980 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



atile, less easily burned, and therefore more tenaciously retained by the body, 

 with more pernicious results. 



Ethyl Ether, C 2 H 5 .O.C 2 H 5 . This is formed by the action of sulphuric acid on 

 alcohol, thus : 



C 2 H 5 OH + H 2 S0 4 = C 2 H 5 HS0 4 + H 2 0. 



C 2 H 5 HS0 4 + C 2 H 5 OH =(C 2 H 5 ) 2 + H 2 S0 4 . 



Ether is a solvent for fats, resins, and ethereal oils. Respired with air its action is like that 

 of chloroform, producing temporary paralysis of the nerves and nervous centres. Since it 

 boils at 35.5 its tension in the blood is always high, and it is probably not burned in the 

 body to any great extent, but when present is eliminated through the breath. 



Ethers in general are neutral and very stable bodies, and may be considered oxides of 

 organic radicles. They may all be prepared by boiling the corresponding alcohol with sul- 

 phuric acid. Mixed ethers, in which the radicles are different, are prepared by boiling two 

 different alcohols with sulphuric acid : 



CH 3 HS0 4 + C 2 H 5 OH = CH 3 OC 2 H 5 + H 2 S0 4 . 



Methyl-ethyl ether. 



Chloral Hydrate, CC1 3 CHO + H 2 or CC1 3 CH(OH) 2 . This is the hydrated form of 

 trichlor-ethyl aldehyde, CC1 3 CHO, and is used as an anaesthetic. It is an interesting fact 

 that when fed it partially reappears in the urine as urochloralic add, which consists of 

 trichlor-ethyl alcohol, CC1 3 CH 2 OH, combined with glycuronic acid (which see). This is a 

 notable illustration of reduction in the body, the change from an aldehyde to an alcohol. 



Acetic Acid, CH 3 COOH. Acetic acid, the second of the fatty-acid series, 

 is found in the intestinal tract and in the feces, being a product of putrefaction 

 (see p. 988). It is more easily burned than formic acid, and when absorbed is 

 resolved into CO 2 and water. It is found in traces in the urine, the total 

 amount of fatty acids normally present being 0.008 gram per day. 1 Like 

 formic acid, and accompanied further by the higher acids of the series, it is 

 present in the blood, sweat, and urine whenever there is an abnormal proteid 

 decomposition (leucocythaemia, diabetes). 



Acetic acid is the product of the oxidation of alcohol. This may be 

 brought about through the presence of spongy platinum, or through the action 

 of bacteria (Mycoderma aceti) on dilute alcohol (preparation of vinegar, sour- 

 ing of wine : for reaction see p. 976). Acetic acid, as well as other higher fatty 

 acids, is one of the products derived from proteid through its putrefaction, its dry 

 distillation, its fusion with potash, and its digestion with baryta water in sealed 

 tubes. Formic, acetic, and propionic acids are products of dry distillation of 

 sugar (formation of caramel). These facts are of importance in their rela- 

 tion to the question of the production of fat in the body. Acetic and the 

 higher fatty acids are, further, products of the dry distillation of wood and 

 of the fermentation of cellulose (see p. 976). Putrefaction of acetates may 

 take place in the intestines, the reaction being as follows : 



2CH 3 COONa + 2H 2 O = Na 2 CO 3 + 2CH 4 + H 2 O -f CO,. 



These products are similar to those in the marsh-gas fermentation of cellulose. 

 Vinegar, whose acidity is due to acetic acid, is used as a condiment. 



Acetyl-acetic Acid, or Aceto-acetic Acid, CH 3 .CO.CH 2 .OOOH. This 



1 V. Jaksch : Zeitschrift filr physiologische Chemie, 1886, Bd. 10, p. 536. 



