SPECIFIC GRAVITY OF SOIL. 215 



rable pa^^er will remain a model of one application of the sciences 



to agriculture.* 



The researches of M. Schtibler were directed to the mineral sub- 

 stances which are generally found in soils, viz : 1st. silicious sand ; 

 2d. calcareous sand ; 3d. a sandy clay containing about y^^ths of 

 sand; 4th. a strong clay containing no more than about f-oths of 

 sand ; 5th. a still stronger clay containing no more than about y^^th 

 of sand ; 6th. nearly pure clay ; 7th. chalk, or carbonate of lime in 

 the pulverulent state ; 8th. humus ; 9th. gypsum ; 10th. light gar- 

 den earth, black, friable, and fertile, and containing, in 100 parts, 

 clay 52.4, quartzy sand 36.5, calcareous sand 1.8, calcareous earth 

 2.0, humus 7.3; 11th. an arable soil composed of clay 51.2, silicious 

 sand 42.7, calcareous sand 0,4, calcareous earth 2.3, humus 3.4 ; 

 and 12th. an arable soil taken from a valley near the Jura, contain- 

 ing clay 33.3, silicious sand 63.0, calcareous sand 1.2, calcareous 

 earth and humus 1.2, loss 1.3. 



The object of these inquiries was to ascertain, 1st. the specific 

 gravity of soils ; 2d. their power of retaining water ; 3d. their 

 consistency; 4th. their aptitude to dry; 5th. their disposition to 

 contract while drying ; 6th. their hygrometric force ; 7th. their 

 power of absorbing oxygen ; 8th. their faculty of retaining heat ; 

 and 9th. their capacity to acquire temperature when exposed to the 

 sun's rays. 



Specific gravity of soils. The weight of soils may be compared 

 in the-dry and pulverulent state, or in the humid state, or the spe- 

 cific gravity of the particles which enter into their composition may 

 be determined. This last information is easily obtained by the fol- 

 lowing method : take a common ground stopper bottle, weigh it 

 stoppered and full of distilled water ; let it then be emptied, in order 

 that a known quantity of the soil, in the state of powder and quite 

 dry, may be introduced into it, A quantity of water is now poured 

 in, and the phial is shaken to secure the disengagement of all air 

 bubbles ; the phial is then filled with distilled water, and when the 

 upper part has become clear the stopper is replaced ; the phial is 

 then wiped dry and weighed again. The difference between the 

 weight of the phial full of water plus that of the matter, and the 

 weight of the phial containing the matter and the water mixed, gives 

 the weight of the water displaced by this matter. Thus : 



Weipht of the phial full of water 60.0 



Weight of the matter ••34.0 



84.0 



vVeight of the phial containing the mingled earth and water 74.4 



Difference of water displaced 9.6 



wliich is the weight of the volume of water equal to that of the 

 matter introduced into the phial ; we have consequently for the spe- 

 cific gravity of the earth ^;|=^2.5, the weight of the water having 

 l»een taken as 1. 



* Stchiibler, Annals of French Agriculture, vol. xl. p. 123, 2d Miie*. 



