S T O 
S T O 
STO 
IS 
Oxide of iron, 
Oxide of chromium, 
Oxide of nickel. 
Oxide of copper, 
Potass, 
Soda, 
Water, 
Alumina, 
Silica, 
Magnesia, 
Lime, 
Baryfes, 
Glucina, 
Zirconia, 
Yttria, 
Stones, .saline. Under this arrangement 
are comprehended all the minerals which 
have an earthy basis combined with an acid. 
1 he minerals belonging to it are of course 
salts, and as such have been described under 
their respective names. But as they occur 
native in states which cannot always be imi- 
•tated by art, it will be necessary to take a 
view of them as they are found in the earth. 
r I hey naturally divide themselves into five 
genera ; as only live earths have hitherto 
been discovered native in combination with 
an acid. 1 hese genera, and the species be- 
longing to them, are the following : 
I. Calcareous Salts. 
J. Garbonat of lime, 
2. Suiphat of lime, 
3. Phosphat of ligiie, 
4. Flu at of lime, 
5. Arseniat of lime. 
II. Barytic Salts. 
1. Garbonat of barytes, 
2. Suiphat of barytes. 
III. Strontian Salts. 
1. Garbonat of strontian, 
2. Suiphat of strontian. 
IV. Magnesian Salts. 
1. Suiphat of magnesia, 1 
2. Garbonat of magnesia, 
3. Borat of magnesia. 
V. Aluminous Salts. 
1. Alum, i 
2. Mellat of alumina, 
3. Fluat of alumina-and-soda. 
The minerals belonging to this order are 
distinguished without much difficulty from 
the last. Almost all of them are insoluble in 
water ; but soluble in nitric acid, or in hot 
sulphuric acid. Most of them melt before 
the blowpipe. I heir specific gravity varies ; 
but it is often above 3.5 when the mineral is 
too soft to scratch glass. None of them have 
the metallic lustre. 
STONEHENGE, in antiquity, a famed 
pile or monument of huge stones on Salisbury 
plain, six miles distant from that city. 
It consists of the remains of four ranks of 
rough stones,. ranged one within another, some 
of them, especially in the outermost and third 
rank, twenty feet high, and seven broad ; sus- 
taining others laid across their heads and fast- 
ened by mortises, so that the whole must 
have antiently living together. 
Antiquaries are now pretty well agreed that 
it was a British temple ; and Dr. Langwith 
thinks it might easily be made probable at 
least, that it was dedicated to the sun and 
moon. 
S TONE WARE. Underthe denomination 
stone ware are comprehended all the different 
artificial combinations of earthy bodies which 
are applied to useful purposes. These vary 
in their names according to their external ap‘- 
pearance, the manner in which they are ma- 
nufactured, and fhe purposes to which they 1 
are applied. Thus we have porcelain, stone 1 
ware, pots, crucibles, bricks, tiles, &c. Ail I 
these substances, however, are formed on the 
same principles, nearly of the same materials, i 
and ow '5 their good’ qualities to the same | 
causes. 
I hese combinations have been known from 1 
the remotest ages of antiquity. They were well : 
known to the Jews, as we learn from the Old j 
J estament, long before the Babylonish cap- ; 
tivity. Porcelain, or the finest kind of stone ; 
ware, was early brought to perfection in China 
and Japan ; but the discovery of the art of 
making it in Europe is of much later date. 
Specimens of it were brought first from 
Chinr. and Japan to modern Europe. These 
were admired for their beauty, were eagerly 
sought after, and soon became the ornaments 
of the tables of the rich. Various attempts 
were made to imitate them in different coun- 
tries of Europe, but the greater number were j 
without -success. Accident led to the dis- | 
covery in Germany about the beginning of j 
the 18th century. A chemist in Saxony, du- j 
ring a set of experiments in order to ascertain 
the best mixtures for making crucibles, stum- 
bled upon a compound which yielded a porce- 
lain similar to the eastern. In consequence of 
this discovery, Saxony soon produced porce- 
lain scarcely inferior to that of Japan in beauty, 
and superior to it in solidity and strength : 
but its composition was kept secret ; nor were 
there any accurate ideas respecting the com- 
ponent parts of porcelain among men of 
science, till Reaumur published his disserta- 
tions on the subject in 1727 and 1729. He 
examined the porcelain of Japan, 1 kind the dif- 
ferent imitations of it which had been pro- 
duced in France and other parts of Europe. 
r J he texture of the first was compact and 
solid, but that of the imitations was porous. 
