222 
B 1 S 
B I S 
ment, except the bishop of Man, and as 
sucn sit and vote in the house of lords ; they 
are barons in a threefold manner, viz. feudal, 
in regard to the temporalities annexed to 
their bishoprics ; by writ, as being summon- 
ed by writ to parliament ; and lastly, by pa- 
tent and creation : accordingly, they have 
the precedence of all other barons, and vote 
as barons and bishops, and claim all the pri- 
vileges enjoyed by the temporal lords, ex- 
cepting that they cannot be tried by their 
peeis ; because, in cases of blood, they them- 
selves cannot pass upon the trial, for they 
are prohibited, by the canons of the church, 
to be judges of life and death. 
BlbKET. See Baker. 
BISMILLAH, a solemn form used by the 
Mahometans, at the beginning of all their 
books and other writings, signifying “ in the 
name of the most merciful God.”” 
It is also used among the Arabs as a word 
oi invitation to eat. An Arab prince fre- 
quently sits down to eat in the street before 
his own door, or under the shade of a wide- 
spreading tree, and calls all that pass, even 
beggars, by this word, who come and sit 
down to eat with him ; “ for,” says Pocock, 
“ the Arabs are great levellers, and set every 
body on a footing with themselves.” 
BISMUTH, in natural history, a genus of 
the semi-metals, the most usual appearance 
of which is in form of an ore, intimately 
mixed with silver, a large quantity of arse*- 
nic, and an earthy matter which yields co- 
balt 
The ancients were acquainted with bis- 
muth, but they confounded it with tin. It 
is mentioned occasionally by the alchymists 
and earlier mineralogists ; and referred 'some- 
times to tin, sometimes to lead, and some- 
times to antimony. The German miners 
gave it the name of lectum argenti ; and ap- 
pear to have considered it as silver begin- 
ning to form, and not yet completed. ° 
Bismuth is of a reddish-white colour, and 
almost destitute of taste and smell. It is 
composed of broad brilliant plates adhering 
to each other. The figure of its particles, 
according to Hauy, is an octahedron, or 
two four-sided pyramids applied base to 
base. r 
Its hardness is 7. Its specific gravity is 
9.8227. 
When hammered cautiously, its density, as 
Muschenbroek ascertained, 'is considerably 
increased. It is not therefore very brittle ; 
it breaks, however, when struck smartly 
by a hammer, and consequently is not mal- 
leable. Neither can it be drawn out into 
wire. Its tenacity has not been ascertained. 
When heated to the temperature of 4600, 
it melts ; and if the heat is much encreased, 
it evaporates, and may be distilled over in 
close vessels. When' allowed to cool slowly, 
and when the liquid metal is withdrawn, as 
soon as the surface congeals it crystallizes 
in parallelepipeds, which cross each other at 
right angles. 
When exposed to the air, it soon loses its 
•lustre, but scarcely undergoes any other 
change. It is not altered when kept under 
water- 
Only two oxides of bismuth are at present 
known. But the combination of this metal 
with oxygen has been more neglected by 
chemists than almost any other. 
When kept melted in an open vessel, 
BIS 
its surface is soon covered with a dark-blue 
pellicle ; when this is removed, another suc- 
ceeds, till the whole metal is oxidized. When 
these pellicles are kept hot and agitated in 
an open vessel, they are soon converted 
into a brownish powder, known by the name 
of brown oxide. This is the protoxide of 
bismuth. According to Fourcroy, it is com- 
posed ot ninety parts of bismuth, and ten of 
oxygen. 
When bismuth is raised to a strong 
red heat, it takes fire, and burns with a faint 
blue flame, and emits a yellow smoke. When 
this is collected, it is a yellow powder, not 
volatile, which lias been called yellow oxide 
of bismuth. 
When bismuth is dissolved in nitric acid, 
if water is poured into the solution, a white 
powder precipitates, which was formerly call- 
ed magistery of bismuth, and at present white 
oxide of bismuth. According to the experi- 
ments of Klaproth, it is composed of 81.3 
parts bismuth and 17.7 of oxygen. This 
oxide is used as a paint under the name of 
pearl white. 
The oxides of bismuth are very easily con- 
verted into glass ; for that reason bismuth is 
sometimes used in the process of cupellation 
instead of lead. It was first proposed for 
that purpose by Dufay in 1727, and his ex- 
periments were afterwards confirmed by 
Pott. ' 
These oxides are easily reduced when 
heated with charcoal or other combustible 
bodies ; for the affinity between bismuth and 
oxygen is but weak. 
Bismuth has not been combined with 
carbon or hydrogen, neither does it seem 
capable of combining in any notable propor- 
tion with phosphorus. 
Sulphur combines readily with bismuth by 
fusion. The sulphuret of bismuth is of a 
bluish-grey “colour, and crystallizes into beau- 
tiful tetrahedral needles. It is composed of 
85 parts of bismuth and 15 of sulphur. 
