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XVIII. The Bakerian Lecture. — On the Continuity of the Gaseous and Liquid States 
of Matter. By Thomas Andrews, M.D . , F.B.S., Vice-President of Queen's College , 
Belfast. 
Received June 14, — Read June 17, 1869. 
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 few numerical determinations of the pressures exerted in these experiments *. 
In the following year Faraday succeeded in liquefying, by the aid of pressure alone, 
chlorine and several other bodies known before only in the gaseous form *j\ 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 aeriform body A second 
memoir by Faraday, published in 1826, greatly extended our knowledge of the effects 
of cold and pressure on gases §. Begnault has examined with care the absolute change 
of volume in a few gases when exposed to a pressure of twenty atmospheres, and Pouillet 
has made some observations on the same subject. The experiments of Natterer have 
carried this inquiry to the enormous pressure of 2790 atmospheres; and although his 
method is not altogether free from objection, the results he obtained are valuable and 
deserve more attention than they have hitherto received ||. 
In 1861 a brief notice appeared of some of my early experiments in this direction. 
Oxygen, hydrogen, nitrogen, carbonic oxide, and nitric oxide were submitted to greater 
pressures than had previously been attained in glass tubes, and while under these pres- 
sures they were exposed to the cold of the carbonic acid and ether-bath. None of the 
gases exhibited any appearance of liquefaction, although reduced to less than of 
their ordinary volume by the combined action of cold and pressure^] - . In the third 
edition of Miller’s ‘ Chemical Physics,’ published in 1863, a short account, derived from 
a private letter addressed by me to Dr. Miller, appeared of some new results I had 
obtained, under certain fixed conditions of pressure and temperature, with carbonic acid. 
As these results constitute the foundation of the present investigation and have never 
been published in a separate form, I may perhaps be permitted to make the following 
extract from my original communication to Dr. Miller. “ On partially liquefying car- 
bonic acid by pressure alone, and gradually raising at the same time the temperature to 
* Annales de Chimie, 2& me serie, xxi. pp. 127 and 178 ; also xxii. p. 410. 
t Philosophical Transactions for 1823, pp. 160-189. { Annales de Chimie, 2^ me serie, lx. pp. 427, 432. 
§ Philosophical Transactions for 1845, p. 155. || Poggexdorff’s £ Annalen,’ xciv. p. 436. 
Report of the British Association for 1861. Transactions of Sections, p. 76. 
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