THE SOUTHERN PLANTER. 



101 



the decayed vegetation quickly evaporates, and 

 that when it remains under it nourishes the crop 

 until it is matured. I also find the above to be 

 a labor-saving system. I have long been op- 

 posed to turning up the land to the winter's frost, 

 but I find, unless clovered land intended for corn' 

 is fallowed by the 15th of February, that it al- 

 most invariably suffers by the worm ; my clo- 

 vered land I, therefore, fallow in winter, if pos- 

 sible, and that for timothy and herdsgrass in the 

 spring. 



Respectfully, A Fluvannian. 



LIME. 



To our poor thinking, by far the most able, 

 the most profound, and the most practical dis- 

 sertation that we have ever seen upon the appli- 

 cation of lime to the soil, is to be found in the 

 " Third Part of Lectures on Agricultural Che- 

 mistry, by James F. W. Johnston, M. A. F. 

 R., &c. &c. &c." We will endeavor, by means 

 of comments and extracts, to present the general 

 views of the lecturer in an abridged and con- 

 densed form before our readers, assured, that it 

 will form at least an excellent text for the notes 

 and commentaries of such of our correspondents 

 as are versed in this interesting and important 

 subject. 



In the first place, Mr. Johnston calls the 

 hearer's attention to the five different states in 

 which, under the general name of lime, this 

 substance is applied to the soil, and these dis- 

 tinctions he seems particularly anxious to en- 

 force, because he conceives that a confusion of 

 them has lead to much of that contrariety of 

 opinion that exists upon the subject. The first 

 grand destruction is between mild and caustic 

 lime. Pure lime has a wonderful affinity for 

 carbonic acid, with which it combines to form a 

 carbonate of lime ; when it loses its causticity, 

 and changes some of its other properties. With 

 this tendency to attract carbonic acid from the 

 atmosphere, lime is always found after long ex- 

 posure in the state of a carbonate. By subjec- 

 tion to heat, the carbonic acid is expelled and 

 the causticity restored. Q,uick lime, or that 

 from which the carbonic acid has been expelled, 

 when subjected to the action of water, combines 

 with it, and becomes converted into a milder or 

 less caustic compound, which among chemists 

 is known by the name of hydrate of lime. By 

 exposure to the atmosphere, quick lime becomes 

 air slacked; that is, one-half of the lime unites 

 with the water, and the other half with the car- 



bonic acid of the atmosphere. In this state, it 

 is only half caustic, and has a tendency to at- 

 tract more carbonic acid from the atmosphere 

 until it becomes a perfect carbonate, and entirely 

 mild. Nature also furnishes lime in another 

 form, that is when it is united with a double 

 proportion of carbonic acid : it is then called a 

 Bi-carbonate. In this form, it is readily soluble, 

 and hence springs are often impregnated with 

 it, and the waters that gush from fissures in the 

 lime stone rocks, spread it through the soil in 

 their neighborhood, and sweeten the land. 



Mr. Johnston seems to think that the presence 

 of lime in some shape or other is absolutely ne- 

 cessary to the productiveness of a soil, inasmuch 

 " as it seems that in nature all cultivated plants 

 do absorb lime by their roots from the soil, and 

 make use of it h> some way in aid of their 

 growth." But there are several states of che- 

 mical combination in which it may exist ; as in 

 that of a phosphate, a humate, a silicate, a carbo- 

 nate, a sulphate, &c. For the detection of all 

 these, Mr. Johnston furnishes appropriate tests, 

 but as it is known to the generality of readers 

 only in the forms in which it is most usually 

 found, viz : either as a sulphate or carbonate. We 

 extract his remarks on these two compounds 

 alone : 



"In that of sulphate of lime or gypsum. — In 

 this state also it is not a constant, and in a few 

 cases only an abundant, constituent of the soil, 

 Its presence may be detected by the deposition 

 of minute ciyslals on the sides cf the vessel 

 | during the evaporation of the solution obtained 

 by boiling the soil in distilled water. Or, its 

 presence may be inferred if, after observing that 

 oxalate of ammonia causes a precipitate in one 

 small portion of the solution, it be found that 

 nitrate of baryta also throws down a white pre- 

 cipitate from another small portion. 



"In the state of carbonate, lime is generally 

 supposed most usually to exist, and most abun- 

 dantly in all soils. If on pouring dilute mu- 

 riatic acid upon a soil, a visible effervescence or 

 escape of minute bubbles of gas manifest itself, 

 or if, when the experiment is made in a tube 

 closed at one end, and inverted over water or 

 mercury, bubbles of gas collect in the upper end 

 of the tube — the soil contains some carbonate. 

 If after ammonia has been added to the solution, 

 oxalate of ammonia throws down a white pre- 

 cipitate of oxalate of lime — the soil contains 

 carbonate of lime." 



We have been frequently asked what quantity 

 of lime is to be apnlied to an acre. We will en- 

 deavor to give Mr. Johnston's views on this 



