LIQUID HYDROGEN.' 



By Professor Dewak, M. A.. LL. D., F. R. S., M. R. I. 



My colleague, Lord Raylelgh, in his conmiemoration lecture dealt 

 so admirably and exhaustively with some of the discoveries of our 

 great predecessors in this institution that it will be unnecessary to 

 pursue further the lines of historical treatment in this lecture. 

 Instead of discoursing generally on the chemical side of the work 

 of Da\y and Farada}^ and their successors, it has seemed to me more 

 appropriate to attempt some experimental demonstrations of the 

 latest modern developments in a field of inquiry opened out to science 

 by the lal)ors of the two illustrious chemists just mentioned. With 

 this object in view, my discourse this evening will be confined to the 

 subject of liquid hydrogen. Davy said: "Nothing tends so much to 

 the advancement of knowledge as the application of a new instrument. 

 The native intellectual powers of man in different times are not so 

 much the causes of the different success of their hibors as the peculiar 

 nature of the means and artificial resources in their possession." The 

 new instrument of research, which for the first time we haA'^e to 

 experiment with before an audience, is the liquid form of the old 

 inflanmiable air of Cavendish. Lavoisier toward the end of the last 

 centur}' had the scientific acumen to declare that, in his opinion, "'if 

 the earth were suddenly transported into a very cold region, the air, or 

 at least some of the aeriform fluids which now compose the mass of our 

 atmosphere, would doubtless lose their elasticity for want of a sufficient 

 temperature to retain them in that state. They would return to the 

 liquid state of existence and new liquids would be formed, of whose 

 properties we can not at present form the most distant idea." Black, 

 about the same time, in discussing the properties of hydrogen, makes 

 the following suggestive observations: " We may now further remark, 

 with regard to inflammable air, that it is at presG?nt considered as one 

 of the simple or elementary bodies in nature. I mean, however, the 

 basis of it, called the hydrogen by the French chemists; for the inflam- 

 mable air itself, namely, hydrogen gas, is considered as a compound of 



^ Centenary commemoration lecture, Royal Institution of Great Britain, "Wednes- 

 day, Jmie 7, 1899, His Grace the Duke of Northumberland, K. O., president, in the 

 chair, by Professor Dewar, M. A., LL. D., F.R.S., M. R. L, FuUerian professor of 

 chemistry R, 1, 



259 



