444 PROCEEDINGS OF THE AMERICAN ACADEMY 



Three precipitations left the titanic oxide of these experiments 

 nearly free from alumina, but three such treatments involve a good 

 deal of labor, and, moreover, it is evident that the precipitate still holds 

 with tenacity traces of alumina. The experiment of attempting to 

 remove residual alumina after a single precipitation, by trenting the 

 product of fusion of the precipitate in sodic carbonate with boiling 

 water, filtering, igniting the residue, again fusing with a little sodic 

 carbonate, and proceeding from this point to dissolve in sulphuric acid 

 and precipitate once more as before, was therefore tried, and the result 

 is given in the record of (47) to (50). 



Weight of Solution. TiOj found. TiOo by Standard. Error. 



(47) 20.8040 grni. 0.1329 grm. 0.1337 grm. 0.0008 grm.— 



(48) 21.1100 " 0.1345 " 0.1354 " 0.0009 " — 

 (40) 20.9100 " 0.1.332 " 0.1340 " 0.0008 " — 

 (50) 21.0020 " 0.1348 " 0.134(j " 0.0002 " + 



This mode of treatment appears to remove the last traces of alu- 

 mina, and yields a reasonably good separation. 



It appears therefore, to recapitulate, that for the separation of 

 titanium and aluminum either of the processes set forth in the preced- 

 ing work may serve. The first, however, — which is, in brief, the 

 treatment of the solution containing salts of the elements in question 

 with a mixture of microcosmic salt and formic acid, in the proportion 

 of two to three by weight, together with enough ammonic formate to 

 take up the stronger acids, fusing the precipitate in sodic carbonate, 

 extracting with water, fusing the residue in a small amount of sodic 

 carbonate, dissolving in sulphuric acid and precipitating l)y ammonia 

 with the subsequent addition of acetic, and boiling, — thougli probably 

 fairly accurate, is, on account of the nature of the precipitated i)hos- 

 phate, not comparable with the second method in point of convenience. 

 The latter process, which involves many different manipulations, — the 

 introduction into the solution of titanium and aluiniiiuni of enouiih 

 acetic acid to make from seven to eleven per cent by volume of the 

 absolute acid, together with sufficient sodic acetate to fix all of the 

 stronger acids in sodium salts, boiling, filtering, and washing with 

 acetic acid of seven per cent strength, fu.^ing the ignited precipitate in 

 sodic carbonate, extractinof with boilinir water, ajjain fusing the residue 

 with a little sodic carbonate, dissolving in strong sulphuric acid and 

 pouring this solution into water, neutralizing with ammonia, redissolv- 

 ing the precipitate in a known amount of sulphuric acid, and pre- 

 cipitating finally by boiling with acetic acid and sodic acetate as at 



