or glucina is present, they will be dissolved 
in the potass ; while the other substances re* 
main untouched in the form of a powder, 
which we shall call B. 
Into the solution of potass as much acid 
must be poured as will not only saturate the 
potass, but also completely iedissolve any 
precipitate which may have at first appeared. 
Carbonat of ammonia is -now to be added in 
such quantity that the liquid shall taste ol it. 
By this addition the whole of the alumina 
wid be precipitated in white Hakes, and the 
glucina will remain dissolved, provided the 
quantity of carbonat of ammonia used is not 
too small. The liquid is now to be iiltred ; 
and the alumina which will remain on the 
liitre is to be washed, dried, heated red-hot, 
and then weighed. To see if it is really 
alumina, dissolve it in sulphuric acid, and 
add a sufficient quantity ot sulphat of acetat 
of potass; if it is alumina, the whole of it 
will be converted into crystals of alum. 
Let the liquid which has passed through 
the liitre be boiled for some time ; and the 
glucina, if it contains any, will be precipi- 
tated in a light powder, which may be dried 
and weighed. When pure, it is a line, soft, 
very light, tasteless powder, which does not 
concrete when heated, as alumina does. 
The residuum B may contain lime, mag- 
nesia, and one or more metallic oxides. Let 
it be dissolved in weak sulphuric acid, and 
the solution evaporated to dryness. Pour a 
small quantity of water on it. The water will 
dissolve the sulphat of magnesia and the'me- 
tallic sulphats ; but the sulphat of lime will 
remain undissolved, or if any portion dis- 
solves, it may be thrown down by the addi- 
tion of a little weak alcohol. Let it be heat- 
ed red-hot in a crucible, and weighed. The 
lime amounts to 0.43 of the weight. 
Let the solution containing the remaining 
sulphats be diluted with a large quantity of 
water ; let a small excess of acid be added ; 
and then let a saturated carbonat of potass be 
poured in. The oxides of chromium, iron, 
and nickel, will be precipitated, and the mag- 
nesia and oxide of manganese will remain 
dissolved. The precipitate we shall call C. 
Into the solution let a solution of hydrosul- 
phuret of potass be poured, and the manga- 
nese will be precipitated in the state of a 
hydrosulphuret. Let it be calcined in con- 
tact with air, and weighed. The magnesia 
may then be precipitated by pure potass, 
washed, exposed to a red heat, and then 
weighed. 
Let the residuum C be boiled repeatedly 
with nitric acid, then mixed with pure potass; 
and after being heated, let the liquid be de- 
canted off. Let the precipitate, which con- 
sists of the oxides of icon and nickel, be 
washed with pure water ; and let this water 
be added to the solution of the nitric acid and 
potass. That solution contains the chromium 
converted into an acid. Add to this solution 
an excess of muriatic acid, and evaporate till 
the liquid assumes a green colour ; then add 
a pure alkali. The chromium precipitates in 
the state of an oxide, and may be dried and 
weighed. 
Let t he precipitate, consisting of the oxides 
of iron and nickel, be dissolved in muriatic 
acid ; add an excess of ammonia ; the oxide 
of iron precipitates. Let it be washed, dried, 
and weighed. 
STONES. 
Evaporate the solution, and the oxide of 
nickel will also precipitate, or the whole may 
be precipitated by adding hydrosulphuret of 
ammonia; and its weight may be ascertained 
in the same manner as the other ingredients. 
The weights of all the ingredients obtained 
are now to be added together, and their sum 
total compared with the weight of the matter 
submitted to analysis. If the two are equal, 
or if they differ only by .03 or .04 parts, we 
may conclude that the analysis has been 
properly performed ; but if the loss of weight 
is considerable, something or other has been 
lost. The analysis must therefore be repeated 
with all possible care. It there is still the 
same loss of weight, we may conclude, that 
the stone contains some substance, which has 
either evaporated by the heat, or is soluble in 
water. 
A fresh portion of the stone must therefore 
be broken into small pieces, and exposed in 
a porcelain crucible to a strong heat. If it 
contains water, or any other volatile sub- 
stance, it will come over into the receiver ; 
and its nature and weight may be ascertained. 
If nothing comes over into the receiver, 
or if what comes over is not equal to the 
weight wanting, we may conclude that the 
stone contains some ingredient which is sor 
luble in water. 
I’o discover whether it contains potass, let 
the stone, reduced to an impalpable powder, 
be boiled live or six times in succession with 
very strong sulphuric acid, applying a pretty 
strong heat towards the end of the operation, 
in order to expel the excess of acid ; but tak- 
ing care that it is not strong enough to de- 
compose the salts which have been formed. 
