CHOLINE 47 



and trimethylamine is given off, whicli may be recognized by 

 its fish-like smell, 



H0N(CH3),CH,CH,,0H = OHCH^CH.OH + N(CH.,)., 



Choline Trimethylamine 



2. Add platinic chloride to the aqueous solution ; a double 

 platinum salt is formed, which crystallizes on standing. The 

 crystals are soluble in 15 per cent alcohol. Should the crystals 

 not appear, proceed as follows : — 



3. Dissolve choline in alcohol and add an alcoholic solution 

 of platinic chloride. Filter off the yellow precipitate, wash 

 with alcohol and dissolve in as little water as possible. Place 

 the solution in a watch glass, and stand in a desiccator. Hex- 

 agonal plates will be deposited, 



4. In order to detect very small quantities, Rosenheim 

 recommends the following method,* Prepare the double plati- 

 num salt, place a drop or two on a glass slip, and allow to 

 evaporate. Add a drop of a solution containing 2 grams of 

 iodine and 6 grams of potassium iodide in 100 c,c. of water, 

 and examine under the microscope. Dark brown prisms or 

 plates will appear and then disappear as evaporation takes 

 place ; they will reappear on adding another drop of iodine 

 solution. 



Choline is both a tertiary amine and an alcohol ; the 

 aldehyde and acid corresponding to it are both known, 



HON(CH3)3CH2CH20H HON(CH,)3CH2CH(OH)„ HON(CH3)3CH.,COOH 

 Choline Muscarine Betaine 



The aldehyde, which goes by the name of muscarine, occurs in 

 Agarims muscariits ; it is a powerful poison (see p, 265), 



By the bacterial decomposition of choline another very 

 poisonous base, neurine, may be obtained ; this substance 

 differs from choline by the elements of water. 



HON(CH3)3CH2CHaOH HON(CH3)3CH = CHo 

 Choline Neurine 



The choline complex of lecithin on further decomposition 

 can give rise to nitrogen bases, such as dimethylamine HN(CH3).^ 

 and trimethylamine N(CH3)3 ; these substances, which have a 

 fishy smell, also occur in herring brine and are probably there 

 produced from a similar source. They have similarly been 



* Rosenheim : " J. Physiol.," 1905, 33, 220. 



