112 Scientific Intelligence. [March, 



the Institute by Brongniart, on Geology, in which some new doctrines were advanced, 



which were opposed by Cordier ; the discussions on this subject became very 



animated.— Cuvier read a paper on the objects of Natural History, which had 



been collected by the naturalists who accompanied Captain Dumont d'Urville in 



his late voyage round the world.— M. Mathieu read a small paper regarding 



the invention of a new instrument for measuring distances on paper, and also 



for protracting distances correctly on maps : the instrument is extremely simple, 



and I think it will be of great use to the graphic art. — He also read a paper 



lately, describing an Instrument for drawing parallel lines : I have not seen this 



instrument. The Institute is the moat interesting place I ever frequented, there 



is always something new ; all the members are educated, scientific men, eminently 



distinguished in their several departments, well qualified to judge of whatever 



may come before them ; there is no dross or rubbish, the entire body is solid 



and pure.' 



6. — Caoutchouc. 



[From the Journal of the Franklin Institute.] 



We have received from the above-named gentleman some account of his experi- 

 ments on the distension and inflation of Caoutchouc ; he has also read a paper 

 upon the subject before the American Philosophical Society, and several notices 

 respecting them have likewise appeared in the daily journals. We may probably 

 hereafter lay some further details before our readers. The communication 

 referred to contains the following information : 



MODE OF MAKING GUM ELASTIC INTO BAGS, SHEETS, &C 



Soak the gum elastic in sulphuric ether until soft, and almost inelastic, which 

 in o-ood ether will take from 10 to 24 hours. Then, if it is a plate, cut it with a 

 wet knife, or parallel knives, into such sections, or sheets, or shapes, as may 

 be desired, and suffer them to dry ; or if a bag, apply a pipe or stop-cock, and inflate 

 with the mouth rapidly. If the bag should expand equally, more slowly ; and with 

 occasional pauses, if unequally. By such means a bag may be made so thin 

 as to become transparent, and light enough to ascend when filled with hydrogen. 

 By graduating the extent of inflation, sheet caoutchouc of any given thickness is 

 produced. If for blow-pipes, or other purposes, for which it is desirable that 

 the bags should possess contractility, let them be inflated to the desired size and 

 after an hour let out the air. Ever afterwards they will suffer as great a degree 

 of extension, and again contract. If permanent sheets are wanted, the inflated 

 bags are to be hung up until dry, after which no sensible contraction will ensue. 



Caoutchouc softened by ether may he readily stretched by hand, over lasts, 

 assume the shape desired, and may, therefore, be applied to a variety of useful 

 purposes. In the form of straps and twisted strings, its elasticity offers many useful 

 applications. It may he made to assume the form of a tube, to connect parts of 

 chemical and other philosophical apparatus with each other; may be employed 

 as covers for bottles, corks, &c. and indeed wherever the passage of steam, or 

 air is to be prevented. It is also susceptible of numerous applications in 

 medicine and surgery. 



Mr. Mitchill has extended a bag which was not above the size of a skinned English 

 walnut, and which weighed three drachms and a half, until its diameters were 15 

 and 13§ inches respectively. Larger bags have been made to attain a diameter 

 of six feet ; one of these when filled with hydrogen, escaped, and was found at 

 the distance of 130 miles from the city. Balloons so formed have been exhibited 

 before the several classes attending chemical lectures in Philadelphia. 



