296 Browning and Drushel — Separation of Magnesium. 



(sp. gr. 1*20) and about the same amount of hydrobromic acid 

 (sp. gr. 1*3), or 1 to 3 grms. of ammonium bromide evaporated 

 to dryness under a draught-hood, the residue is gently ignited 

 to remove the ammonium salts. The residue is then transferred 

 to a weighed platinum crucible with a small amount of water, 

 a little sulphuric acid (1-1) added, and the solution evaporated 

 to remove the water and excess of sulphuric acid, by placing 

 the crucible on a triangle in a porcelain crucible used as a 

 radiator. After the sulphuric acid has ceased to fume, the 

 crucible is removed from the radiator, and after ignition at the 

 full heat of the Bunsen burner the alkali is weighed as the 

 normal sulphate. 



The results follow in Table II. 



Table II. 



c 



rH 4 ) 3 As0 4 



used 



alculated 



as 



As 2 3 



Dilu- 

 tion. 



NaCl or KCli converted to 

 Na 2 S0 4 or K 2 S0 4 and cal- 

 culated as Na 2 or K 2 



MgCl 2 converted into 

 MgjAsoOv and cal- 

 culated as MgO 





Taken 



Found 



Error 



Taken 



Found 



Error 





grm. 



cm 3 . 



grm. 



grm. 



grm. 



grm. 



grm. 



grm. 



1 



o-i 



100 



0-1194 



0-1191 



0-0003 — 



0-0199 



0-0197 



0-0002 — 



2 



0-2 



150 



0-1194 



0-1196 



0-0002 + 



0-0399 



0-0397 



0-0002 — 



3 



0-45 



250 



0-1 194 



0-1195 



0-0001 + 



0-0998 



0-0998 



o-oooo 



4 



0-45 



250 



0'1194 



0-1194 



o-oooo 



0-0998 



0-0997 



o-oooi — 



5 



0-45 



250 



0-2389 



0-2385 



0-0004 — 



0-0998 



0-0999 



0-0001 + 



6 



0-4 



250 



0-0478 



00481 



0-0003 + 



0-1198 



0-1193 



0-0005 — 



7 



0-35 



250 



0-0956 



0-0957 



0-0001 + 



0-0998 



0-0996 



0-0002 — 



8 



0-35 



250 



0-0956 



0-0957 



o-oooi + 



00998 



0-0994 



0-0004 — 



9 



0-45 



250 



0-0909 



0-0915 



0-0006 + 



0-0998 



0-0993 



0-0005 — 



10 



o-i 



100 



0-0545 



0-0549 



0-0004 + 



0-0006 



0-0004 



0-0002 — 



11 



o-i 



100 



0-1181 



0-1184 



0-0003 + 



0-0040 



0-0038 



0-0002 — 



12 



0-L 



100 



0-1181 



0-1184 



0-0003 + 



0-0040 



0-0038 



0-0002 — 



13 



o-i 



100 















0-0040 



0-0038 



0-0002 — 



14 



o-i 



100 



0-1181 



0-1184 



0-0003 + 



0-0040 



0-0040 



0-0000 



15 



0-2 



100 



0-1181 



0-1183 



0-0002 + 



0-0040 



00039 



o-oooi — 



16 



0-45 



250 



0-1181 



0-1179 



0-0002 — 



0-1002 



0-1004 



0-0002 + 



In experiments 1 to 10, the precipitate of magnesium was 

 allowed twelve to twenty-four hours to settle. In experiments 

 11, 12 and 13, 15 per cent alcohol was used to hasten the com- 

 plete precipitatiou of the magnesium, and in experiments 14, 

 15 and 16 the salt and ice mixture was used for the same pur- 

 pose. 



