52 
BRITISH ASSOCIATION.- 1835 . 
(Dr. Dalton observed that there could be no doubt that carbonate 
of magnesia might be volatilized, since Dr. Henry had informed him 
that a quantity of this substance was always driven off whenever the 
heat was carried beyond a certain point.) 
Mr. Hartop made a communication on the'use of the hot air 
blast in the manufacture of pig iron, in which he showed that the 
saving said to be effected by the use of hot air had been overrated, 
as a considerable portion of the alleged saving had been previously 
effected by other improved processes. 
The general saving on the average he stated to be no more than 
10s. per ton, and observed, that the price of such iron in the market 
had actually fallen from 15s. to 20s. per ton, while that from cold air 
at the same time rose 5s. per ton in Yorkshire. (This statement gave 
rise to observations on the part of several gentlemen, who stated that 
no such reduction in price of iron made by hot air had occurred 
in other parts of the country, and that, as prepared in Glasgow and 
many other places, it had not been deteriorated. This method has 
in consequence been adopted in every smelting-house in Scotland, 
and the annual produce of the works in that country during the last 
ten years has been nearly doubled. 
Reference was also made to processes adopted in the Russian 
smelting-works, which showed that by a judicious adjustment of the 
quantities of cold air introduced by the blast, a saving could be ef¬ 
fected approaching even to that obtained by the use of hot air.) 
Account of some Chemical Processes. By Francis Barker, M.D, t 
Prof. Chem. Trin. Coll. Dublin . 
It has been known since the time of Bergman, that diluted acetic 
acid has little or no action on peroxide of iron; but it is not, per¬ 
haps, generally known that this oxide may be completely separated 
from sulphuric or muriatic acid, and probably from most other 
acids, by an alkaline acetate, the alkali exerting its usual action of 
detaching the peroxide, whilst the acetic acid remains inactive and 
does not unite with it, and that by means of the acetate of potash, 
peroxide of iron may be completely detached from the oxide of 
manganese, one portion of the acetate of potash decompounded by 
the salt of manganese producing acetate of manganese, which re¬ 
mains in a state of solution, whilst the other portion of the acetate 
of potash separates the peroxide of iron, on which the diluted acetic 
acid has no action. The advantages arising from this mode of 
operating are obvious, as it gives the chemical analyst the means of 
separating the oxides of iron and manganese by agents easily ob¬ 
tained and in the hands of every chemist. 
As the success of this method depends in a great measure on at¬ 
tention to minute details in the mode of conducting the process, 
