+ 28.6
Indian, 3 | 5 | + 66.2
Eastern, 4 | 5 | - 26.0
Eastern, 5 | 5 | - 30.6
Senegal, 6 | 5 | - 17.6
Senegal, 7 | 5 | - 18.4
Senegal, 8 | 21/2 | - 19.6
Senegal, 9 | 5 | - 38.2
Senegal, 10 | 5 | - 25.8
Amrad | 21/2 | + 57.6
Australian, 1 | 5 | - 28.2
Australian, 2 | 5 | - 26.4
Brazilian, 1 | 21/2 | - 36.8
Brazilian, 2 | 21/2 | + 21.0
Dextrin, 1 | 5 | +148.0
Dextrin, 2 | 5 | +133.2
Ghatti, 1 | 5 | - 39.2
Ghatti, 2 | 5 | - 80.4
----------------+----------------+-----------------

These numbers do not show any marked connection between the viscosity,
etc., of a gum and its specific rotatory power.

When gum arabic solution is treated with alcohol the gum is precipitated
entirely if a large excess of spirit be used. With a view to seeing if
the precipitate yielded by the partial precipitation of a gum solution
was identical in properties to the original gum, we examined several
such precipitates from various gums to ascertain their rotatory power.
We found in each case that the specific rotatory power of the alcohol
precipitate redissolved in water was not the same as that of the
original gum. In other words these gums contained at least two bodies of
different rotatory powers, of which one is more soluble in alcohol than
the other. O'Sullivan obtained similar results with pure arabin. The
experiments were conducted in the following manner:

(a.) Five grammes of a dextro-rotatory gum (No. 3 in table) were
dissolved in 20 c.c. of water. To the solution was added 90 c.c. of 95
per cent. alcohol. The white precipitate which formed was thrown on to a
tared filter and washed with 30 c.c. more alcohol. The total filtrate
therefore was 140 c.c. The precipitate was dried and weighed = 2.794
grammes or 55.88 per cent. of the total gum. The precipitate was then
redissolved in water, bleached as before and diluted to a 5 per cent.
solution. This was then examined in the polarimeter. Readings gave the
value [alpha]_{D} = +58.4 deg.. The previous rotatory power of the gum was
+66 deg.. Now the