512 History of Luminescence 



Why stagnating Water does not Sparkle at all. 



However, in order to produce this Effect, it is necessary that the Parts 

 of the Salt should be very smooth and slippery, wherefore Sea Water 

 which has been kept a long Time, and Brine whose Parts are covered 

 with Dirt and as it were rusty, are no Ways proper to produce these 

 Sparks. 



Why this Shining is chiefly seen in Summer. 



It is further necessary, that the Parts of fresh water, which are rolled 

 about the Particles of Salt, should be extremely pliable, so as to be able 

 to unfold themselves very easily, and give the particles of Salt liberty 

 to disengage themselves; now this can never be but only in the greatest 

 Heat of the Summer; and therefore we ordinarily see such sparks in that 

 Season only. 



When it is that all Sorts of Waves are not proper to produce these 

 Sparks. 



Lastly, it is evident that in order to this, the agitation must be very 

 violent, and the Parts of the Salt must move with their Points forward, 

 that they may the more easily disengage themselves from the Drops of 

 Water; and this is the Reason why the Sparks do not come from all the 

 Waves nor from every Drop of the same Wave. 



It is quite obvious that Rohault had no conception of a biological 

 explanation of sea light. His arguments are definite, if somewhat 

 forced. Another Cartesian, Antoine LeGrand (1692, part H: 45) 

 also attribtited the phosphorescence of the sea to the 



stiff particles of Salt; for by their penetrating little Bodies, the particles 

 of the 2nd Element they meet with in their way, may be so expelled, as 

 that some of the particles of the 3rd element, may be only surrounded 

 with the 1st element, and by it be carried away, and driven on to the 

 Eye, by a continued Range of the Globuli. 



Other Early Explanations 



Descartes thus brought the explanation of sea light in line with 

 his general conception of particles of matter in motion, either as 

 vortices or vibrations, and Rohault added some details. Descartes 

 was one of the earliest philosophers to develop a purely physical 

 theory, which, in one form or another, usually regarded the phos- 

 phorescence as due to friction. However, it must not be stipposed 

 that Descartes' views were accepted by all the philosophers, even 

 those in France. 



Nicolas Papin, a physician and uncle of the famous Denis Papin 

 (1647-1712) , wrote a small tract, Traite de la Lumiere de la Mer, 

 as an appendage to his book, Raisonnements Philosophique touchant 



