946 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



By reduction in its simplest sense is meant the removal of oxygen wholly 

 or in part from the molecule. Example : reduced haemoglobin from oxy- 

 hamioglobin, iron from oxide of iron (Fe 2 O 3 ). Reduction may likewise be 

 accomplished by simple addition of hydrogen to the molecule, or by the sub- 

 stitution of hydrogen for oxygen. These two processes may be represented 

 respectively by the reactions : 



CH 3 CHO + H 2 = CH 3 CH 2 OH. 



Ethyl aldehyde. Ethyl alcohol. 



CH 3 COOH + 2H 2 = CH 3 CH 2 OH + H 2 O. 



Acetic acid. Ethyl alcohol. 



Ozone, O 3 . Ozone is a second form of oxygen possessing more active oxi- 

 dizing properties than common oxygen. It is found in neighborhoods where 

 large quantities of water evaporate, and after a thunder-storm. 



Preparation. (1} An induction current in an oxygen atmosphere breaks up some of 

 the molecules present into atoms of nascent or "active" oxygen , the powerful 

 affinities of whose free bonds enter into combination with oxygen, = to form 



ozone, /\, 



(2) Through the slow oxidation of phosphorus, 



P 2 + 3H 2 + 20 2 = 2H 3 P0 3 + (0). 



(3) On the positive pole in the electrolysis of water. 



In each of the above cases ozone is formed by the action of nascent oxygen on oxygen. 



Properties. Ozone is a colorless gas, hardly soluble in water, and having 

 the peculiar smell noted in the air after thunder-storms. Ozone has powerful 

 oxidizing properties due to its third unstable atom of oxygen, oxidizing silver, 

 which oxygen of itself does not. But ozone is not as oxidizing as nascent or 

 "active" oxygen, which may convert carbon monoxide into dioxide, and 

 nitrogen into nitrous acid. Ozone cannot occur in the cell, as any nascent 

 oxygen formed would naturally unite not with oxygen, but with the more 

 readily oxidizable materials of the cell itself. Ozone acts on an alcoholic solu- 

 tion of guaiacum, turning it blue ; blood-corpuscles give the same reaction 

 with guaiacum, hence it was thought that haemoglobin converted oxygen into 

 ozone. However, this test is not a test for ozone, but for " active " atomic 

 oxygen, which is produced from the ozone and in the decomposing blood-cor- 

 puscle (see theory of Traube below, and that of Hoppe-Seyler under Peroxide 

 of Hydrogen). Ozone converts oxyhaBmoglobin into methsemoglobin. 



Theory of Traube as to the Cause of Oxidation in the Body. Indigo-blue 

 dissolved in a sugar-solution gives up oxygen in the atomic state for the oxida- 

 tion of sugar, and the solution be'comes white. If shaken in the air the blue 

 coloration reappears, owing to the absorption of oxygen by the indigo. Hence 

 indigo has the power of splitting oxygen into atoms, and acts as an " oxygen- 

 carrier " between the air and the sugar. Traube is of the opinion that an 

 " oxygen-carrier " exists in the blood-corpuscles. Sugar is destroyed by stand- 

 ing in fresh defibrinated blood ; serum alone does not effect this, nor does a 

 solution of oxyhsemoglobin, but it may take place in the extract obtained by 



