CH. vr. ARABIAN ALCHEMISTS. 41 



Hermes Trismegistus about 2000 years before Christ We 

 know very little of this Hermes, artd indeed we are not sure 

 whether he is not altogether an imaginary person ; but the 

 Alchemists, as the people were called who tried to make 

 gold, considered themselves followers of Hermes, and often 

 called themselves Hermetic philosophers. To melt the mouth 

 of a glass tube so as to close it was called securing it with 

 'Hermes, his seal,' and even to this day a bottle or jar 

 which is closed so that it is air-tight is said to be hermeti- 

 cally sealed. 



The Arabs were a very superstitious people, and believed 

 in all kinds of charms ; and this idea of making gold in a 

 mysterious way took a great hold of them. Many thousands 

 of clever men occupied themselves in the supposed magic 

 art of alchemy. We need not study it here, but only observe 

 how very useful it was in teaching the first facts of chemistry. 

 These men, who were many of them learned, clever, and 

 patient, spent their lives in melting up different substances 

 and watching what changes took place in them. In this 

 way they learnt a good deal about the materials of which 

 rocks, minerals, and other substances are made. 



One of the first things they discovered was that, by 

 heating substances, they could often drive something out of 

 them which was invisible, and yet that they could collect this 

 invisible something in bottles ; and in some cases if they put 

 a light to it, it exploded violently, breaking the bottle to 

 atoms. Now because this was invisible, and yet so power- 

 ful, they thought it must be like the spirit of man, which 

 can do so much and yet cannot be seen, and for this reason 

 they called it ' spirit/ We know r, v that when we heat 

 substances up to a certain point we drive apart the matter of 

 which they are made, and it floacs off as steam or gas into the 

 air; so that this spirit noticed by the Arabs was vapour or gas. 



