ORGANIC MATl'ERS OK TlIK SOIL. :i:iO 



(besules, perhaps, unaltered vegetable matters) ttvo char- 

 acteristic ingredients, which have been designated tihnie 

 add and ulmin, (so named from liaving been found in a 

 brown mass that exuded from an ehn tree, vlmus being 

 the Latin for ebu). These two bodies (lem:in<l particular 

 notice. 



"When brown peat is boiled with water, it gives a yel- 

 lowish or pale-brown liquid, being but little soluble in 

 jiure water. If, however, it be boiled with dilute solution 

 of carbonate of soda (sal-soda), a dark-brown liquid is 

 obtained, which OAves its color to ulmate of soda. The 

 alkali dissolves the insoluble ulmic acid by combining 

 with it to form a soluble compound. By repeatedly heat- 

 ing the same portion of peat Avith new quantities of sal- 

 soda solution, and pouring off the liquids each time, there 

 arrives a moment when the peat no longer yields any color 

 to the solution. The broAvn peat is thus separated into 

 one portion soluble, and anotlier insoluble, in earl)onate of 

 soda. ZTlmle acid has passed into the solution, and iflmi/i* 

 remains undissolved (mixed, it may be, with unaltered 

 vegetable matters, recognizable by their form and struc- 

 ture, and with sand and mineral substances). 



By adding hydrochloric acid to the brown solution as 

 long as it foams or effervesces, the ulmic acid separates in 

 brown, bulky flocks, and is insoluble in dilute hydrochloric 

 acid, but is a little soluble in pure water. When moist, it 

 has an acid reaction, and dissolves readily in alkalies or 

 alkali-carbonates. On drying, the ulmic acid si. rinks 

 greatly and remains as a brown, coherent mass. 



The u/miii* Avhich remains af'ier treatment of brown 

 peat with carbonate of soda is an indifferent, neutral (i. e., 

 not acid) body, which has the same composition as the 



* The abovu statoincnt is iii;ukM)ii tlie niithority ol' Miildei-. Tlu- wi-iter has, 

 however, found, in several cases, that, continued treaimenl with carbonate uf 

 soda alone completely dissolves the humus, leavinj; a residue of cellulose which 

 yields nothing to caiistic alkali. He is, therefore, inclined to disbelieve in the 

 existence of ulmin and humin as distinct from ulmic and hiimic acida. 



