On Phosphoric Add and Phosphorus. 161 



With regard to the value, nitrate of lead may, T presume, 

 be manufactured at less than 4-5ths of the price of tl.c ace- 

 tite. The last we know requires chat the lead be previously 

 prepared and oxidated ; and much time is spent in the ope- 

 ration : on the contrary, the nitrate may be made directly 

 from the metal itself in the metallic statCi 



When phosphate of soda was decomposed by these me- 

 tallic salts, 1 found invariably a material difference in favour 

 of nitrate of lead : for 100 grains of the nitrate decomposed 

 120 of the neutro-salinc salt ; whereas loO of the acetite of 

 lead required but 77 grains of the same phosphate. 



l^ie metallic phosphate formed by the nitrate of lead and 

 phosphate of soda was pure; but that procured by the ace- 

 tite was contaminated with an oxide, or a kind, as I suspect, 

 of sub-acetiic of the metal ; and this circumstance alone 

 decidedly urged me to reject it as a test, and to abide by, 

 and rely on, nitrate of lead alone in every future analysis. 



I know both of these metallic salts have been proposed 

 for the preparation of phosphorus 5 but in no work what- 

 ever, especially of the elciiietitary kind, has any decided 

 preference been bestowed on tiie nitrate of lead : on the 

 ctantrary, the acetite is generally prescribed even by authors 

 of the most modern date. 



These remarks naturally point out the most frugal method 

 to procure pho: phorus : the process, therefore, I should 

 prefer is briefly this : — 



To decompose phosphate of soda by nitrate of lead ; to 

 \vash and separate the metallic phosphate ; and, in the usual 

 manner, by means of charcoal, distil off the phosphorus. 



I have chosen phosphate of soda, in order to procure the 

 phosphorus quite pure; as I apprehend, without great cau- 

 tion, some sulphates may exist when the acid is prepared 

 from bones, agreeably to Nicholas de Nancy's process, and 

 may eventually be converted into sulphur, which, we know, 

 will rise and distil os'erwith the phosphorus. This suspicion 

 was entertained by my much respected friend the late Mr» 

 Woulfe. 



In many places, such as in garrisons, several public esta- 

 blishments, and amongst manufacturers, where urine might 

 be collected with more decency, an immense quantit)^of 

 phosphate of lead may be formed daily, and returned for 

 a quantity of nitrate of lead, with which they should be 

 furnished for the purpose. I need not say this is Giobcrt's 

 process, that of decomposing the phosphates in urine ; such 

 as are capable of it, by nitrate of lead too. I am surprised 



Vol. 20. No. 78. AW» 1804. L it 



