acids on zinc or iron, and he describes its properties in the first part of his paper "On Factitious Airs." In the same paper he discussed the properties of fixed air (carbon dioxide), and proved that fixed air and the air produced during fermentation were the same.
Early in his career Cavendish made researches into the properties of heat—discoveries in regard to specific and latent heat which anticipated those subsequently made and published by Black—but it is said suppressed them that he might not enter into rivalry with the learned Scotch professor. One pauses in wonder to contemplate a man who could give away fame in so easy-going a fashion, and, moreover, was willing to do so.
The life of Cavendish presents a deeply interesting, but difficult, problem for the student of psychology.
His immense library was available to all his scientific acquaintances on condition that they did not disturb the owner; and on one occasion he was induced to allow a fellow-worker of small means to reside in his London library in order to catalogue and rearrange it. After leaving London, the poor fellow was not in the best of health, and was indifferently provided for. It was suggested to Cavendish that he was deserving of "a little annuity for life." "Well, well, well, a cheque for ten thousand pounds, would that do?" asked Cavendish; and a cheque for that amount was accordingly written. This was the only generous act in his long life of eighty years; and he
