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N the 31st of January last the Royal Society of England held a special meeting in Burlington Gardens. Formal invitation to this meeting had been extended to the members of two other scientific bodies, and an audience of at least eight hundred, which included the most distinguished scientific men of England, assembled to listen to the account of the discovery of a new substance in our atmosphere. This discovery, made by Lord Rayleigh and Prof. Ramsay, had been announced at the Oxford meeting of the British Association last August; but five months of patient and strenuous work proved necessary before the investigators felt prepared to publish the detailed results of their research.

Our atmosphere consists essentially of a mixture of oxygen and nitrogen. To the oxygen it owes its power of supporting respiration and combustion; while the nitrogen, inert and incapable of chemical union under ordinary conditions, acts as a diluent, tempering the fierceness of the chemical activity which un-mixed oxygen possesses. Both of these gases were discovered more than one hundred and twenty years ago; they have long been recognized as elementary substances, and innumerable analyses have established the proportion in which they occur in air.

When a measured quantity of air, carefully freed from the moisture and carbon dioxide which it always contains, is passed through a tube filled with red-hot copper, the oxygen is fixed by the copper, and the residual gas, amounting to four fifths of the original volume, is found to be incapable of supporting combustion. It is, in fact, what all chemists have considered, up to the time of this brilliant discovery, pure nitrogen.

It is now proved beyond all possible doubt or question that this atmospheric nitrogen is not a single substance, but contains, mixed with it to the amount of about one per cent, another heavier gas, whose existence was previously unknown and unsuspected. To this new substance, which out-nitrogens nitrogen in its chemical inertness, its discoverers give the name of argon

Besides its occurrence in the free state in air, nitrogen is found in combination in animal and vegetable substances, in saltpeter or niter (from which its name is derived), and is a constituent of