124 NATURAL MANURES. VI. 



evolution being 16*3 c.c. per hour (on the sixth day). The gas 

 contained 15-8 c.c. of hydrogen, 4217*5 c.c. of carbon dioxide, 

 and 4577-4 c.c. of marsh gas (equal to 4*72 grammes of carbon, 

 6-033 grammes of oxygen and 0*819 gramme of hydrogen). 



The loss suffered by the manure is shown by the following 

 table, which gives the amounts, in grammes, of the various 

 constituents in the dried manure before and after the experi- 

 ment : 



Carbon. Hydrogen. Oxygen. Nitrogen. Minerals. 



Before ... 12-67 1-653 10-70 0-453 3-69 

 After ... 7-92 1-125 7-08 0-392 3-79 



Loss ... 4-75 0-528 3-70 0-061 0-10 (gain) 

 No free nitrogen was found in the gases, the loss of nitrogen 

 being due to its liberation as ammonia, which would be lost in 

 drying. The oxygen and hydrogen in the gases evolved, in- 

 cluding the hydrogen lost as ammonia, exceed by 2 -333 

 grammes and 0*305 gramme that lost by the manure, showing 

 that water enters into the reactions by which these gases are 

 produced. 



Preservation of Farm-yard Manure. The best means of 

 using farm-yard manure, whether fresh or rotted, and the 

 most advantageous manner of treating it so as to minimise 

 the loss of fertilising ingredients, are matters which have re- 

 ceived much consideration and about which the greatest 

 diversity of opinion, especially among farmers, exists. 



Such obvious precautions as the prevention of loss of soluble 

 matter by drainage hardly need mention here, unless it be to 

 show how r rich in fertilising materials such drainage often is. 

 In fresh manure the liquid portion consists mainly of urine, 

 which has been shown to be rich in nitrogen and potash. 



The dark brown drainage from old manure heaps is often 

 rich in manurial matters ; a sample analysed by Voelcker con- 

 tained nearly 2% of solid matter, including 0-04% nitrogen, 

 0'52% of carbonate and chloride of potassium, and a con- 

 siderable quantity of phosphoric acid. It is obviously desi- 

 rable that such drainings should be preserved, either by the 

 use of sufficient litter best peat or peat moss to absorb it, 

 or by collecting it in a tank. 



Of more importance from the chemical aspect is the loss of 



