I visited Sir Kenelm Digby, with whom I had much discourse on chemical matters. I showed him a particular way of extracting oil of sulphur, and he gave me a certain powder with which he affirmed that he had fixed ☿ (mercury) before the late King. He advised me to try and digest a little better, and gave me a water which he said was only rain water of the autumnal equinox, exceedingly rectified, very volatile; it had a taste of a strong vitriolic, and smelt like aqua fortis. He intended it for a dissolvent of calx of gold; but the truth is, Sir Kenelm was an arrant mountebank. Came news of the gallant Earl of Derby's execution by the rebels.