406 Prof. W. N. Hartley and Mr. H. Ranmge. 



A brownish coloured precipitate was removed by filtration. It con- 

 tained copper, lead, and silver, but no gallium. The nitrate was 

 boiled to expel sulphuretted hydrogen, and the gallium precipitated 

 with ammonia as described above. The precipitate was collected and 

 ignited. It weighed 0*0288 gram. 



This residue possessed a very light yellow colour. One milligram 

 was burnt in the oxyhydrogen flame ; its spectrum shows the two 

 gallium lines very strongly. Lines of sodium, potassium, iron, calcium, 

 and lead are present, but those of the last three are exceedingly weak. 



The remaining 0*0278 gram of residue was fused with hydrogen 

 potassium sulphate ; water and sulphuric acid were added, and the 

 crucible heated until fumes of sulphuric acid were evolved. Water 

 was again added, and a small residue removed by filtration. This 

 residue weighed 0*0040 gram. 



The gallium was separated from the iron by two extractions with 

 caustic soda solution. The ferric hydrate was dissolved in. hydro- 

 chloric acid, and reprecipitated by ammonia. The ferric oxide 

 weighed 0*0022 gram. 



The gallium in the nitrate was then reprecipitated and weighed as 

 oxide. It weighed 0*0213 gram. 



A few drops of sodium phosphate were added to the filtrate, and 

 sufficient ammonia to make it turn red litmus paper blue. After 

 boiling for a few minutes the liquid was filtered, the paper being 

 dried and burnt in the oxyhydrogen flame. The gallium lines are 

 present in its spectrum, but are very weak. 



The oxide of gallium now possessed a scarcely perceptible, faint 

 yellow colour. It does not. represent the whole of the gallium present 

 in the sample, as a small quantity was removed and lost in testing 

 the precipitations and residues. We are able, however, to estimate 

 this quantity by comparing the lines in the different spectra with 

 lines and spectra obtained by heating weighed quantities of gallium 

 oxide. In this way we estimate the total quantity of gallium to be 

 as follows : 



Pure oxide _____ ........ ....... . 0*0213 gram. 



In 0*001 gram of impure oxide ---- 0*0008 



In residue insoluble in HKS0 4 ---- 0*0004 



In other substances ........... . ', . 0*001 



Ga s 3 , total ........ 0'0235 gram. 



0*0235 gram of pure Ga 2 3 contains 0*0175 gram of gallium, 



equal to ' 175 * 1Q = 0*00304 per cent. 

 575 



One part of gallium is contained in 33,000 parts of ornde iron. 



