210, 211] 



Analysis of Basic Slag 



133 



Dissolve it in dilute ammonia, and wash the filter well with 

 hot water, collecting the solution and washings in an 8-oz. 

 beaker. Neutralise the liquid with HC1, then add 20 c.c. of 

 magnesia mixture and 20 c.c. of strong ammonia. Stir well, 

 and allow to stand for an hour and a-half. Filter, wash with 

 ammonia, dry, ignite, and weigh as Mg 2 P 2 7 . 



210. Calculation. — In the case of basic slag the calcula- 

 tion is simple, as nothing is required beyond the percentages 

 of lime, phosphoric acid (P 2 5 ), and silica. The difference 

 between the sum of these percentages and 100 is put down as 

 oxide of iron, &c. It consists of MgO, A1 2 3 , FeO, V 2 3 , and 

 SO ;5 . 



The following are a few typical results : 



211. Estimation of Fineness. — The value of basic 

 slag is greatly increased by being well ground ; therefore it is 

 often necessary to test its fineness. This is readily done by 

 weighing out 10 grams into a small wire sieve having 100 

 meshes to the linear inch. It is ordinarily said that the whole 

 of the 10 grams should pass through this, but in practice it is 

 generally found that from 70 to 95 per cent, passes through. 

 The sieve is shaken until as much has been passed through as 

 will go, and this is collected and weighed. 



