n 9 



of the time, tended to disappear, or rather to return toward the 

 ancient superstitions. In the Key to Painting, as in the Egyptian 

 papyrus and the texts of Zosimus, are mentions of prayers to be 

 recited during the operations ; and in this way alchemy remained 

 intimately connected with magic in the middle ages as well as in 

 antiquity. 



When civilization began to revive during the Latin middle 

 ages, toward the thirteenth century, in the midst of a new 

 organization, our races took up anew the taste for general ideas, 

 and these, in the sphere of chemistry, were sustained by practices, 

 or rather they obtained their support in the permanent problems 

 raised by them. Thus the alchemistic theories were suddenly re- 

 vived, with new vigor and development, and their progressive evo- 

 lution, while improving industry, gradually eliminated the super- 

 stitions of former times. Thus was finally constituted our modern 

 chemistry, a rational science, established on purely experimental 

 bases. The science was therefore born in its beginning of indus- 

 trial practices ; it kept course with their development during the 

 reign of ancient civilization ; when science went down with 

 civilization, practice survived and furnished science a solid 

 ground on which it was able to achieve a new development 

 when the times and the minds had become favorable. The his- 

 torical connection of science and practice in the history of civili- 

 zations is therefore manifest. There is in it a general law of the 

 development of the human mind. Translated for The Popular 

 Science Monthly from the Revue des Deux Mondes. 



SKETCH OF SIR JOSEPH HENRY GILBERT. 



ON the 29th of July, 1893, the little village of Harpenden, in 

 Hertfordshire, England, witnessed a rare ceremonial and 

 was stirred by unusual emotions. The presidents of the scientific 

 societies of England were there, with other of the most eminent 

 men of science in the kingdom and foreigners of like standing ; 

 while others, their peers, were represented by letters. Mr. Her- 

 bert Gardner, M. P. and Minister of Agriculture of the United 

 Kingdom, presided; by his side were the Duke of Devonshire, 

 President of the Royal Agricultural Society ; the Duke of West- 

 minster, who, as chairman of the Executive Committee of the 

 Rothamsted Jubilee Fund, might be considered as manager of 

 the business for which the meeting was held ; Lord Kelvin, Presi- 

 dent of the Royal Society ; Dr. Michael Foster ; Dr. H. E. Arm- 

 strong, President of the Chemical Society ; Prof. Charles Stewart, 

 President of the Linnsean Society ; Sir J. D. Hooker ; Sir John 



