TECHNICAL CHE MIST BY. 305 



the steam passes likewise into the globe. Under these circum- 

 stances we shall find that sulphuric acid is formed in large 

 quantities in the globe. 



Now for the explanation of its formation. Sulphur 

 dioxide, as we have seen, cannot by itself take up oxygen 

 from the air, but if any of the red nitrous fumes, such 

 as nitrogen peroxide, (NO a ), be present together with water, 

 then the sulphur dioxide can take up oxygen from the 

 red fumes, and thus sulphuric acid is formed. This is 

 expressed by the equation 



S0 2 + Hp + N0 2 = H,S0 4 + NO. 



The moment that the nitric oxide, NO, one of the products 

 of this reaction, comes into contact with the free oxygen 

 of the air, it combines to form the peroxide of nitrogen 

 again, thus : 



and this peroxide is ready again to give up half its oxygen 

 as soon as it meets with sulphur dioxide and water. So 

 that, as you will readily understand, an infinitely small 

 quantity of red fumes is able to convert an infinitely large 

 quantity of sulphur dioxide, oxygen, and water into sul- 

 phuric acid, for these red fumes simply serve as the carriers 

 of the atmospheric oxygen to the sulphur dioxide. This is, 

 then, the theory of the manufacture of sulphuric acid, so 

 far as we yet understand it. 



Let us now pass on to the practical part of our subject, 

 and trace the progress of the manufacture from the earliest 

 and most rude methods up to the most perfect plans in use 

 at the present day. 



Cornelius Drebbel appears to have been the first to intro- 

 duce the present system of manufacture into England, but 

 the first satisfactory information concerning the methods 

 adopted was given by a quack doctor of the name of Ward, 

 who shortly after the year 1740 introduced into England a 

 process for making the acid, originally proposed in France 

 by Messrs. Lef evre and Lemery. This consisted in burning 

 a mixture of sulphur and nitre in a large glass globe or 

 bell containing water. The globes were of some forty to fifty 

 gallons in capacity. A stoneware pot was introduced, and 



VOL. ii. x 



