5 0 D O C U M E N T 5 J U N E 1 9 2 7 [1] Einstein had misspelled Ernest Solvay’s name as early as 1911 (see Einstein to Ernest Solvay, 22 November 1911, [Vol. 5, Doc. 312]). [2] See Abs. 9. The Fifth Solvay Congress was planned for 24–29 October. [3] Einstein refers to the work leading up to Einstein 1928b (Doc. 91), the follow-up paper to Einstein and Grommer 1927 (Vol. 15, Doc. 443). There, Einstein and Jakob Grommer had asserted that if one represents massive particles by singularities in the metric field, then the gravitational field equations uniquely determine the equations of motion of the particles. They gave an argument that relied on a certain “equilibrium condition,” interpreted as the gravitational field surrounding the par- ticle being stationary (on p. 9 of the paper), and announced that a follow-up paper would attempt to extend the argument to the case of electrons, i.e., particles that are both massive and electrically charged. Indeed, the authors argue that the equations of motion of electrons (i.e., the Lorentz force law) are uniquely determined by the Einstein-Maxwell equations. At the same time, Einstein aims to get rid of assuming the equilibrium condition. [4] In the fall of 1926, Einstein had informed Grommer, who had often fulfilled this function since about 1917, that he could no longer support him as his assistant with the 200 M monthly stipend. Einstein later complained to his wife that Grommer had been “impudent” (“frech” see Einstein to Elsa Einstein, 4 October 1926 [Vol. 15, Doc. 374]). Nevertheless, he succeeded in obtaining replace- ment funding for Grommer from the Notgemeinschaft der Deutschen Wissenschaft for the period 1 December 1926 to 1 May 1927, and tried to further the publication of Grommer’s Hebrew mathemat- ics textbook (see Einstein to Friedrich Schmidt-Ott, 20 October 1926 [Vol. 15, Abs. 605]), Einstein to Notgemeinschaft der Deutschen Wissenschaft, 11 December 1926 (Vol. 15, Abs. 672), and “Pro- posal to Publish Jakob Grommer’s Book,” 21 October 1926 (Vol. 15, Doc. 388).