THE CHEMISTRY OF THE ANIMAL BODY. 533 



decomposition product of lecithin, methane is likewise evolved in small 

 quantity. 1 Further, methane may be produced from the putrefaction of metal- 

 lic acetates : 



CaC 4 H 6 4 + 2H 2 = CaC0 3 + C0 2 + H 2 + 2CH 4 . 

 Properties. — A colorless, odorless gas which hums with a dull flame. It is 

 absorbed by the blood, and in the herbivora is given off by the lungs often in 

 larger quantity than from the rectum. 2 In man only little is produced. Methane 

 is not oxidized in the body, and is harmless when respired, even when 10 or 20 

 per cent, in volume is present. 3 



Trichlormethane, or Chloroform, CHC1 3 . — This temporarily paralyzes nerves and 

 nerve centres. It is principally removed as vapor through the lungs, but is partially 

 burned, thereby increasing the inorganic chlorides in the urine. 4 After giving chloroform 

 it may itself occur in the urine, and likewise a substance which reduces Fehling's solu- 

 tion, glycuronic acid (which see). 



Methyl Aldehyde, or Formic Aldehyde, H.CHO. — This may be pro- 

 duced synthetically by passing vapor of methyl alcohol mixed with air over 

 an ignited platinum spiral, 



CH 3 OH + O = H.CHO + H 2 0. 



On cooling the vapor, the aldehyde is found dissolved in the alcohol. On 

 evaporation of the alcohol, the aldehyde, through condensation of three of 

 its molecules, forms a crystalline body having the composition (HCHO) 3 and 

 called paraformic aldehyde. This latter treated with calcium or magnesium 

 hydrate again suffers condensation with the production of formose, C 6 H 12 6 , a 

 sweet-tasting sugar (Butlerow, Loew) identical with ^-fructose (Fischer). 

 Baeyer 5 first suggested that the sugar synthesis in the plant was analogous 

 to the above process. He conceived the reduction of carbon dioxide to 

 carbon monoxide, which united with chlorophyll, and afterward through 

 hydrogen addition became formic aldehyde ; then in upward stages became 

 metaformic aldehyde, sugar, starch, and cellulose. Reinke 6 has shown the 

 presence of formic aldehyde in chlorophyll leaves, and believes its produc- 

 tion due to the reduction of carbonic acid through the power of the sun 

 on the leaf, thus : 



H 2 C0 3 = HCHO + 2 . 



Bach 7 states that carbonic acid and water in the presence of uranium acetate 

 yield formic aldehyde and nascent oxygen when placed in the sun. According 

 to Stocklasa, 8 400 grams of fresh leaves (128 grams dry) of the sugar beet 



1 Hasebroek: Zeitschrift fitr physiologische Chemie, 1888, Bd. 12, S. 148. 



2 B. Tacke : Quoted by Bunge, Physiologisehe Chemie, 3d ed., 1894, S. - JS 1. 



8 Paul Bert: Complex rendus de la Societe de Biologic, 188*>, p. ,VJ3. Abstract in Malay's 

 Jahresbericht iiber Thierchemie, 1886, Bd. 16, 8. 364. 



4 A. Zeller: Zeitschrift fur physiologische Chemie, 1883, Bd. 8, S. 74. 



5 Beriehte der dcutschen chemischen Gesellschaft, 1870, Bd. 3, S. 67. 



6 Ibid., 1881, Bd. 14, S. 2144. 



7 Ibid,, 1894, Bd. 26, S. 502 and 689. 



8 Stocklasa: Zeitschrift fiir physiologische Chemie, 1896, Bd. 21, S. 83. 



