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LVII. On dilating Caoutchouc Bottles by Inflation. By 
B. M. Forster, Esq. 
To Dr. Tilloch. 
Sir, — Tur great expansibility of the Caoutchouc or India- 
rubber is well known: but I am not aware that. any endeavours 
have heretofore been made to inflate the bottles made of that 
substance, with air, with a view to enlarge their capacity. On 
Tuesday the 19th instant, I threw some air into a small bottle 
of it, with a condensing syringe, which caused a small blister (if 
so I may call it) on the lower part of the bottle; since which, by 
proceeding in the same way, the bottle was enlarged from about 
two inches and a half (diameter) to about six and a half. 
Ido not know exactly the dimensions. The mode of the ex- 
pansion is to me rather surprising: the globe did not expand in 
an uniform manner, but a blister was formed which increased 
from what may be called the bottom (if the term bottle is used) 
towards the neck, where the syringe was connected. I have 
this evening blown it up without a condensing syringe to very 
nearly six inches diameter. For some way below the neck the 
India-rubber retains its usual appearance, not being stretched 
out like the other part; which part has the look of an animal’s 
bladder, full blown; or a globe of thin horn. I am of opinion 
that globes of this kind will in many respects be found prefer- 
able to bladders for philosophical and other purposes. If the ex- 
pansion can be continued to a very considerable extent, I am in 
hopes that air balloons may be made with these globes. In two 
trials I have burst the bottles before the expansion was arrived 
at nearly the degree to what it was in the instance above men- 
tioned. 
It has appeared to me remarkable, when (warmed) paper 
has been’ excited with a piece of India-rubber, that the rubber 
showed very little signs of being electric, although the paper was 
strongly electrified. This caowtchouc globe when rubbed on pa- 
per (warmed) becomes strongly electric, and produces sparks 
attended with snappings. 
Walthamstow, Essex, March 26, 1822. B. M, Forster, 
LVIII. On 
