1 



Figure 5. — Oven por ihi 1 vlcination 01 bones, about 

 1870. "The operation is carried out in a rather high 

 oven, such as shown .... The fresh bones are thrown 

 in .11 the top of the oven. B. First, fuel in chambei 1 is 

 lighted, and a certain quantity of bones is burnt on the 

 grid D. When these bones are burning well, the oven is 

 gradually filled w iih bones, and the combustion maintains 

 itself without addition of other fuel. A circular gallery, 

 ( '. surrounds the bottom of the oven and carries the 

 products of combustion into the chimney, 11. The 

 calcined bones are taken out at the lower opening, < >. b) 

 removing the bars of grid 1>." translation of the 

 description from Figi lit. Vfer, it htstn volume 



3. 1874. page 537.) 



RAW BiE SUPER-PHOSPHATE, 



or 



C5 



I' 



11 



The Great Substitute for Peruvian Guano ! 



CHEAP, ACTIVE AND PERMANENT. 



Figure 6. \\ usvertisemeni w i ih view ol 

 plant for manufacturing superphosphate 

 about 1867. 1 From I I Freedley, 

 Philadelphia and its Manufacturers ir< 

 288. 1 



his manner of writing the formulas, each dot over the 

 symbol for the element was to indicate an atom of 

 ox) gen : tlms. lie wrote: 



II I' 



III' and II IV 



>*Thomas GRAHAM, Philosophical Transactions of th 

 S Land ■ 1833), pp. 25 I 284 



PAPER 10: IIlMi iRV OF PHOSPHt IR1 S 



Graham had come to this understanding of the phos- 

 phoric acids through his previous studies ol "Alcoates, 

 definite compounds of Salts and Alcohol analogous to 

 the Hydrates" I 1831 1. Liebig started from analogies 

 he saw with certain organic acids when lie formulated 

 the phosphoric acids with a constant proportion ol 

 water (aq.) and varying proportions of "phosphoric 

 .11 nl" (P) .iv follows: 



183 



