
ON THE ACTION OF AIR AND WATER UPON IRON. 29 
point of view, but of practical importance, and as no correct measures as yet 
exist, or at least have been published, of the amount of loss of metal by 
oxidation and abrasion of railway bars, I have thought it desirable to institute 
some experiments to determine, first, whether there be any difference in the 
amount of corrosion of rails in and out of use; secondly, if there be any, to 
discover on what the effect depends; thirdly, to distinguish numerically 
between the loss due to corrosion, and that due to abrasion by traffic. 
These experiments I have been enabled to commence on the Dublin and 
Kingstown Railway, by the favour of the Directors of that line, and hope soon 
to have others in operation upon the Ulster Railway, which is a single line, 
with traffic of course in both directions over the same rails. I have not as yet 
obtained any results (from insufficient lapse of time) which I can consider 
trustworthy, but so far I have not been able to recognize any distinct differ- 
ence of corrosion between the used and unused rails; on a future occasion, 
however, I hope to be able to lay my results fully before the Association. 
390. With this exception, and a few others merely of scientific interest, the 
present Report completes the investigation of all. the more important prac- 
tical desiderata on the subject of the corrosion of iron, &c. entrusted to me by 
the British Association, and I hope that as the information obtained by its 
liberal assistance becomes more known, it will be found of practical use by 
all who are engaged in the constructive use of iron, the substance perhaps 
‘the most valuable and important of all those with which Providence has 
endowed us. 
Nore py THE AUTHOR.—Since the preceding Report was sent to press, I have learnt with 
satisfaction that the principles therein developed for preventing the fouling of iron ships have 
been already acted on; that the Iron Queen and the Ben Ledi iron steamer have been coated 
with a composition of tallow, bright varnish, arsenic, and, I believe, sulphur, and. that in the 
former case all fouling was prevented; and after the vessel had made two voyages to the Tro- 
pics, she was found perfectly clean when docked on her return. 
From the bottom of the Ben Ledi ten tons weight of mussels and barnacles are stated to 
have been removed previous to the application of the above poisonous varnish, which, although 
different from that I have recommended, not so efficacious, and not harmless as regards its ree 
action upon the iron hull, is still quite identical in principle with mine. 
R. M. 
June 26, 1843. \- 
