394 G. F. Barker on normal and derived Acids. 
molecules of water lost, to yield the meta-acid may be indica- 
ted by a numeral prefix to the meta, as above. Hence, as 
.0,, and H,,P,,0,,. The first’ is a tetra-phos 
phoric acid, the ortho-acid of which is reproduced by adding 
to it seven molecules of water. The second is derived from 
deca-phosphoric acid, by the loss of nineteen molecules of water. 
ence the salts are sodic hepta-meta-tetra-phosphate and sod 
enneadeca-meta-deca-phosphate; meaning that the former }8 
derived from four molecules of the. ortho-acid by the loss of 
seven molecules of water, and the latter is nineteen removes 
from ten acid molecules. These acids and their derivatives are 
exceedingly numerous, Wurtz is inclined to view them as ac 
cumulated bodies, similar to the polyethylenic slcome j stat 
athe sear 
ing that as PbO may be added to Fy. 0, producing Pb’ 0, 
ro. Z 2 
and pp, fO% 90 to OPH?" Lo, (80,)’Omay be added, viel 
és 2 g (SO,)" ual 
ing the fuming or Nordhausen sulphuric acid (SO,)” +9: &4 
to H,8,0., our penta-meta-di-sulphuric acid. This process 
however, leaves the basicity of the mas unaltered ; and hence 
18 insufficient in many cases. . 
_ The number of these acids may be illustrated by @ 
showing the di- and tri-acids of the tetrad silicon, and of 
pentad Sree, with the various meta acids derived from 
them, as follows : | 
— 1¢ places above cited these authors speak of di-silicic acid, referring 
a to any acid containing two silicon atoms. The normal disilcie aid 
oe however, is H.Si,0,; whereas my di-silicic acid is HySia tog 
So. of ortho-silicie acid, from which by the loss of H,0, is oP 
2Si,0;, mono-meta-di-silicic acid. 
