198 Minnig — Separation and Estimation of Aluminium. 



from iron, was dissolved in water and the solution was stand- 

 ardized by precipitating the aluminium hydroxide, igniting 

 and weighing the oxide. The acetone-acetyl chloride mixture 

 was made up in the proportion of four of acetone to one of 

 acetyl chloride. In each experiment a portion of the standard 

 solution was measured from a pipette into a small beaker and 

 evaporated on the steam-bath to the smallest possible volume. 

 To the concentrated solution, cooled by immersing the beaker 

 in running water at a temperature of about 15° or in ice water, 

 the acetone-acetyl chloride mixture was added drop by drop, 

 with stirring, to the amount of 15 cm3 to 20 cm3 . The precipitate 

 was transferred to a perforated crucible, washed with the pre- 

 cipitating mixture, dried for ten or fifteen minutes high above 

 a low Eunsen flame, which was gradually increased to its full- 

 est heat. Covering the precipitate with red mercuric oxide (to 

 prevent mechanical loss during the ignition) and igniting under 

 a good draft-hood was tried in a few cases, but without advan- 

 tage over the simpler method. The results of experiments 

 made with the pure aluminium chloride are given in Table I. 





Table 



I. 





Solution of 



A1C1 3 .6H 2 



taken 



A1 2 3 



by 



standard 



A1 2 3 

 found 



Error 



cm 3 



grm. 



grm. 



grm. 



5 



0-0213 



0-0213 



00000 



5 



0*0213 



0-0212 



—o-oooi 



5 



0-0213 



0-0213 



o-oooo 



5 



0-0213 



0-0214 



+ 0-0001 



5 



0-0213 



0-0215 



+ 0*0002 



10 



0-0426 



0-0426 



0-0000 



In Table II are given the results obtained by similar pro- 

 cedure in the precipitation of the aluminium chloride from 

 solutions containing also known amounts of ferric chloride. 







Table II. 







Solution of 



A1C1 3 .6H 2 



taken 



A1 2 3 



by 



standard 



Fe 2 3 



present 



as chloride 



A1 2 3 

 found. 



Error 



cm 3 



grm. 



grm. 



grm. 



grm. 



5 



0213 



0-0293 



0-0215 



+ 0-0002 



5 



0-0213 



0-0293 



0-0211 



— 0-0002 



5 



0-0213 



00293 



0-0213 



o-oooo 



5 



0-0213 



0*0293 



0-0212 



—o-oooi 



5 



0-0213 



0-0293 



0*0213 



o-oooo 



5 



0-0213 



0-0293 



0-0214 



+ 0-0001 



10 



0-0426 



00293 



0-0426 



o-oooo 



10 



0-0426 



0-0586 



0-0425 



—o-oooi 



