118 
For reference sec also : 
9. Gmelin. " Chemistry," xv, 296. Articles -Melitose, Eucalin. 
10. A. H. Allen." Commercial Organic Analysis" (J. and A. Churchill), Vcl. i, 
(1885): p. 191, Glucoses (Eucalyptoss, Eucalyn); p. 192, Saccharoses (Melitose, 
Eucalypton ; Melezitosc). 
11. D. Hooper. " Chemical Notes on Mannas." Druggists' Circular, 4, 1891, 
and brief abstract in Bulletin of Pharmacy, v, 117. Eucalyptus manna is referred to 
amongst others. 
12. A. Ebert. " Ueber Isopulegon," by Alfred Ebert, Zurich, 1908, being his 
thesis for Ph.D. 
This paper contains a useful account of the various kinds of manna from different 
parts of the world. It concludes with a long bibliography of the subject. It contains 
a contribution to the knowledge of rare kinds of manna. The first part of the work 
contains no reference to Australian products. The second part, " Contribution to the 
knowledge of rare kinds of manna and allied substances," contains several pages on 
Australian products. From page 82 to 87 he describes the Eucalyptus mannas ; the 
description is mainly chemical. 
So far we have been dealing with the ordinary manna of Eucalypts. Now we 
come to Lerp or Lerp Manna, which was first chemically examined by Dr. Thomas 
Anderson in 1849 (see the reference at p. 113). 
The following additional references will probably be sufficient from the chemical 
point of view : 
13. F. A. Fliickiger. Vierteljahresschr. de Wittstein, 1868, xvii, 161. A 
chemical investigation of Lerp. 
This substance occurs on the leaves, and consists of white threads, clotted together by a syrup 
proceeding from the insect (Psylla eucalypti) which spins those threads. It contains, in round numbers 
of water, fourteen pa.rts ; thread-like portion, thirty -three parts ; sugar, fifty-three parts. The threads 
possess many of the characteristic properties of starch, from which, however, they are sharply distinguished 
by their form. When lerp is washed with water the sugar dissolves and the threads swell slightly, but 
dissolve to a slight extent, so that the solution is coloured blue by iodine. The threads, freed from sugar 
by washing, consist of a substance called Lerp-amylum. 
Lerp-amylum is very slightly soluble in cold water, not perceptibly more so in water at 100, 
but entirely soluble to a thin transparent liquid when heated to 135 in sealed tubes with thirty parts 
of water. This solution, on cooling, deposits the original substance in flocks, without forming a jelly at any 
time. The separation is almost complete. 
If the material employed in this experiment were entirely free from sugar, the liquid left after the 
separation of the flocks will also be free from sugar. The flocks deposited from solution are insoluble ia 
boiling water, therefore lerp-amylum suffers no chemical change on being heated to 150 with water. 
Heated in the air-bath to 190 while dry, it turns brown, and is afterwards merely reddened by solution 
of iodine ; at the same time it becomes partly soluble in hot water, hence it appears that lerp-amylum 
undergoes a change similar to that which occurs when starch is converted into dextrin. By oxidation 
with nitric acid it yields oxalic acid, but no mucic acid ; it is neutral to vegetable colours, and is not 
precipitated by lead acetate, and is, therefore, not to be confounded with the gums, &c. 