Bismuth combines with almost all the me- 
tals, but few of its alloys are much used. 1. 
Equal parts of bismuth and gold form a 
brittle alloy, nearly of the same colour with 
bismuth; the specific gravity of which is 
greater than tiie mean. 2. The alloy of 
bismuth and platinum if also very brittle. 
When exposed to the air, it assumes a purple, 
violet, or blue colour. The bismuth can 
scarcely be separated by heat. 3. Bismuth 
combines readily with silver by fusion. The 
alloy is brittle, lamellar, and nearly of the 
colour of bismuth. This alloy is sometimes 
formed, in order to purify silver by the pro- 
cess of cupellation. 4. Mercury combines 
readily with bismuth, either by triturating 
the metals together, or by pouring two parts 
of hot mercury into one part of melted bis- 
muth. This amalgam is at first soft, but it 
becomes gradually hard. When melted and 
cooled slowly, it crystallizes. When the 
quantity of mercury exceeds the bismuth 
considerably, the amalgam remains fluid, 
and has the property of dissolving lead and 
rendering it also' fluid. This triple com- 
pound may be Altered through shamoy 
leather without decomposition. Mercury 
is sometimes adulterated with these metals ; 
but the imposition may be easily detected, 
not only by the specific gravity of the mer- 
cury, which is too small, but because it drags 
a tail, as the workmen say ; that is, when a 
drop of it is agitated on a plane surface, the 
drop does not remain spherical, but part of 
it adheres to the surface, as if it was not com- 
pletely fluid, or as if it was inclosed in a thin 
pellicle. 5. Copper forms with bismuth a 
brittle alloy of a pale-red colour, and a spe- 
cific gravity exactly the mean of that of the 
two metals* alloyed. 6. Bismuth combines 
but imperfectly with iron. The alloy is brittle, 
and attracted by the magnet even” when the 
bismuth amounts to three-fourths of the 
whole. The specific gravity of this alloy is 
less than the mean. 7. Bismuth and tin unite 
readily. A small portion of bismuth increases 
the brightness, hardness, and sonorousness 
of tin : it often enters into the composition 
of pewter. Equal parts of tin and bismuth 
form an alloy that melts at 280 degrees ; 
eight parts of tin and one of bismuth melt 
at 390 degrees; two parts of tin and one of 
bismuth at 330 degrees. 8. The alloy of 
lead and bismuth is of a dark-grey colour, 
and close grain. It is ductile," unless the 
bismuth exceeds the lead considerably. Bis- 
muth encreases the tenacity of lead prodi- 
giously. Muschenbroek found, that the te- 
nacity of an alloy composed of three parts 
ot lead and two of bismuth, was ten times 
greater than that of pure lead. The speci- 
fic gravity of this alloy is greater than the 
mean. y. When eight parts of bismuth, five 
of lead, and three of tin, are melted toge- 
ther, a white-coloured alloy is obtained, 
which melts at the temperature of 212 de- 
grees, and therefore remains fusible under 
boiling water. 10. The alloy of bismuth is 
brittle, and formed of thin plates. 11. Bis- 
muth does not combine with zinc. 
BISON, see Bps. 
BISSECTION, in geometry, the division 
of a line, angle, &c. into two equal parts. 
BISSEXTILE, in chronology, a year con- 
sisting of three hundred and sixty-six days, 
being the same with our leap-year. 
The true solar year, or that space of time 
which flows while the sun is moving from any 
one point of the ecliptic till he returns to the 
same point again, consists of 365 days, 5 
hours, 48 minutes, 57' seconds. The year 
made use of by the antient Egyptians con- 
sisted ot 365 days ; which being less than the r 
true solar year by nearly six hours, they lost 
a day every four years. * Julius Caesar being 
high-priest among the Romans, and consider- 
ing the inconveniences arising from this me- 
thod of computation, ordered that every 
fourth year should have an intercalary day, 
and that this additional day should be added 
to the month ot February ; wherefore this 
method of computation is called the Julian 
account, or old style. 
Yet, as the true length of the year consists 
of 365 days, 5 hours, 49 minutes nearly, it 
follows that, according to this way of reckon- 
ing, at the end of every four years the civil 
year will begin 44 minutes sooner than it did 
before, consequently in 33 1 years it will an- 
ticipate by one whole day : for this reason 
pope Gregory XIII. set himself upon reform- 
ing the calendar; and finding, in the year 
1582, that the equinox had anticipated” ten 
whole days, he ordered that these ten days 
should be taken out of the calendar that year, 
and the lltli of March should be reckoned 
the j?2 1 st ; and ordered that every hundredth 
year, which, according to the Julian form, 
was to be bissextile, should be a common 
