1 96 Miscellanies. 



bag may be made so thin as to become transparent and light enotigh 

 to ascend when filled with hydrogen. By graduating the extent of 

 inflation, a sheet of 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 after 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, af- 

 ter which no sensible contraction will ensue. 



Bags softened by ether may be stretched readily by the hand, over 

 lasts, hat blocks, or other moulds, so as to assume the shape desired, 

 and may be so applied to a variety of useful purposes. In the form 

 of straps and twisted strings, its elasticity oflfers many useful applica- 

 tions. It is easily formed into tubes to connect apparatus, &;c. 



Some of the bags have been extended to six feet in diameter ; 

 one of these being filled with hydrogen, escaped, and was found one 

 hundred and thirty miles from the place. A bag, originally the size 

 of an English walnut, was extended until fifteen inches in diameter. 



Dr. Mitchell states, that oil of sassafras softens caoutchouc so that 

 it can be applied with a brush, and that upon drying by exposure to 

 air, it becomes again simple elastic caoutchouc. Many applications 

 of it as a varnish, in this state, are suggested. — Franklin Journal, 

 V. 122. 



2. Strength of Wine and other Bottles. — M. Collardeau has con- 

 structed a machine for the purpose of trying the strength of wine 

 bottles. It has been presented to the Academic des Sciences, and 

 reported upon by M M. Hachette and D'Arcet. The bottle to be 

 tried is held at the neck by means of a lever, having three branches, 

 which grasp it below the ring ; being then filled with water, it is con- 

 nected by means of pipes, with a forcing-pump, the pipe having a 

 cap furnished with leather, which is firmly held down by the appa- 

 ratus upon the mouth of the bottle j the pressure upon the parts here 

 increases with the pressure of the water within the bottle. Besides 

 the pump, levers, and connecting pipe, there is also a manometer 

 connected with the interior of the bottle to shew the pressure exert- 

 ed. When a bottle is burst in this way by the hydraulic press, no 

 violent dispersion of its parts takes place, unless indeed, in place of 

 being Jilled with water, a portion of air is left in ; then when it breaks 

 !t flies to pieces, and would cause danger if exposed. 



