xx ii CONTENTS. 



MEMOIR XXIX. 



ON THE DISTRIBUTION OF CHEMICAL FORCE IN THE SPECTRUM. 



The curves of the calorific, luminous, and chemical spectra. Their er- 

 rors. Inappropriateness of the term actinic rays. There is no local- 

 isation of chemical effects. Every radiation can produce some specific 

 effect. Case of the silver compounds. Bitumens and resins. Car- 

 bonic acid. Colors of flowers. Law of Grotthus Chlorine and hy- 

 drogen. Bending of stems of plants. Absorption essential to chemical 

 action. Decomposition of silver iodide. Union of chlorine and 

 hydrogen. Angstrom's law. General conclusions. Chemical force 

 exists in every portion of the spectrum. Each radiation exercises 

 chemical influences proper to itself Page 404 



MEMOIR XXX. 



ON BURNING GLASSES AND MIRRORS THEIR HEATING AND CHEM- 

 ICAL EFFECTS. 



Can concentrated rays produce new chemical decompositions? Effects of 

 amplitude, frequency, and direction of vibration in the ether-waves. 

 Clock lenses for long exposures. Decomposition of water by chlorine. 

 Attempt to decompose it by bromine and iodine. Use of absorbing 

 troughs. Dry silver iodide not decomposed by light. Decompositions 

 under water. Decompositions in a spherical concave. Effect of ex- 

 traneous mixtures. They do not make collodion more sensitive. 

 Antagonize tion of radiations. Case of electric spark. Effects of 

 polarized light. Attempts to polarize light by an electro-magnet. 

 Mechanical cause of decompositions by light 436 



