ACTION OF WATER ON IRON. 253 



lurst Report upon Experiments, instituted at the request of 

 the British Association, ujjon the Action of Sea and River 

 Water, ivhether clear or foul, and at various temperatures, 

 upon Cast and Wrought Iron. By Robert Mallkt, 

 M.R.I.A. Ass. Ins. C.E. 



1. Thk subject of the present report, for the furtherance of 

 which the Association, at its last meeting, made a grant of 

 money, is one of great interest in a scientific point of view, and 

 of paramount importance as an inquiry of civil engineering. 

 Scarcely half a century has elapsed since the adaptation of iron 

 in its various forms to the many purposes of the engineer, upon 

 a scale before unknown, and as forming parts of public struc- 

 tures whose limit of duration was to be measured, not by years, 

 but by centuries, first made it necessary to inquire — What was 

 the durability of the apparently hard and intractable material 

 employed ? What were the forces likely to occasion its destruc- 

 tion ? How would they act ? What would be their results ? 

 And what were the means of arresting their progress ? 



Yet important as a full answer to these inquiries would be, 

 and though the application of iron in construction to harbours 

 and ships, bridges and railways, and the innumerable other con- 

 trivances by which the engineer subdues and administers the 

 forces supplied by the Creator to the social wants of man, yet 

 our information upon this fundamental subject is scarcely more 

 advanced than it was twenty years ago ; and while the chemist 

 is not precisely informed as to the nature of the changes which 

 air and water (our most universal elements), separate or toge- 

 ther, produce on iron, the engineer is without data to determine 

 what limit their corroding action sets to the duration of his as- 

 piring and apparently unyielding structures. The investigation, 

 therefore, is one full of importance to science and to the arts ; 

 and although the commands of the British Association, as re- 

 spects it, have not been neglected, yet the conditions of the 

 subject were such, and the difficulties and delays in procuring 

 the requisite specimens of iron so great, that the following re- 

 port consists chiefly of a general survey of the present aspect 

 of this field of knowledge, and of the operations commenced or 

 intended by us for extending its boundaries, than of acquisi- 

 tions already made. 



2. It comprises, therefore, — 1st, a very brief "precis" of the 

 actual state of chemical knowledge of the subject at large, viz. 



