THE EARLY DAYS OF CHEMISTRY 13 



Geber and his disciples, namely salt, or, as he terms it, 

 ' salt of the philosophers ' ; it is the constituent of matter, 

 which confers solidity, and which remains after the volatile 

 mercury and sulphur have been removed by heat. 



In the first half of the sixteenth century Paracelsus 

 extended and applied the suggestion of Basil Valentine, 

 and founded what became known as the school of ' iatro- 

 chemists' a body of men who taught that the chief 

 object of chemistry is not the transmutation of metals, 

 but the application of chemical substances to medical 

 uses. He adhered, however, to Valentine's theory of the 

 three principles ; but he applied them to the human 

 body, teaching that the organism itself consists of these 

 principles, and that disease, owing its origin to a deficiency 

 of one of them, is to be combated by its being restored 

 to the system. Increase of sulphur, he taught, gives rise 

 to fever and the plague ; increase of mercury to paralysis 

 and depression ; and of salt, to diarrhoea and dropsy. Too 

 little sulphur in the organism produces gout ; delirium is 

 caused by distilling it from one organ to another, and so 

 on in fanciful theorisings. One of the most fantastic is his 

 attributing the nutrition of the body to a beneficent spirit, 

 named the ' Archseus,' who resided in the stomach, and 

 presided over the function of digestion. But these 

 curious notions have little bearing on the development 

 of chemistry. The teaching of Paracelsus, however, had 

 the good effect of directing attention to an important 

 branch of chemistry its use in pharmacy. And from 

 his time onwards, indeed, up to the middle of last cen- 

 tury, many of the best-known chemists had received a 

 medical training, and the ranks of chemical investigators 

 were largely recruited from the medical profession. 



Although the alchemists, after the beginning of the 

 seventeenth century, exercised little influence on the 

 progress of chemistry, they continued their fruitless 



