2 
J A M 
JAP 
axle ; and at other times by a vertical wheel 
with sails like the float-boards of a mill ; but 
the above is the more customary construc- 
tion. 
JACK-Flag, in a ship, that hoisted up at 
the sprit-sail top-mast head. 
JACK ALL. See G'anis. 
JACOB’S staff, a mathematical instru- 
ment otherwise called cross-staff. SeeCROss. 
JACOBITFS, in church history, a sect of 
Christians in Syria and Mesopotamia ; so 
called either from Jacob, a Syrian, who lived 
in the reign of the emperor Mauricius ; or 
from one Jacob, a monk, who flourished in 
the year 550. 
JACOBUS, an antient gold coin worth 
twenty-five shillings. 
JACQUINIA, a genus of the monogynia 
order, in the hexantlria class of plants ; and 
in the natural method ranking with those of 
which the order is doubtful. The corolla is 
decemfid ; the stamina inserted into the re- 
ceptacle; the berry monospermous. There 
are four species, shrubs of South America. 
JADE-stone, lapis nephriticus, or Jaspa- 
chates, a genus of siliceous earths. It gives 
lire with steel, and is semitransparent like 
flint. Jt does not harden in the fire, but 
melts in the focus of a barning-glass into a 
transparent green glass with some bubbles. 
A kind brought from the river of the Ama- 
zons in America, and called circoncision 
stone, melts more easily in the focus into a 
brown opaque glass, far less hard than the 
stone itself. The jade-stone is unctuous to 
the touch; whence Mr. Kirvvan seems to 
suspect, that it contains a portion of argil- 
laceous earth, or rather magnesia. The spe- 
cific gravity is from 2.970 to 3.389 ; the tex- 
ture granular, with a greasy look, but exceed- 
ingly hard, being superior in this respect even, 
to quartz itself. It is infusible in the fire, 
nor can it be dissolved in acids without a 
particular management ; though M. Saus- 
sure seems to have extracted iron from it. 
Sometimes it is met with of a whitish milky 
colour from China ; but mostlv of a deep or 
pale green from America. The common 
lapis nephriticus is of a grey, yellowish, or 
olive colour. It has its name from a suppo- 
sition of its being capable of giving ease in 
nephritic pains, by being applied externally 
to the loins. It may be distinguished from 
all other stones by its hardness, semipeflu- 
cidity, and specific gravity. 
According to Hoepfner it is composed of, 
47 silica 
38 carbonat of magnesia 
9 iron 
4 alumina 
• 2 carbonat of lime 
100 . 
JALAP,/7//«p«, in botany, a plant of the 
pentandria monogynia class. See Convol- 
vui.cs, and Materia Medica. 
IAMBIC, in ancient poetry, a sort of 
verse, so called from its consisting, either 
wholly or in great part, of iambuses. 
I AlvIBUS, in antient poetry, a simple foot 
consisting of a short and a long syllable. 
JAMES, or knights of St James, a military 
order in Spain, tirst instituted about the year 
1170, by Ferdinand II. king of Leon and 
Gahcia. 
JANIZARIES, an order of the Turkish 
JAP 
infantry, reputed the grand signior’s guards, 
and the main strength of the Ottoman army. 
JANSENISTS, in church-history, a sect 
of the Roman catholics in France, who fol- 
low the opinions of Jansenius, bishop of 
Ypres, and doctor of divinity of the univer- 
si ies of Louvain and Douay, nearly those of 
Calvin, in relation to grace and predestination. 
JAPANNING is properly the art of var- 
nishing and painting ornaments on wood, in 
the same manner as is done by the natives of 
Japan in the East Indies. 
The substances which admit of being ja- 
panned are almost every kind that are dry 
and rigid, or not too flexible ; as wood, me- 
tals, leather, and paper, prepared for the pur- 
pose. 
Wood and metals do not require any other 
preparation, but to have their surfaces per- 
fectly even and clean ; but leather should be 
securely strained, either on frames or on 
boards ; as its bending, or forming folds, 
would otherwise crack and torce oil the coats 
of varnish. Paper should be treated in the 
same manner, and have a previous strong 
coat of some kind of size ; but it is rarely 
made the subject of japanning till it is con- 
verted into papier macht?, or wrought by 
other means into such form, that its original 
state, particularly with respect to flexibility, 
is changed. 
