STATE AGRICULTURAL SOCIETY. 105 



Bodies which absorb the gas or vapor* of water are calle<l 

 hygroscopic. This property of a soil is of the utmost agricultu- 

 ral importance, because : 1st — it is connected with the perma- 

 nent moisture which is necessary to vegetable existence, and, 

 2d — since the absorption of water-vapor determines the absorp- 

 tion of other vapors and gases. 



In the following table from Schiibler we have the results of a 

 series of experiments carried out by that philosopher, for the 

 purpose of determining the absorptive power of different kinds 

 of earths and soils. He found that dry earths did not absorb 

 oxygen; this is because being in constant contact with air they 

 were saturated with this gas before the experiments begun; when 

 however, the soil was wet with water, an absorption was found to 

 occur. The first column of figures gives in thousandths the 

 quantity of oxygen absorbed by the moist soil during thirty days; 

 the second column the quantity, also in thousandths, of moisture 

 absorbed by the previously dried soil, in twenty-four houi-s. 



Quartz sand, 1 



Gypsum,.. _ 1.7 1 



Lime-sand, _ 4 3 



Plough land, _ 10.5 23 



Clay soil, (60 per cent, clay,) 6 28 



Slaty marl, _ 7 33 



Loam, 7 35 



Fine carbonate of lime, 7 35 



Heavy clay soil, (80 per cent, clay,) 9 41 



Garden mould, (7. per cent, humus,) 11.5 52 



Pureclay, 10 49 



Carbonate of Magnesia, (fine powder,) 11 82 



ITumus, 13 120 



It is seen, that witli two exceptions, the rate of absor})tion for 

 oxygen and for watery vapor increases in the same order. It is 

 probable then that the oxygen was to some degree absorbed and 

 held in solution by the water with which the earth was moistened. 

 The two excej)tions are soils rich in vegetable matter, (humus.) 

 They absorbed j)ro}H)rtioiially more oxygen for a cliemical reason; 

 it united witli tlieir rarlxm and liydmgcn, firming carbonic acid 

 and water. Probably the larger share of the absorption of oxygen, 



• The term Can is jipplied to permanently leriforin bo<liea — J'aportosuch as readilj aiaunie 

 % liquid state. Tbo differcDcc is only relative. 



