2 BULLETIN 283, U. S. DEPARTMENT OF AGRICULTURE. 



phate, at least 2,000,000 tons or over 56 per cent of the total sulphuric 

 acid produced was thus consumed. A large tonnage of acid is also 

 consumed annually in the manufacture of ammonium sulphate, a 

 by-product of the coking and gas industries, and also in the produc- 

 tion of what are known to the fertilizer trade as "base goods/' con- 

 sisting of acidulated hair, wool, tankage, or other nitrogenous refuse 

 of the packing industry. 



Table I. — Production of sulphuric acid in the United States for the years 1911, 1912, 



1913, by grades. 



Year and grades. 



Quantity. 



Value. 



Price per 

 ton. 



1911: 



Tons. 



1,026,896 



421, 165 



751,541 



10, 728 



Dollars. 

 5,447,958 

 2,624,042 

 9,176,297 

 121, 575 



Dollars. 

 5.31 





6.23 





12.21 





11.33 









2,210,330 



17,369,872 



7.86 









12,688,456 



» 17,313,822 



6.44 







1912: 



1,047,483 

 451,172 



774,772 

 66, 166 



5,378.411 

 2,727,764 

 9,360,630 



871,214 



5.13 





6.05 





12. OS 





13.17 









2,339,593 



18,338.019 



7.84 









2 2, 876, 000 



: 17,572,837 



6.11 







1913: 



1,643,318 



509, 929 



797, 104 



63,158 



9,212.917 

 3,202,528 

 9,282,422 



5.61 





6.28 





11.65 





15.62 









3,013,509 



22,684,526 



7.53 









3 3,538,9S0 



a 22, 366, 482 



6.32 







1 Exclusive of acids of strength greater than 66° Baunie. 



2 Exclusive of electrolyte and acids of strength greater than 66° 15aum<§. 



3 Exclusive of 22,947 short tons of fuming acid, not convertible, valued at §318,044. 



METHODS OF MANUFACTURE. 



There are two general methods employed in the manufacture of 

 sulphuric acid, namely the " contact process" and the "lead-cham- 

 ber method." It is not within the scope of this paper to discuss 

 in detail the numerous modifications of these two methods, but 

 classified lists of the patents on the subject, together with short 

 abstracts thereof, are given at the end of this paper. 



THE CONTACT PROCESS. 



Briefly the contact process consists in passing a purified mixture 

 of air and sulphur dioxide derived either from sulphur or burning 

 pyrites over some catalytic agent heated to dull redness, thereby 

 effecting the further oxidation of the sulphur dioxide. The result- 

 ing sulphur trioxide is then usually absorbed in sulphuric acid, pro- 

 ducing a very concentrated product. 



