\Ql PHILOSOPHICAL TRANSACTIONS. [ANNOI78I. 



ether, the smell of that fluid cannot be perceived through it ; but I never saw a 

 glass stopple that could produce the same effect. By opening the bottle very 

 often, or by long keeping, the cork becomes loose, in which case it must be 

 changed; and thus ether, spirit of wine, or any fluid, excepting those which 

 corrode cork, may be preserved. 



I shall now describe a method of purifying vitriolic ether, which is very easy 

 and expeditious, though not very profitable: this method I learned of Mr. 

 Winch, Chemist, in the Haymarket. Fill about a quarter of a strong bottle 

 with common ether, and on it pour about twice as much water, then stop the 

 bottle, and give it a shake, so as to mix for a time the ether with the water. 

 This done, keep the bottle without motion, and with the mouth downwards, till 

 the ether is separated from the water and swims over it, which requires not above 

 3 or 4 minutes of time; then open the bottle, and keeping it still inverted, let 

 the greatest part of the water come out very gently; after this the bottle being 

 turned with the mouth upwards, more water must be poured in it, and in short 

 the same operation must be repeated 3 or 4 times. Lastly, all the water being 

 separated from the ether by decanting it with dexterity, the ether will be found 

 to be exceedingly pure. By this means I have purified common vitriolic ether, 

 which could not affect elastic gum, and have reduced it into such a state as that 

 elastic gum was easily dissolved by it. Indeed this purified ether appeared by 

 every trial to be purer than I ever saw it, even when made after the best usual 

 method, and in the most careful manner. The only inconvenience attending 

 the process is, that a vast quantity of ether is lost. Not above 3 or 4 ounces of 

 a pound of common ether remain after the purification. As the greatest part of 

 the ether is certainly mixed with the water that is used in the process, it may 

 perhaps be worth while to put that water into a retort, and to distil the ether 

 from it, which must come sufficiently pure for common use. It is commonly 

 believed, that water combines with the purest part of ether, when those 2 fluids 

 are kept together; whereas, by the above described process, the contrary is esta- 

 blished; perhaps when ether is kept in contact with water for a long time, the 

 purest part of it may appear to be lost, because the ether may be combined with, 

 and may retain some water in itself, at the same time that the water combines 

 with and retains some ether; whereas the case may be different when the ether 

 is quickly washed in water, and is immediately after separated from it: but in 

 respect to this I have not yet made any experiments, so as to be able to decide 

 the matter. 



1. Experiments relating to the expansion of mercury. — The difficulty and un- 

 certainty attending the various methods hitherto proDosed for investigating the 

 expansion ot quicksilver, or its increase of bulk when rarefied by a given degree 

 of heat, determined me to contrive some method by which this purpose might be 



