^ M4I. Berthelot and De Luca on Glyterihe. 



86lubility in the same solvents. But the mannitic compounds 

 possess a greater fixity, a less fluidity, and a stro^nger tend- 

 ency to assume the solid form, although these tendencies are not 

 so marked as to excite attention. The compounds are decora- 

 posed, under the prolonged influence of the alkalies, with the 

 formation of mannitane, or anhydrous mannite, C® H^ 0^, which' 

 difi^ers from mannite by one equivalent of water, and is trans- 

 formed into mannite by prolonged contact with water. Manni- 

 tane is also formed by heating mannite to 200° C. ^ 



With acetic acid mannite forms only one compound, a bittef 

 liquid substance ; the compound of mannite mth butyric acid is in- 

 teresting, inasmuch as both its constituents are entirely derived 

 from the fermentation of sugar, and yet it has all the characters 

 of a neutral fatty matter. With palmitic, and with stearic acid, 

 mannite forms compounds which are crystalline and resemble 

 palmitine and stearine; when melted, they appear like wax. 

 W^ith oleic acid, a neutral, almost colourless substance is obtained, 

 of the consistence of modeller's wax. Benzoic acid unites with 

 mannite in two proportions. The first, which consists of one 

 equivalent of acid and one of mannite, is a viscid, almost solid 

 substance ; in the other, one equivalent of mannite unites with 

 three of benzoic acid. Both these resemble resins, and are very ■ 

 stable and difiicult of decomposition. «« 



Mannite forms with tartaric acid an acid compound which is^ 

 tribasic. It bears the same relation to the benzoic acid com- 

 pound of mannite which sulphovinic and tartrovinic acids do to 

 benzoic aether. The mannitartaric acid forms with lime a neutral 

 salt containing four equivalents of water, and with magnesia a 

 basic salt containing thirty equivalents of water. 



Mannite, heated with oxalic acid to 100°, experiences the 

 same decomposition as does glycerine under the same circum- 

 stances* ; carbonic acid free from carbonic oxide is liberated, and. , 

 at the same time formic acid is produced, which remains com-7 

 bined with the mannite. 



With hydrochloric acid, mannite forms a neutral crystalline 

 compound. By enclosing mannite in a sealed tube along with 

 potash and bromide of sethyle, a compound of mannite and alco- 

 hol is formed, analogous to the mixed alcohols of Williamson. 



The compounds of mannite with sulphuric acid and with nitric 

 acid are already known. They are also strictly analogous to the 

 compounds formed by glycerine with those acids. 



Berthelot and De Lucaf have investigated the action of the 

 chloride and bromide of phosphorus on glycerine. The action of 



* Phil. Mag. July, 1866. 

 t Comptes Rendus, July 14. 



¥lH 



