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PROFESSOR A. M. WORTHINGTON ON THE 
1886, succeeded in reaching, with alcohol, a tension of 7‘9 atmospheres or 116 pounds 
per square inch, and, with strong sulphuric acid, 11'8 atmospheres or 173 pounds per 
square inch. 
(3) The method of cooling, discovered by M. Berthelot, and described by him in 
a paper entitled “ Sur la Dilatation Forcee des Liquides,” published in 1850 (‘ Ann. 
de Chimie/ vol. 30, 1850, pp. 232-237), by which he succeeded in obtaining a great 
variety of liquids in a state of very considerable mechanical extension, the amount of 
which he appears, however, rather to have estimated than to have measured, but 
which, according to his estimate, was as much as of the whole volume in the case 
of water, in the case of alcohol, and in that of ether. 
In M. Berthelot’s experiments the liquid, freed of air by long boiling, nearly 
filled a straight, thick-walled glass tube, the small residual space being occupied by 
its vapour. When slightly heated the liquid expanded and filled the whole tub.e, 
but on being again cooled remained extended, still filling the tube, of which it at last 
let go its hold with a loud metallic click, when the bubble of vapour re-appeared. It 
was from the length of this bubble that the extension vras calculated. 
It will be observed that methods (1) and (2) afford measures of the tensile stress, 
but not of the strain or extension; while, on the other hand, the method (3) affords 
a measure of the strain but not of the stress. The object of the present paper is to 
describe the process by which, after a great variety of trials made during the past 
six years, I have succeeded in what, so far as I am aware, has not been previously 
attempted, viz., in obtaining simultaneous measures of stress and strain in a liquid 
under tension. The measures are not, indeed, as numerous as could be wished, for 
reasons that will appear in the sequel, but they are fairly consistent, and mark a 
stage in an investigation with which I hope to proceed further, and to which I am 
anxious to attract the attention of more skilful experimenters. 
That a liquid can pass into and exist stably in a state of tension without any 
breach whatever of physical continuity has been denied or questioned by eminent 
physicists,* and the contrary is commonly asserted by writers on Hydrodynamics.! 
The experiments to be described will be found, I think, to remove the last possibility 
of doubt upon the matter. 
Method of Experimenting . 
The mode of subjecting the liquid to tensile stress is essentially that of Berthelot, 
and may be briefly described as follows :—'The liquid is contained in a strong closed 
glass vessel which it nearly fills at the ordinary temperature of the air. The small 
space not filled by liquid is occupied only by its vapour. Dissolved air, and especially 
the film of air which at first lies between the liquid and the walls of the vessel, is got 
rid of, as far as possible, by prolonged boiling before the vessel is sealed up. 
* See Balfour Stewart, ‘ Elementary Physics,’ § 69, p. 70. 
t See Lamb, ‘ Treatise on the Motion of Fluids,’ § 9, p. 7. 
