Chemistry and Physics. 399 
ZnF ,, 3KF, crystallizes in regular octahedrons, while of the salts SiF,, 
3NH,F and TiF,, 3NH,F, the first crystallizes in square prisms and the 
second either in square prisms or cubes. The other oxyfiuoniobates de- 
scribed have the formulas NbOF,, 3KF, HF, isomorphous with SnF,, 
3KF, HF; 8NbOF,, NOPE oF, and sly obta 4KF+2aq. The fluo- 
author describes sais of zine and copper having respectively the formulas 
bOF F,,-++-6aq, isomorphous with fluosilicate, fluostannate and fluo- 
titanate 2 zinc, and N ete Cal, -++-4aq, isomorphous with fluotitanate 
448° C. in the vapor of sulphur was “Sitio to be 7-8 , and taken in the 
vapor of eae at 860° was found to be 7 89; the formula given re- 
hae 4 48, while Rose’s formula, Nb,Cl,, would require 7:05. In me 
the vapor-density of chlorid of niobium was found to be 9°6; 
the foinitile NbC], (Nb=94) requires 9°4, while Rose’s formula re- 
quires 8°6, 
The minerals tantalite and niobite have, nepigg to Marignac, re- 
spectively the formulas Ta,0,,Fe@ and Nb, ©,, FeO (in equivalents 
aO,, FeO and NbO,, FeO). The tantalite from Timi represents the 
first and the niobite from Greenland the second type, and the different 
tr The ato i 
c 
constitution of the two pages agree entirely with his own .— Bibliotheque 
Univ. de Geneve, xxiii, p. 167 and 249; Deville and Troost in Comptes 
foie “for June 12 2th, 1865; also Marignac in Ann. der _— ba 
Pharm., exxxvi, p. 295. 
Note pectin’ nac’ s researches clearly show that niobium and tantalum 
are pentatomic or quinquivalent, and they are thus associated with the 
nitrogen group, which therefore contains nitrogen, phosphorus, arsenic 
antimony, bismuth, niobium and tantalum. Niobic and tantalic acide 
2KF, NbF,O,,3KF, and TaF,,2KF. The ncn 7 oe nio- 
Hen has - analogue in the well known oxychlorid of phosphorus, 
Cl,0,.— 
4. On Yu ‘trie and Erbia.—Baur and Bunsen have published the re- 
sults of an elaborate investigation of the earths found in gadolinite, and 
