410 EXPEKIMENT STATION RECOED. 



A reliable method for determining the citric acid-soluble phosphoric acid 

 in Thomas powder, M. Popp (Chem. Ztg., 36 (1912), No. 99, p. 937). — The 

 author claims that in determining the citric acid-soluble phosphoric acid in slag 

 powder with direct methods, high results are very often obtained. Better figures 

 c-an be gotten if the silicic acid is first removed with hydrochloric acid, but the 

 procedure is a tedious one. The Lorenz method, which has been proposed, yields 

 good results, but it is an expensive and cumbersome method. Wagner's method 

 was also tried, but the results were unsatisfactory. 



The following is considered a rapid method : To 50 cc. of the citric acid extract 

 add 25 cc. of an iron citrate solution, 100 cc. of a 0.3 per cent hydrogen peroxid 

 solution, and 25 cc. of magnesia mixture, and stir for 15 minutes. The method 

 can not be used for Wolters' phosphate without some change in the procedure. 



The reagents used are made as follows: (1) Iron citrate solution: One kg. of 

 citric acid is placed in a porcelain dish and mixed with 30 gm. of iron chlorid, 

 dissolved in 50 cc. of water ; next 4 liters of 20 per cent ammonium hydroxid is 

 added slowly and carefully, being sure that every particle is dissolved. The 

 solution is then brought into a 5-liter bottle, cooled, and filled to the mark with 

 water, and filtered. (2) Hydrogen peroxid solution : This is made by diluting 10 

 cc. of perhydrol (30 per cent) with water to make 1,000 cc, and then diluting 

 100 cc. of this 3 per cent solution to 1,000 cc. (3) Magnesia mixture: Five hun- 

 dred and fifty gm. of magnesium chlorid and 700 gm. of ammonium chlorid are 

 placed in 10-liter bottles containing 2 liters of water. When the salts are dis- 

 solved, 1,750 cc. of 20 per cent ammonium hydroxid solution is added, filled to 

 the 10-liter mark with water, and filtered after a few days. 



The author desires that experiment stations make some comparative tests 

 between this and other methods, and where any concordant results are obtained 

 with certain slags asks that a sample of the slag be sent him. 



Determining: the citric acid-soluble phosphoric acid in Thomas slag powder, 

 W. FucHS and P. Wagner {Chem. Ztg., 36 (1912), No. 110, pp. 1037-1039).— A 

 discussion in regard to the method recommended by Popp above. 



It is claimed that the authoi's about 10 years ago showed that slags rich in 

 silicic acid were usually poor in iron. Thinking that either an addition of iron 

 or aluminum would eliminate the errors noted in the analysis of such slags. 

 they made tests showing that iron was the preferable substance to add. 



Weibull (E. S. R., 14, p. 630) and later others added solutions of ferric chlorid 

 to the citric acid extract, but the authors found that by adding an amount 

 equivalent to 0.044 gm. of iron in the shape of ferrous chlorid, better results 

 could be obtained. The precipitation was later conducted by removing the 

 hydrogen snlphid contained in the acid solution with 10 cc. of 0.3 per cent 

 hydrogen peroxid, and then adding 25 cc. of ammonium citrate solution con- 

 taining 0.044 gm. of iron, followed by a magnesia mixture. 



The method is given below, as it is claimed that Popp did not describe the 

 authors' method correctly. 



(1) Iron containing ammonium citrate solution: Two kg. of citric acid is 

 placed in a. 10-liter bottle and covered with 100 cc. of iron chlorid solution 

 which contains 12 gm. of iron in the ferrous form. To this is added carefully, 

 and at intervals, about 8 liters of 20 per cent ammonium hydroxid solution, 

 making sure that the citric acid is fully dissolved, and after cooling filled to the 

 10-liter mark with 20 per cent ammonia. (2) Magnesia mixture: One hundred 

 and ten gm. of crystallized pure magnesium chlorid, and 140 gm. of ammonium 

 chlorid are dissolved in 1,300 cc. of water, and then 700 cc. of ammonium 

 hydroxid (8 per cent NHs) is added. After allowing the mixture to stand for 

 a few days, it is filtered. (3) Precipitation of the phosphoric acid: Fifty cc. 

 of the citric acid extract of the Thomas slag is brought into a beaker glass, and 