When both were exposed to a strong heat, 
the first remained unaltered, but the others 
melted into glass. From these experiments 
he drew the following ingenious conclusions : 
Porcelain owes its semitransparency to a 
kind of semivitrification which it lias under- 
gone. Now it may receive this two ways: 
1. Its component parts maybe such as easily 
vitrify when sufficiently heated ; but the de- 
gree of heat given may be just sufficient to 
occasion a commencement of vitrification. 
This porcelain when strongly heated will 
easily melt. Such, therefore, was the compo- 
sition of the European imitations of porcelain. 
2. It may be composed of two ingredients ; 
one of which easily vitrifies, but the other is 
not altered by heat. When a porcelain com- 
posed of such materials is baked in a sufficient 
heat, the fusible part melts, invelopes the in- 
fusible, and forms a semitransparent substance, 
which is not farther altered by tiie same de- 
gree of heat. Such therefore must be the 
porcelain of Japan. Father Entrecolles, a 
missionary to China, had sent an account of 
the Chinese mode of making porcelain, which 
coincided exactly with this ingenious thought 
of Reaumur. The ingredients, according to 
him, are a hard stone called petunse, which 
they grind to powder, and a white earth call- 
ed kaolin, which is intimately mixed with it. 
Reaumur found the petunse fusible, and the 
kaolin infusible, when exposed separately to a 
violent heat. See Porcelain 
Stone ware is not formed by mixing together 
| the pure earths, which would be a great deal 
too expensive ; but natural combinations or 
mixtures of earths are. employed. These 
combinations must possess the following- pro- 
perties : 1 . They must be capable, when re- 
duced to powder, of forming with water a 
paste sufficiently ductile to be made into any 
form which is required. 2. This paste, after 
being exposed to a sufficient heat, or after 
being baked as it is termed, must -acquire such 
a permanent degree of hardness as to be able 
to resist the action of the weather and of water. 
3. The vessels formed of it must in that state 
be capable -of resisting changes of tempera- 
ture. 4. They must be able to resist a strong 
heat without being melted. 5. 4 hey must 
not be permeable to liquids, nor liable to be 
acted on by chemical agents. 
Common clay possesses a good many of 
these qualities. When finely ground, if may 
be formed into a very ductile paste ; heat 
makes it hard enough to strike fire with steel, 
ami capable of resisting the action of most 
chemical agents ; and it is not liable to be 
melted by heat. Glav accordingly was the 
first substance employed, and it "is still em- 
ployed for a variety of purposes. 
Bricks, for instance, are always made of this 
substance. The clay is dug out of the earth, 
and after being exposed for some time to the 
air is reduced to powder; and formed into a 
paste with water. The bricks are then formed 
in moulds, exposed for some time to dry in 
the open air, and then burnt in a large 'fur- 
nace constructed on purpose. Tiles which 
are employed for covering houses are formed 
in the same way. The clay, however, is 
finer, and it is usually ground 'in a mill. 
Bricks and tiles should be impervious to 
water: they should be capable of withstanding 
the action of heat, and not be subject to 
moulder. It is obvious that these qualities 
must depend upon the nature of the clay of 
which they are formed, and on the degree 
in which they have been burned. Clay is a 
mixture of alumina and silica in various pro- 
portions. When the proportion of alumina 
is great, the brick contracts much in its di- 
mensions, and is apt to crack during the burn- 
ing. Clay therefore must be chosen which 
contains the proper proportion of silica, or 
the defect must be remedied by addin" sand. 
Bergman recommends the addition of°a little 
lime, which has the property of rendering the 
clay fusible. r I lie clay of which bricks and 
tiles are made contains some oxide of iron : 
hence the red colour which it acquires when 
burnt. 
But though the addition of lime may be 
proper in some cases in the manufacture of 
bricks and tiles, it would be exceedingly im- 
proper in other cases. Lime ought" to be 
carefully excluded from the clay destined for 
making pots, and every other utensil which is 
to be exposed to a violent heat, as it renders 
the clay fusible. Now lime enters not unfre- 
quently into the composition of clays. It is 
evident therefore that all clays are not proper 
for the manufacture of stone ware. They 
must be free from lime, barytes, and every 
other ingredient which renders them fusible. 
They must also be free from metallic oxides*, 
J which not only render them fusible, but also 
| injure the colour of the porcelain. The ejavs 
j which answer are those which consist of’ a 
mixture of alumina and silica. These. are 
1 known by the names of potter’s clay, tobarco- 
| pipe clay, porcelain-clay, &c. according to 
