CEM 
calcine them ; or sometimes to repair flavvs 
and cracks, and for a variety of other 
smaller purposes. 
From the vast variety of receipts for 
lutes and cements of ditferent kinds, the 
following may be selected, which will an- 
swer most of the purposes of the experi- 
mental chemist. To prevent the escape 
of the vapours of water, spirit, and liquors 
not corrosive, the simple application of slips 
of moistened bladder will answer very well 
for glass, and paper with good paste for me- 
tal. Bladder, to be very adhesive, should 
be soaked some time in water moderately 
warm, till it feels clammy, it then sticks 
very w'ell : if smeared with white of egg, 
instead of water, it adheres still closer. 
Another very convenient lute is linseed 
meal, moistened with water to a proper 
consistence, well beaten, and applied pretty 
thick over the joinings of the vessels. This 
immediately renders them tight, and the 
lute in some hours \dries to a hard mass. 
Almond paste will answer the same pur- 
pose. The use of the above lute is so ex- 
tensive, that no other is required in closing 
glass vessels in preparing all common dis- 
tilled liquors ; and it will even keep in am- 
monia, and acid gasses, for a longer time 
than is required for most experimental pur- 
poses. It begins to scorch and spoil at a 
heat much above boiling, and therefore 
will not do as a fire-lute. It is still firmer, 
and dries sooner when made up with milk, 
or lime water, or weak glue. A number of 
very cohesive cements impervious to water 
and most liquids and vapourSj and ex- 
tremely hard when once solidified, are 
made by the union of quick-lime with many 
of the vegetable or animal mucilaginous li- 
quors. The variety of these is endless. We 
may first mention the following, as it has 
been extensively employed by chemists for 
centuries. Take some whites of eggs with 
as much water, beat them well together, 
and sprinkle in sufficient slaked lime, to 
make up the whole to the consistence of 
thin paste. The lime should be slaked by 
being once dipped in water, and then suf- 
fered to fall into powder, wdiich it will do 
speedily with great emission of heat, if well 
burnt. This cement should be spread on 
slips of cloth, and' applied immediately, as 
it hardens or sets very speedily. While 
hardening, it may he of use to sprinkle over 
it some of the lime in fine powder. This 
cement is often more simply, and as conve- 
niently managed, by smearing slips of linen 
OB both sides witli white of egg, and w'hen 
CEN 
applied to the joining of the vessels, shak- 
ing some powdered lime over it : it then 
dries very speedily. Another lute of the 
same kind, and equally good, is made by 
using a strong solution of glue to the lime, 
instead of the white of egg : it sets equally 
soon, and becomes very hard. A mixture 
of liquid glue, white of egg, and lime, makes 
the hit d'ane, which is so firm, that broken 
vessels united with it arc almost as strong 
as when sound. None of these lutes, how- 
ever, will enable these vessels to hold li- 
quids for any great length of time. Milk 
or starch, with lime, make a good but less 
firm lute. A very firm and singular lute of 
this kind is made by rubbing down some of 
the poorest skimmed-milk cheese with wa- 
ter, to the consistence of thick soup, and then 
adding lime, and applying as above : it an- 
swers extremely well. Lime and blood, 
with a small quantity of brick-dust, or 
broken pottery, stirred in, is used in some 
places as a very good water-cement, for 
cellars and places liable to damp. 
All the above-mentioned cements,, wdth 
lime, become very hard by drying, inso- 
much that tliey cannot be separated from 
glass vessels without the help of a sharp 
knife and some violence; and hence deli- 
cate vessels and long thin tubes, cemented 
with it, are apt to break when the appara- 
tus is taken down, and sometimes even by 
the mere force of contraction in setting. It 
is a gi-eat advantage, however, that they 
may be applied immediately to any acci- 
dental crack or failure of the lute already 
on, notwithstanding a stream of vapour is 
bursting through ; and in Idi'ge distillations 
it is of advantage ahvays to have some of 
the materials at hand. 
CENCHRUS, in botany, a genus of the 
Pdlygamia Monoecia class and order. Na- 
tural order of Gfa.sses. Essential charac- 
ter: invol. laciniate, echinate, two -flow- 
ered ; calyx glume twn-flowered, one male, 
the other hennaplirodite ; Herm. , corolla 
glume awnless ; stamina three ; seed one ; 
male corolla glume awnless ; stamina three. 
'Phere are eleven species, all natives of both 
Indies. 
CENSOR of books, are a body of doctors 
or others established in divers countries to 
examine all books before they go to the 
press, and to see they contain nothing con- 
trary to faith and good manners. 
In England, w e had formerly an officer 
of this kind, under the title of licenser of 
the press ; but since the revolution, our 
press has been laid under no such restraint. 
I 2 
