PLANT CASE FOR GROWING PLANTS. 



C83 



thpy have Livg'e ojien spaces at the bottom and 

 through their centres, they permit the moisture 

 to percolate freely through tlie whole of the soil. 

 'J'he bottom being pro]ierly fitted, is fixed to 

 the sides by brass screws, and other brass bands 

 at the corners and bottom are fixed on with 

 brass nails, no iron being used in any part. 

 Along tlie upper edge of the box a groove is sunk 

 to receive the lower edge of the glass roof, which 

 rests securely in it. This groove is lined with 

 lead, its inner lip is one-sixteenth of an inch 

 lower than the outer, and at each end is a notch 

 one-eighth of an inch only above the bottom of 

 the groove, to allow the condensed moisture 

 which trickles down the inside ot the glass to 

 flow back to the soil. Instead of lead, the lining 

 of this groove should be of brass, which would 

 prevent the galvanic action which arises from 

 the contact of the two different metals. The 

 glass cover which fits on to this box is framed 

 of brass, into which common or plate glass is 

 accurately fitted. It is furnislied with a door 

 on one side, also fitted close, but admitting of 

 being easily opened when required. Along the 

 top of the roof inside, two brass rods extend, 

 from which small pots containing plants may be 

 suspended. The whole of the frame work is 

 well fitted and nicely put together, so as to pre- 

 clude, as far as could well be done, all interchange 

 1)etween the air in the case and that in the room. 

 The conservatory being thus prepared, its bottom 

 was covered with broken potsherds to the depth 

 of two inches, over which was spread an inch of 

 very turfy loam. The remaining space in the 

 box was filled with soil, composed of equal 

 parts of peat and loam, with which a portion of 

 rough white sand, amounting to about one-twen- 

 tieth part, and free from iron, was mixed. After 

 being planted, between three and four gallons 

 of water were freely showered over the tops of the 

 plants from a fine rosed watering pot. Tliis was 

 continued till the water ran freely from two holes 

 made in the bottom of the box for that purpose. 

 After draiuing for twenty-four hours, the holes 

 were tightly fitted with corks, and the glass roof 

 or cover was then put on. The plants were 

 chiefly exotics, from various regions of the globe, 

 among which were the dwarf palm, aloe, 

 rhododendron, cycas, pitcher plant, gentian, 

 primrose, lycopodinm stoliniferum, saraceniie, 

 &c. The case witli its plants was then placed 

 at the window allotted for it, which had a 

 southern aspect, with the morning sun for seve- 

 ral hours daily. During the sunny part of the 

 day, the temperature within the case was several 

 degrees higher than that in the room, while in 

 the absence of sunshine, or when a fire was kept 

 up, the temperature of the room was highest. 

 At other times, when neither sun nor fire pre- 

 vailed, the temperature within and without the 

 case rose and fell simultaneously. At no period 



of the winter did the temperature of the room 

 fall to the freezing point, nor, it is believed, rise 

 in summer higher than to about 80°. No fresh 

 water was given during the whole period of trial 

 (twelve months,) nor was the door of the case 

 opened, but to remove a dead leaf or plant that 

 had damped off. Once only was the case taken 

 ofi^, in order to check the lycopodium stolinife- 

 rum, which had grown so luxuriantly as to shade 

 and injure the other phmts. At the end of the 

 year, all the plants were, with a very few ex- 

 ceptions, in full vigour. The primroses had 

 flowered, and the other plants had increased 

 more or less in size. The trojiical plants were 

 as healthy and luxuriant as the others, though 

 the mean temperature was comparatively low. 

 From this interesting experiment, it appears 

 that a confined atmosphere, by retaining the 

 moisture of the soil and preventing evaporation, 

 and consequent dissipation of moisture, precludes 

 the necessity of a periodical supply of water. 

 That from the still and undisturbed state of the 

 air, and from the limited extent of the evapora- 

 tion, less heat is necessary even for tropical 

 plants, and that by the two vegetative functions 

 somewhat analogous to respiration and digestion, 

 an equilibrium of oxj'gen and carbonic acid gas 

 is preserved in the atmosphere surrounding the 

 growing plants. This circumstance will be better 

 understood by a reference to the experiments of 

 De Saussure, which were communicated to the 

 public in 1707. This distinguished chemist 

 found that when garden peas, which had attained 

 to the height of between three inches and four 

 inches, were placed in a recipient of atmospheric 

 air, inverted in a saucer filled with water, and 

 tlien set aside in a room well lighted, but which 

 did not receive the direct raj'S of the sun, they 

 grew well. At the end of ten days, the volume 

 of air was considerably diminished, its purity 

 greatly impaired, and it still retained -jj^ of car- 

 bonic acid. Plants of montha aquatica effected 

 similar changes in the air, whilst they continued 

 to grow in the shade : whence it is inferred that 

 plants, like animals, continually deteriorate the 

 air, by converting its oxygen into carbonic acid 

 gas, wdien tliey vegetate in the sh.ade ; a result 

 confirmed by many experiments made by Mr 

 Ellis, and given to the juihlic in the yeare 1807 

 and 1811. 



In ])rosccuting his experiments on vegetation 

 under the direct influence of light, M. De Saus- 

 sure was led, with others, to the conclusion, that, 

 if the air which may have been deteriorated by 

 the growth of plants in the shade be exposed foi 

 a short time to the sim's rays, it recovers its 

 former purity. In his Rechcrches CUmiqucs sur 

 la Vegetation, published in 1004, he has esta- 

 blished this position by numerous experiments 

 on various plants, as mentha aquatica, lythnim 

 snlicaria, pinus sylvestris, genevensis, and cactus 



