THE GREAT LONDON CHEMISTS 25 



others in small quantity, must be added to those contained 

 in water to produce a ' pompion ' ; but it was a great step 

 to show that no salt, sulphur, or mercury were necessary. 

 Boyle viewed the ' pompion ' as simply transmuted water. 

 He quotes from M. de Roche, who stated that he had 

 transmuted earth into water, and vice versa. Of the 

 correctness of M. de Roche's opinion, he is not quite 

 sure, but he attaches a certain amount of weight to it. 



His second line of attack is to prove that the so-called 

 elements are themselves further resolvable. And begin- 

 ning with sulphur, he points out that what the chymists 

 understand by sulphur has not always the same properties. 

 It is, however, always inflammable. Sulphur, in the then 

 accepted meaning of the word, was the inflammable 

 portion obtained on distilling an animal or vegetable 

 substance; mercury, another portion, not miscible with 

 the sulphur; but uninflammable, and having taste; the 

 residue on incineration, or, as it was termed, the caput 

 mortuum, was salt. In an old writing on the subject, 

 salt is said to be the basis of solidity and permanency 

 in compound bodies ; oil or sulphur (the two words came 

 to have nearly the same meaning) serves the purpose of 

 making the mass more tenacious ; mercury is to leaven 

 and to promote the ingredients, and earth is to soak and 

 dry up the water in which the salt is dissolved. 



We note here a change in the manner of regarding 

 elements. They are no longer principles, or abstract 

 qualities of matter, but they exist in the matter, and can 

 be extracted from it by suitable processes. Their number 

 varied ; and phlegm or water was now accepted as elemen- 

 tary, now rejected, as suited the purpose of the theorist. 

 Boyle clearly showed that these elements had not always 

 the same properties; that the sulphur and mercury not 

 only differed in every respect from brimstone and quick- 

 silver, but that one variety, obtained by distilling wood, 



