7G MODERN" HIGH FARMING. 



It was, however, reserved for one Gerard Dornaeus to describe 

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

 pamphlet published in the year 1570. 



English makers originally prepared their acid by burning cop- 

 peras in brick ovens at a high temperature, and condensing the 

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

 mercial value of which was one thousand dollars per ton. This 

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

 enormous 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, which we need not stop at, we 

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

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

 portions 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, 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 regu- 

 lated by a slide moving in the iron furnace-door ; the vapors being 

 taken off through the roof into the adjoining chamber. 



Progressively and finally we have arrived at our present position, 

 and this will naturally continue to be improved upon as chemistry 

 moves onward. The principal points in sulphuric acid production, 

 requiring consideration by our contemporary industrials may be 

 thus summed up : 



A. What kind of furnace or burner is best calculated to effect 

 the complete combustion of the pyrites, including "smalls ?" 



B. What are the best dimensions to accord to the leaden cham- 

 bers in which the combination takes place ? 



C. How to obtain the maximum results from the sulphur ore 

 at a minimum expenditure of nitrate of soda ? 



The manufacturer who has satisfactorily solved all these problems, 

 may be said to walk in the very front rank, and has no competition 

 to fear from any quarter. 



