To realize the importance of the work in which Mme. Lavoisier participated, it suffices to recall the fact that her husband, as one of the creators of modern chemistry, was the first to demonstrate the existence of the law of the conservation of matter, which declares that in all chemical changes nothing is lost and nothing is created. The co-discoverer with Scheele and Priestly of oxygen, he was the first one to exhibit the role of this important element in the phenomena of combustion and respiration and the first, also, to lay the foundations of a chemical nomenclature. We are not, then, surprised to learn that Mme. Lavoisier's salon, even long after her lamented husband's death, was frequented by the most eminent savants of the time. For here were gathered such scientific luminaries as Cuvier, Laplace, Arago, Lagrange, Prony, Berthollet, Delambre, Biot, Humboldt, and others scarcely less brilliant. After the conclusion of Mme. Lavoisier's work in the laboratory of her husband, little was accomplished by women in chemistry for more than half a century. The reason was simple. Chemistry was not a part of the curriculum of studies for girls either in Europe or America. Even "during the sixties," writes a teacher of one of the prominent female seminaries of the United States, "the study of chemistry was mostly confined to the textbook, supplemented once a year by a course of lectures from an itinerant expert, who with his tanks of various gases produced highly spectacular effects." When one recollects that the first institution in America--Vassar--for the higher education of women was not opened until 1865, one will understand that there were previously to this date few opportunities for women to study either chemistry or any of the other sciences. The first scientific institution to open its doors to women was the Massachusetts Institute of Technology. This was on May 11, 1876, when the governing board of the institute decided that "hereafter special students in chemistry shall be admitted without regard to sex." In less than a year after this event every department of this institution was open to women, and any one who could pass the requisite examination was admitted as a student. Five years, however, before women were formally admitted to the courses of chemistry an energetic young graduate from Vassar, eager to devote her life to the pursuit of science, had, as an exceptional favor, been allowed to enter the Institute as a special student in chemistry. As she was the first woman in the United States to enter a strictly professional scientific school, her entrance marks the beginning of a new epoch in the history of female education. The name of this ardent votary of science was Miss Ellen Swallow, better known to the world as Mrs. Ellen H. Richards.