296 SCIENCE PROGRESS 



Instead of preparing it by the old method of passing dry 

 ammonia into the aldehyde dissolved in ether, the author finds 

 that it may be obtained more rapidly by mixing the aldehyde 

 with a strong aqueous solution of ammonia when, on cooling, 

 the substance separates out in a pure condition. Aldehyde 

 ammonia, when freshly prepared in this way, is a trimolecular 



compound (CH 3 CH\ vru I , but, on keeping, it gradually 



changes to the bimolecular compound, according to the equa- 

 tion 



2(C 2 H 7 NO) 3 = 3 (C 2 H 7 NO) 2 . 



The ordinary methods employed for benzoylating poly- 

 hydric alcohols, result in the replacement of all the hydroxyl 

 groups. Emil Fischer (Berichte, 191 5, 48, 266) has now suc- 

 ceeded in partially benzoylating dulcitol and mannitol, and 

 has prepared mono-and di-benzoyl dulcitol C 6 H 13 6 , COC 6 Hs and 

 C 6 Hi20 6 (COC 6 H 5 )2,and tetrabenzoyl mannitol C 6 H 10 O 6 (COC 6 H 5 ) 4 . 

 The method adopted consists in making the acetone com- 

 pound of the alcohol by shaking the latter with acetone 

 containing 1 per cent, of hydrogen chloride, as described by 

 the same author some years ago (Berichte, 1895, 28, 1168). 

 Treated in this way mannitol gives mannitol triacetone. 



C 6 H u 6 + 3 CH 3 COCH 3 = C 15 H 26 5 + 3 H 2 0. 



From this substance the partially benzoylated alcohol 

 tetrabenzoyl mannitol can be obtained by treatment with 

 benzoyl chloride and quinoline followed by the removal of the 

 acetone complex by means of a 5 per cent, alcoholic solution 

 of glacial acetic acid. 



The influence of under-mastication (bolting) and over- 

 mastication (Fletcherising) upon the utilisation of ingested 

 protein has recently been investigated by Foster and Hawk 

 (J. Amer. Chem. Soc. 191 5, 37, 1347). According to Chitten- 

 den thorough mastication of food is a material aid to the 

 digestion, while Metchnikoff considers that it is harmful to 

 chew food very long, and only to swallow it after keeping it in 

 the mouth for a considerable time. A disorder known in 

 America as " Bradyphagism " caused by the habit of eating too 

 slowly is apparently cured by eating more quickly. Accord- 

 ing to the authors the importance of chewing of protein foods 

 has been overestimated, for, as they point out, all high protein 



