J. 1. Smith on determining the Alkalies in Minerals. 239 
when the contents of the crucible are rapidly dissolved out, the 
crucible is taken out and washed over the capsule, the contents 
of the capsule are then evaporated to dryness over a sand-bath, 
and if thought necessary, it may be completed over the lamp, 
Without danger of the spitting which occurs in the soda fusion ; 
this evaporation to dryness is not absolutely necessary, but the 
advantage of it is, that any great excess of hydrochlorie acid is 
got rid of, and the precipitate in the next operation is less bulky 
than it otherwise would be. ; 
20.To the dry mass a little hydrochloric acid is added, and 
carbonate of ammonia is slowly added until there is an excess of 
the same ; the solution becomes at first quite thick with the pre- 
Cipitate, but-in a short time (especially with a little warming over 
’ it might contain (in a feldspar, for instance,) were this latter 
Precipitated separatel y by ammonia; and this circumstance is of 
much importance in diminishing the length of the operations and 
e-amount of water accumulated by filtering it from several 
Mecipitates, “i 
©. Tt will -be seen that thus far, the operations have been car- 
"ed on in the eapsule in which the fasion was dissolved. .'The 
Contents of the capsule are now thrown on a filter, but before 
ong this, it is well to pour on a little of the solution of the 
Carbonate of ammonia, and see if the clear part of the liquid be 
tendered turbid, in other words, ascertain if sufficient car 
of ammonia had been originally added. oe 
22. The solution that passes through the filter contains much 
_ moniac, the alkalies of the mineral, and a little lime. If 
magnesia be one of the ingredients of the silicate examined, some 
of this is also present; and in still rarer instances some of the 
arths soluble in carbonate of ammonia. ‘This last complicates 
me degree the remaining steps in the analysis. It is best to let 
ae: pass into a glass flask; the — of pen at wr 
<j, . ‘2 another vessel, and concentrated to a sma Ik, 
des fo the first filtrate, and the whole boiled for some time to 
wwe off the carbonate of ammonia.* When no great haste is 
inated in the matter, the whole filtrate (first portions as well as 
Washings ) are collected in a beaker, aud concentrated over a 
Sand-bath, What remains now to do, is to separate from the al- 
S the substances above alluded to. I commence by getting 
* What f P e 5 gs 
Temains j ae , fluorid of calcium, oxyd of iron, 
“atbonate of 1; in the filter is silica, alumina, ' 
