1877.] On Molecular Changes in Iron ana Steel. 127 



Goubareff (D.) Renovation Sociale basee sur les lois de la Nature. 8vo. 



Paris 1876. The Author. 



Mensbrugghe (G. van der) Application de la Thermodynamique a l'etude 



des Variations d'energie potentielle des surfaces liquides. 8vo. 



Bruxelles 1876. The Author. 



Wilson (Erasmus), F.R.S. Lectures on Dermatology, delivered in the 



Royal College of Surgeons in 1871-73, 1874-75. 2 vols. 8vo. 



London 1873-75. The Author. 



April 12, 1877. 



Dr. J. D ALTON HOOKER, C.B., President, in the Chair. 



The Presents received were laid on the table, and thanks ordered for 

 them. 



The following Papers were read : — 



I. " On certain Molecular Changes which occur in Iron and 

 Steel during the separate acts of Heating and Cooling." By 

 Professor Norris, M.D., Queen's College, Birmingham. 

 Communicated by G. Gore, F.R.S. Received August 15, 

 1876. 



(Abstract.) 



In the course of certain researches in Physiological Physics, in which 

 the author of this paper has been for some time past engaged, it became 

 necessary, with a view to learn how far it bore upon the subject in hand, 

 to inquire into the nature of a peculiar fact which was observed by his 

 friend Mr. Gore, and published in the Proceedings of the Royal Society, 

 January 28th, 1869, under the title of "A Momentary Molecular Change 

 in Iron "Wire." In this communication it was shown that if a strained 

 iron wire were heated to redness by a voltaic current or other means, 

 on being allowed to cool, the contraction of cooling was at a certain 

 point, and for a limited period, arrested by an action of elongation. 



" With wires of iron 0*65 millim. thick (No. 23) and 21-5 centims. 

 long, strained to the extent of ten ounces or more, and heated to full red- 

 ness, the phenomenon was clearly developed. For example, the needle 

 of the instrument went with regularity to 18*5 of index-plate ; the cur- 

 rent was then stopped ; the needle instantly retreated to 17*75, then as 

 quickly advanced to 19*75, and then went slowly and regularly back, but 

 not to zero. After shutting off the source of heat, the wire contracted 

 0*75 millim., and then expanded 2 millims. ; so that it returned 1*25 millim. 



vol. xxvi. K 



