President's Address. 13 



fuming liquid of Libavius, was due to one of his researches. 

 The object which he had principally in view in the course of 

 his labours was the preparation of medicines, but he was 

 also well known for his power of making artificial gems. He 

 seemed to be able to imitate almost any precious stone with 

 considerable fidelity ; this he did by a process which no doubt 

 was not very generally known in his day, but which is now 

 common enough. 



About thirty years after the death of Paracelsus, there was 



born in Brussels the celebrated John Baptist Von Helmont, 



who is said to have made such rapid progress in his studies, 



that he delivered public lectures at the age of seventeen. 



Notwithstanding some curious errors into which he fell, or 



rather from which he did not succeed in extricating himself, 



Helmont assisted materially the progress of chemical science. 



Previous to his time the almost universal belief seems to have 



been that when a metal is dissolved in acid, it is destroyed ; 



he showed, however, that this supposed destruction did not 



take place, but that the metal during this action passed into 



a state of solution, from which it could by proper processes 



be recovered. Helmont also was the first who formally 



attacked the old theory of the four elements. He asserted 



that earth could not properly be considered an element, 



as it was possible to convert it into water ; and fire, he 



maintained was not an element, because it had no material 



existence. He certainly was correct in his enunciations, 



that neither earth nor fire are elements, but the reason he 



gives why earth should not be considered an element is a 



remarkably poor one, and not worthy of a man of Helmont's 



powers. The other two elements of Aristotle, viz., air and 



water, he admitted were elementary in their nature. Water 



being a single and true chemical compound, we cannot 



wonder that — in those dark days when chemistry was still in 



its early infancy, being indeed as yet hardly born — it should 



be regarded as being composed of one kind of matter only; 



but it does seem surprising that Helmont, who was so far in 



advance, and who in fact was the first to demonstrate that 



there are different kinds of air, should have been contented 



to consider air as an element. Among the many valuable 



