The Seventeenth Century 147 



Here we have excellent examples of the point of view of one 

 chemist at the end of the seventeenth century. 



ISAAC NEWTON 



As Francis Bacon bridged the sixteenth and seventeenth centuries. 

 Sir Isaac Newton (1642-1727) may be said to have connected the 

 seventeenth and eighteenth. The experiments and thought which 

 went into his work were largely products of the severiteenth century. 

 Newton first obtained a prism in 1666. He delivered a course of 

 lectures ^"^ on optics at Cambridge University in 1669-1671 and com- 

 municated his discourse to the Royal Society as a "New Theory 

 about Light and Colours " in 1672. It contained the germ of the 

 corpuscle theory, and described the supposed properties of an aether 

 pervading all space. This paper led to publication of the Opticks in 

 1704, followed by later editions in 1717, 1721, and 1730. 



The first edition of Opticks contained only sixteen queries and 

 practically nothing on luminescence. In the second edition (1717) 

 Newton omitted some mathematical tracts, and enlarged some of 

 the sixteen queries of the first edition and added fifteen more, 

 making thirty-one in all. It is among the " Questions " in the 1717 

 edition that Newton listed many different ways of producing light. 

 After speaking of incandescence as due to vibratory motions within 

 bodies he referred {Opticks, 2nd ed., 361-318, 1718) , to other light 

 emissions as the result of similar vibratory motions: 



Qu. 8. Do not all fix'd Bodies, when heated beyond a certain degree, 

 emit Light and shine; and is not this Emission perform'd by the vibrat- 

 ing motions of their parts? And do not all Bodies which abound with 

 terrestrial parts, and especially with sulphureous ones, emit Light as 

 often as those parts are sufficiently agitated; whether that agitation be 

 made by Heat, or by Friction, or Percussion, or Putrefaction, or by any 

 vital Motion, or any other Cause? As for instance; Sea- Water in a raging 

 Storm; Quicksilver agitated in vacuo; the Back of a Cat, or Neck of a 

 Horse, obliquely struck or rubbed in a dark place; Wood, Flesh and Fish 

 while they putrefy; Vapours arising from putrefy'd Waters, usually call'd 

 Ignes Fatui; Stacks of moist Hay or Corn growing hot by fermentation; 

 Glow-worms and the Eyes of some Animals by vital Motions; the vulgar 

 Phosphorus agitated by the attrition of any Body, or by the Acid Par- 

 ticles of the Air; Amber and some Diamonds by striking, pressing or 

 rubbing them; Scrapings of Steel struck off a Flint; Iron hammer'd 

 very nimbly till it become so hot as to kindle. Sulphur thrown upon it; 

 the Axletrees of Chariots taking fire by the rapid rotation of the Wheels; 

 and some Liquors mix'd with one another whose Particles come together 



«^ Later published as Optical lectures (1728) or Lectiones opticae (1729) in both 

 English and Latin. 



