Proceedings 2 1 1 



of the compounds entirely free from either lead or antimony or both. 

 No less than twenty different variations of process recommended 

 by authors of texts and practical chemists were tried with no complete 

 success. At last the following plan was devised which at least for the 

 ore in question works v/itli entire satisfaction. ■. 



PROCESS. 



1. Digest one gram of ore in strong hydrochloric acid containing 

 a little nitric acid, for half an hour. Then if necessary add more hy- 

 drochloric acid and about 5cc of nitric to complete the solution. 

 Heat a few minutes and dilute. Filter and weigh residue as insoluble 

 siliceous gangue. 



2. Boil the filtrate and add enough dilute sulphuric acid to pre- 

 cipitate all of the lead in the form of PbSOi. Add alcohol and allow to 

 stand several hours, or better, evaporate till white fumes appear. Di- 

 lute cautiously, filter and weigh. 



3. To the filtrate from the precipitation in (2) add ammonium 

 chloride and ammonia in considerable excess. The precipitate con- 

 tains the iron in the form of Fe. Og He which is filtered and ignited and 

 weighed as Fe^ O3. 



4. Pass H2 S gas through the filtrate from (3). A grayish white 

 precipitate of zinc, ZnS, and of copper, CuS, are formed. Filter. The 

 filtrate contains antimony still in solution, the two mixed precipitates 

 must be treated for separation. 



5. To the filtrate from (4) add hydrochloric acid to acid reaction 

 and H2S gas. Antimony sulphide Sbo S3 forms. Filter and follow the 

 usual method of handling this precipitate. 



6. Dissolve the precipitate from (4) in hydrochloric acid. To this 

 add HoS gas which will precipitate copper as CuS. Filter and ignite 

 weighing as either Cu, S or Cu. O,. (The amount of copper is the 

 same in each.) 



7. To the filtrate from (6) add ammonia to strong reaction and 

 pass Ha S gas through. Zinc is precipitated, ZnS. Weigh as. Zn O. 



Analysis of the ore made after this scheme separated easily and 

 completely, and the results checked within the usual limits of error. 



The list of delinquent dues was referred to Professor Hall 

 and Secretary Meeds. 



Hon. Frank Ives of Crookston, Minn, was elected delegate- 

 of the Academy to the International Congress of Geologists to^ 

 be held at St. Petersburg during the coming summer. 



235th Meeting, April 5, 1897. 



Twenty-one persons present. 

 TVesident Winchell in the chair. 

 I'rogram : 



