27* EGYPTIAN AGRICULTURE. 



the fact, already mentioned, that the nitrogen is contained 

 in the urine, which is almost entirely lost. A certain 

 quantity remains, and in order to prevent the loss of this 

 by fermentation, and at the same time to help to deodorise 

 the whole, gypsum, (sulphate of calcium) is added. This 

 is used in Egypt on account of its low price (80 P.T. 

 per ton). 



The drying of the sewage should take pJace as rapidly 

 as possible to prevent fermentation. For this reason, the 

 area of the basin in which the sewage is placed should be 

 of sufficient size that the daily loss by evaporation is equal 

 to the quantity of liquid added. The basins are shallow ; 

 if deep, much material is stored, and consequently a long 

 time is required to dry and to manufacture. In Cairo, the 

 sewage is first discharged into distributing basins which 

 are at a slightly higher level than those for evaporating, 

 and are provided with iron gratings ; workmen rake over 

 the material to remove foreign matter, stones, etc., the 

 latter being carted away. The sewage is pushed through 

 the evaporating basins and during the days of filling, as 

 well as during the first five days of drying the gypsum 

 is added, which helps the process. When sufficiently dry, 

 the material is removed and transported to be spread out 

 to further dry. The product is sold under the name of 

 " Matieres Premieres" at about P.T. 65 per ton, and 

 contains : 



Nitrogen 1'50# 



Phosphoric aci d 1'75# 



Better qualities may contain 1*75% of nitrogen, 2'^% 

 of phosphoric acid and 'o% of potash. 



