IN 1904 Prof. N. S. Kurnakov (1860–1941) invented a new form of recording pyrometer which was a great improvement on that of Roberts-Austen. In 1910 Prof. A. A. Baikov still further improved this pyrometer by a modification which allowed the recording of the differential curve to be superimposed on the ordinary cooling or heating curve. This apparatus provided a very delicate method for the thermal analysis of alloys and minerals, called by Kurnakov in 1913 'physico-chemical analysis'1. Through the initiative and enthusiasm of Kurnakov, a very flourishing school of research was established, and in 1918 a special Institute of Physico-Chemical Analysis was founded at the Academy of Sciences.