Various Notices* 
5^1 
ply was first practised by a private individual at Paisley. This 
public spirited adventurer was amply remunerated for his expen- 
diture, and we cannot doubt but that similar speculations on a lar- 
ger scale, if propea'ly conducted, will yield an ample return to the 
first subscribers. We hope the example which has thus been 
given will be followed by public spirited individuals in other large 
towns. Its benefits would soon be felt, and it would yield advan- 
tages to the community in general, which cannot be calculated 
Upon.** ( 4 Comm. Mag. 121.J 
Sheet Iron. Ordnance. Iron Cables . — In consequence of in- 
formation requested of me, I have found it necessary to make some 
enquiries, as to the manufacture of Sheet Iron. The fault of this 
article when made in this country, is stated to be, that the plates, 
or sheets, are rough and uneven in consequence of the scales they 
acquire in the process of heating for the purpose of being rolled. 
The appearance of the plates is mended, by being annealed or 
slightly blued, but this is no cure for the evil. My notions on the 
subject are these. 
Every metal, particularly Iron, when exposed to atmospheric 
air in a red heat, will attract and combine with the oxygen of the 
atmosphere, and become oxyded. The oxyded iron will either 
scale off, or remain upon the plate in the form of scales, and make 
it rough. The cause of the scales and of the roughness of the sur- 
face, therefore, is oxyded iron. The cause of the iron becoming 
oxyded, is that a current of air, not deprived of its oxygen by the 
coals, comes in contact with the hot iron, and deposits its imcon- 
sunued oxygen in the metaj. 
When a plate of iron is laid upon charcoal for the purpose of 
being heated previous to its being roiled, the interstices of the 
charcoal admit more air than the charcoal can consume, or de-oxy- 
genate : that air combines with the under side of the plate, which 
thereby becomes rough and scaly : the upper side of the plate 
becomes less so, because the air that passes over it is in part de- 
prived of its oxygen. If there be three plates, the bottom of the 
undermost will be most oxyded, and then the top of the uppermost. 
The middle plate will be free from scales ; it is heated in the 
same manner as if it were in a muffle, which is the method of heat- 
ing the iron intended to be rolled, in some parts of England, and 
effectually prevents the imperfection complained of. 
! If, instead of charcoal, a bituminous stone coal is used, the iron 
I plate comes away from the fire much purer and cleaner^ Th^ 
