lU CHEMICAL MANUEES. 



cent NHS = 20*2 per cent N and about 1 per cent moisture, which 

 is an advantage for the manufacturer, for the mixtures 9x9 have 

 to be delivered with a maximum of 6 to 7 per cent of moisture, those 

 of X 10 with a maximum of 8 to 9 of moisture, if it be not desired 

 to be exposed to annoyances by the formation of lumps (? loose 

 caking in the sacks). To obtain very homogeneous superphosphate 

 of ammonia (ammoniated superphosphate) the sulphate of ammonia 

 is added during the " dissolving" of the superphosphate by dissolv- 

 ing this salt in the sulphuric acid used to decompose the super- 

 phosphate, but this method of proceeding is not applicable except 

 with small amounts of sulphate of ammonia.^ 



The process generally used in making "superphosphate of 

 ammonia " (or ammoniated superphosphate) is as follows. The 

 dry superphosphate of ammonia delivered in 10 ton wagons, being 

 stored and analysed, the amount of superphosphate and sulphate 

 required to give a mixture of 9 x 9 has to be calculated. Suppose 

 that the sulphate of ammonia contains 20-5 N, then 20-5 kg. 

 correspond to 100 kg. (NHJ^SO^, 9 kg. correspond therefore to 



100 X 9 



— ^ — - — = 12 kg. (NHJ.^SO^. There remains then for the super- 



AiJ'D 



phosi^hate 100 - 42 = 58 kg. These 58 kg. of superphosphate 

 must contain 9 kg. of soluble phosphoric acid, which corresponds to 



77 — = 15-5 per cent of phosphoric acid. To make the mixture 



oSt 



the 10 metric tons of sulphate of ammonia are laid in a heap 33 ft. 



long and on each heap the necessary portion of superphosphate to 



the total of 12-777 metric tons. Two labourers mix the two with 



the shovel, making the whole into one heap and recommence the 



same in an inverse direction. The mixer is then passed through 



Carr's disintegrator or the toothed crusher, then it is laid on a big 



heap in the warehouse for the ingredients to combine.- 



Mixtures of superphosphate and sulphate of ammonia exhibit 



phenomena of a peculiar nature. They gradually heat and become 



damp to the touch ; they dry again, and owing to the formation of 



gypsum, they harden more and more. The reaction lasts for a 



variable time. It depends on the nature of the superphosphate and 



1 Quite so, but there is no necessity to actually mix the ammonia 

 with the acid before running the latter into the mixer. The sulphate can go 

 up the cups like other ingredients, and precede the other ingredients if the man 

 in charge fancies that style of mixing. The translator, however, has no great 

 faith in the solvent action of sulphuric acid after it has been so far converted 

 into an acid sulphate of ammonia. He prefers to send the sulphate up the 

 cups last, after the acid has done all the work it is intended to do. — Tr. 



2 A disintegrator, whether Carr's or any other make, has its use in manure 

 factories, but it is not at all necessary to resort to it on every occasion and 

 to put all the manure made in the factory through it without rhyme or 

 Teason. — Tr. 



