate the natural climate in urtiticii;! ones 
provided for tropical plants; and on this point experience has proved that when these plants ore 
growing, a heat of K-V by day, and 70" by night, is the proper temperature for tlicin. The season 
to apply this high temperature, thus encouraging vigorous growth, should be when t!..- neat of our 
own country is at the highest ; for thru there is also the greatest amount of light, an element equally 
necessary for the well-being of the plants as boat. The season of growth, thru, should c| uuaci cp 
in May, and continue till September. 
