8 Proceedings of the Roijal Physical Society. 



seem on the whole to have contributed much to the common 

 stock of chemical knowledge. 



Coming nearer home, we find during the life of Albertus 

 Magnus, a celebrated alchemist, and a great countryman of 

 our own — Koger Bacon — being tried at Oxford on a charge of 

 magic. To this charge he replied in his well-known treatise, 

 in which he showed that what had been ascribed to super- 

 natural agency was really due to the ordinary operations of 

 nature. 



Bacon, there is little doubt, was in advance of his time in 

 regard to scientific matters in general ; thus he is said to 

 have invented, or at least improved, the telescope, and also the 

 camera obscura, and to have made many other discoveries. 

 The proof regarding many of the inventions ascribed to him 

 is no doubt a little defective, but we have certainly sufficient 

 evidence to show that he at all events was possessed of great 

 learning, and of many accomplishments which in his day were 

 very rare. 



With all these, however, he does not seem to have done 

 very much for chemistry, although to him must be given the 

 honour of having first pointed out the difference which 

 exists between what I may perhaps call theoretical alchemy, 

 or alchemy — or, more properly speaking, chemistry — studied 

 for its own sake or for the advancement of the science, and 

 practical alchemy, or the pursuit of alchemical operations for 

 the purpose of personal gain. Whether Bacon invented gun- 

 powder is not very certain ; it is probable he did not. It is 

 tolerably plain, however, that he was in some degree acquainted 

 with it, and he was no doubt the first in England who pos- 

 sessed any real information regarding it. Thus he speaks, 

 though somewhat obscurely, it must be admitted, of a com- 

 pound of saltpetre which possessed extraordinary properties. 

 By mixing this salt with certain other ingredients, which, 

 although they are not directly named, are evidently sulphur 

 and charcoal, he says you can make thunder and lightning 

 if you know the method of mixing them. And he furthermore 

 speaks of a kind of matter of which a quantity not larger 

 than a man's thumb can be made to produce a horrible noise 

 and a sudden flash of light. This matter thus darkly hinted 



