Professor Clarke, having become a member of the American Association for the Advancement of Science in 1869, assisted, in 1875-'76, in the organization of its section on chemistry, a branch which had theretofore been but little represented in the Proceedings of the association. Prof. S. W. Johnson was elected chairman of the new section for the meeting in 1876 at Detroit, and Professor Clarke was commissioned to make the necessary efforts to insure a full attendance of chemists and others interested in the applications of chemistry. In 1888 he presided over the section; and he has ever been active in building it up, and in the development of the American Chemical Society. Professor Clarke has published about seventy-five scientific papers in various journals, and many popular articles, especially in Appletons' Journal and the Popular Science Monthly. His first scientific paper, A New Process in Mineral Analysis, was published in the American Journal of Science for March, 1869. Other important papers have related to analytical methods, to the constitution of the tartrates of antimony, and to topics on chemical mineralogy, including especially the constitution of the silicates. Many of his popular articles relate to educational affairs, and present forcible arguments for a fuller recognition of science in the course of instruction, and cogent demonstrations of the need of better teaching of science and better qualified teachers. When occasion has arisen, he has fearlessly exposed and denounced humbug in education. In a paper on The Higher Education, published in the seventh volume of the Popular Science Monthly, having defined the purpose of true education as being "to develop the mind; to strengthen the thinking faculties in every possible direction; to render the acquisition of new knowledge easier and surer; to increase the student's resources; and to render him better fitted for dealing with the useful affairs of the world," he sets forth the advantages of science over the ancient and even the modern languages for the accomplishment of it. Science, he reasons, furnishes as good an instrument for cultivating the memory, and has the additional advantage of strengthening the perceptive powers too, for in it the eye, the ear, and all the instruments of the senses are trained to observe facts accurately, as they are not trained to so great a degree in language study. It again takes the lead in the cultivation of the pure reason; for it gives grand laws and generalizations already deduced or in process of deduction. "The discovery of these natural laws may be counted among the greatest achievements of the human mind. To follow out the processes by which they were discovered gives the mind its most rigid training, and elevates the tone of thought in many other respects. The intellect becomes self-reliant and yet conscious of its own weak points." Also, in æsthetic development, scientific education is put foremost.