USE OF GYPSUM. IQl 



:' the carbonate of ammonia continues as long as a 

 trace of it exists. 



The beneficial influence of gypsum and of many- 

 other salts has been compared to that of aromatics, 

 which increase the activity of the human stomach 

 and intestines, and give a tone to the whole system. 

 But plants contain no nerves ; we know of no sub- 

 stance capable of exciting them to intoxication and 

 madness, or of lulling them to sleep and repose. 

 No substance can possibly cause their leaves to ap- 

 propriate a greater quantity of carbon from the 

 atmosphere, when the other constituents which the 

 seeds, roots, and leaves require for their growth are 

 wanting.* The favorable action of small quantities 

 of aromatics upon man, when mixed with his food, 

 is undeniable ; but aromatics are given to plants 

 without food to be digested, and still they flourish 

 with greater luxuriance. 



It is quite evident, therefore, that the common 

 view concerning the influence of certain salts upon 

 the growth of plants evinces only ignorance of its 

 cause. 



The action of gypsum or chloride of calcium really 

 consists in their giving a fixed condition to the 

 nitrogen — or ammonia which is brought into the 

 soil, and which is indispensable for the nutrition of 

 plants. 



In order to form a conception of the effect of 



* In 1831, 1 suggested to a well known and most successful culti- 

 vator (Mr. Haggerston), the application of a weak solution of chlorine 

 gas to the soil in which plants were growing. It appeared to act 

 merely as a stimulant, the plants flourished for a time with great lux- 

 uriance, and in some the foliage was remarkable. The leaves of a 

 Pelargonium (well known as the Washington Geranium) attained the 

 diameter of a foot, but the flowers were by no means equal to those 

 of similar plants cultivated in the usual manner; the plants soon 

 perished. Probably a supply of nutriment proportioned to the increased 

 demand was not supplied. 



The necessity for this supply is now well known, and Pelargoniums 

 are now grown with great luxuriance and perfection, both of leaves 

 and flowers, by the free use of " manure water," obtained by steeping 

 horsedung in rain-water. The soil, too, best adapted to the plants is 

 chiefly prepared from decayed vegetable matter, derived from decom- 

 posed leaves and plants, mixed with that from the sods of fields. 



9* 



