ON THE ACTION OF AIR AND WATER UPON IRON. il 
metal. The crystallized state appears to be essential to its production in the 
cases of wrought iron and steel. The pieces of raw cast steel experimented 
on were found converted into plumbago for about jth of an inch in depth, 
and on removing this, the surface of the metal was found covered with a 
beautiful interlacing of crystals. 
318. Several experiments have been made to endeavour to arrive at a more 
perfect knowledge of the nature and formation of this peculiar substance, as 
yet, I regret to say, without much success, owing to the circumstance that 
the same substance cannot be produced at will, or in a moderate time by the 
action of acids on iron, and that great difficulty has been found in obtaining 
_ specimens both of the substance, and of the iron from which it resulted, in a 
fit state for experiment, viz. not acted on by air. I have however been 
favoured by Major-General Pasley, R.E., with some specimens from the Royal 
George, sent to me in hermetically sealed vessels, which promise to give the 
desired information as to what passes when this curious substance heats 
spontaneously in air, and how it is formed. 
Attempts have also been made to collect and examine the peculiar organic 
bodies produced along with this by the action of acids, &c. on iron and steel. 
These substances are of great chemical interest by adding to the small num- 
ber of organic bodies known to be formed directly. They are of the families 
of hydrocarbons and extractive matters, produced by the action of the evolved 
hydrogen upon the nascent carbon of the iron. They are produced, how- 
ever, in very minute quantity in relation to the volume of hydrogen, and 
hence it has been necessary to operate on immense volumes of the gas evolved 
from iron, &c. to collect these new bodies in sufficient quantity for examina- 
tion; owing to this, to their entanglement with the sulphur, phosphorus, &c. 
of the iron, and to the powerful affinity of some of them for oxygen, they 
have as yet not been collected in mass sufficient for accurate examination. 
Two hydrocarbons have however been distinguished, one solid at common 
temperatures, and the other liquid and highly volatile, besides the bodies of 
the extractive or apotheme class. _ 
With respect to the plumbago, I am led to believe that the amount of car- 
bon in a given bulk is generally greater than that due to the same bulk of the 
metal removed, and that in such cases the additional carbon has been depo- 
sited by decomposition of the carbonic acid contained in the water. The 
present, however, is not the place for incomplete researches, which those be- 
longing to this branch of my subject are, and as to which I hope at some 
future time to lay further results before the Association. 
_ $19. The rusts removed from the several classes of specimens after the first 
immersion have been submitted to chemical examination ; their compositions 
do not differ from those given in the preceding Reports, and vary with the 
time of formation. ; 
_ Omitting the accidental substances introduced either from the iron or the 
water, they are all hydrated oxides and carbonates of iron, and tend, in pro- 
_ portion to the duration of reaction, nearer and nearer to approach the formula 
2 Fe; O; + 3 HO, becoming in fact artificial brown hematite, more or less 
: thixed with Fe O + C O,, or spathic iron ore. When very old these rusts 
_ appear to lose constituent water and become “fer oligiste ;’ they are imper- 
feetly crystallized; such I found to be the case with some taken from a bar 
on one of the towers of York Minster. They always give traces of ammonia. 
When formed in foul sea water, they generally include microscopic crystals 
of iron pyrites, and always in small quantity basic salts (sulphates and chlo- 
rides), with earthy carbonates formed by decomposition of the saline con- 
tents of sea water. 
