42 
distinguished Honorary Members. Dr. Rank in e 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- 
ing 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 Avith 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. 
