376 TlMEHRI. 
In one respect Balata shews a very marked and important difference 
from Gutta Percha and that is in its behaviour under the influence of 
the atmosphere. Whilst Gutta Percha when exposed to light and air 
soon becomes altered on the surface and changed into a brittle resinous 
substance, into which the whole of the mass is gradually converted in 
the course of time, Balata on the other hand is but slowly acted upon 
under these circumstances. 
I enclose a piece of Balata tissue which has now been in my posses- 
sion quite six years and although it shows a peculiar mealy efflores- 
cence due to a chemical change it is still supple and coherent ; a similar 
tissue of Gutta Percha would have long before now become entirely 
converted into a brittle resin. 
The electrical isolating quality of Balata is said to be quite equal to 
that of Gutta Percha. Altogether there seems no question about the valu- 
able properties of Balata, all that is wanted is a sufficient and constant 
supply and a somewhat lower price. But even v at its present price I 
think it would find a ready market if it came in larger quantities and 
thus enabled the manufacturers to use it for applications on a large scale. 
As far as I could make out it is used by itself and not mixed with 
Gutta Percha. 
One thing is also greatly in favour of Balata and this is the great 
purity in which it is brought into the market, when compared with the 
extent and the many kinds of extraordinary admixtures with which 
raw Gutta Percha is now adulterated before it reaches this country. 
I think this is all I have to say about Balata and hope it will help to 
encourage the people of Demerara in producing more of it. 
Yours sincerely, 
HUGO MULLER. 
Local Literature. — A paper entitled " Explorations in 
the neighbourhood of Mounts Roraima and Kukenaam 
in British Guiana" has been published by Mr. HENRY 
WHITELY in the August number of the Proceedings of 
the Royal Geographical Society (1884). Mr. Whitely 
is a collector of birds who in the course of some wander- 
ings round Roraima has made some valuable additions to 
the cabinets of European ornithologists. A valuable 
