140 
Mr Parkin, On a reserve carbohydrate, 
extracted several times with cold water,, till the mucilaginous 
matter was dissolved out. The extract was filtered to remove 
particles in suspension, such as starch grains ; then evaporated 
down to a small bulk, refiltered and finally poured into a large 
excess of alcohol, when a quantity of white flocculent matter 
separated out. This was collected, dissolved in water and re- 
precipitated by alcohol. Then treated similarly a third time, and 
fihally dried on a porous plate. About 1*5 grams of a translucent 
almost colourless tough solid were thus obtained. This substance 
swells and dissolves slowly in water to form an opalescent solution, 
which does not give any marked colour with iodine. On account 
of the opalescence its behaviour to polarised light could not be 
studied with any degree of accuracy. Dilute solutions indicated a 
dextrorotary power. 
A definite quantity, 0’959 gram, of this substance dried till 
constant in weight, was dissolved in water, and the volume made 
up to 100 c.c. Of this 25 c.c. were taken and boiled for one hour 
with 2 per cent, sulphuric acid. The hydrolysis is not so quickly 
effected as in the case of inulin, but one hour’s boiling with this 
strength of acid sufficed to complete it ; alcohol ceased then to 
cause any precipitation, and the opalescence had quite disappeared, 
leaving a perfectly clear solution. This hydrolysed portion first 
showed levorotation, gradually changing to the opposite sign, and 
after standing a few hours the rotation became constant. 
Angle of rotation in 200 mm. tube when constant = + 0 o, 23. 
The cupric reducing power of the hydrolysed liquid was esti- 
mated by ascertaining the weight of copper obtained from the 
cuprous oxide formed on boiling with Fehling’s reagent. 
Weight of copper calculated for the 100 c.c. = T7 grams. 
These two results do not agree at all closely on the assump- 
tion that the sugar is glucose (dextrose), arising from the hydrolysis 
of dextrin. The 1*7 grams of copper are equivalent to 0 9 54 gram 
of glucose, which should give a rotation at least four times as 
great as that found. A second experiment with another portion 
of the solution revealed the same discrepancy. 
The feeble dextrorotary power and the fact of the opticity 
being at first left-handed, suggest at once mannose which exhibits 
this form of multirotation. If it is this sugar, then, the character- 
istic hydrazone should be deposited in the cold on the addition of 
phenylhydrazin and acetic acid — a reaction which distinguishes 
mannose from all the other hexoses. 
Some of the hydrolysed liquid, previously neutralised with 
calcium carbonate, was concentrated on the water-bath, filtered to 
free it from the calcium sulphate deposited, and then added to a 
mixture of phenylhydrazine and acetic acid. After standing a 
short time a bulky yellowish amorphous precipitate settled down. 
