FROM CALCINING OF IRONSTONE. L85 



hearths the gas could he prevented from spreading to the injury of 

 any crops around them, whether of grain or wood. There is a large 

 percentage of sulphur in the ironstone, and while the stone is under- 

 going the process of calcining, sulphurous acid gas is generated, 

 which is very destructive to vegetation; hut heing more than twice 

 as heavy as common air, it does not rise much higher than the top of 

 the heaps, and might he confined within proper screens. The gas 

 has an offensive smell, which is never felt far from the works, 

 unless when carried along hy the wind. 



Note. — The effects of different gases on trees and vegetation 

 generally is an important subject, and demands the attention of 

 proprietors and foresters at the present time, in order that more 

 information may be ohtained. Some valuahle papers have "been 

 published of late years treating of the subject. Eeference may he 

 made to the following : — Gladstone " On the Growth of Plants in 

 various Gases," " Philosophical Magazine," 4th series, vol. ii. p. 

 215 ; Turner and Christison " On the Effects of Poisonous Gases on 

 Vegetation," "Edinburgh Medical and Surgical Journal," vol. 

 xxviii. p. 356 ; Livingston " On the Effects of Narcotic and Irri- 

 tant Gases on Plants," " Transactions of the Edinburgh Botanical 

 Society," vol. vi. p. 380. — Ed. 



