KERRIDGE (Tookey), Phyllis, English chemist, d-1940. Her higher education was at University College, London, following the PhD in 1927, she took medicine and gained the MRCS in 1933 and the MRCP in 1937. The use of her maiden name Tookey continued professionally after marriage. From 1935 she was a lecturer in physiology at University College. After a short career, spent mainly acquiring qualifications, she died. Phyllis is notable for her original PhD thesis ‘Use of the Glass Electrode in Biochemistry’. With many straightforward chemical reactions an ordinary glass electrode provides an adequate electrical signal to determine the pH. However, when dealing with biochemical reactions the changes to be detected may be minute and the potentials resulting would be undetectable. Another limitation is that reaction volumes and tube sizes are also minute, it was not practicable to enlarge electrodes so as to get measurable potentials. Kerridge’s answer was to maximise the electrode surface area, without increasing the size of the outer container. She heat treated the platinum electrode with potassium chloride at red heat and generated a huge effective surface area for the potential measurement. It then became feasible to insert such fine electrodes into living tissue layers to follow the biochemical reactions in vivo, a major advance