Lessons of REEs History

REEs history is very instructive. It was written by dozens of self-sacrificing and hard-working chemists of several generations and there was no place in it for those who were after easy fame and success. Tedious and endlessly repeated procedures for separating twin-elements required boundless patience. 

REEs history was greatly affected by the discovery of new rare-earth minerals. We have already told you about the great importance of discovering deposits of samarskite and monazite which satisfied all the requirements of scientists for materials. This dependence on material is unparalleled in the history of other elements. And, finally, nothing else posed so many difficulties to the periodic table as the prob- 

The discoveries of helium and radon stand out as unusual. Radon was discovered as a result of radioactivity studies, or, more precisely, owing to the application of the radiometric method. Therefore, we shall deal with it in Chapter 11, which is devoted to the history of radioactive elements. The discovery of helium occupies an exceptional place in the history of chemistry. In 1868 a line was detected in the spectra of solar prominences, which could he assigned to none of the elements known on the earth. This line was attributed to a new element on the sun which was called helium . Twenty seven years later helium was first extracted on Earth. 

Helium s unusual story attracted attention of many scientists and science historians, but the real sequence of events was distorted in numerous descriptions which overgrew with a lot of fictional details. Even a legend was invented— 

The French astronomer J. J anssen and the English astronomer N. Lockyer are considered to he the discoverers of helium. They studied the total solar eclipse of 1868 which was especially convenient to observe on the Indian ocean shores. In letters sent to the Paris Academy of Sciences and read ont at one of its sessions they wrote that the spectra of the snn photographed during the eclipse contained a new yellow line corresponding to an unknown element. To commemorate this remarkable event (the discovery of a new element existing on the snn hnt not on the earth) a special medal was minted. 

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