542 POPULAR SCIENCE MONTHLY. 



ties by means of suitable reagents, whicli would at the same time 

 color it. These coloring reagents were designated, generally, the 

 philosopher's stone. 



Governed by these ideas, the Greco-Egyptian alchemists obtained 

 a great variety of metallic alloys, some white and nearly as un- 

 changeable as silver, to which they assimilated them; others yellow, 

 and having a stability like that of gold, of which they gave them 

 the name. Real gold and silver were besides often included in 

 the composition of these alloys, when they were regarded as the seed, 

 and were supposed to multiply, as if they had been living beings, 

 under the action of certain ferments. The alchemists frequently 

 found that their recipes for transmutation were not sufficient to pro- 

 duce gold and silver; that after combining a certain number of 

 properties, others were still wanting; at this point they fell back 

 upon the mystic part of their science. The confusion between real 

 silver and gold and the white and yellow alloys was carefully nursed 

 by the alchemists, who even went so far as to call gold and silver 

 metals which were only superficially colored by the action of mer- 

 cury and the sulphurets of arsenic, and metals that were only cov- 

 ered with a golden varnish. This confusion of language exists even 

 in the industries of our o\vn times, as when manufacturers speak 

 of the gold of a color or a cloth. — Translated for the Popular 

 Science Monthly from the Revue des Deux Mondes. 



THE LIFE AND WORK OF FELIX HOPPE-SEYLER.* 



By albert p. MATHEWS. 



1]^ the summer of 1895 the world lost two men, each of whom, 

 in his own way and in his own country, had exerted an un- 

 usual influence on the development of science. They were born 

 and they died within a few months of each other. Each was en- 

 dowed by ISTature with the gift of seeing the relationship of appar- 

 ently unrelated phenomena; each passed through a medical train- 

 ing; each devoted time, much against his will, to dissection and 

 anatomy; each was a fighter for what he believed true; each was 

 gifted with a winning personality that attracted friends from all 

 sides; each was a great teacher, having a ready sympathy for young 

 students, and each was remarkable for the breadth of his knowledge 

 and the keenness of his insight. One was Thomas H. Huxley, an 

 Englishman, the other Felix Hoppe-Seyler, a German. 



* In part adapted from an article entitled Zur Errinnerung an Felix Hoppe-Seyler. By 

 E. Baumann and A. Kossel. Zeitschrift fiir physiologische Chemie, Bd. xxi, 1895. 



