PHOSPHORUS FERTILIZERS 



139 



at a time, larger mixers are constructed of brick, protected 

 by some means from the action of the acid. 



TABLE 18. 



POUNDS OF ACID CONSUMED BY 100 POUNDS OF ROCK PHOSPHATE FOR 

 EACH PER CENT. OF THE CONSTITUENT STATED. 



The use of the table can best be explained by an example. 



Algerian phosphate. 



Calcium phosphate 

 Oxide of iron and alumina 

 Calcium carbonate 

 Water 

 Unestimated 



Acid (D =1-56) 



65-0 x 1-14 = 74-2 



0-6 x 3-34 = 2-0 



j.6'0 x 1*46 = 23-4 

 5'0 



13*4 X 0'12 = I'6 



Pounds of acid for 100 pounds phosphate 101*2 



The manufacturer used equal weights so as to leave some 

 insoluble phosphate. 



It is now possible to produce bricks having a high degree 

 of resistance towards sulphuric acid, and to manufacture 

 cements which make a satisfactory acid-resisting mortar to 

 join such bricks. There are many well-known brands of 

 these acid-resisting bricks, known as blue brick, metalline, 

 etc., and these are joined together with cements which con- 

 sist very largely of ground-up bricks of a similar type, together 

 with small quantities of lime and silicate. One particular 

 recipe is ground stone waste passing through a No. 30 sieve, 

 8 parts ; fine I y eighton sand, 7 parts ; ground blue brick 

 passing through a No. 60 sieve, 2 parts ; plaster of Paris, 

 one -eighth part, all mixed intimately together, and subse- 

 quently treated with 3 parts of sodium silicate solution with 

 a specific gravity of i -3. Such a strength of sodium silicate 

 can be made by diluting the strong syrup of sodium silicate 



