56 MODE OF TESTING THE PRESENCE OP CALX. 



ble others to detect its errors, if any exist. To analyze a specimen 

 of soil completely, requires an amount of scientific acquirement 

 and practical skill to which I make no pretension. But merely to 

 ascertain the absence of calcareous earth (or carbonate of lime), 

 or, if present, to find its quantity, requires but little skill., and less 

 science. 



The methods recommended by different agricultural chemists for 

 ascertaining the proportion of calcareous earth in all soils, agree in 

 all material points. Their process will be described, and made as 

 plain as possible. A specimen of soil of convenient size is dried, 

 pounded, and weighed, and then thrown into muriatic acid diluted 

 with three or four times its quantity of water. The acid combines with, 

 and dissolves the lime of the calcareous earth, and its other ingre- 

 dient, the carbonic acid, being disengaged, rises through the liquid 

 in the form of gas, or air, and escapes with effervescence. After 

 the mixture has been well stirred, and has stood until all effer- 

 vescence is over (the fluid still being somewhat acid to the taste, to 

 prove that enough acid had been used, by some excess being left), 

 the whole is poured into a piece of blotting paper, folded so as to 

 fit within a glass funnel. The fluid containing the dissolved lime 

 passes through the paper, leaving behind the clay and silicious 

 sand, and any other solid matter ; over which, pure water is poured 

 and passed off several times, so as to wash off all remains of the 

 dissolved lime. These filtered washings are added to the solution, 

 to all of which is then poured a solution of carbonate of potash. 

 The two dissolved salts thus thrown together (muriate of lime, 

 composed of muriatic acid and lime, and carbonate of potash, com- 

 posed of carbonic acid and potash), immediately decompose each 

 other, and form two new combinations. The muriatic acid leaves 

 the lime, and combines with the potash, for which it has a stronger 

 attraction and the muriate of potash thus formed, being a soluble 

 salt, remains dissolved and invisible in the water. The lime and 

 carbonic acid being in contact, when let loose by their former part- 

 ners, instantly unite, and form carbonate of lime, or calcareous 

 earth, which, being insoluble, falls to the bottom. This precipitate 

 is then separated by filtering paper, is washed, dried and weighed, 

 and thus shows the proportion of carbonate of linie contained in 

 the soil.* 



In this process, the carbonic acid which first composed part of 

 the calcareous earth, escapes into the air, and another supply is 

 afterwards furnished from the decomposition of the carbonate of 

 potash. But this change of one of its ingredients does not alter 

 the quantity of the calcareous earth, which is always composed of 



* More full directions for tli6 analysis of soils may be foiAid in Kirwan's 

 Essay on Manures, llozier's Cours Complet, &c., and Davy's Agricultural 

 Chemistry. 



