X CONTENTS. 



gen. Pulmonary Circulation is due to the Oxydation of Venous Blood, and its Direction is there- 

 fore from the Venous to the Arterial Side. Uses and Action of the Heart. 



Portal Circulation. Capillary Relations of Arterial, Portal, and Venous Blood to the Liver. Three 

 Sources of Force in conducting the Portal Circulation. 



Action in Asphyxia. Case of obstructed Trachea . '. . . . . . . Page 33 



CHAPTER IV. 



ON THE PHYSICAL CONSTITUTION OF THE SUNBEAMS AND ON THE PRISMATIC SPECTRUM. 



Mode of isolating the Coloured Rays. Newton's Prismatic Spectrum. Theory of the Colours of 

 Light. Illuminating Calorific and Chemical Powers of the Spectrum. Newton's Processes for 

 purifying the Spectrum. Fixed Lines. Mellonts Experiments on the Distribution of Heat. 

 Physical Independence of Heat. HerscheFs Experiments on the Thermic Spectrum. Chemical 

 Action of the different Regions of the Spectrum on a Daguerreotype Plate. Chemical Action on 

 other Bodies ............... 41 



CHAPTER V. 



ON THE INTERFERENCE SPECTRUM. 



Defects of the Prismatic Spectrum. Mode, of forming the Interference Spectrum. Its Peculiarities. 

 The Distribution of the Colours, and Law of their Intensities. Reflected Interference Spectrum. 

 Its Fixed Lines. Wave-lengths of the Seven Great Rays. 



Melloni's Researches on the Distribution of Heat in Perfect Prismatic Spectra. Apparent Identity 

 of Light and Heat. 



Distribution of Chemical Force in the Interference Spectrum. Comparison of the Fixed Lines in 

 the Prismatic and Interference Spectrum. Mode of Defining Chemical Effects by Wave-lengths 

 or by Times of Vibration.- Impression on Bromide of Silver. On Chloride of Silver. Total 

 Change in the Distribution of Heat in the Interference Spectrum . . . . .52 



CHAPTER VI. 



EXPERIMENTS PROVING THAT IT 13 IN THE YELLOW REGION OF THE SPECTRUM THAT THE REDUCTION 

 OF CARBONIC ACID BY THE LEAVES OF PLANTS TAKES PLACE. 



Several Imponderable Principles in the Sunbeam. Sennebier's Experiments to determine to which 

 of these the Effect is due. Experiments of Morren and Daubeny. Defects of the Mode of oper- 

 ating with Absorbent Media and Glasses. 



Decomposition of Carbonic Acid in the Prismatic Spectrum. Process of conducting the Experi- 

 ment. It is in the Yellow Region that the Decomposition takes place. No Gas is evolved in the 

 Violet ,".... 61 



CHAPTER VII. 



ON THE VARIOUS IMPONDERABLE AGENTS EXISTING IN THE DIFFERENT REGIONS OF THE SPECTRUM. 



Different Agents existing in the Spectrum. Description of the Tithonic Rays. Their Name. 

 Physical Independence of Heat. Of the Chemical Rays. Their Constant Association with Light. 

 Detithonizing Action of Yellow Solutions. Argument for their Independence. Other Invisible 

 Principles in the Sunbeam, such as the Phosphoric Rays. Examination of the Theory of M. 

 Becquerel . . . . '._'.. 65 



CHAPTER VIII. 



IT IS YELLOW LIGHT WHICH CONTROLS THE PROCESS OF DIGESTION IN PLANTS. 



Examination as to which of the Principles mentioned in the preceding Chapter is engaged in the De- 

 composition of Carbonic Acid. It is not Radiant Heat. Melloni on the Ideal Coloration of Heat. 

 Analogies in the Case of Light. HerscheVs Results. 



