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G. F. Barker—Physiological Chemistry. 63 
temperature in a rae over sulphuric acid, has uniformly 
the composition €, ortion was the n exposed to 
humid air till it was wt hydrated, and then dried over 
chlorid of calcium at the ordinary temperature, until it ceased 
to i weight. This specimen yielded on analysis the formula 
Gig Bag Oy ys. & oe of water remains united in this case 
to . gto up ©,2 H25 ,,; which is the glycogen formula given 
above, doubleds. Tits, the author thinks, is the true composi- 
tion of glycogen, since it agrees perfectly ‘with the experiments 
and views of Musculus on dextrin, and also with the current 
views on this class of bodies. Moreover, the lead compoun 
obtained by precipitating a solution of glycogen with basic 
plumbic acetate is €,. 
(76.) On the 15th of March, ‘1868, Evutensure published* 
the results of some experiments which he had conducted in the 
laboratory of Professor Stideler, on the sugar-forming power 
of the liver. He had repeated the experiments of Ritter, fol- 
owing most explicitly his directions ; and to his great surprise 
obtained a distinct sugar-reaction several times. Indeed, 
sufficient potassic hydrate was added, and the boiling continued 
for a long time, the reaction never failed. The liver-extract, 
therefore, prepared by Ritter’s method, contains uniformly a 
trace of s mete To settle the question ‘whether this sugar ori- 
ginated in an imperfection of this method, Eulenburg modi- 
- fied the pose as follows : the abdomen of a rabbit was opened 
__ by a transverse incision just below the sternum, a fragment was 
torn from the liver, and immediately triturated in a mortar 
with pounded glass and strong alcohol. Every trace of fer- 
ment-action is excluded by the instantaneous action of the al- 
cohol ; in a few seconds, the piece taken is bruised to the finest 
pulp. "The alcoholic extract is digested at a gentle heat, fil- 
tered, the alcohol evaporated, the residue dissolved in a little 
water, precipitated by a few drops of plumbic acetate, filtered, 
the lead removed by sulphydric acid, again filtered, warmed to 
expel excess of the gas, exactly neutralized with sodic hydrate, 
and then used for testing, A somewhat more rapid method is 
to treat the filtrate, after precipitation with plumbic acetate, 
with sodic hydrate till the turbidity at first produced disap- 
pears ; the excess of lead left in the solution being without ef- 
ct on the sugar-reaction. In testing, for sugar, Eulenbur 
oer: Stadeler’s mixture.f It is raised to boiling, the liqui 
‘ 
: 
J. pr. Ch., 
+ The phir i stion—wvhieh contains 0-1 gram of a or 0°1252 of oxyd 
in every 10 c. c.—is prepared by dissolving 10 grams pur er wire in about 
Cc. pion ote 9p hydrochloric acid, with some nitric sold. carefully neutral- 
izing the excess of acid, and diluting the cold —— to 1000 ¢. ¢. The tartaric 
acid sclirilon: alos 16 grams acid in every 40 ¢ The potassic hydrate ri 
