162 MANURE. 



definite proportion to the phosphates ; hence it may meas- 

 ure their quantity. Nitrogen makes manure hotter or 

 colder. This causes change among the particles to begin, 

 and to be carried on in the manure. Motion begins here, 

 and is communicated to seeds and plants. Hence, crops are 

 in proportion to the energy of these changes and motions. 



207. This is a practical view of a practical subject. The 

 nitrogen present in the manure expresses its true value. 

 This position is substantiated by the experience of practical 

 men. The experiments undertaken by order of the Saxon 

 and Prussian authorities, to ascertain -whether the contents 

 of the sewers of the cities of Dresden and Berlin, could be 

 applied to fertilizing the barren lands in their vicinity, may 

 be offered to prove its correctness. These varied in every 

 form, and continued for a long period, prove that if a soil 

 without manure yields a crop of three for one sown, then 

 the same land yields, dressed 



With cow-dung, 7 for one sown, 



" horse-dung, 10 " " 



" human manure, 14 " " 



Now the nitrogen in these has been shown, taking the 

 minimum of nitrogen in the human, at 1-J- per cent, is as 

 1 : 1.50 : 3, whilst the above numbers are to each other, as 

 1 : 1.43 : 2. 



Cojfisidering how varied is the composition of night-soil, 

 and how much diluted by various mixtures, this agreement 

 is as near as ought to have been expected, in experiments 

 whose objects were so totally different from that of ascer- 

 taining the quantity of nitrogen in each different manure. 



208. Many modes of using night-soil are in use, all 

 depending on convenience, and modified by locality, and 

 other circumstances. Perhaps no mode is preferable to that 

 long used in Flanders. It has the sanction of a people whose 



