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C E R 
CERVIE'RES, a town of France, in the department of 
t>Jie Rhone and Loire : fix leagues fouth-weft of Roanne. 
CERVINA'RA, a town of Italy, in the kingdom of 
Naples, and province of Principato Ultra : twelve miles 
fcuth-weft of Benevento. 
CERVIO NE, a town of the ifland of CorfiGa : twenty 
miles eaft of Corte. 
CERVISPI NA,/. in botany. See Rhamnus. 
CER'VON, atown of France, in the department of the 
Nyevre, and chief place of a canton* in the di it rift of 
Corbigny : three miles- eaft of Covbigny. 
CERU'LEAN, or Ceruleous, adj. [caruletis, Lat.] 
blue ; fky-coloured.—It afforded a folution with now 
and then a light touch of-fky colour, but nothing near fo 
high as the ceruleous tinfture of filver. Boyle. 
From thee the faphire folid ether takes 
Its hue cerulean. Thomfon. 
CERULITIC^, adj. Having the power to produce a 
blue colour.—The feveral fpecies of rays, as the rubific, 
cerulific, and others, are ieparated one from another. 
Grew. 
CERU'ME.N, f. [tat.] The wax or excrement of the 
ear. Its ufe is, to.invifcate and flop ini'efts from enter¬ 
ing and irritating the membrana tympani. It is fepa- 
rated from the glands in that part of the ear where it is 
found ; and is fluid when firft difcharged, but foon 
thickens by drying. Wax, under fome circumftances, is 
found to occafion deafnefs. 
CF/RUSE,/. \_ccrujfa, Lat.from x»5«;,wax, or from 
razaz, Arab, white-lead, or white paint-] A calx of 
lead produced by expofing this metal to the vapours of 
vinegar. To prepare this colour, the lead is caft into 
plates about one twentieth part of an inch thick, four or 
five inches wide, and two feet long. Thefe are rolled 
up in a fpiral form, in fuch a manner that the fpace of 
half an inch is left between each revolution. They are 
then placed in earthen pots which have three projedtions 
within, to prevent them from refting on the bottom. 
Some good vinegar is then poured in, lo as to reach no 
higher than the lower edge of the leaden fpiral, and the 
pots are then buried in dung beneath lheds. A great 
number of tliefe are difpofed befide each other, each pot 
•being covered with a leaden plate and boards, by which 
contrivance the number of pots is multiplied by placing 
them above each other in ftrata. At the expiration of a 
month or fix weeks they are taken out, and the white 
lead feparated by unrolling the coils. It is then ground 
in mills, and dried in the lhade for ufe. Some writers 
diftinguifh this calx by the name of white-lead, and ap¬ 
ply the termcerufe to denote a mixture of white-lead and 
chalk. Lead is found native in the form of cerufe, or 
the white calx. 
A patent for two new and ingenious methods of mak¬ 
ing cerufe or white-lead, was granted on the 18th of Au- 
guft 1797, to Archibald earl of Dundonald, the procefs 
whereof is defcribed as follows : “ Lead is to be brought to . 
the ftate of a calx or oxide, the calx is to be mixed with 
muriat of potafh or fal digeftivum Sylvii, or with the oxy¬ 
genated muriat of potafh, or with the folution of either 
of thefe falts, in the proportion which fhall be found re- 
quifite ; this, for the moll part, may be reckoned at one 
part of fait, by weight, to five parts of the calx of lead. 
The materials are to be intimately mixed by grinding, 
or otherwife, and are to be ftirred at different times, to 
expofe frefh furfaces to the aftion of the air ; and are to 
be alternately wetted with water, (either impregnated, or 
not, with fixable air or carbonic acid,) and dried by ex- 
pofure to atmofpheric air, or to any air in which car- 
boric acid is contained, until the complete aftion of the 
materials, the one on the other, is effefted : in this ftate, 
they confift of a cerufe or white-lead or carbonat of 
lead, and muriat of potafh. The' muriat of pot-afh 
"s, by wafhmg, to be feparated from the cerufe or white- 
dead 5 to be concentrated by evaporation j and to be pre- 
C E R 
ferved, to aft again on more of the calces of lead. Laff- 
ly, the white-lead is to be ground, levigated, and dried. 
