72 ALDEHYDES AND ALCOHOLS 



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 separation of inositol from the plant juices is effected 

 as follows : — 



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

 able, 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 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 prismatic 

 crystals. 



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

 in alcohol and ether. It crystallizes in prisms, it is not 

 fermentable and it does not reduce Fehling's solution. 



Identification. 



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 calcium chloride 

 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. 



Inositol also occurs in combination with phosphoric acid. 

 This compound, known as phytin, appears to be an acid 



