DESTRUCTIVE EFFECT OF IRON-RUST. 



TRANSLATED FKOM THE GEEMAN JOURNAL " AUS DER NATUR," VOL. 13, PA6K 153. 



It has been frequently observed that in timber of old ships where- 

 ever iron nails or bolts have been driven the wood in their proximity 

 is entirely altered. All around, to a distance of an inch and more, 

 and parallel to the direction of the woody fibres, as far as the iron 

 has entered, a part of the material is dissolved away, leaving the re- 

 mainder half charred, as it were, and quite brittle, so that it may be 

 easily broken into pieces, the fibres having entirely lost their cohesion. 

 Thus, the wood around the nails has the appearance as if these nails 

 were driven in when red hot. This injurious effect of the iron-rust 

 may be considered as one of the principal causes of the want of dura- 

 bility of our ships. 



Rust not only originates in places alternately wet with sea- water 

 and again exposed to the air, but also where the iron is permanently 

 submerged under water, for this also contains the elements for the 

 production of rust, namely: carbonic acid and oxygen. Rust, as is 

 generally known, is an oxide of iron, and as soon as it comes into 

 contact with wood it gives off part of its oxygen and becomes reduced 

 to protoxide. The latter takes up a new portion of oxygen and 

 transfers it again to the wood, and by the uninterrupted repetition 

 of this process a slow oxydation or decay of the wood is effected. 

 Thus the protoxide of iron in this case plays a part similar to that of 

 the nitric oxide in the manufacture of sulphuric acid, with the only 

 difference that the transfer of oxygen in the one case is of essential 

 benefit to arts, and in the other, decidedly injurious. 



In order to demonstrate the fact that oxide of iron is reduced by 

 the mere contact with organic substances not yet in a state of putre- 

 faction, Kuhlmann, in Lille, has instituted different experiments, the 

 results of which confirm the correctness of this assertion. When 

 hydrated oxide of iron was shaken with cold solutions of several col- 

 oring matters such as log-wood. Brazil-wood, cochineal, curcuma, 

 mahogany, but not indigo arid litmus, they became decolorized, lac dyes 

 having been formed. In these the iron was found in the state of 

 protoxide, and consequently the oxide of iron had lost a portion of 

 its oxygen by the action of the coloring matter. Solutions of cane- 

 sugar, grape-sugar, and gum were boiled with hydrate of oxide of 

 iron. Of these the grape-sugar acted powerfully, reducing the oxide 

 even when cold; this action was less with cane-sugar, and least with 

 gum. When oil of bitter almonds was heated with dry hydrate of 

 oxide of iron, to a temperature of 100°,* it was altered into benzoic 

 acid, which enters into combination with the protoxide of iron. 



-Probably Celcius scale. — Translator. 