It is proper here to ftate, that muriat of potafn or fait of 
Silvius has, in moft Chemical treatifes, been reprefented 
to be of little or no ufe in the arts ; and, as it is a fait 
which very rarely occurs as a refiduum from chemical 
mixtures or combinations, it might the moreeafily efcape 
the notice, and experiments of chemical perfons, or of 
perfons in fearch of difcoveries connefted with different 
branches of manufafture. Muriat of potafh poffefles pro¬ 
perties different from muriat of foda or fea-falt: and, in 
the prefent inftance, produces a change on the calces of 
lead, not effefted when muriat of foda only is ufed. The 
application of muriat of potafh to the calces of lead, for 
the produftion of cerufe or carbonat of lead, is not there¬ 
fore to be confounded with the attempts of others to pro¬ 
duce a carbonat of lead, by the mixture of muriat of 
foda with the calces of lead. When the muriat of potafh, 
or, more properly fpeaking, its folution, is mixed with 
the calx of lead, a change takes place ; the vegetable al¬ 
kali of the muriat of potafh is difengaged in a cauftic 
ftate, while the muriatic acid enters into combination 
with the calx of lead, and forms muriat of lead. By the 
expofure of the materials to atmofpheric air, or to air 
containing the carbonic acid, this acid is attrafted by the 
cauftic vegetable alkali, and, as it is received, is rranfmit- 
ted to the lead, forming therewith a carbonat of lead or 
cerufe ; while, in return, the alkali takes back, from the 
muriat of lead, the muriatic acid, in a ftate more oxyge- 
genated than that in which it exifted in the muriat of pot- 
nfh when firft applied. The muriat of pot-afh recovered 
is to be applied for making, with the calces of lead, more 
cerufe or carbonat of lead. It has been found moft ad¬ 
vantageous not to ufe the calx of lead very highly calcin¬ 
ed : in this highly calcined ftate, I generally ufe a fmall 
proportion of lead in a metallic ftate along with the calx. 
The procefs of mixing lead with the calx or calces of 
lead, for making, with muriat of potafh, cerufe or car¬ 
bonat of lead, is to be included under the patent to which 
this fpecification refers. And I do hereby farther declare, 
that the other method or procefs for making cerufe or 
white-lead, for which the letters patent herein before re¬ 
cited have been obtained, is as follows : that is to fay, in 
this method or procefs, muriat of foda or fea-falt is to be 
fubftituted for muriat of potafh, and it, or its folution, is 
to be mixed in the fame manner, with the calx or calces 
of lead, as in the firft procefs or method herein before 
mentioned. To this mixture, after the proper degree of 
aftion has taken place, a fufficient quantity of vegetable 
alkaline fait is to be added, to give or procure to the lead 
the carbonic acid, which is more fpeedily done when the 
vegetable alkali is in a ftate of carbonat. The falts are 
then to be feparated from the cerufe or carbonat of lead, 
by waffling oft’ the two lalts, confifting of foda or mine¬ 
ral alkali, and muriat of pot-afh ; or the foda may be fe¬ 
parated before the pot-afh is added to the materials. Laftly, 
the cerufe or carbonat of lead is to be levigated, and dried. 
The muriat of pot-afh, when feparated, is to be preferv- 
ed, and applied to operate on more oft the calx or calces 
of lead ; and this comes under the defcription given in 
the firft method or procefs herein before mentioned.” 
A patent was alfo granted to Mr. John Wilkinfon, of 
Caftle-head in Lancashire, on the 18th of June 1799, for 
the following method of making white-lead j which he 
defcribes thus: “ Inftead of corroding blue lead, by vi¬ 
negar, in pots, with the heat of dung or bark, accord¬ 
ing to the prefent method of making it, I take litharge, 
and grind it exceeding fine in fea-water, or any other la- 
line mixture ; and, by repeated trituration, waffling, and 
bleaching, cerufe or white-lead of the belt quality, is ob¬ 
tained. The cerufe may be procured without the acid 
mixture, which is merely ufed to facilitate the procefs : 
levigation, repeated wafhings, and drying, being fuffi¬ 
cient, upon allowing more time for the operation, by the 
medium of the common air. 
CE'RUSE 
