1880.] Mr. W. Crookes. On a Fourth State of Matter. 469 



June 10, 1880. 



THE PRESIDENT in the Chair. 



The Presents received were laid on the table, and thanks ordered for 

 them. 



Dr. John Attfield, Dr. Clifford Allbutt, Rev. William Henry Dal- 

 linger, Mr. William Turner Thiselton Dyer, Lient.-Col. Henry 

 Haversham Godwin- Austen, Prof. David Edward Hughes, Mr. Henry 

 M. Jeffery, Mr. J. Fletcher Moulton, and Dr. John Rae were admitted 

 into the Society. 



The following Papers were read : — 



I. " On a Fourth State of Matter," in a letter to the Secretary. 

 By W. Crookes, F.R.S. Received May 17, 1880. 



7, Kensington Park Gardens, London, W., 

 April 29, 1880. 



Dear Professor Stokes, 



In introducing the discussion on Mr. Spottiswoode and Mr. Moulton's 

 paper on the " Sensitive State of Vacuum Discharges," at the meeting 

 of the Royal Society on April 15th, Dr. De la Rue, who occupied the 

 chair, good-naturedly challenged me to substantiate my statement 

 that there is such a thing as a fourth or ultra-gaseous state of matter. 



I had no time then to enter fully into the subject ; nor was I pre- 

 pared, on the spur of the moment, to marshal all the facts and reasons 

 which have led me to this conclusion. But as I find that many other 

 scientific men besides Dr. De la Rue are in doubt as to whether matter 

 has been shown to exist in a state beyond that of gas, I will now 

 endeavour to substantiate my position. 



I will commence by explaining what seems to me to be the constitu- 

 tion of matter in its three states of solid, liquid, and gas. 



I. First as to Solids : — These are composed of discontinuous mole- 

 cules, separated from each other by a space which is relatively large — 

 possibly enormous — in comparison with the diameter of the central 

 nucleus we call molecule. These molecules, themselves built up of atoms, 

 are governed by certain forces. Two of these forces I will here refer 

 to — attraction and motion. Attraction when exerted at sensible dis- 

 tances is known as gravitation, but when the distances are molecular it 

 is called adhesion and cohesion. Attraction appears to be independent 

 of absolute temperature ; it increases as the distance between the 



2 l 2 



