Gooch and Eddy — Separation of Magnesium. 447 



Table II. 



MgO 

 taken 



as 

 MgCl 3 



grm. 



MgO 



weighed 



grm. 



Error 

 in MgO 



0-1444 0-1446 



0-1444 0-1449 



0-1444 0-1445 



0-1444 0-1445 



MgO 



found 



as 



MgoP 2 7 



grm. grm. 



A 



+ 0-0002 0-0001 



+ 0-0005 0-0000 



+ 0-0001 o-oooo 



+ 0-0001 o-oooo 



Vol. Vol. 



of of 



Original alcohol precipi- 

 vol. added tant. 

 cm 3 cm 3 cm 3 



0-1444 

 0-1444 



0-1443 —0-0001 

 0-1440 —0-0004 



B 



o-oooo 



0-0002 



50 

 50 



50 

 50 



50 

 100 

 100 

 100 



50 

 50 



Vol. of 



solution 



used in 



washing 



cm 3 



50 

 50 



From the results of section A of this table, it appears that 

 the precipitation of the magnesium brought about in 100 cm3 of 

 a saturated ammoniacal ammonium carbonate solution contain- 

 ing 50 per cent of alcohol is complete. From the result of sec- 

 tion B it appears that the precipitation produced in 150 cm3 of a 

 one-third saturated solution of ammonium carbonate containing 

 50 per cent of alcohol is reasonably complete. 



Table III shows the details of certain experiments in which 

 the separation of magnesium from the alkalies was attempted 

 by the precipitation processes of Table II. In the experiments 

 of A the precipitation was brought about by treating the solu- 

 tion of magnesium chloride and the alkali chlorides, concen- 

 trated in the highest degree, with the saturated ammoniacal 

 ammonium carbonate solution containing 50 per cent of alcohol. 

 In the experiments of B, an equal volume of absolute alcohol 

 was added to the water solution containing magnesium chloride 

 and the alkali chlorides, and to this mixture was added the 

 saturated ammoniacal ammonium carbonate solution containing 

 50 per cent of alcohol. In the experiments of C the precipi- 

 tate was made as in the experiments of B, but, after pouring 

 off the supernatant liquid through the asbestos felt of a weighed 

 perforated platinum crucible, was dissolved in the beaker by 

 warming with the least possible amount of hydrochloric acid. 

 The solution was diluted with water to 50 cm3 and treated as in 

 the first precipitation. The second precipitate was collected 

 upon the asbestos felt through which the supernatant liquid 

 had been filtered after the first precipitation, ignited, and 

 weighed. The filtrates were tested for dissolved magnesium 

 as in former experiments. In experiments in which the fil- 

 tration was made after twenty minutes it was found advisable 

 to hurry the crystallization by stirring the mixture for not less 

 than five minutes after adding the precipitant. 



