298 R. T. BAKER.AND H. G. SMITH. 
To determine the amount of other sugars present, if any, two 
grams of the same manna were taken, dissolved in water, a small 
quantity of dilute hydrochloric acid added, and then boiled for 
half an hour. The solution was then cooled, made neutral, and 
brought up to 200 cc. It required 73 cc. of this solution to reduce 
5.cc. of Fehling’s copper solution, or equal to 3-425 per cent. of 
total sugars. As the glucose present equals 2-15 per cent., the 
manna contains, therefore, 1:275 per cent. of a sugar or sugars 
other than glucose. 
Determination of the Mannite.—The mannite for this purpose 
was obtained from the manna by the following method, whereby 
it is obtained fairly pure at the first crystallisation. A quantity 
of the powdered manna was boiled in a small quantity of rectified — 
spirit. The alcohol when removed was dark coloured, and deposited 
some mannite on cooling; it appeared to contain the greater 
portion of the sugars. This portion was discarded. The manna 
was then boiled in several portions of rectified spirit, these were 
mixed together; on cooling a good quantity of mannite crystal- 
- lised out in needles and plates. It was fairly white in colour and 
the alcohol was but slightly coloured. The crystals were removed, 
placed on a porous slab to drain, recrystallised from water, and — 
again drained on the slab. The mannite is thus readily obtained 
almost pure. For the more delicate reactions the mannite was 
again recrystallised from alcohol and water. The use of animal 
charcoal was not needed. 
The tests whereby these crystals were determined as mannite 
are as follows :— 
1, The crystals are rhombic prisms. 
2. They were very soluble in water ; slightly soluble in cold 
alcohol, readily on boiling ; and were insoluble in ether. 
3. When dissolved in water the solution had no action on light 
in the polarimeter, being optically inactive. 
4. When the crystals were dissolved in water and treated with 
fresh yeast, no fermentation took place during twenty-four hours. 
5. When boiled with Feliling’s solution no reduction took place, 
