396 G. F. Barker on normal and derived Acids. 
tetrad directly united, lose two bonds, and neces act asa 
hexad. Fe,Cl, or Fe “Cl, Mn“O,, opti 3) Cr"Cl,, etc., are 
examples of binaries so formed. With hydryl oe. cube 
produced are quite numerous, and many of them occur as min- 
erals, Thus ortho-ferric base H ,Fe"O, is limonite, and ortho- 
aluminic base H Al"O, is gibbsite. "From these are derived 
mon 
ganic base. Perm rmanganic and pee “tide, ‘H,Mn,0, 
and H,Cr,O,, as was stated on page 389, must contain their 
law of saturation, supposes that the manganese and chromium 
atoms are directly united, and makes an oxygen atom intervene 
between each negative atom and the hydryl, thus :— 
Permanganic acid. Perchromic acid. 
oS mH 
°o o 
bad | 
| £3 
Okie MoO O=Cr—Cr=0 
I i I dl 
g 
On either La cate aan constitution is anomalous f 
The same n takes place with oa carbon group 0 
tetrads canes e"cl,, Sn“O,, Ti'N,, ith b 
— such a series of compounds as the “following, becomes 
possi 
Carbon. Silicon. : 
Ortho-oxalic a acid, H,€“0, Hi" 0° 
Mono-meta oxalie acid, HG"... H,S8i Os 
Di-meta-oxalic aci mG OC, H Si". 
Di-carbonic tri-oxyd, C0, Siv0; 
Tn the carbon series, the di-meta form is ordinary oxalic - 
: ps which the group may be named. The ortho-oxalic a 
1s represented in plumbic saduoscocalaee Pb’ ” O°, but 
mono-meta acid seems to be unknown. The silicon compoun 
ry of a di-silicic tri-oxyd ee 
quosya ny have reported tho with _ BE the hydrates beeen to it. 
orp oe plat ao has now been given, of the co ‘of 
he relation 0 
to tothe a chlorhydrines, scl no Rear oe id being con 
