BIS 



BIS 



In England there are twenty -four bi- 

 shoprics, and two archbishoprics; in Scot- 

 land none at all ; in Ireland eighteen 

 bishoprics and four archbishoprics ; and 

 in Popish countries they are still more 

 numerous. 



BISMUTH, one of the brittle and easi- 

 ly fused metals. The ores of this metal 

 are very few in number, and occur chief- 

 ly in Germany. This, in some measure, 

 Recounts for the ignorante of the Greeks 

 and Arabians, neither of whom appear to 

 have been acquainted with bismuth. The 

 German miners, however, seem to have 

 distinguished it at a-pretty early period, 

 and to have given it the name of bismuth ; 

 for Agricola describes it under that name 

 as well known in Germany, and considers 

 it as a peculiar metal. The miners gave 

 it also the name of tectum argenti ; and 

 appear to have considered it as silver be- 

 ginning to form, and not yet completed. 

 Mr. Pott collected, in his dissertations on 

 bismuth, every th ; ng respecting it con- 

 tained in the writing's of the alchymists. 

 Beccher seems to have been the first 

 chemist who pointed out some of its most 

 remarkable properties. Bismuth is of a 

 reddish white colour, and almost destitute 

 both o,f taste and smell. It is composed of 

 broad brilliant plates, adhering to each 

 other. The figure of its particles, accord- 

 ing' to Hauy, is an octahedron, or two four- 

 sided pyramids, applied base to base. Its 

 specific gravity is 9.82. When hammered 

 cautiously, its density, as Muschenbrocck 

 ascertained, is considerably increased. It 

 is not therefore very brittle : it breaks, 

 however, when struck smartly by a ham- 

 mer, and consequently is not malleable. 

 Neither can it be drawn out into wire. 

 Its tenacity, from the trials of Muschen- 

 broeck, appears to be such, that a rod 

 one eighteenth of an inch in diameter is 

 capable of sustaining a weight of nearly 

 29lbs. When heated to the temperature 

 of 476 it melts ; and if the heat be much 

 increased it evaporates, and may be dis- 

 tilled over in close vessels. When allow- 

 ed 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 metal is withdrawn as soon as the surface 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 kept melted at a moderate heat, it 

 becomes covered with an oxide of a 

 greenish grey or brown colour. In a more 

 violent heat it is volatile, and may be su- 

 blimed in close vessels ; but with the 

 access of air, it emits a blue flame, and 

 its oxide exhales in a yellowish smoke, 

 condensible by cold bodies. This oxide 

 is very fusible ; and is convertible by 

 heat into a yellow transparent glass. Sul- 



VOL, II, 



phuric acid acts on bismuth, and sulphur- 

 ous acid is disengaged. A part of the bis- 

 muth is dissolved, and the remainder is 

 changed into an insoluble oxide. Nitric 

 acid dissolves bismuth with great rapidi- 

 ty. To one part and a half of nitric acid, 

 at distant intervals, add one of bismuth, 

 broken into small pieces. The solution, 

 is crystallizable. It is decomposed when 

 added to water ; and a white substance is 

 precipitated, called magistery of bismuth, 

 or peai-1-white. This pigment is defect- 

 tive, inasmuch as it is liable to be chang- 

 ed by sulphuretted hydrogen, and by the 

 vapours of putrifying substances in ge- 

 neral. Muriatic "acid acts on bismuth. 

 The compound, when deprived of water 

 by evaporation, is capable of being su- 

 blimed, and affords a soft salt, which de- 

 liquesces into what has been improperly 

 called butter of bismuth. Bismuth is ca- 

 pable of forming the basis of a sympathe- 

 tic ink. The acid employed for this pur- 

 pose must be one that does not act on 

 paper, such as the acetic. Characters 

 written with this solution become visible 

 when exposed to sulphuretted hydrogen. 



B1SBECTION, in geometry, the divi- 

 sion of a line, angle, &.c. into two equal 

 parts. 



BISSEXTILE, or leap-year, a year con- 

 sisting of 366 days, and happening every 

 fourth year, by the addition of a day in 

 the month of February, when that year 

 consists of 29 days. And this is done, to 

 recover the 6 hours which the sun takes 

 up nearly in his course more than the 

 365 days commonly allowed for it in 

 other years. 



The day thus added was by Julius Cae- 

 sar appointed to be the day before the 

 24th of February, which among the Ro- 

 mans was the 6th of the calends, and 

 which on this occasion was reckoned 

 twice ; whence it was called the bissex- 

 tile. By the statute De anno bissextile, 

 21 Hen. III. to prevent misunderstand- 

 ings, the intercalary day and that next be- 

 fore it are to be accounted as one day. 



To find what year of the period any- 

 given year is, divide the given year by 4, 

 then if remains it is leap year ; but if 

 any thing remain, the given year is so ma- 

 ny after leap year. But the astronomers 

 concerned in reforming the calendar in 

 1582, by order of Pope Gregory XIII. 

 observing that in four years the bissextile 

 added 44 minutes more than the sun 

 spent in returning to the same point of 

 the ecliptic ; and computing that in 133 

 years these supernumerary minutes would 

 form a day ; to prevent any changes be- 

 ing thus insensibly introduced into thfe 



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