learning some of the secrets of art from the well-known Franciscan. This relation between two such distinguished men has not hitherto been noticed, and is certainly a curious point in the history of the times. The _De Alchimia_ presents several features which distinguish it from the _Liber Luminis_. One of these is an early passage which refers to the correspondence between the metals and the planets, and explains that when the latter are named we must understand that the former are intended. Near the end of the treatise a description of the _materia chemica_ occurs, but it would seem as if this had been written to supplement that given in the _Liber Luminis_, for it deals, not with salts, alums, vitriols, or volatile substances, but with the different varieties of what the author calls ‘gummae,’ which, however, are mineral substances;[140] and with ‘tuchia’ in all its various kinds. Many words and phrases, however, might be cited to show how the strain of doctrine observable in the _Liber Luminis_ is continued with scarcely any change in the _De Alchimia_. We have hardly read a line in the first receipt before we meet with the expression ‘sanguinem hominis rufi’ recalling the ‘sanguinem hominis rubei’ of the _Liber Luminis_. The ‘pulvis bufonis’ indeed is here replaced by another ingredient derived from the animal kingdom, the ‘sanguis bubonis’; but, reading a little further, we find the familiar ‘urina taxi’ again recommended as an almost universal solvent and detergent. Evidently both works proceeded from one and the same alchemical school. The number of Arabian chemists[141] cited in the _De Alchimia_ seems to show that if these books came from a Greek source it was not that of ancient times, but some Byzantine school that had borrowed much from Eastern alchemists.