232 HISTORY OF SCIENCE. 



Boyle first proposed several of the methods which the analytical 

 chemist still uses as the most delicate means of recognizing the pre- 

 sence of certain substances. For instance, it was he who introduced 

 the use of vegetable infusions, or papers tinted with them, to find 

 whether a liquid be acid or alkaline. The employment of tincture of 

 galls to discover traces of ferruginous compounds, of nitrate of silver 

 to detect common salt, and of ammonia to recognize the presence of 

 copper, is due to Boyle. He complains of the chemistry of his time 

 for being merely a matter of routine a collection of experiments 

 without connection or philosophic order, and resting on no solid prin- 

 ciple. 



Among the noteworthy chemists of the seventeenth century may be 

 named JOHANN KUNCKEL (i 6 1 2 1 702), the discoverer of phosphorus, 

 and he freely communicated his method of preparing that substance to 

 several persons, although he did not publish the method in his works, in 

 order, as he says, that he might not become the indirect cause of serious 

 accidents arising from the very inflammable nature of the substance. 

 It should be mentioned that a Dr. Brand, of Hamburg, was the first 

 who prepared phosphorus, but he kept the process secret. Kunckel 

 in Germany, and Boyle in England, appear, however, to have inde- 

 pendently rediscovered the process, guided only by a knowledge that 

 the source of the new substance was urine. Kunckel attacked the 

 alchemical theory, and declared that, after working in chemistry for 

 sixty years, he had neither discovered sulfur fiscum nor found how it 

 could make part of any metal. 



JOHANN JOACHIM BECKER (1635 1682), a German chemist, whose 

 writings show some tendencies towards the alchemical doctrines, is 

 chiefly noticeable by the circumstance of his works containing the 

 germs of a theory which was developed by the Bavarian chemist and 

 physician, GEORGE ERNEST STAHL (16601734), who afterwards be- 

 came very famous. It was the doctrine of Becher that metals contain 

 a combustible principle, which he calls " an inflammable earth." This 

 doctrine was the foundation of Stahl's theory of Phlogiston. Such was 

 the name Stahl gave to the " inflammable earth " of Becher, and he 

 regarded it as a subtle principle residing in inflammable bodies and 

 in metals. Fire is according to Stahl nothing but rapid escape of 

 the phlogiston contained in the combustible body. When a metal, 

 lead for example, is heated in the air, it gives up its phlogiston, and 

 is converted into a dull powder, or calx, as it was then termed. The 

 calx of lead, or litharge, is lead deprived of its phlogiston, and it has 

 only to be again united with phlogiston to become again the metal. 

 If, therefore, lead calx be heated with charcoal, which contains much 

 phlogiston, the phlogiston will leave the charcoal, and, uniting with the 

 calx, will reproduce the metallic lead. Thus, according to Stahl, the 

 calcination of a metal is an analytical operation that is, a separation 

 of the metal into the calx and phlogiston of which it is compounded ; 



