S8 WATER NECESSARY TO LIFE — ITS SOLVENT POWER. 



smell. It enters largely into the constitution of all living animals and 

 plants, and forms upwards of one half of the weight of all the newly 

 gathered vegetable substances we are in the habit of cultivating or col- 

 lecting for the use of man. [See page 30.] 



Not only does it enter thus largely into the constitution of all ani- 

 mals and plants, but in the existing economy of nature it« presence in 

 large (juantities is absolutely necessary to the persistence of animal and 

 vegetable life. In the midst of abundant springs and showers, plants 

 shoot forth with an amazing rapidity, while they wither, droop, and die, 

 when water is withheld. How much the manifestation of life is de- 

 pendent upon its presence, is beautifully illustrated by some of the hum- 

 bler tribes of plants. Certain mosses can be ke[ clong in the herbarium, 

 and yet will revive again when the dried specimens are immersed in 

 water. At Manilla a species of Lycopodium grows upon the rocks, 

 which, though kept for years in a dried state, revives and expands its 

 foliage when placed in ^^ater [the Spaniards call it Triste de Corazon, 

 Sorrow of the Heart. — BurneVs Wanderings, p. 72.] Thus life lingers 

 as it were, unwilling to depart and rejoicing to display itself again, when 

 the moisture returns.* 



There are, however, three s])eeial properties of water, which are in 

 a high degree interesting and important to the practical agriculturist, 

 and to which I beg to direct your particular attention. These are: 



1°. Its solvent power; 



2^. Its affinity for certain solid substances ; and, 



3°. The degree of affinity by which its own elements are held to- 

 gether. 



1°. When pure boiled water is exposed to the air, it gradually ab- 

 sorbs a quantity of the several gases of which the atmosphere is com- 

 posed, and acquires more or less of a sparkling appearance and an agree- 

 able taste. The air which it thus absorbs amounts to about -^\h. of its 

 own bulk, and is entirely expelled by boiling. When thus expelled, 

 this air, like that obtained from snow, is found on examination to contain 

 the oxygen, nitrogen, and carbonic acid in proportions very different from 

 those in wiiich they exist in the atmosphere. In the latter, oxygen is 

 present to tVie amount of only 21 per cent, by volume, while the air ab- 

 sorbed by water contains 30 to 32 per cent, of the same gas. In like 

 manner, the mean quantity of carbonic acid in the air does not exceed 

 roooo^^ parts (0-05 per cent.) of its bulk, while that expelled from water, 

 which has been long exposed to the air, varies from 11 to 60 ten thou- 

 sand parts (0-11 to 0-6f per cent.) 



• In some species of animals, life is in like manner suspended by the absence of water. 

 The inhabitants of some land and even marine shells may be dried and preserved for a long 

 time in a siiate of torpor, and afterwards revived by immersion in water. The Cerithium 

 Armatum has been brought from the Mauritius in a dry state, while snails are said to have 

 been revived after being dried for 15 years. The vibrio tritici (a species of worm), was re- 

 stored by Mr. Bauer, after an apparent death of nearly six years, by merely soaking it in 

 water. The Furadaria Anastobea, a small microscopic animal, may be made to undergo 

 apparent death and resuscitation many times, by alternate drying and moistening. Accord- 

 ing to Spallanzani, animalculi have been recovered by moisture, after a torpor of 27 years. 

 These facts tend to lessen our surprise at the alleged longevity of the seeds of plants. 



t Of these gases when unmixed, water absorbs very different quantities. Thus 100 vo- 

 lumes of water at 60° F., absorb3-55 of oxygoi, 153 ol'^ hydrogen, 147 of nitrogen, (/ienry,) 

 106 of carboiiic acid, or 7800 of ammonia. 



