260 Intelligence and Miscellaneous Articles. 
their chromates worthy of notice ; and the more so, as it adds one 
to the few methods already devised for the analysis of substances 
containing both these earths. I had remarked some time before, that 
when a solution of neutral chromate of potash was added to one of 
muriate of strontia considerably diluted, no precipitation took place 
until the mixed solutions were boiled, and. even then that a large 
quantity of strontia was still held in solution; whilst, on the other 
hand, the action of the neutral chromate of potash on a solution of 
muriate of barytes was widely different ; for let the solution of barytes 
be ever so largely diluted, yet chromate of potash invariably produced 
precipitation ; so much so that wherever a sulphate was capable of 
detecting this earth, chromate of potash also indicated its presence. 
Wishing to examine some minerals supposed to contain both strontia 
and barytes, it occurred to.me that the property possessed by a dilu- 
ted solution of muriate of strontia of not precipitating with chromate 
of potash, might be made available for analytical purposes. I there- 
fore made a few experiments to ascertain the fitness of this salt as an 
agent for separating the salts of these earths when dissolved in a large 
quantity of water. These experiments at first did not afford very 
exact results; for the precipi:ated chromate always appeared to in- 
dicate rather more barytes than was originally taken: but tnis was 
found to be owing to the chromate, like the sulphate of barytes, re- 
quiring ignition before weighing, to expel a little water which obsti- 
nately adheres to it when dried at low temperatures ; this error was 
entirely obviated by heating the chromate to redness previous to 
weighing it. 
The cause of the error being thus ascertained, 20 grs. of carbonate 
of strontia and 5 grs. of carbonate of barytes were dissolved in dilute 
muriatic acid ; the solution wascarefully evaporated to dryness to expel 
the excess of acid; the dry sait was redissolved in distilled water, and 
the solution diluted to a pint and a half ; to this was added a dilute 
solution of chromate of potash, made with transparent crystals, in 
order to prevent the otherwise possible admixture of sulphate or 
carbonate. After standing for a short time it was filtered, and the 
chromate of barytes washed, dried, and ignited; weight 6°53 grs.= 
5 grs. of carbonate. The solution and washings were then evapora- 
ted to reduce the liquor to a smaller compass, and a solution of 
sesquicarbonate of ammonia added, which precipitated carbonate of 
strontia ; this when collected and dried weighed 19°19 grs. 
Another experiment, in which the quantity of barytes exceeded that 
of the strontia, was conducted in a similar manner, with the exception 
of the employment of less water (2 pint) to dissolve the dry salt be- 
fore the addition of the chromate of potash. In this case there were 
obtained from 12 grs. of carbonate of barytes, and 8 grs. of car- 
bonate of strontia, 15-8 grs. of chromate = 12°09 grs. of carbonate of 
barytes, and 7°26 grs. of carbonate of strontia. 
In both the above experiments it will be remarked that there is less 
carbonate of strontia obtained than was originally taken: thisis owing 
to strontia not being entirely precipitated by a solution of sesquicar- 
bonate of ammonia ; for when this salt and muriate of strontia are 
