June 3, 1892.] 



SCIENCE. 



315 



was lost in passing from one to the other; even at times 

 when he was not passing through the laboratory, a student 

 requiring an answer to a serious question was always at liber- 

 ty to seek him in his private laboratory or his library. He re- 

 stricted his personal instruction, however, to a fourth of the 

 students who were at work in the laboratory building, turn- 

 ing over the rest completely to his assistants. He lectured 

 three to five times a week for two consecutive hours, always 

 on elementary .subjects. In winter the course was upon 

 general inot-ganic chemistry ; in summer upon organic chem- 

 istry. These lectures were profusely illustrated, very enter- 

 taining, and remarkably lucid. But their purpose was 

 evidently much more to interest the beginner and to show 

 him the beauties of the treasures within reach, than to pre- 

 sent an actual key to these treasures, or, in other words, 

 to deeply impress facts upon his mind. For eloquence and 

 noble enthusiasm no speaker could surpass him. 



As a teacher in the laboratory he was painstaking to the 

 last degree. Restricting himself to a favored few and prac- 

 tically limiting the range of their instruction to organic 

 synthesis, he endeavored to visit each at his desk once or 

 twice a day, and would give him all the time he needed. 

 Each new comer was put, for a longer or shorter period, 

 at the preparation of well-known compounds, merely for the 

 sake of practice. It was delightful to see the interest which 

 he took in this routine work, the manner in which he made 

 each tyro feel as if something depended upon the careful 

 completion of these tasks. He would hail each carefully 

 prepared specimen as if it were the most novel thing in the 

 world to himself, and if it happened to be a substance upon 

 which he had worked in former years, he would take especial 

 pleasure in exhibiting all its properties. After a certain 

 time, the student would be put upon an "original" investiga- 

 tion. As a general thing, it must be confessed, the results 

 of these investigations did not show too much originality. He 

 generally assigned subjects closely allied to work that was 

 being done or had been done in his own private laboratory, 

 the work of his students generally presenting corroborative 

 evidence to results already obtained. But he always en- 

 couraged original thought, and was very ready to give credit 

 for it. Whether the student was dull or bright, whether his 

 investigation proved interesting or not, Hofmann was always 

 helpful and encouraging; the only thing he could not stand 

 was laziness. As a matter of fact, in spite of the freedom 

 from disciplinary control in German universities, few Ameri- 

 can college laboratories could show so constant an attendance 

 at all hours. He always took the greatest interest in the 

 personal welfare of his students, and, especially if they were 

 foreigners, would treat them as if they were instrusted to his 

 personal care. 



In his own work, he was indefatigable, and his private 

 assistants, of whom there were four or more, certainly had 

 arduous duties to perform ; he would frequently work with 

 them from 8 a.m. until 11 p.m. When he was a younger man, 

 there were times when work was continued in relays, without 

 any intermission, until it was completed. But there was 

 never a lack of volunteers to fill any vacancy on his staff of 

 assistants, even though the pay was very moderate. In re- 

 turn, he was kindness itself in looking out for their future 

 and in providing for their relaxation in vacation time, so 

 that they were always his enthusiastic followers. 



As to his scientific achievements, the present writer is not 

 sufficiently presumptuous to even hint a personal opinion; he 

 believes, however, that it is the general judgment among 

 those best qualified to speak, that Hofmann's great success 



was due to his great energy, his marvelous dexterity of 

 manipulation and observation, and careful deductive rea- 

 soning, rather than to any startling brilliancy of invention, 

 such as that of his master, Liebig. Hofmann's contributions 

 both to pure and to industrial chemistry are those of the 

 investigator, not of the inventor. He neither invented the 

 "type" theory of Laurent and Gerhardt; nor did he first 

 discover the production of coloring matter from aniline ; in 

 the various discussions of the fundamental structural for- 

 mulae, he rarely took part. But, the type theory once 

 given, it was he who did the most to elucidate the " am- 

 monia-type;" when rosaniline had been produced, it was his 

 privilege to clearly explain the reasons that had brought 

 about this happy accident and to show how the whole gamut 

 of colors could be produced in a similar manner. The com- 

 plicated ureides, the innumerable benzol derivatives, the 

 natural and artificial alkaloids were all manipulated by him 

 in a manner to make them more accessible to further study 

 and more useful to mankind. Generalizations and meta- 

 physical speculations were entirely foreign to his nature. 



A peculiarly apt illustration of this bent of his mind may be 

 found in the manifold apparatus he invented for the purposes 

 of demonstration or investigation. While it never involved 

 the application of new principles, as did those of Lavoisier, 

 Gay-Lussac, Davy, Faraday, or Victor Mayer, it always 

 showed the most thorough knowledge and most ingenious 

 applications of all established methods of physics and of 

 chemistry. For elegance and for the unfailing certainty of 

 success in working, the apparatus invented by him will 

 always stand pre-eminent. 



To illustrate his energy and power of self-sacrifice, I 

 would instance the occurrences after a serious illness which 

 befell him at the age of 68, in the spring of 1886. He had 

 been confined to his room for several weeks, and was not 

 allowed to see anyone; barely recovered, he sent for his 

 assistants, to hear their reports and sketch out new work; 

 before he was allowed to leave his own house he sent for his 

 students, day by day, to talk over their progress. As soon 

 as the physician grudgingly assented, he resumed his lectures, 

 not only speaking for two hours a day, at the regular hours, 

 but actually striving to make up for lost time by giving an 

 additional lecture three times a week from 6 to 8 A. M. ! Such 

 a tax upon the strength of an old man, weakened by sick- 

 ness, seems tremendous. But he seemed not to mind it Id 

 the least. 



As a traveller, too, he was untiring: fatigue which com- 

 pletely overcame younger men, did not seem to exist for 

 him; as a matter of fact, the extreme Orient and Australia 

 were the only civilized regions which he did not visit, and 

 these he would surely have sought to reach, if his conscien- 

 tiousness had not prevented his seeking a sufficiently pro- 

 tracted leave of absence. 



He always spoke with special pleasure of his visit to the 

 United States in 1883, and seemed greatly to appreciate the 

 cordiality of his reception here. Probably he had a better 

 understanding of the limitation imposed upon scientific 

 research in America than do most foreigners; for he has 

 always praised what has been done, without churlishly 

 demanding the perfection reached at older and more firmly 

 established centres of knowledge. 



In his private life, he was greatly beloved by all who 

 knew him, and he certainly was able to make and maintain 

 the warmest friendships. In his later years, he devoted 

 much of his time and ability to the bitter-sweet task of seal- 

 ing this intimacy with an eloquent testimonial to the worth 



