122 Mr. Dalton on Sulphuric Ether. [Feb. 



about 0-72 and 0-98 respectively ; and whenever the under fluid 

 is extremely light, then the upper one is extremely heavy, but 

 the two never approximate nearer than 0'9;3 and U-82 respect- 

 ively. As far as 1 have found, I am pretty well convinced that 

 in this last case the heavy fluid is constituted of 1 atom of ether, 

 1 of alcohol, and 6 of water; and the light fluid of 1 ether, 

 1 alcohol, and 1 water, being a true ternary compound of the 

 three elements. These facts are beautifully exhibited by a 

 single experiment. Let equal volumes of pure ether and water 

 be agitated together ; on subsiding, the ver;f heavy and veiy 

 light fluids are immediately perceived ; let then pure alcohol be 

 added by degrees, and agitated ; it will be observed that both 

 fluids have increased in voluoe upon each addition, till at length 

 the upper fluid arrives at its maximum volume and specific gra- 

 vity. A further addition of alcohol then diminishes the volume 

 of ether till at length it disappears, and the v/hole becomes one 

 uniform fluid. 



The boihng point of ether I find forms a curious part of its 

 history ; I mean that point of temperature when its vapour is of 

 sufiicient force to balance the weight of the atmosphere. In my 

 early experiments I found the point by immersing a thermometer 

 in the boihng fluid, when it stood at 102° ; but in subsequent 

 experiments I used a barometer tube bent about one third from 

 the sealed end, and the legs laid parallel. A small portion of 

 ether was let up to the sealed end, and the tube from thence to 

 a little past the turn was filled with mercury. The instrument 

 thus prepared was immersed in a tall jar of warm water till the 

 vapour arose from the ether and depressed the raercuiy, which 

 ascending in the other leg, v/as brought to a level in the two. In 

 this way, the same ether, in the temperature of 98'^, exhibited a 

 force equal to the atmosphere. Something like this I find takes 

 place in alcohol of 0-83 specific gravity. It boils in a phial at 

 17G°; but in a tube its vapour is equal to the atmosphere in a 

 temperature of 172^. Pure ether of 0-72 specific gravity boils 

 in the tube at 95° or 96°, as Gay-Lussac has observed ; but in a 

 phial I find the thermometer may be raised to 98° in the boihng 

 liquid. The boiling point of a mixture of pure ether and pure 

 alcohol may be made to vary from 96° to 170°; but we cannot 

 infer the boiling point from a knowledge of the proportions of the 

 mixture ; it is always much nearer that of ether than the pro- 

 portions would indicate. Indeed it is the same with alcohol and 

 water, and all similar mixtures. A mixture of equal parts of 

 alcohol and water boils at 183° ; whereas by the rule of propor- 

 tion it ought to boil at 194°. A mixture of four parts ether and 

 three parts alcohol I found boiled at 1 17° in the tube, and 122° 

 or 123"^ in the air, which by proportion should have boiled at 

 127°. It was of specific gravity 0*769, and might, therefore, be 

 •onsidered as between the second and third quality. 



The modifications of the boiling point of ether produced by 



