78 On the Desutphuration of Metals, 



Scotland, Ireland, and northern parts of England. It is 

 an animal, when tamed, very familiar, and will eat bread 

 and milk, willow-sticks, elm, bark, &c., and no doubt 

 might be imported with safety ; but as these two last-men- 

 tioned animals are not likely to be attended to immediately, I 

 shall say no more respecting them for the present. 



Pine Timber. There are many thousand of large pine 

 trees on the borders of the lakes, rivers, 8cc. in Upper Ca- 

 nada, which might be marked and secured for naval pur- 

 poses, and which might be floated down to Montreal and 

 Quebec with great ease, and which no doubt would be of 

 great benefit in furnishing a large supply of good masts for 

 the navy of this empire. 



XII. Memoir upon the Desulphuraiion of Metals. By 

 M. Giteniveau, Engineer to the Mines. 



[Concluded from vol. xxxi. p. 213. "| 



Roasting of Galena. 



It is extremely difficult completely to desulphurate galena 

 by roasting: the affinity of its component parts for oxy- 

 gen does indeed effect their disunion quickly enough ; but 

 that of the new compounds, the sulphuric acid and the 

 oxide of lead, gives birth to a new combination, which re- 

 tains the sulphur, and thus forms an obstacle to the desul- 

 phuration : to this same affinity of the oxide of lead for 

 the sulphuric acid, we must attribute the facility with 

 which this acid is formed in the roasting of galena. 



I shall examine in detail the various processes to which 

 this important decomposition gives rise, as I think they 

 will explain numerous and complex phsenomena. 



Whatever care is taken in roasting galena, it is impossible 

 to convert all the sulphur into sulphurous acid, and to avoid 

 the formation of sulphuric acid ; the result always gives a 

 mixture of oxide and of sulphate of lead. 



In roastings performed upon a large scale, and in a regu- 

 lated atmosphere, the proportion of sulphate of lead is much 



more 



