ADULTERATION OF PHOSPHATIC SLAGS 223 



to the fluorin test, while the basic slags, on the contrary, respond 

 to the hydrogen sulfid test. This test, however, was applied only 

 to the few samples we have had and may not be a uniform 

 property. 



The absence of fluorin might not prove the absence of adul- 

 teration, but its presence would, I believe, certainly prove the 

 fact of the adulteration in that particular sample. 



The fluorin test is applied by Bottcher in the following man- 

 ner: 80 From 10 to 15 grams of the slag are placed in a beaker 

 10 centimeters high and from five to six centimeters in diam- 

 eter, with 15 cubic centimeters of concentrated sulfuric acid, 

 stirred with a glass rod, and covered with a watch-glass, on the 

 under side of which a drop of water hangs. If there be formed 

 upon the drop of water a white murky rim, it is proof that a 

 mineral phosphate containing fluorin has been added. After from 

 five to 10 minutes you can notice on the clean watch-glass the 

 etching produced by the hydrofluoric acid. According to Bottcher 

 an adulteration of 10 per cent, of raw phosphate in slag can be 

 detected by this method. 



(8) Solubility in Water. Solubility in water is also a good 

 indication, natural phosphates being totally insoluble in water, 

 while a considerable quantity of the basic slag will be dissolved 

 in water on account of the calcium oxid or hydroxid which it 

 contains. If the loss on ignition is low, and the volume-weight 

 and water-solubility high, the analyst may be certain that the 

 sample is a pure slag. 



In comparative tests made in the laboratory of the Division of 

 Chemistry with a sample of basic slag and seven samples of 

 Florida phosphate, the percentages of material dissolved by water 

 and by a five per cent, solution of citric acid were found to be as 

 follows : 



Water-soluble. Soluble in 5 per cent, citric acid 



Per cent. Per cent. 



Basic slag 0.97 16. 10 



Florida phosphate o.oi 4. 15 



0.09 4-66 



0.02 3.43 



0.08 3.61 



0.02 3.79 



0.05 4.46 



O.O2 4.24 



99 Chetniker-Zeitung, 1894, 18 : 565. 



