METHOD OF WYATT 243 



the separation of iron and alumina in the presence of a large ex- 

 cess of lime and phosphoric acid is subject to widely varying 

 results, but that the error due to the excess of iron in the weighed 

 product is partly corrected by the one due to the deficiency of 

 alumina. 



214. Method of Wyatt. A method, formerly very extensively 

 used in this country, both in private laboratories and by fertiliz- 

 er factories, for determining iron and alumina is described by 

 Wyatt. 2 It is claimed for this method, which is a modification 

 of the acetate process, that, while it may not be strictly accurate, 

 yet it is rapid and easy, and in the hands of trained analysts 

 yields concordant results. Fifty cubic centimeters of the first 

 solution of the sample in aqua regia, or an amount thereof equiv- 

 alent to one gram of the phosphate, are rendered alkaline by 

 ammonia. The resulting precipitate is first redissolved by hydro- 

 chloric acid, and then a slight alkalinity is again produced with 

 ammonia. Fifty cubic centimeters of strong acetic acid are added, 

 the mixture stirred, placed in a cool place and left until cold. 

 The precipitate is separated by filtration and washed twice with 

 boiling water. The vessel holding the filtrate is replaced by the 

 beaker in which the precipitation was made. The precipitate 

 is dissolved in a little 50 per cent, hot hydrochloric acid and the 

 filter washed with hot water. After rendering slightly alkaline, 

 as in the first instance, the treatment with acetic acid is repeated 

 as described. The precipitate is washed this time, twice with cold 

 water containing a little acetic acid and three times with hot water. 

 The precipitate is dried, ignited, and weighed as iron and alumi- 

 num phosphate. Half of this weight may be taken to represent the 

 quantity of iron and aluminum oxids, for all the general purposes 

 of the factory or the control of the daily work at the mines. 



To separate the iron and alumina the ignited precipitate just 

 described is dissolved in hot hydrochloric acid, filtered into a 100 

 cubic centimeter flask, and made up to the mark by hot wash- 

 water. 



The phosphoric acid is determined in one-half of the filtrate 

 and in the remaining half the iron is reduced with zinc and 

 * Phosphates of America, 4th Edition, 1892 : 150. 



