300 Wells $ Foote — One Hundred Years of Chemistry. 



published a simple method for the mechanical analysis 

 of soils to determine their suitability for wheat-culture, 

 and Hilgard, between 1872 and 1874, described an elab- 

 orate study of soil-analysis. J. P. Norton, a Yale 

 professor, in 1847 (3, 322) published an investigation 

 on the analysis of the oat, which was awarded a prize of 

 fifty sovereigns by a Scotch agricultural society, while 

 Johnson, Atwater, and others have contributed articles 

 on the analysis of various farm products. 



Industrial Acids and Alkalies, 



One hundred years ago sulphuric acid was manufac- 

 tured on a comparatively very small scale in lead 

 chambers. In 1818, an English manufacturer of the 

 acid introduced the modern feature of using pyrites in 

 the place of brimstone, while the Gay-Lussac tower in 

 1827 and the Glover tower in 1859 began to be applied as 

 great improvements in the chamber process. Within 

 about twenty years the contact process, employing plat- 

 inized asbestos, has replaced the old chamber process to 

 a large extent. It has the advantage of producing the 

 concentrated acid, or the fuming acid, directly. 



During our period the manufacture of sulphuric acid 

 has increased enormously. Very large quantities of it 

 have been used in connection with the Leblanc soda pro- 

 cess in its rapid development. It came to be employed 

 extensively for absorbing ammonia in the illuminating- 

 gas industry, which was in its infancy one hundred years 

 ago. New industries such as the manufacture of ' ' super- 

 phosphates" as artificial fertilizers, the refining of petro- 

 leum, the manufacture of artificial dyestuffs and many 

 other modern chemical products have greatly increased 

 the demand for it, while its employment in the production 

 of nitric and other acids, and for many other purposes 

 not already mentioned, has been very great. 



The manufacture of nitric acid has been greatly 

 extended during our period on account of its employment 

 for producing explosives, artificial dyestuffs, and for 

 many other purposes. Chile saltpeter became available 

 for making it about 1852. This acid has been manufac- 

 tured recently from atmospheric nitrogen and oxygen by 

 combining them by the aid of powerful electric dis- 

 charges. This process has been used chiefly in Norway 

 where water-power is abundant, as it requires a large 

 expenditure of energy. A still more recent method for 



