376 Catalogue of Works on Gardening, fyc 



On the Growth of Plants in closely glazed Cases. By N. B. Ward, F.L.S. 

 8vo, pp. 95. London, ] 842. 



The simple yet comprehensive principle on which plants are grown in 

 closed cases does not, Mr. Ward observes, appear to be clearly understood, 

 and the object of the present work is to remove erroneous notions respecting 

 it. This self-imposed task is most beautifully and philosophically executed 

 under the following heads: — i. On the Natural Conditions of Plants, n. 

 On the Causes which interfere with the Natural Conditions of Plants in large 

 Towns, &c. in. On the Imitation of the Natural Conditions of Plants in 

 closely glazed Cases, iv. On the Conveyance of Plants and Seeds on Ship- 

 board, v. On the Application of the closed Plan in improving the Condition 

 of the Poor. vi. On the probable future Application of the preceding 

 Facts. 



Natural Conditions of Plants. — Plants are influenced by the atmosphere, 

 heat, light, moisture, varieties of soil, and periods of rest. The effect of an 

 impure, as compared with a pure atmosphere, is exemplified in the plants 

 which grow in large towns, or within the reach of manufactures evolving 

 noxious gases, as compared with those which grow in the open country. 

 Plants grow in different degrees of heat, from 32° to 170° or 180°, in which 

 last temperature certain Cacti alone are found to live. The intensity of light 

 to which plants are subjected varies from almost total darkness to a light 

 double that of our brightest summer's day. The state of atmospheric moisture 

 varies as much as those of atmospheric heat and light. All plants require 

 rest, and obtain it in some countries by the rigour of winter, and in others by 

 the scorching and arid heat of summer. 



Plants in large Toiuns suffer from deficiency of light, dryness of the atmo- 

 sphere, fuliginous matter with which the air of large towns is always more or 

 less loaded, and the evolution of noxious gases from manufactories. 



Of all these atmospheric causes tending to depress vegetation in large 

 towns, Mr. Ward is of opinion that the fuliginous matter is the most influ- 

 ential. Sulphurous acid gas generated in the combustion of coal, when added 

 to common air in the proportion of a J 0o or 1 ' part, has sensibly affected 

 the leaves of growing plants in 10 or 12 hours, and killed them in 48 hours 

 or less ; and hydrochloric or muriatic acid gas, in the proportion of ^ of a 

 cubic inch to 20,000 volumes of air, produced an injurious effect in a few 

 hours, and entirely destroyed the plant in two days. Such were the results 

 of experiments made by Drs. Turner and Christison, and quoted in an article 

 on Mr. Ward's plant-cases, by the late Daniel Ellis, Esq., in our Volume for 

 1839, p. 488. Mr. Ward has no doubt of the correctness of the experiments 

 quoted ; but he contends " that it yet remains to be proved that there exists 

 generally, in the atmosphere of London or other large cities, such a propor- 

 tion of these noxious gases as sensibly to affect vegetation." (p. 17.) In 

 proof of this, Mr. Ward refers to the hundreds of geraniums and other plants, 

 seen in the windows of shops and small houses in numerous parts of London, 

 " growing very well, and without any crisping or curling of their leaves, care 

 being taken in these instances to keep the plants perfectly clean, and free 

 from soot." Now, Mr. Ward's cases " can, and do, exclude the fuliginous 

 portion of the atmosphere," and hence the thriving of the plants grown in 

 them. These cases, however, cannot exclude gases mixed with the atmo- 

 sphere ; from which it may be concluded that the proportion in which delete- 

 rious gases exist in it is not such as to be injurious to vegetation, nothing 

 like so much so as the " acidulous emanations " which issue from the nume- 

 rous chimneys of the chemical factories in a certain part of Glasgow, and 

 which our correspondent in that city informs us " wither up the leaves in the 

 course of a few hours " (p. 150.), while the fuliginous particles, according to 

 the same correspondent, are not concerned in injuring vegetation. 



Mr. Ward next shows, by quotations from Turner's Elements of Chemistr//, 

 and from other works, that the constant tendency of the gases and vapours 



