86 THE LIFE AND LEGEND OF MICHAEL SCOT 



to bear we have only to turn to the passage in 

 which, speaking of alum, the author says : c sicut 

 illuminat pannos, ita illuminat martem ut recipiat 

 formam lunae. Ut enim lana illuminatur ita et 

 metalla illuminantur.' 1 A distinction is clearly 

 present in the writer's mind between the substance 

 and the form of the metals. He probably held 

 that there existed but one common metallic sub- 

 stance, which assumed the appearance of iron, 

 gold, or silver, according to the form which it had 

 received. His employment of the title Liber 

 Luminis Luminum was meant to indicate that 

 the purpose of his book was that of teaching the 

 student how metals might best be purified and 

 improved. Their inferiority, when of the baser 

 kind, he conceived as an impurity, manifesting itself 

 in the imperfect forms of lead, iron, tin, and copper. 

 He believed that this being removed or changed by 

 art, they might be made to shine with the lustre 

 and indeed possess the only distinctive quality of 

 gold and silver. That we have rightly read the 

 meaning of this title seems plain from a curious 

 spelling which may be noticed in the Liber Dedali. 

 6 Illuminantur ' there appears as ' aluminantur/ 

 The chemistry taught in these books did in fact pre- 

 scribe the use of alum as a great means of purifying 

 and refining the metals. 



The preface of the Liber Luminis closes with a 

 brief summary of the chapters which compose the 

 work itself. The first of these deals with the 

 different salts used in this chemistry : common salt ; 

 rock salt ; alkali ; sal ammoniac ; nitre and others. 

 The second treats in like manner of the various 



1 Liber Luminis Luminum, ii. 1. 



