IV.] EARL Y HISTOR Y OF SUPERPHOSPHA TE 121 



been made ; — " Whereas bones, bone ash, and bone 

 dust and other phosphoritic substances have been 

 heretofore employed as manures, but ahvays, to the best 

 of my knowledge, in a chemically undecomposed state, 

 whereby their action on the soils to which they have 

 been applied has been tardy and imperfect. And 

 whereas it is in particular well known that in the case 

 of a large proportion of the soils of this country, the 

 application of bone dust is of no utility in producing 

 crops of turnips on account of the slow decomposition of 

 the bone dust in the soil, and the consequent exposure 

 of the young plant for a long period to the ravages of 

 the turnip fly. Now, the first of my said improvements 

 consists in decomposing, in manner following, the said 

 bones, bone ash, bone dust, and other phosphoritic 

 substances. Previous to using them for the purposes 

 of manure, I mix with the bones, bone ash, or bone 

 dust, or with apatite or phosphorite, or any other 

 substance containing phosphoric acid, a quantity of 

 sulphuric acid just sufficient to; set free as much 

 phosphoric acid as will hold in solution the unde- 

 composed phosphate of lime." 



Subsequently, on becoming acquainted with Liebig's 

 published suggestion, Lawes amended his patent by 

 disclaiming all references to bone and bone products, 

 and confining it to "apatite and phosphorite, and 

 other substances containing phosphoric acid." Follow- 

 ing on his patent, Lawes began the manufacture of 

 superphosphate on a commercial scale, establishing a 

 factory at Deptford and using for the purpose at first 

 bone ash and later the crag coprolites from Suffolk, to 

 which Henslow's paper in 1845 had attracted attention. 

 The first advertisement appears in the Gardetier's 

 Chronicle and Agricultural Gazette in 1843, the price 

 being 4s. 6d. per bushel. From the dates of Liebig's 



