1 2 Biography of Berzelius. 



potassium with silica. Berzelius found that it was impure sili- 

 cium, which, when washed with water, could be obtained free 

 from all fluorine compounds. It then contained only an ad- 

 mixture of silica, which could be extracted by concentrated 

 hydrofluosilicic acid, after having previously been slowly 

 heated to redness. He moreover shewed that the silicium 

 could be obtained in different states of density, and with dif- 

 ferent characters. 



This unexpected result induced him to undertake similar 

 investigations with fluoride of boron. We are indebted to him 

 for a correct knowledge of the decomposition of fluoride of 

 boron by water, and of the composition of the fluoborides, as 

 well as an easy method of preparing boron, by treating fluo- 

 boride of potassium with potassium. He likewise disco- 

 vered at this time the gaseous chloride'of boron, and correct- 

 ed the views of the composition of boracic acid by his own 

 experiments and those of Arfvedson. He moreover prepared 

 the compounds of fluoride of titanium with metallic fluorides, 

 especially fluoride of potassium, from which body he shewed 

 how metallictitanium was to be obtained by means of potas- 

 sium. This is the only method by which titanium can be 

 obtained in a pure state ; for the experiments of Wbhler have 

 proved that the substance found in the slags of iron furnaces, 

 and formerly called metallic titanium, contains nitrogen and 

 cyanogen. The compounds of fluoride of tantalum with me- 

 tallic fluorides were also prepared, and he obtained metallic 

 tantalum in the same way as titanium. He then reduced zir- 

 conium from the zirco-fluoride of potassium by means of 

 potassium, studied the characters of zirconia, and finally 

 turned his attention to the double compounds of fluoride of 

 molybdenum and fluoride of wolfram with metallic fluorides, 

 of which, however, he only prepared the compounds of fluoride 

 of potassium with molybdate and tungstate of potash. 



Berzelius had intended to pursue these very interesting 

 investigations of fluorine compounds further. But when he 

 found that a distinguished French chemist had also com- 

 menced the study of fluorine compounds, and had already 

 named some newly discovered ones, he gave up his intention. 



It must be remarked, that in these investigations Berzelius 



