Directions:

Royal Society of Medicine (see Manaccan LINK: Manaccan411), 1 Wimpole Street - N51 30.94 W0 08.82.
Royal College of Chemistry (RCC) 1846-1872, involved in studies of thallium and helium, progenitor of the Chemistry Department of Imperial College, now a clothes shop, 299 Oxford Street - N51 30.89 W0 08.69.
RCC, first site for one year 1845, 16 Hanover Square - N51 30.86 W0 08.67.
Cavendish's 1st home 1738-1783, where he discovered hydrogen, 13 Great Marlborough Street - N51 30.87 W0 08.31.