THE papers by Faraday on the Liquefaction of Gases, here reprinted, give an account of the earliest work carried out at the Royal Institution on that most interesting and important subject, with which the Institution has been more or less intimately associated for three-quarters of a century. The extreme beauty and simplicity of Faraday's experiments, as well as the peculiarly felicitous manner in which his various experiments are described, render these papers especially instructive, and suitable for reproduction in the series to which this little volume belongs.

It was considered advisable to reprint Faraday's Historical Statement respecting the Liquefaction of Gases, and, for the sake of greater completeness, to include, in the form of an Appendix, the papers of Mr Northmore which are particularly referred to in that Statement.