101 B. B. Biggs — Separation of Magnesium Chloride 



tions with sulphuric acid in excess, evaporating, igniting and 

 weighing as sulphate.* 



The potassium chloride was obtained from the chlorate. 

 The chloride of sodium was prepared from sodium hydrate 

 (obtained from sodium) and further purified by precipitation 

 by hydrochloric acid. 



Both solutions were standardized by evaporating weighed 

 portions to dryness, drying at about 300° C. and weighing. 



The solutions, thus standardized, were fouud to contain 

 respectively 0-5293 grm. ]STaCl, - 5112 grm. KC1 and the equiv- 

 alent of '41-16 grm. MgO to the 100 grams. 



Three series of separations, containing severally- mixtures o± 

 magnesium chloride and one or the other or both of the alka- 

 line chlorides, were made. The solutions were evaporated 

 nearly to dryness. The residue, if any, was taken up with the 

 smallest possible quantity of water and a few drops of hydro- 

 chloric acid. 30-40 cc of amyl alcohol were then added and 

 the water was expelled by bringing the alcohol to the boiling 

 (128°-130° C.) Eight or ten drops of benzyl chloride were 

 added and the solution was evaporated to about 10 cc . A per- 

 forated crucible, an asbestus felt and pressure were used in 

 filtering. The filtrate was transferred to a weighed platinum 

 dish and the alcohol driven off by evaporation on a water bath. 

 As soon as the solution became viscous water was added and 

 the evaporation repeated. The residue was finally taken up 

 with water and sulphuric acid was added in slight excess. 

 This solution was evaporated to dryness and the residue ignited 

 and weighed as sulphate. The amyl alcohol precipitate was 

 dissolved and transferred to a weighed platinum dish, evapo- 

 rated to dryness and heated in an air bath at a temperature of 

 about 300° C. and weighed. 



The solubility corrections, as determined by Gooch,f were 

 introduced, viz : For every 10 cc of amyl alcohol solution, ex- 

 clusive of washings, 0*00051 grm. was added to the weight of 

 the insoluble chlorides in case the residue was potassium chloride, 

 O'OOOll grm. in case it was sodium chloride and '00092 grm. in 

 case both were present. Equivalent amounts were taken from 

 the weight of the magnesium sulphate. 



The results of these separations, including determinations in 

 many cases of the amounts of magnesia carried by the chloride 

 precipitates, are here given. 



* Several determinations as phosphate were made which, though agreeing 

 together, gave somewhat lower results than were obtained by weighing the mag- 

 nesium as sulphate. This may be due to impurities in the chloride or, as is 

 more probable, it may be owing to the slight solubility of the phosphate 



f Am. Chem. Jour., vol. ix. p. 4 8. 



