ALCOHOLS IN PLANTS 389 



It may be looked upon as a plastic substance since Maquenne 

 has found that it disappears from the young fruits of Phaseolus 

 as ripening proceeds. 



Preparation. 



The method of separation of inositol from the plant juices 

 is based on the fact that it forms a compound with lead oxide. 



The sap is expressed from the organ, or, if this be imprac- 

 ticable, the parts are ground up very thoroughly with water. 

 The liquid is then filtered and, if it gives an acid reaction, is 

 neutralized by the addition of baryta water. 



A solution of basic lead acetate is then added until no more 

 precipitate comes down. The precipitate consists of a com- 

 pound of inositol with lead oxide (2C 6 H 12 O 6 5PbO), and is 

 filtered off, then washed and suspended in water, and saturated 

 with a current of sulphuretted hydrogen. The lead sulphide 

 is filtered off and the filtrate evaporated on a water bath to the 

 consistency of a syrup. On the addition of alcohol, containing 

 one-tenth of its volume of ether, inositol is deposited in pris- 

 matic crystals. 



Inositol has a sweet taste, is soluble in water but insoluble 

 in alcohol and ether. It crystallizes in prisms, and does not 

 give any reactions characteristic of true hexoses. For instance, 

 it is not fermentable, it does not reduce Fehling's solution, and 

 its solution does not give a brown coloration with potash. 



I den tification. 



1. When moistened with a little dilute nitric acid, then 

 evaporated almost to dryness, and made alkaline with am- 

 monia, the addition of a few drops of chloride of calcium 

 produces a rose-red coloration. 



2. A solution of inositol evaporated to dryness with a few 

 drops of mercuric nitrate produces a yellow stain which on 

 heating turns red. 



3. Solutions of inositol are not optically active. 



With regard to its significance in the plant there is evidence 

 to show that inositol is a transitory substance and is used up in 

 the synthesis of other substances. 



