78 MANUFACTURE OF FERTILIZING MATERIALS 



passed through a disintegrator or through a toothed 

 crusher and a very homogeneous mixture is thus 

 obtained. Inert materials should be avoided in 

 these mixings. By mixing high strength super- 

 phosphate with low strength superphosphate com- 

 mon kinds can be made without recourse to inert 

 materials, such as sand, plaster, etc. 



Although the composition of ammoniated su- 

 perphosphate is very variable, the most usual 

 strength being 9 X 9, 5 X 10 or 6 X 12, the first figure 

 indicating the percentage of nitrogen, the second 

 the percentage of soluble phosphoric acid, this 

 manure is in great esteem. It is analogous to dis- 

 solved Peruvian guano to which farmers are accus- 

 tomed. It, moreover, presents this advantage, 

 that its acid retrogrades less easily in the soil than 

 that of pure superphosphate, seeing that the sul- 

 phuric acid combines first with the bases which it 

 encounters in arable land. The mixture of super- 

 phosphate with sulphate of ammonia is easily 

 made. Sulphate of ammonia is delivered in a 

 finely ground granular condition. It contains 24.5 

 per cent NH 3 =20.2 per cent N and about 1 per 

 cent moisture, which is an advantage for the man- 

 ufacture, for the mixture 9x9 must be delivered 

 with a miximum of 6 to 7 per cent of moisture, 

 that of 5x10 with a maximum of 8 to 9 per cent 

 moisture, if it is desired to avoid annoyances 

 by the formation of lumps or loose caking in 

 the sacks. To obtain very homogeneous super- 

 phosphate of ammonia, the sulphate of ammo- 



