SIR J. J. THOMSON'S reference to the discovery of argon, in his review in NATURE of December 6 of the life of Lord Rayleigh, will be read by chemists with surprise but without conviction, and though his comments upon chemistry must be received with the respect due to a late president of the Royal Society, they must also give rise to a certain amount of amusement. It is, however, with positive pain that many chemists have read Prof. Armstrong's letter upon this subject published in NATURE of January 10. What does he mean by “behind the scenes” and “Ramsay and his ways”?