138 R. B. Riggs — Separation of Iron, Manganese and 



Weight of MnO found In 



Weight of Fe 

 taken. 



Weight of 



MnO 



taken. 



1st filtrate 

 IromFe. 



2d filtrate. 3d filtrate 



s. Total. 



Error. 





grm. 



grm. 



grm. 



grrr 



i. grm. 



grm. 



grm. 



(14.) 



0-2248 



0-3341 



0-0342 



0-0005 none 



0-0347 



0-0005 + 



15.) 



0-2248 



0-0678 



0-06R1 



0-0006 trace 



0-0687 



0-0006 + 



16.) 



0-2250 



0-1088 



0-1073 



0-0013 none 



0-1086 



0-0002 — 



lii.) 



0-2252 



0-1500 



0-1477 



0-0024 none 



0-1501 



0-0001 + 



(18.) 



0-2253 



0-2042 



0-2003 



0-0034 trace 



0-2037 



0-0005 — 





eight of Ca' 



W 



eight of CaO found in 









1 st Fe filtrate. 



2d] 



?e filtrate. 





W 



IstMn 



2dMn 







taken 



filtrate. 



filtrate. 





Total. 



Error. 





grm. 



grm. 



grm. 



grm. 



grm. 



grm. 



(14.) 



o-ivoo 



0-1650 



0-0025 



0-0020 



0-1695 



0-0005 — 



(15.) 



0-1700 



0-1640 



0-0044 



o-ooio 



0-1694 



0-0006 — 



(16.) 



0-1702 



0-1611 



o-oo 



74 



0-0013 



0-1698 



0-0004— 



(17.) 



0-1700 



0-1640 



0-0038 



0-0016 



0-1694 



0-0006 — 



(18.) 



0-1701 



0-1614 



0-0059 



0-0023 



0-1696 



0-0005 — 



111 separating calcium from manganese in the first filtrate 

 from iron three precipitations were made. In no case did the 

 third filtrate contain enough calcium to show. 



From the above analyses the necessity of two precipitations 

 in separating manganese from iron and calcium from iron and 

 manganese is evident. More than that seem superfluous. 



In general the amount of manganese found in the second 

 filtrate from iron is proportional to its total quantity. It fre- 

 quently happens however that in neutralizing the solution, 

 preparatory to the acetate separation, the manganese is pre- 

 cipitated and partially oxidized, in which case its resolution is 

 impracticable. This oxidation is probably due rather to the 

 action of the air than to any after effect of acetic acid. In 

 separating manganese and calcium the completeness of a single 

 separation seemed to depend, if anything was to be inferred 

 from the above analyses, as well on the nature of the manga- 

 nese precipitate as on its quantity. 



It will be noticed that the manganese errors, with but one 

 exception (16) are positive and the calcium errors, with one 

 exception (12), are negative. This is to be anticipated. The 

 positive error in the case of manganese comes from the use of 

 a non-volatile precipitant. The negative error of calcium is 

 probably owing to the fact that the oxalate is not absolutely 

 insoluble. 



The indications being that two precipitations are necessary, 

 where the calcium and manganese are either or both present 

 in quantities, a series of separations was made varying both 



