1836] 



FARMERS' REGISTER. 



135 



Yet it cannot be doubted, that the practical 

 farmer may derive important benefit ii-om acquir- 

 ing so much of this lanijuage, as will enable him 

 to understand the chemical explanation of the nu- 

 n)erous changes which are continually taking 

 place in the natural actions which it is his high 

 privilege to call into his service, to direct in part, 

 and modify in degree. So also are there certain 

 chemical elements and compounds, with the pro- 

 perties of which he ought to be acquainted if he 

 wish to be able to direct his practical skill with 

 more etTect, even in circumstances tamiliar to him, 

 hut which may be absolutely necessary, or will at 

 any rate save waste of labor and loss of time, 

 when the knowledge acquired by practice, in one 

 place, is to be employed in a new situation, and 

 under a change of" circumstances. 



It is -he object of this introduction to exhibit, 

 in such form as may be intelligible to those who 

 have not made general chemistry an object of stu- 

 dy, a concise view of such of the laws and facts 

 of that science, as are absolutely necessary for the 

 agriculturist who may wish to improve his prac- 

 tice, and which are more |)articularly required by 

 those who wish to avail themselves of the know- 

 ledge contained in the subjoined essay. To do 

 this has been found no easy task. It would be in 

 itself difficult, but to the author of this introduc- 

 tion has been more particularly so, as he has for 

 years been in the habit of imparting instruction to 

 those whose habits of life ami thoughts are as re- 

 mote as posssible fiom those of the practical 

 fiirmer; persons to whom the particular language 

 of chemistry is an aid, instead of" an impediment; 

 and who, with ample time at their command, have 

 an opportunity of pursuing the study of the sci- 

 ence, step by step. Fully aware of these difficul- 

 ties, both general and peculiar, this attempt would 

 not have been made, and certainly not persisted in, 

 had it not have been for the instances of an intel- 

 ligent, scientific, and successful farmer, who has 

 urged the completion of the task as an object 

 likely to be beneficial to those, who, with perhaps 

 equal zeal and native powers of mind, have not 

 enjoyed, like himself, the advantages of a scien- 

 ific education. 



The atmosphere which surrounds our earth is 

 the first object to which our attention should be 

 directed. This is the vehicle of the moisture, 

 which, whether it fall in the form of rain or dew, 

 run in streams, or issue from springs, is abso- 

 lutely essential to the success of the farmer's la- 

 bor. It is also, as we shall presently see, impor- 

 tant to him on other accounts. 



The greater part of the atmosphere is made up 

 of a mixture of substances, each of which has the 

 same mechanical properties as the whole mass. 

 These air-like substances are known to chemists 

 by the name of gases. 



Of these gases, two make up by fiir the greater 

 portion of atmospheric air, and exist in it in the pro- 

 portion of about four to one. That which is the 

 largest in quantity,and makes up nearly four-filths 

 of the whole atmosphere, is called in the Essay of 

 M. Puvis, by the name of Azot, but is more 

 usually known in English by the name of nitro- 

 gen. 



This substance, although in the largest propor- 

 tion, is the least important of the gases in its chem- 

 ical eflfects. It does not aid in supporting the life 

 of animals, nor in maintaining the burning (com- 

 hustion) of inflammable bodies. 



The part of the atmosphere which is absolute- 

 ly necessary for these purposes, is called by the 

 name of oxygen, and nearly makes up the remain- 

 ing filth part of the atmospheric air. In its sup- 

 l)ort of lif(3, it Jilways, and in maintaining combus- 

 tion often, unites with a chemical element, which 

 is called carbon. This is familiarly known aa 

 forming the principal part of charcoal. In its 

 union with carbon, oxygen forms a peculiar gas 

 known by the name of carbonic acid. 



Carbonic acid is always found in small quan- 

 tities in the atmosphere, to which it is furnished by 

 the breath of animals and the fijmes of burnrno' 

 bodies. It is, when in con,«iiderable quantities, 

 fiUal to the life of animals, but is prevented from 

 accumulating to an injurious extent, in conse- 

 quence of its being taken up by water; it is there- 

 fore dissolved, in proportions about equal to those 

 in which it is formed, by rivers^ lakes, the ocean, 

 and the moisture of the soil. 



Water exists in the atmosphere in the form of 

 vapor. The great source of this vapor is the ex- 

 tended surface of the ocean; and it is governed 

 by a mechanical law, by which it is continually 

 tending to distribute itself uniformly over the 

 whole surface of the earth. It may thus exist in 

 as large quantities over the surface of the dryest 

 land as over that of the ocean itself". This ten- 

 dency to equal distribution is continually counter- 

 acted by the changes in the sensible heat (temper- 

 ature) of the atmosphere, and of the surfiice of 

 the earth, which follow the alternations of day and 

 night, and the vicissitudes of the seasons. By these 

 alternations and changes, the vapor is caused to 

 fall (precipitated) in the form of rain, snow, hail, 

 dew, or white frost, according to circumstances. 

 As such changes of temperature are more fre- 

 quent on the land than on the ocean, the Avater 

 which falls on the former, in either of these forms, 

 is greater in quantity than that which falls on equal 

 surfiices of the latter. Thus, by a wise and be- 

 nevolent provision of Providence, the water of 

 the ocean is continually furnishing vapor, which 

 is precipitated on the land for the support of vege- 

 taiion and the supply of springs, and whose ex- 

 cess is poured back into the ocean in streams and 

 rivers. 



Water has been found by chemists to be a com- 

 pound substance, made up of two elements. One 

 of these, which forms eight-ninths of its weight, 

 is the gas already mentioned under the name of 

 oxygen; the other, a pecuUar gas, known by the 

 name of hydrogen. 



Hydrogen, when free, is the lightest of all 

 known bodies, rising and floating in atmospheric 

 air; it not only combines with oxygen, to form 

 water; but with carbon to form a great variety of 

 compounds — gaseous, liquid, viscid, and solid. It 

 also combines with nitrogen, and forms a gas 

 known by the name of ammonia, which is well 

 known by the peculiar smell it gives to spirits of 

 hartshorn (liquid ammonia.) 



Hydrogen also combines with sulphur, forming 

 a gas known by the name of sulphuretted hydro- 

 gen; this exists in the atmosphere, but in such 

 small quantities as only to be detected by the 

 nicest chemical tests. It combines in like manner 

 with phosphorus, forming phosphoretted hydro- 

 gen gas, whose presence in the air is occasionally 

 perceptible. 



Oxygen, as we have seen, unitea with carbon 



