154 The Phosphates of America. 



covered crucible. The net weight = CaO in one gramme of the 

 material. 



It is customary in our laboratory to ignite and weigh this residue 

 three times, or until the two last weights are identical. 



Magnesia (MgO). 



The filtrates and all the washings from the lime determination, 

 as above detailed, are well shaken together, and concentrated by 

 boiling to about 100 c.c. 



After allowing the liquid to become quite cold, it is poured into 

 a beaker, the flask carefully rinsed out into the same with distilled 

 water, and the liquid made very strongly alkaline with ammonia. 



After well stirring, the mixture is covered with a watch-glass 

 and allowed to stand over night. The precipitate of ammonio- 

 magnesium-phosphate is then carefully filtered through an ashless 

 filter, the beaker thoroughly washed out with dilute ammonia by 

 means of a rubber-tipped rod, and the washings brought on the 

 filter. The latter is then finally washed twice with the ammonia 

 water, placed in the drying-oven, calcined in a tared porcelain 

 cru;ible, at first at a very low, then at the highest obtainable heat, 

 and weighed as Mg 2 P 2 O 7 . The weight X .360 = MgO in one 

 gramme of the material. 



If all the foregoing determinations have been performed with 

 the required care, the quantities found should add up to a total very 

 closely approximating 100. Assuming that this is the case, we 

 suggest that a reliable opinion may at once be formed for the 

 manufacturer, as to the industrial value of any mineral phosphate, 

 by combining the various isolated bodies as follows : 



The magnesia is multiplied by 2.10. Result carbonate of magnesia. 



The carbonic anhydride left over by 



the magnesia is multiplied by.. 2.27 " carbonate of lime. 



The fluorine is multiplied by 2.05 " = fluoride of lime. 



The sulphuric acid is multiplied by 0.75 " = iron pyrites. 



The lime remaining after satisfying 

 the carbonic anhydride and 

 fluorine is multiplied by 1.84 "J = phosphate of lime. 



The phosphoric acid, if any, remain- 

 ing after this satisfaction of 



lime is multiplied by . . . . 2.00 " = phosphate of iron and 



alumina. 



If all the phosphoric acid be used up by the lime available 

 under this scheme, the iron and alumina may be regarded as having 



