INTERNATIONAL STEEL STANDARDS COMMITTEE 173 



solution, after correction, be found necessary to oxidize the molyb- 

 dic solution after passing through the jones reducing tube, the 

 amount of phosphorus found is 0.0000597X8.6=0.051 per cent. 



150. Methods of the International Steel Standards Committee. 30 

 This method was adopted by the committee appointed to con- 

 sider all the rapid methods for the determination of phosphorus 

 in iron and steel, and was recorded as giving the best methods 

 of procedure which are known at present and securing data 

 which are of great accuracy if the details of the process are 

 carefully observed. The process is conducted as follows: 



From one to two grams of the drillings of iron or steel, accord- 

 ing to the phosphorus which they contain, are placed in a 250 

 cubic centimeter erlenmeyer flask and covered with 100 cubic 

 centimeters of nitric acid of 1.135 specific gravity. The flask is 

 covered with a watch-glass and the mixture is heated until the 

 solution is complete and the nitric acid is boiled off. Ten cubic 

 centimeters of strong potassium permanganate solution are added 

 and boiling continued until the pink color has disappeared and 

 the manganese dioxid has separated. Afterwards a few drops 

 of the solution of sulfurous acid are added and a small crystal of 

 ferrous sulfate, or a solution of 0.5 gram of sodium hyposulfite 

 in 10 cubic centimeters of water. The addition of these reagents 

 is continued at short intervals until the precipitated manganese 

 dioxid is dissolved. After boiling for two minutes the flask is 

 placed in cool water or allowed to stand until it is cool, and 

 then 40 cubic centimeters of dilute ammonia of 0.96 specific 

 gravity are added. The precipitated ferric hydrate will redis- 

 solve when the liquid is thoroughly mixed. After cooling to 

 about room temperature the flask is stoppered and shaken for 

 five minutes, either by hand or in a shaking machine. After 

 standing for a few minutes, the contents of the flask are poured 

 on a filter and washed with acid ammonium sulfate, prepared 

 by adding 1 5 cubic centimeters of strong ammonia to one liter of 

 water and 25 cubic centimeters of strong sulfuric acid, until 

 two or three cubic centimeters of the wash-water give no reac- 

 tion for molybdenum with a drop of ammonium sulfid. Any 

 30 Blair, The Chemical Analysis of Iron, 6th Edition , 1906 : 92. 



