42 



distinguished Honorary Members. Dr. Rankine was one 

 of the earliest investigators of the dynamical theory of heat, 

 and contributed eminently in the work of bringing that 

 theory to its present advanced condition. Besides this, he 

 was perhaps more successful than any other man in apply- 

 inof his own discoveries, and those of his fellow labourers in 

 abstract science, to practical use. His treatises on the 

 Steam Engine and other Prime Movers, Applied Mechanics, 

 Machinery, &c., form what may justly be termed an Encyclo- 

 paedia of Civil Engineering. Called away in the prime of 

 life, his loss is one of the most severe that could have 

 befallen science. 



Mr. William H. Johnson, B.Sc, called attention to the 

 action of sulphuric and hydrochloric acids on iron and steel 



If after immersion for say ten minutes in either of these 

 acids a piece of iron or steel be tested, its tensile strength 

 and resistance to torsion will be found to have diminished. 

 Exposure to the air for. several days or gentle heat will 

 however completely restore its original strength. On break- 

 ing a piece of iron wire after immersion in sulphuric acid 

 and gently moistening the fracture with the tip of the 

 tongue, bubbles of gas arise causing the wetted portion to 

 appear to boil. The most careful washing and coating with 

 lime after being dipped in the acid, and even its subsequent 

 drawing, in which process it is reduced in diameter by pass- 

 age through a die, does not interfere with either of these 

 phenomena; which only gradually disappear by exposure 

 to the air, or more quickly by gentle heat. 



Prolonged immersion in acid has a tendency to produce 

 a crystalline structure in even the best wrought iron. 



