Biography of Berzelius. 199 



and shewed, with the greatest certainty, there could not pos- 

 sibly be any oxygen in crude iron. He determined the quantity 

 of carbon by converting it into carbonic acid. Subsequently 

 he attempted to estimate the carbon directly, by dissolving 

 the iron through the agenc}^ of chloride of silver or chloride 

 of copper. At that time attention had not been directed to 

 the difference between the chemically combined and the me- 

 chanically intermixed carbon or graphite. This was not re- 

 cognised until subsequently by Karsten, who also proved 

 that graphite consisted of carbon alone, and contained no 

 iron. While prosecuting the analysis of crude iron, Berzelius 

 made several interesting observations ; thus, among others, 

 he was led to propose the use of benzoic acid as a means of 

 separating peroxide of iron from protoxide of manganese and 

 magnesia, instead of the then more costly succinic acid re- 

 commended by Gehlen. He further shewed, that on treat- 

 ing crude iron with nitric acid, an extractive substance, having 

 the most perfect resemblance to the extract of vegetable 

 mould, is produced from the carbon of the iron. He also 

 accidentally discovered during this analysis the interesting 

 double salt of persulphate of iron and sulphate of ammonia, 

 the composition of which he was the first to determine qualita- 

 tively with accuracy. This salt he at first regarded as alum, 

 on account of the form, though he found no alumina in it. 

 He moreover pointed out that the silica which he obtained 

 after the solution of the iron did not exist in the crude iron as 

 such, but as silicium. However important the various facts 

 ascertained during this investigation might be, still Berzelius 

 was not fully satisfied w r ith the results obtained, since he could 

 not rely upon the correctness of the method which he had 

 employed for the quantitative determination of carbon nor of 

 magnesia, whose presence in the solution of crude iron he had 

 proved. On this account, he published his investigation 

 under the modest title of Attempt to Analyse Crude Jron. 



I now come to the most important period of Berzelius' 

 scientific activity. His previous achievements were owing 

 more to fortunate chance than to any leading ideas. He was, 

 to a certain extent, incited by the scientific interest of the 

 time to take up the galvanic investigations, by the friendly 



