104 MANNANE AS AN ARTICLE OF HUMAN FOOD. 



There are prepared a powder and a gelatinous mass from 

 the root-stock. To prepare the powder, the root-stock is sliced 

 into thin pieces after all the skin is removed. These slices are 

 hung up to dry, and after several weeks are ground in a mortar, 

 and sifted. 



To prepare namakonniaku, as the gelatinous mass is called, 

 the powder or the root-stock is well boiled with water, then 

 ground into a pasty mass, forced through a sieve, and transferred 

 into a large wooden tub, mixed with an equal quantity of slaked 

 lime and double the amount of water, and kneaded with the feet. 

 After the mixture has become homogeneous, it is boiled with 

 lime water until it forms a gelatinous mass. r) 



Chemical Investigation- 



The powder of konniaku above mentioned served principally 

 for my experiment. It was boiled with 3% solution of sul- 

 phuric acid for several hours. On filtering a yellowish solution 

 was obtained which was neutralized with barium carbonate, 

 decolorised with animal charcoal, filtered, and evaporated to 

 a syrup, from which no crystals could be obtained. It was 

 soluble in cold water and dilute alcohol, had a strong power of 

 reducing Fehling's solution, had a very sweet taste and turned 

 the plane of polarization to the right. This syrup consists 

 evidently, to a great extent, of mannose, for even a very small 

 quantity of it at once gave in the usual way treated in the cold 

 with solution of acetate of phenylhydrazin, a colorless crystalline 

 precipitate soluble in hot water and hot alcohol, and thus very 

 easily purified. The melting point of this purified precipitate 

 was found to be 195 — 20oC°. 



There can be no doubt that this was mannose-phenyl- 

 hydrazon, as this substance was easily transformed by further 

 treatment with phenylhydrazin into phenyl-glucosazon melt- 



1) The workmen have to avoid inhaling the fine powder by covering the nose 

 with a cloth, as the powder irritates the throat. 



2) This mass is made to freeze in winter, whereby its aspect changes; this 

 product is preferred and is called " korikonniaku.'' 



From the root-stocks, a kind of paste is made which is principally used to in- 

 crease the lustre of clothes and which is far superior to starch paste, and cheaper 

 than the latter. Paper treated with this paste of konniaku is used instead of oiled 

 paper for our umbrellas and water-proof clothes. 



