818 THE POPULAR SCIENCE MONTHLY. 



Among the minerals and metals known to the Egyptians are 

 also mentioned the emerald, malachite, copper in alloys, iron, lead, 

 tin, and mercnry, the mobility of which caused it to be regarded 

 as living; whence the name quicksilver. Their tinctorial art 

 included dyeing in yellow, white, and black ; and they could also 

 dye purple by means of alkanet and archil. All these changes 

 brought about in the appearance of bodies seemed to be modifi- 

 cations of their properties, and consequently to legitimize the 

 expectation of effecting transmutation. We should, however, 

 recollect that the idea of the fixedness of the properties of bodies 

 is wholly modern. Even Bacon wrote in the seventeenth century : 

 " Observing all the qualities of gold, we find that it is yellow, 

 very heavy, of a certain specific gravity, malleable, and ductile to 

 a certain degree ; and whoever is acquainted with the formulas 

 and processes necessary to produce at will the yellow color, the 

 high specific gravity, the ductility, and knows, also, the means 

 of producing these qualities in different degrees, will perceive 

 the means and be able to take the measures necessary to unite 

 these qualities into a definite body ; and from this will result its 

 transmutation into gold." This was, in fact, the dream and the 

 mastering passion of the alchemy of the middle ages and the 

 Renaissance. 



These conceptions were very ancient, and must be looked for 

 in their original forms in the Greek philosophy. The germ of 

 the doctrine of transmutation is in the Tirnseus. It rests on the 

 idea of primitive matter, the indifferent supporter of all the qual- 

 ities that can be heaped upon it. Plato insists upon the idea, 

 which he regards as fundamental, that " the thing which re- 

 ceives all bodies never comes out from its ■ own substance. It is 

 the common basis of all the different substances, and is deprived 

 of all the forms which it would receive otherwise." The primary 

 matter was supposed to be composed of fire, which made it visi- 

 ble, earth, which made it tangible, air, and water, which assured 

 the union of the earth and the fire — these four elements being 

 formed of minute corpuscles, susceptible of changing into one 

 another ; for we see, says Plato, " that water, in condensing, be- 

 comes stone and earth, and in melting and dividing itself up, 

 becomes wind and air. Air inflamed becomes fire ; fire, condensed 

 and extinguished, resumes the form of air ; air, thickening, 

 changes into mist, and then flows as water ; and from water are 

 formed earth and stones." 



All bodies were believed to be the seat of a transformation of 



this kind. Under the influence of this thought, Proclus wrote, 



' Things being never able to preserve a nature of their own, who 



shall dare affirm that one of them is this rather than the other ? " 



It is, therefore, by virtue of a necessary law of nature that bodies 



