574 PROCEEDINGS OF THE KEW YORK MEETING 



also he contributed to the improvement of analytical processes, publishing 

 in 1879 a paper "On a new volumetric method of determining fluorine." 



It appears that up to this time his interests were centered in the purely 

 chemical phase of his work, and it is doubtful whether he looked upon 

 the study of mineralogy as the probable occupation of his life, for in 1880 

 he went to Strasburg to attend the lectures and laboratorj^ of Professor 

 Eudolph Fittig for the purpose of acquiring advanced methods of work 

 in organic chemistry. He also attended some of the lectures in miner- 

 alogy given by Professor P. Groth. While in Strasburg he published, 

 with Professor Fittig, a paper on some of the hydrocarbon compounds 

 investigated in his laboratory. 



Whatever may have been his intention at this time, his course as a 

 mineralogist was determined upon his return to New Haven, in the 

 autumn of 1881, by the opportunity offered him to become instructor in 

 mineralogy in the Sheffield Scientific School in place of Doctor George W. 

 Hawes, who had been called to Washington, D. C., to take charge of the 

 geological department of the National Museum. 



Assuming the responsibilities of this position four years after his 

 graduation, he threw into the work of the course in determinative miner- 

 alogy and blowpipe analysis all the energy and enthusiasm of his nature, 

 injecting into the laboratory methods the skill and precision that char- 

 acterize his own analytical operations. At first his interest in miner- 

 alogy was chiefly in its chemical side, since the work with the students 

 largely involved the chemically determinative phase of the subject, and 

 his publications continued to treat of the chemical composition of various 

 minerals ; but an increasing interest in the physical properties of minerals 

 and in their crystallography led him in 1884 to go to Germany for the 

 second time, and to study with Professor Eosenbusch at Heidelberg the 

 methods of investigation so successfully employed by him in the petro- 

 graphical laboratory. This experience was followed by a broadening of 

 his methods of work and of the range of his investigations, so that the 

 phj'^sical characters of minerals, especially the optical properties and the 

 crystal form, were studied, in addition to their chemical composition. 

 In these operations he developed the same skillfulness of manipulation 

 and thoroughness which characterize his chemical work. 



In 1886 he became responsible for all of the mineralogical instruction 

 given in the Sheffield Scientific School, owing to the fact that the school 

 had increased to such a size as to require in its management all of the 

 time and energy of its director. Professor Brush. In 1888 Penfield was 

 appointed assistant professor, and in 1893 he was created a professor, and 

 in consequence Ijecame a member of the governing board of the Sheffield 

 Scientific School. 