One principal variation from the method 
formerly used in japanning is, the omitting 
any priming, or undercoat, on the work to 
be' japanned. In the older practice, such a 
priming was always used ; the use of which 
was to save in the quantity of varnish, by 
filling up the inequalities in the surface of 
the substance to be varnished. But there is 
a great inconvenience arising from the use 
of it, that the Japan coats are constantly li- 
able to be cracked, and peeled off, by any 
violence, and will not endure near so long 
as the articles which are japanned without 
any such priming. 
Of the nature of Japan grounds. — -When 
a priming is used, the work should first he 
prepared by being well smoothed with fish- 
skin or glass-paper, and being made tho- 
roughly clean, should- be brushed over once 
or twice with hot size, diluted with two- 
thirds water, if it is of the common strength. 
The priming should then be laid on as even 
as possible, and should be formed of a size, 
of a consistency between the common kind 
and glue, mixed with as much whiting as will 
give it a sufficient body of colon f to hide the 
surface of whatever it is laid upon, but not 
more. This must he repeated till the ine- 
qualities are completely tilled up, and then 
the work must be cleaned off with Dutch 
rushes, and polished with a wet rag. 
When wood or leather is to be japanned, 
and no priming is used, the best preparation 
is to lav two or three coats ot coarse var- 
nish, composed in the following manner. 
Take of rectified spirit of wine one pint, 
and of coarse seed-lac and resin each two 
ounces; dissolve the seed-lac and resin in the 
spirit, and then strain off the varnish. 
This varn'sh, as well as all others formed 
of spirit of wine, must be laid on in a warm 
place ; and if it can be conveniently mana- 
ged, the piece of work to be varnished should 
be made warm likewise ; and for the same 
rea-on, all -dampness should be avoided; for 
either cold or moisture chills this kind of 
7 
varnish, and prevents its taking proper hold 
of the substance on which it is laid. 
When the work is so prepared, or by the 
priming with the composition of size and 
whiting above described, the proper japan 
ground must be laid on, which is much the 
best tormed of shell-lac varnish, and the co- 
lour desired, except white, which requires a 
peculiar treatment ; and if brightness is 
wanted, then also other means must be pur- 
sued. 
The colours used with the shell-lac varnish 
may be any pigments whatever, which give 
the tint of the ground desired. 
As metals never require to be under-coated 
with whiting, they may be treated in the 
same manner as wood or leather. 
Method of painting Japan work. — Japan 
work ought properly to be painted with co- 
lours in varnish ; though, for the greater dis- 
patch, and in some very nice work in small, 
tor the freer use of the pencil, the colours 
are sometimes tempered in oil ; which should 
previously have a fourth part of its weight 
of gum animi dissolved in it; or in default 
of that, gum sandarach, or guni mastich. 
When the oil is thus used, it should be well 
diluted with oil of turpentine, that the co- 
lours may lie more evenly and thin ; by which 
means fewer of the polishing or upper coats 
of varnish become necessary. * 
In some instances, water-colours are laid 
on grounds of gold, in the manner of other 
paintings ; and are best, when so used in 
their proper appearance, without any varnish 
over them; and they are also sometimes so 
managed as to have the effect of embossed 
work. The colours employed in this way, 
for painting, are best prepared by means of 
isinglass si^e, corrected by honey or sugar- 
candy. The body, of which the embossed 
work is raised, need not, however, he tinged 
with the qxterior colour, but may be best 
formed of very strong gum-water, thickened 
to a proper consistence by bole armenian and 
whiting in equal parts ; which being laid on 
the proper figure, and repaired when dry, 
may be then painted with the proper co- 
lours, tempered with the isinglass size, or, in 
the usual manner, with shell-lac varnish. 
Manner of tarnishing japan work. — The 
finishing of japan-work depends on the laying 
on, and polishing, the outer coats of varnish 
which are necessary, as well in the pieces 
that have only one simple ground of colour, 
as with those that are painted. This is in 
general done best villi conimoq seed-lac 
varnish, except in the instances, and on those 
occasions, where particular methods are 
deemed to be more expedient; and the 
same reasons which decide as to the fit- 
ness or impropriety of the varnishes, with 
respect to the colours of the ground, hold 
equally with regard to those of the painting. 
For where brightness is the most material 
point, and a tinge of yellow will injure it, 
seed-lac must give way to the whiter gums ; 
but where hardness and a greater tenacity 
are most essential, it must be adhered to ; 
and where both are so necessary, that it is 
proper one should give way to the other in 
a certain degree reciprocally, a mixed var- 
nish must be adopted. 
This mixed varnish, as we have alrea dy 
observed, should be made of the picked 
seed-lac. The common seed-lac varnish. 
