306 Proceedings of Philosophical Societies. [Apric, 
This mean, which corresponds very nearly with the analysis of 
Berzelius, is considered as exhibiting the true composition of phos- 
phate of lead. From this the weight of an atom of phosphoric 
acid is shown to be 3'649. From experiments with iodine, &c. 
it is shown that an atom of phosphorus weighs more than one and 
less than two: from this it follows that phosphoric acid is a com- 
pound of 2 atoms oxygen + | atom phosphorus; or by weight of 
2 oxygen + 1:649 phosphorus. According to this result phosphoric 
acid is composed of 
Phosphorus ........--++5- ate teh | 
QR Re edicts ee cs Se ee oe ee seus 121°28 
This does not differ much from the composition of phosphoric 
acid deduced from the combustion of phosphorus. A mean of 
both methods is taken, and the constituents of phosphorie acid 
are considered as 
Phosphorus ......-/c00+sess0-05 eae, 100 
OSGPED 0's, 5 ofr no m.neieys Hs = apres oes 123°37 
This gives us 1°634 for the weight of an atom of phosphorus ; 
2-634 for the weight of an atom of phosphorous acid; and 3°634 
for the weight of an atom of phosphoric acid. 
The remainder of the paper is taken up with an account of the 
composition of the phosphates. The most remarkable of these are 
the combinations of phosphoric acid and lime, The author has 
ascertained the existence of no fewer than six salts composed of 
these two constituents. The following are the names and compo- 
sition of these bodies : 
Atoms. Weights. 
Cos ae ee 
Acid. Lime. Acid. Lime. 
1. Quadrosteo-phosphate .......... 5 + 1... 100 + 19°86 
2. Binosteo-phosphate .......+.. . 5+ 2,..,100 + 39:73 
3° Bige-phosphate .....2-+e+eees 5 +3 ...100 + 59°58 
4. Osteo-phosphate, or earth of bones 5 + 4 .. 100 + 79°47 
5. Phosphate .... 05-0220 0s-e0008 .5 + 5... 100 + 99°33 
G. Ge-phosphate, or apatite..... on DS + 6, JOO. STAG 
The most important of these salts, and the one always formed in 
common circumstances, is the fourth. The second is obtained by 
dissolving osteo-phosphate in phosphoric acid. The first salt is pro- 
cured when we decompose osteo-phosphate by sulphuric acid. 
That acid removes three fourths of the lime, and Jeaves one fourth 
united to all the phosphoric acid. It constitutes the glacial phos- 
phoric acid of the shops, or the substance employed in the prepara- 
tion of phosphorus. ‘The third salt may be obtained by dissolving 
apatite in phosphoric acid. The fifth salt was formed by dissolving 
the requisite quantity of lime.in muriatic acid, mixing it with the 
due proportion of phosphoric acid, evaporating the mixture to dry- 
ness, and exposing it to a red heat. The three first salts fuse before 
the blow-pipe into a transparent glass, tasteless, and insoluble 
2 
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