THE CHEMISTRY OF THE ANIMAL BODY. 947 



the action of a 0.6 per cent, sodium-chloride solution on blood-corpuscles. 1 

 The action here has been described as that of catalysis, that is, an action in 

 which some substance effects decomposition in another substance without per- 

 manent change in itself. In this case the substance in the blood-corpuscle, 

 whatever it may be, is defined as an " oxygen-carrier," taking molecules of 

 oxygen from oxy hemoglobin and giving atomic oxygen for the oxidation of 

 the sugar. 



Old turpentine is highly oxidizing. This action was once believed to be due to absorbed 

 ozone. If old turpentine be mixed with water and filtered, the aqueous extract has the 

 same properties, due to the fact that an oxidized product which is soluble in water, gives 

 off', under favorable conditions, atomic oxygen. 2 



Detection. Moist strips of filter-paper soaked in starch-paste containing potassium 

 iodide turn blue when exposed to the action of ozone, due to the liberation of free iodine, 

 which colors the starch : 



2KI + H 2 + 3 = 2KOH + 0, + 21. 



This liberation of iodine is likewise accomplished by chlorine, bromine, some nitrous oxides, 

 and peroxide of hydrogen. 



Water, H 2 O. Water is found on the earth in large quantities, and its 

 vapor is a constant constituent of the atmosphere. It is a product of the 

 combustion of animal matter, and occurs in expired air almost to the point of 

 saturation. It is furthermore given off by the kidneys and by the skin. It 

 is a necessary constituent of a living cell, and forms 67.6 per cent, of the 

 weight of the human body (Moleschott). Removal of 5 to 6 per cent, of 

 water from the body, as for example in cholera, causes the blood to become 

 very viscid and to flow slowly, no urine is excreted, the nerves become excess- 

 ively irritable, and violent convulsions result. 3 



Preparation. (1) By passing an electric spark through a mixture of one volume of 

 oxygen and two volumes of hydrogen. 



(2) By the combustion of a food as, for example, 

 C 6 H 12 O 6 + 12O = 6CO 2 + 6H 2 O. 



Sugar. 



(3) Distilled water is made in quantity by boiling ordinary water and condensing the 

 Tapors formed in another vessel. 



Properties. Water is an odorless, tasteless fluid of neutral reaction, colorless 

 in small quantities, but bluish when seen in large masses. It is a bad conductor 

 of heat and electricity. It conducts electricity better when it contains salts. 

 It is nearly non-compressible and non-expansible ; thus in plant-life, through 

 evaporation on the surface of the leaf, sap is continuously attracted from the 

 roots of the tree. The solvent properties of water give to the blood many of 

 its uses, soluble foods being carried to the tissues and soluble products of 

 decomposition to the proper organs for elimination. 



When water is absorbed by any substance the process is called hydration, 

 as an example of which may be cited the change of calcium oxide into 



1 Kead W. Spitzer : Pftuger's Archiv, 1895, Bd. 60, p. 307. 



2 N. Kowalewsky : Centralblatt fur die medicinische Wissenscha/t, 1889, p. 113. 



3 C. Voit: Hermann's Handbuch, 1881, Bd. vi., 1, p. 349. 



