66 Correspondence of Jerome Nickles. 
Art, XITI.—Correspondence of Prof. Jerome Nicxuks, dated 
Nancy, France, Oct. 22, 1867. 
On some new Fluorids—While examining some time since 
the haloid compounds corresponding to the oxyds of a higher 
order, I made* the discovery that the periodids are less stable 
than the perbromids, which in turn are less so than the corres- 
ponding io hcony of chlorine or the perchlorids. These last 
are the most stable, so much so in fact, that some of them do 
not act upon gold, while the corresponding compounds of bro- 
mine and iodine dissolve this metal with varying facility. 
From this fact the stability of these compounds may be con- 
cluded to stand in inverse ratio to the weight of the equivalent 
of the halogen which they contain. Another conclusion seems 
to be derived from these researches, that a tendency to depart 
from the character of a neutral body and act the part of an 
acid is developed along with the stability ; this is one of the 
results from my researches on the perchlorid of lead, Fluorine 
having a lower equivalent than chlorine, I have endeavored 
by way of control to obtain certain of its combinations which 
correspond to chlorids or bromids already recognized and 
studied. The following will show that these new compounds 
all act like acids. Take for example iron. ee of 
,h 
more stability and Fe*Cl* does not decompose when heated, 
and will even form double salts, (for example, 2KCl+Fe? cl? 
+2HO, of Fritsche. Now I have found that the sesquifluorid 
of iron is still better fitted to form saline combinations, or 
- fluo-salts, as they are called by Berzelius, who made known & 
+Fe?F?*, and another QKF+Fe:F*, Ihave 
obtained analogous compounds, both with sodium and ammo- 
nium, and with such alkaloids as quinine and brucine. These 
double salts are more or less soluble in water; at the boiling 
_ temperature they decompose, leaving yellow ferruginous flakes. 
With acetate of lead they give a white precipitate which be- 
comes yellow on heating; on the contrary, the white cloud caused 
“by the nitrate of lead does not become yellow, but dissolves 
under the influence of heat. Nitrate of bismuth has no 
es on aioe gives a white precipitate. Ferro- 
* Tia ies HE vol. alii, p. 94. sce iw t th vo ii, p. 9. 
2 oe 