Water is now to be poured on ; and the 
residuum, which dees not dissolve, is to be 
washed with water till it becomes tasteless. 
The watery solution is to be filtred, and eva- 
porated to dryness, in order to drive off any 
excess of acid which may be present. The 
salts are to be again dissolved in water ; and 
the solution, after being boiled for a few mo- 
ments, is to be filtred and evaporated to a 
consistence proper for crystallizing. If the 
stone contains a sufficient quantity of alu- 
mina, and it potass is present, crystals of 
alum will be formed : and the quantity of po- 
tass may be discovered by weighing them, it 
being nearly -Jath of their weight. If the 
stonedoesnot contain alumina, or not in suf- 
ficient quantity, a solution of pure alumina 
in sulphuric acid must be added. Some- 
times the alum, even when potass is present, 
does not appear for several days, or even 
weeks ; and sometimes, when a great quan- 
tity of alumina is present, if the solution has 
been too much concentrated by evaporation, 
sulphat of alumina prevents the alum from 
crystallizing at all. Care, therefore, must be 
taken to prevent this last source- of error. 
The alum obtained may be dissolved in wa- 
ter, and barytes water poured into it as long 
as any precipitate forms. The liquor is to 
be filtred, and evaporated to dryness. The 
residuum will consist ot potass and a little 
carbonat of potass. The potass may be dis- 
solved in a little water. This solution, eva- 
porated to dryness, gives us the potass pure, 
which may be examined and weighed. 
If no crystals of alum can be obtained, we 
must look' for some other substance than po- 
tass. The stone, for instance, may contain 
71 / 
soda. The presence of this alkali ^ may be 
discovered by decomposing the solution in 
sulphuric acid, already described, by means 
of ammonia. The liquid which remains is to- 
be evaporated to dryness, and the residuum 
is to be calcined in a crucible. By this me- 
thod, the sulphat of ammonia will be volati- 
lized, and the soda will remain. It may be 
redissolved in water, crystallized, and ex- 
amined. 
If sulphuric acid does not attack the stone, 
as is often the case, it must be decomposed 
by fusion with soda, in the same manner as 
formerly directed with potass. The matter, 
after fusion, is to be diluted with water, and 
then saturated with sulphuric acid. 'I lie so- 
lution istabe evaporated to dryness, the re- 
siduum again dissolved in water, and evapo- 
rated. Sulphat of soda will crystallize first ; 
and by a second evaporation of the stone, 
contains potass and alumina, .crystals ot alum- 
will be deposited. 
Stones, earthy. Cronstedt divided this 
order into nine genera, corresponding to 
nine earths ; one of which he thought com- 
posed the stones arranged under each genus. 
The names of his genera were, calcateae, sili- 
ceae, granatinre, argillaceay micaceai, fluores, 
asbestinre, zeolithica?, magnesia?. All his 
earths were afterwards found to be com- 
pounds, except the first, second, fourth, and 
ninth. Bergman, therefore, in his Sciagra- 
phia, first published in 1782, reduced the 
number of genera to five ; which was the 
number of primitive earths known when he 
wrote. Since that period five new earths 
have been discovered. Accordingly, in the 
latest systems of mineralogy,. the genera be- 
longing' to this order are proportionally in- 
creased. Each genus is named from an earth, 
as follows : 
1. Jargon genus,. 5. Magnesian genus, 
2. Siliceous genus, 6. Calcareous genus, 
3. Glucina genus, 7. Barytic genus, 
4. Argillaceous genus, 8. Strontian genus. 
Mr. Kirwan, in his valuable? system of mi- 
neralogy, has adopted the same genera.- I n- 
der each genus those stones are placed which 
are composed chiefly of the earth which 
gives a name to the. genus, or which at least 
are supposed to possess the characters which 
distinguish that earth. 
A little consideration will be sufficient to 
discover that there is no natural foundation 
for these genera. Most- stones are composed 
of two, three, or even four. .ingredients ; and 
in many cases the proportion of two or more 
of these is nearly equal. Now, under what 
genus soever such minerals are arranged, the 
earth which gives it a name must form the 
smallest part of their composition. Accord- 
ingly, it has not been so much the chemical 
composition as the external character, which 
has guided t he mineralogist, in the distribution 
of his species. The genera cannot be said., 
properly to have any character at all, nor the 
species "to be connected by any thing else 
than an arbitrary title. This defect, which . 
must be apparent in the most valuable sys- 
tems of mineralogy,, seems to have arisen 
chiefly from an attempt to combine together 
an art ificial and natural system. 
The only substances which enter into the 
minerals belonging to this order, in such: 
quantity as to deserve attention, are the fol- 
lowing : 
