84 The Phosphates of America. 



CHAPTER VI. 



SULPHURIC- ACID MANUFACTURE. 



UNTIL Mr. Rodwell published his book, " The Birth of Chemis- 

 try," we had always been led to believe that the discovery of sul- 

 phuric acid was due to Basil Valentine, but we have now reason to 

 suppose that it was known long before his time. 



It was reserved for one Gerard Dornaeus to describe with 

 tolerable exactitude what it really was, and this he did in a pam- 

 phlet published in the year 1570. 



English makers originally prepared it by burning copperas (pro- 

 to-sulphate of iron) in brick ovens at a high temperature, and con- 

 densing the vapors which distilled off as an impure oil of vitriol, 

 the commercial value of which was $1000 per ton. This process 

 gave way to the use of sulphur and nitre, burnt together in enor- 

 mous glass globes and concentrated by boiling in glass retorts, the 

 product being called " oil of vitriol made by the bell." 



Passing on by successive stages, at which we need not stop, we 

 arrive at the year 1746, and find the first leaden chamber erected in 

 that year in Birmingham by Messrs. Roebuck and Garbett, the 

 proportions of raw material employed being seven or eight pounds 

 of sulphur to one pound of saltpetre. This mixture was placed 

 upon lead plates standing in water within the chamber, and was 

 ignited by means of a red-hot iron bar thrust in through a sliding 

 panel in the wall. 



Shortly after this time came the introduction of a separate apart- 

 ment for burning the sulphur in a current of air, which was regula- 

 ted by a slide moving in the iron furnace-door, the vapors being 

 taken off through the roof into the adjoining chamber. 



Progressively and finally, the industry in Europe has now 

 reached a point which may be almost considered perfect, there be- 

 ing little room for improvement in works constructed to comply 

 with all the requirements of modern progress and modification. 



In order to make ourselves completely understood by those who 

 know little or nothing of the subject, we have prepared the an- 

 nexed drawing of a modern sulphuric-acid works, and may state 

 that when sulphur (S) is burnt in air it combines with the oxygen 



