396 R. H. Chittenden— Oxidation product of Glycogen. 



added. The flask was then closed and heated as before until 

 the bromine had all been taken up, after which, on cooling, the 

 gases were liberated and 40 grams more bromine added, and the 

 flask treated as before. After this, 10 grams of bromine were 

 added three times, so that 160 grams of bromine were employed 

 in the oxidation of 50 grams of dried glycogen. 



The fluid was then transferred to an evaporating dish and 

 heated on a water-bath until somewhat concentrated. When 

 cool the fluid was diluted with an equal volume of water, then 

 mixed with freshly precipitated and thoroughly washed silver 

 oxide until all bromine was removed from the fluid. After 

 the silver bromide had completely settled, the fluid was filtered 

 off and the silver contained in it precipitated by hydrogen 

 sulphide. The silver sulphide was removed by filtration, 

 and the filtrate upon partial evaporation left a yellowish-red 

 fluid with strong acid taste and reaction. This was an impure 

 solution of an acid which decomposed carbonates with avidity. 

 In this manner 150 grams of dried glycogen were oxidized, in 

 parts of 50, giving in all sufficient acid for the following exper- 

 iments. Two methods of purification were employed. The first 

 consisted in treating this impure solution of "the acid with 

 chemically pure animal charcoal, and precipitating the filtrate 

 with an excess of alcohol, to remove inorganic salts derived 

 from the glycogen, which the latter always contains in sn-iall 

 quantity. This alcoholic filtrate is evaporated on the water- 

 bath, when a moderately pure solution of the acid results. 



The second and better method, however, is to treat the impure 

 acid with pure calcium carbonate, on the water-bath, when a solu- 

 ble calcium salt is obtained which is filtered off", and, after concen- 

 tration, crystallizes out on standing several days. After washing 

 the crystals with a little cold water, they are dissolved in a large 

 quantity of hot water, and precipitated while still hot by basic 

 lead acetate. This precipitate of a lead salt of the acid is washed 

 with hot water, then emulsionized with water and decomposed 

 by hydrogen sulphide. The lead sulphide is removed by filtra- 

 tion, the fluid evaporated, and then mixed with an excess of 

 dilute alcohol. The precipitate, if any forms, is filtered off, 

 and the filtrate on evaporation leaves the pure acid as a thick 

 colorless syrup, which, after standing several months, shows as 

 yet no signs of crystallization. A solution of the acid in water 

 has an acid reaction on litmus ; a strong acid taste ; is not pre- 

 cipitated by alcohol, and dissolves freshly precipitated hydrated 

 copper oxide to an azure-blue fluid, which remains blue when 

 heated, but after long boiling shows strong reducing action. 



Calcium Salt.— On treating an aqueous solution of the acid with 

 calcium carbonate, on the water-bath, a violent evolution of 

 carbonic acid takes place, and, after some time, a soluble calcium 



