56 



FARMERS' REGISTER- 



[No. 1 



imal and vegetable Jife, or to produce those phe- 

 nomena of composition and decomposition, Avhicli 

 are constantly renewing the surlace of the globe. 

 The specific gravity of pure azote is to that of 

 the atmosphere in the proportion of 0,691 to 

 10,000. 



2. Oxygen gas forms about one-fifth of the at- 

 mosphere. The specific gravity of oxygen is to 

 that of the atmosphere, as 11,036 to 10,000. The 

 effects produced by oxygen are equally numerous 

 and important; it supports animal life by respira- 

 tion; and combining with the carbon of the blood, 

 it produces the greatest proportion of animal heat. 

 Tlic germination of s'eds is ])romoted by this gas, 

 and it is absorbed by the leaves of plants during 

 the night: by its combination with the metals the 

 oxides of them are formed. It is likewise the neces- 

 sary agent of combustion, and concurs powerfully 

 in the decomposition of all animal, vegetable, and 

 mineral substances. 



In all cases where oxygen exerts its action, 

 it combines with some one of the elements upon 

 which it afits, fbiming acids with carbon, azote, 

 sulphur, phosphorus, and many of the metals; 

 water with hydrogen, &c. The nature of the 

 compositions, of which oxygen is an element, va- 

 ries according to the proportions in which it enters 

 into combination. 



When we survey the extent and importance of 

 the operations performed by this gas, and espe- 

 cially when we consider that it is constantly form- 

 ing new bodies, with which it afterwards ceases to 

 have any connexion, we are almost led to fear, 

 that the atmosphere must be, sooner or later ex- 

 hausted of this active and regenerating principle; 

 but nature, we find, is continually repairing the 

 loss thus sustained, by the production of equiva- 

 lent quantities. The leaves of plants, under the 

 influence of the solar rays, pour ibrth into the at- 

 mosphere torrents of oxygen, produced by (he de- 

 composition of carbonic acid and of water; of 

 which they appropriate to themselves the carbon 

 and the hydrogen. 



It is without doubt possible, that in many situ- 

 ations the reproduction of oxygen is not in pro- 

 portion to its consumption. Tfiis must happen 

 especially where great quantities are required for 

 respiration, or to support combustion. But this de- 

 ficiency is only partial and momentary; for the 

 great mobility of the atmospheric fluid enables it, 

 almost immediately, to restore its equilibiium from 

 all points. The agitation of the wind mixes to- 

 gether, in proportions nearly constant, both the el- 

 ements of which the atmosphere is composed, 

 and the principal fluids which are found in it. 



The creation or dcsiruction of any element is 

 not to be found in the operations of nature. The 

 numerous phenomena of composition and decom- 

 position, which take place upon the surface of the 

 globe, present only changes ef combinations, 

 which arc formed according to fixed, eternal, and 

 unchangeable laws. Thus nature is regenerated, 

 without being impoverished; and matter experi- 

 ences only those changes which are reproduced 

 uniformly and periodically, especially in organic 

 bodies. 



3. Carbonic acid is found constanfly, but in va- 

 rious proportions, in the atmosphere. Though 

 much heavier than azote or oxygen, its weight 

 being to that of the latter, as 1,520 to 1,000, it is 

 found disseminated throughout the whole atmos- 



pheric region. The elder M. de Saussure has, by 

 means of lime-water, drawn it from the air upon 

 the summit of Mont Blanc. From the results of 

 all the experiments that have been made, there 

 can be no doubt, that the proportions of azote and 

 oxygen in the composition of the atmosphere are 

 uniform and nearly invariable; and it appears to 

 be likewise proved, that carbonic acid is also 

 found there, and at all heights, but in various pro- 

 portions. 



M. Th. de Saussure has compared tlie differ- 

 ent portions of carbonic acid in the atmosphere 

 which he has analyzed, and found the diflierence 

 between them, in summer and in winter, to be as 

 follows. 



In winter. 



31st of January, 1809, 10,000 parts of air 



contained - - carbonic acid 4,570 



2d of February, 1811 - " " 4,660 



7th of January, 1812 - " " 5,140 



The mean term in winter from 10,000 parts of air 



was, 



In volume - 4,790 



In weight - 7,280 



In summer. 



20tli of August 1810 10,000 parts of 



air contained - - carbonic acid 7,790 



27th of July, 1811 - " " 6,470 



15th of July, 1815 - " " 7,130 



The mean term in summer from 10,000 parts of 



air was. 



In volume - 7,130 



In weight - 10,830 



Without doubt, when the air is tranquil, or 

 when the carbonic acid, which is produced so 

 abundantly by fermentation, respiration, combus- 

 tion, &c., is retained in confined places, the quan- 

 tity of this acid will exceed the ordinary propor- 

 tion; but from the moment that the agitation of 

 the winds can mingle it with the atmosphere, 

 it is spread and diflused towards all points, accord- 

 ing to certain fixed laws. Unless in some extra- 

 ordinary cases, which form exceptions to the gen- 

 eral rule, carbonic acid exists in the atmosphere at 

 most only in the proportion of ^ij^. 



Carbonic acid is constantly absorbed and de- 

 composed by the leaves of plants. The carbon 

 is appropriated by the i>lants to their own support, 

 and the oxygen is thrown out into the atmosphere. 

 Carbonic acid combines Avith the lime in fresh 

 mortar, and causes it to return to its original state 

 of lime-stone. Under the pressure of the at- 

 mosijhere, water will hold in solution nearly its 

 own volume of carbonic acid, and be slightly 

 acidulaleii by it; but under the force of a greater 

 pressure, it will contain a much greater quantity. 

 Water, thus charged, froths like Champagne 

 wine, which owes its effervescence to the carbon- 

 ic acid produced by the fermentation of the wine 

 in wcll-corkcd bottles. In some recent experi- 

 ments carbonic acid gas has been reduced by com- 

 pression to a liquid state. 



4. Water exists in the atmosphere, under the 

 form of an elastic fluid. When it is absorbed by 

 bodies for which it has a strong aflinity, such as 

 the calcined muriate of lime, the portion of air 

 from which it is taken, is diminished in weight 



