Intelligence and Miscellaneous Articles. 261 
mixed, the former being in excess, the filtered liquor will become 
slightly turbid on the addition of oxalate of ammonia, and stirring the 
solution. 
In the following experiment, in which 10 grs. of each carbonate were 
taken, and oxalate substituted for sesquicarbonate of ammonia, the 
results were chromate of barytes 13-04 grs. = 10 grs. of carbonate, and 
11-9 grs. of oxalate = 10 grs. of carbonate of strontia ; thus showing 
the superiority of oxalate of ammonia as a precipitant for strontia : 
the only precaution necessary is to have the solution neutral. 
Note. Pyroxylic spirit produces a more intense crimson flame witha 
small quantity of muriate of strontia than alcohol does, and conse- 
quently is of greater service as a test for recognising strontia when 
occurring in minute quantity. f 
St. Thomas's Hospital, 
Feb. 1836. 
COMPOSITION OF CARBONATE OF ZINC.—BY MR. J. D. SMITH. 
When solutions of sesquicarbonate of ammonia and sulphate of 
zinc are mixed, a white, bulky, and gelatinous precipitate is produced ; 
this after repeated washings with hot water, by which carbonic acid 
gas is plentifully evolved, falls as a white powder. 80 grs. of this 
powder lost by ignition 22-5 grs., and 81) grs. dissolved in a counter- 
poised bottle of dilute sulphuric acid, lost 12°5 grs. of carbonic acid. 
From these experiments it appears that 80 grs. of this powder are 
composed of 57°5 grs. oxide of zinc, 12°5 gts. of carbonic acid, and 
10 grs. of water ; which numbers indicate a compound of 24 eqs. of 
oxide of zinc, 2 eqs. of water, and | eq. of carbonic acid ; which may 
be viewed either as a 2 carbonate of zinc with 4 eqs. of water, or as 
1 eq. of hydrated subsesquicarbonate of zinc united to | eq. of hy- 
drate of zinc. Its equivalent number being in former case 280, in 
the latter 140, 
or 24 eqs. of oxide of zinc 100 
1 eq. of carbonic acid 22 
2 eqs. of water...... 1S—140. 
St. Thomas's Hospital, 
Feb, 1836. 
ON RIOLITE, A SUPPOSED BISELENIURET OF ZINC, AND HER- 
RERITE, SUPPOSED TO BE CARBONATE OF TELLURIUM.—BY 
PROFESSOR DEL RIO. 
An account is given by Mr. Del Rio, in vol. iv. of the Phil. Mag. 
and Ann., p. 113, of two new minerals found in Mexico ; one supposed 
to be biseleniuret of zinc and sulphuret of mercury, which in honour 
of Mr. Del Rio I have named Riolite ; the other, considered a bisele- 
niuret of zinc and bisulphuret of mercury, | have named Culebrite, 
from the place in which it occurs. 
By the last mail I have received the following letter from Mr. Del 
Rio relative to the first of these substances, and to another mineral, 
supposed to be carbonate of tellurium, which I shall be obliged to the 
