278 
NATURE 
[ Aug. 4, 1870 
THE CONTINUITY OF THE GASEOUS AND 
LIQUID STATES OF MATTER* 
1% may be truly affirmed of Physical Science, that its history, 
for some generations at least, has been one of rapid progress 
and unceasing change, and that its most earnest promoters have 
not claimed infallibility for their opinions, nor finality for their 
results. Its advancing progress has been marked by eras when 
some long-accerted theory or hypothesis, which had appeared so 
closely in iccordance with all known experiments and observa- 
tions as to have been received as an obvious truth, has, by 
further experiments extending into regions previously unexplored, 
been found to be a faulty or incomplete representation of the 
phenomena. 
Such an era has occurred in the discovery recently announced 
by Dr. Andrews of the Continuity of the Gaseous and Liquid 
States of Matter. 
We have all been accustomed to consider matter as existing in 
one or other of three states, —the solid, liquid, and gaseous. 
Bige Ps 
== —— 
The transition, from any one of these states to another, has 
hitherto been regarded as necessarily abrupt ; at least, if we 
except the imperfectly understood conditions of softening or 
plasticity, assumed by such bodies as glass or iron, when gradu- 
ally passing from the solid to the molten condition. The true 
state of the case is now found to be very different. 
The memoir of Dr. Andrews, of which we propose to give an 
account in this article, opens with the following historical résumé 
of previous researches bearing more or less in the direction of 
his investigations :—‘‘ In 1822 M. Cagniard de la Tour observed 
that certain liquids, such as ether, alcohol, and water, when 
heated in hermetically sealed glass tubes, became apparently 
reduced to vapour in a space from twice to four times the original 
volume of the liquid. He also made a fewnumerical determina- 
tions of the pressures exerted in these experiments. In the 
following year Faraday succeeded in liquefying, by the aid of 
pressure alone, chlorine and seyeral other bodies known before 
only in the gaseous form. A few years later Thilorier obtained 
solid carbonic acid, and observed that the coefficient of expansion 
of the liquid for heat is greater than that of any aériform body. 
*“ The Bakerian Lecture for 1869.” _By Thomas Andrews, M.D., F,R.S, 
(Abridged from an Original Essay of Professor James Thomson, LL. I’) 
A second memoir by Faraday, published in 1845, greatly extended 
our knowledge of the effects of cold and pressure on gases. 
Regnault has examined with care the absolute change of volume 
in a few gases when exposed to a pressure of twenty atmospheres, 
Fg. 3. 
and Pouillet has made some observations on the same subject, 
The experiments of Natterer have carried this inquiry to the 
enormous pressure of 2,790 atmospheres; and although his 
method is not altogether free from objection, the results he 
ee 
obtained are valuable, and deserve more attention than they have 
hitherto received.” 
In 1861 a brief notice appeared of some early experiments by 
Dr. Andrews in this direction, Oxygen, hydrogen, nitrogen, 
