2i 4 THE POPULAR SCIENCE MONTHLY. 



CHEMISTEY IX ITS BELATIONS TO MEDICINE* 



By IEA KEMSEN, 



PROFESSOR OF CHEMISTRY IN THE JOHNS HOPKINS UNIVERSITY. 



IF we look back over the field of chemistry, we find that we can 

 easily discern well-characterized periods in its development. At 

 first, in this subject, as in all others, came the period of chaos, during 

 which relations of similar facts were not recognized nor suspected. No 

 defined object was in view; and the development during this period 

 was due almost entirely to accidental observations of facts which 

 presented themselves to men in pursuing their ordinary occupations. 

 Gradually we find that a certain class of men began to make use of 

 chemical facts, as far as they were then known, for a very definite 

 purjDose. This was, to convert ordinary base metals into that metal 

 which possessed the greatest value gold. This purpose gave a pow- 

 erful incentive to the study of chemical phenomena, and, under the 

 influence of the natural passion which affected a comparatively large 

 number of men, the subject of chemistry grew apace. But the impos- 

 sibility of accomplishing the great problem of the alchemists became 

 more and more apparent. No gold was made from baser metals, and 

 no genuine philosopher's stone was discovered ; no panacea for all dis- 

 eases was revealed. A reaction in scientific opinion then began, which 

 led to very much modified views concerning the purpose of chemistry, 

 until about the time of Paracelsus, who was both physician and chem- 

 ist, we find that the opinion prevailed very generally, among those 

 who were most active in investigating chemical phenomena, that the 

 changes which take place in the animal body, under normal conditions, 

 are nothing but chemical changes ; that a disturbance of these normal 

 changes causes the different varieties of disease; and, finally, that the 

 treatment of disease nvust consist in administering such chemical sub- 

 stances as would restore the normal conditions. Paracelsus started 

 these ideas, and others developed them, until they took the exaggerated 

 form comprised in the above statements. According to these ideas, 

 medicine was considered as a branch of chemistry, very much as met- 

 allurgy is now considered as a branch of chemistry. Hence the physi- 

 cians of the date of which I am speaking i. e., from the early part of 

 the sixteenth until some time in the seventeenth century regarded 

 chemistry as the one important subject for those who were to deal with 

 disease. Without a knowledge of this subject they could not com- 

 prehend the processes of life; without it they could not understand 

 disease; without it they could not intelligently administer remedies. 



* From the Animal Address delivered before the Medical and Chirurgical Faculty of 

 Maryland. 



