COMPOSITTON OF SULI'IIURIC ETM-EH. 3 j5 



Thematras was filled with mercury, except a space equal to 

 that of the small column, that had been measured, and this 

 was lilled with ether. I then closed for an instant the ori- 

 fice of the matras, and inverted it in a basin of mercury, 

 under which I opened it. Thus the matras became a kind 

 of imperfect barometer, terminating above in a hollow ball 

 void of air, but filled with the vapour of ether. The length 

 of the column of ether, previously measured, was dimi- 

 nished above a third by the formation of the vapour I have, 

 mentioned. This diminution reduced to weight, and com- 

 pared with the capacity of the body of the matras, gave me 

 the bulk and weight of the vapour of ether in vacuo, and 

 proved, that they were equal, at least as far as could be ex- 

 pected in an experiment on 30 cubic inches, to the bulk and ^ 

 weight of this vapour in atmospheric air, in nitrogen gas, 

 and in hidrogcn gas. The vapour of alcohol is too light, 

 to afford sufficiently decided results by this process. 



In this experiment there are some precautions to be taken, Necfs^ary nre- 

 30 which however there is no dilficulty, 1st, to expel from '^^"^''^"''" 

 the surface of the mercury contained in the barometer a 

 small quantity of liquid ether, which lodges betncca the 

 mercury and the inside of the neck when the matras is in- 

 verted. This may be effected by surrounding it with a cloth 

 warm enough to rediice this etlicr into elastic vapour. — 

 2dly, it is necessary to estimate by a comparative experi- 

 ment, made at the same time and in the same place, with a 

 matras of equal size, the weight of the liquid ether that ad- 

 heres in small quantity to \\\e. inside of the body filled with 

 vapour. 3clly, in stopping the matras to invert \i^ the 

 stopple must not touch the ether. 1 avoided this source of 

 /errour, by fixing in the neck of the matras, near its orifice, 

 a tube closed at the bottom, and filled with the ether in- 

 tended for this experiment. 



I found thus, that a cubic fool: void of air, or filled with 2oz. of ethefi 



air, could contain, at a temperature of 18^ R. [72-5° F.], ^'J ''^° t'-"";' . 

 / 5 i L -J' of a cubic toot- 



about two ounces of invisible ether in the state of gas. The 



extraordinary weight of this vapour instructs us how much 

 ether ig lost, by employing large vessels or globes passing 

 one into another, for the purpose of coudeusers and re- 

 ceivers in distilling this fluid. 



A know- 



