202 J. M. Ordway on Sesquisalts. 
in pure water, while the decabasic and the still more acid com- 
pounds do not lose their solubility by drying. ioe 
Syste acid takes up at least five equivalents of ferric 
is aoe 
base increases. By long digestion ¥e, 1.H. was at length formed. 
The fluorids make an apparent exception to the general rul 
for nothing less than three equivalents of fluorhydric acid woul 
issolve an equivalent of ferric oxyd; nor could I succeed im 
os making soluble basic fluorids of aluminium or chromium. But 
this will appear less strange, if we consider that the normal ses- 
quifluorids of these metals are perfectly soluble in water, while 
: most protofluorids will dissolve only in a large excess of fluor- 
hydric acid or in some other acid. ; 
It also requires three equivalents of tartaric acid to take up 
two of ferric oxyd. And yet acid tartrate of potash dissolves two 
equivalents of hydrated sesquioxyd of iron, making ¥Fe2K...0s 
4 O19. . 
The sulphite, like the sulphate, can only be made sesquibasi¢ 
without disturbance. 
Carbonic acid has little affinity for sesquioxyd of iron; yet aa 
alkaline bicarbonate may retain it in solution for a time; and it 
is probably a basic carbonate that is present in this case, and not 
the mere oxyd, as the old name—“Stahl’s alkaline tincture of 
Mars”—would imply. i 
The basic acetates are not new. Berzelius says: “ Liacide 
acétique forme, avec l’oxyde ferrique, un soussel soluble, qua 
obtient en dissolvant de l’hydrate ferrique récemment précipité 
Jusqu’ 4 saturation compléte dans l’acide acétique. On a ainsl 
ine solution rouge foncée, qui renferme, suivant Bette, Pe Ac, & 
suivant Janssen, #e, Ac.” Both are right, for the tribasic acetate 
enough oxyd of chromium to become — 
