MANURES AND MANURING I087 



nitrogen must be in the form of ammonia. The urine at the time of analysis 

 must therefore not be too fresh ; it must have been in the pit for at least 

 10 to 14 days. It was also found that fairly wide variations of the nitrogen 

 content are accompanied by only slight variations in the specific gravity, 

 and that the relation differs according to whether the urine is from cattle 

 only or a mixture from different livestock. In cattle, urine relations are 

 more regular. 



On the strength of these observations the wri:er designed a densimeter 

 which enables the nitrogen content of the urine to be rapidly ascertained 

 with fair accurac}^ His observations referred only to pure cattle urine. 

 The densimeter very much resembles that for measuring the density of milk ; 

 as in the latter case, it is immersed in the liquid in question and the number 

 of degrees read off on the scale ; the temperature of the urine should be from 

 16 to 170 C. The greater the number of degrees shown, the smaller the 

 content of nitrogen and vice-versa. 



The percentage of nitrogen was ascertained in the urine of a number of 

 different animals by means of the densimeter and the chemical method ; 

 it was found that the result is almost the same by the two methods. The 

 relations ascertained bv means of the densimeter are as follows : 



The densimeter consequently futnishesa means of examining the majo- 

 rity of the cattle urines used in practice. On the basis of these data it 

 is possible to calculate the quantity of liquid manure to be used when grass- 

 land is to be manured with a given quantity of nitrogen. For instance, if 

 the densimeter shows the proportion of nitrogen of 4 to 5 gms per litre and 

 the grass-land is to be manured with 30 kg of nitrogen per hectare (26.8 lbs 

 per acre), from 6000 to 7500 litres (534-668 gallons per acre) of urine must 

 be used. 



The addition of a small quantity of water to the urine does not very 

 much affect the result, but a large quantity is injuriou.-^. 



The densimeter is made by the firm of Hugershoff in Leipzig. 



8^6 - Experiments on Humogen or Bacterised Peat (The wobum Kxperimentai station 



of the Royal Agricultural .Society of England, Pot Culture r.xperinicnls, 1915. 1^') — 

 VOELCKER J. A., in The Journal oj the Royal Auricullural Socit'ly t>f EiiKlaiul, Vol. T^XXVI, 

 PP- 357-363 + plates 9-10. I^ondon, 1915- 



The humogen or bacterised peat of Prof. W. B. BoTTOMr,i:Y was com- 

 pared with nitrateof soda and with controls : i) in pots containing respect- 



