xv i CONTENTS. 



CHAPTER XVI. 



DESCRIPTION OF THE TITHONOMETER, AN INSTRUMENT FOR MEASURING THE CHEMICAL FORCE OF THE 



INDIGO-TITHONIC RAYS. 



The Instrument consists of a Mixture of Chlorine and Hydrogen. It is acted upon by Lamp Light, 

 an Electric Spark at a Distance, fyc. Chlorine and Hydrogen unite in Proportion to the Amount 

 of Light. Mode of measuring out known Quantities of Rays. The Maximum of Action is in 

 the Indigo Space. Construction of the Instrument. Theoretical Conditions of Equilibrium. 

 Preliminary Adjustment. Method of continuous Observation. Method of interrupted Observa- 

 tion. Remarkable Contraction and Expansion . Page 187 



CHAPTER XVII. 



ON TITHONIZED CHLORINE. 



Description of the Experiment. The Change in the Chlorine is not Transient. There are two 

 Stages in the Phenomenon. Rays are absorbed in producing this Change. It is the Indigo Ray 

 which is absorbed. The Action is positive from End to End of the Spec.trum.The Indigo Ray 

 forms Muriatic Acid, as well as produces the Preliminary Tithonization. Change in other Ele- 

 mentary Bodies. Verification of the preceding Results with the Tithonometer . . .198 



CHAPTER XVIII. 



FARTHER CONSIDERATIONS ON THE EXISTENCE OF A FOURTH IMPONDERABLE. 



Defects of former Evidence. A new Photometer. Measures of the Light transmitted by Coloured 

 Solutions. Explosion of Chlorine and Hydrogen by a distant Electric Spark. Absorptive Ac- 

 tion of Media. 



The Absorptive Action on Light and the Tithonic Rays follows different Laws. 



Opacity of Glass for Phosphoric Rays. Determination of the Refrangibility of the Phosphoric 



Rays of an Electric Spark. Refrangibility of the same Rays in the Voltaic Arc of Flame. 



Professor Henry's Experiments. 

 These Facts serve to prove that there are more than three Imponderables K - , . 205 



