103. 



In 1000// of white onlc leaves there are: 90//' mineral salts 



including 23 



During the first about 3o to 4 pounds are dissolved. 

 The following table shows thJa contents in C,H,0,and K of cellu- 

 lose, oaks, peat, brown coal and anthracite: 



lOO,/ : 

 Harae Cellulose 



TABLE 

 oaks 





peat brown anthracite 

 ground 6' below coal 

 surface 



c 

 H 



o 

 c 



4^; 



6 



49 



6 

 43 



39 



5 



36 

 0.8 



64# 



5 



27 



4.1 



24 

 0.6 



2.5 



2.5) 

 ) 



Oak gains C and loses 0. 

 Peat gains C, loses 0, ^ 



H; valuable for humus. 



Hutnic acids. 



pert bog is sour below the surface, because of humic acids, 

 of which there are several: ulmic, humic, crenic and apocrenic acids. 

 Ulmin compounds are injurious to the soil; hurain compounds are benefi- 

 ci-1. With much w.iter the bacteria produce ulmin substances which soon 

 attain a concentration that kills the bacteria and then is purely che- 

 mical in nature. It is brownish (seen in swamps, etc.). The solution 

 gives a litmus reaction indicating acidity, therefore the soils are calfc* 

 ed sour soils. The acidity is due to: ulmic acid, and to apocrenic acid, 

 reacting easily with alkalies to form alkalic compounds. Ulmin is itself 

 indissoluble, but io soluble with an acid. These soils produce sour soil 

 vegetation. In reclamation lime is used. All soils tend to sourness un- 

 der cultivation, especially when very wet. Calcareous soils resist this 

 action longer and arc longer lived and more fertile than non-calcareous 

 soils. Ilumic acids are poisonous to plants; strong, & attack minerals. 



Properties and nature of Kumus: humus is distinctly a colloid; it 

 swells and shrinks with water. Peat shrinks very much; if it is thoroly 

 dried you cannot swell it again. Humus increases with the number of 

 roots gro ;in,v in it. It is porous, plastic, adhesive, colloidal; its 

 volirne increases several times upon absorption of water; it is very 

 absorptive of gases and moisture; its dark color absorbs heat and it 

 warms readily. Its density is 1.4. It is composed of C,N,and 0, and has 

 a complex formula. It may be produced: 



&u&&& 1) Artificially by caustic alkali on sugar or cellulose; 



2) fl*&lft&fc&& Change in fibre by bacteria and fpngi pro- 

 ducing ulmin and humin; 



3) Oxidation of ulmin and humin acids to crenic and apo- 

 crenic acids; 



%% Ulmin and humic acids form indissoluble salts with Ca 

 Crenic and apocrenic* 1 ** soluble w * H 

 Therefore the absence of Ca arid Mg from clayo by leaching, gives 

 f ire 



Humus is important in regard to nitrogen. The amount of li varies 

 according to the locality. Stable manure humus gives 4-8/t- W t wood gives 



