BIT 



BIT 



seasons, directed, that in the course of 

 400 years there should be three sextiles 

 retrenched ; so that etery centesimal 

 year, which is leap year according 1 to the 

 Julian account, is a common year in the 

 Gregorian account, unless the number of 

 centuries can be divided by 4 without a 

 remainder. So 1600 and 2000 are bissex- 

 tile ; but 1700, 1800, and 1900 are com- 

 mon years. 



The Gregorian computation has been 

 received in most foreign countries ever 

 since the reformation of the calendar in 

 1582, excepting some northern countries, 

 as Russia, &c. And by act of parliament, 

 passed in 1751, it commenced in all the 

 dominions under the crown of Great 

 Britain in the year following ; it being or- 

 dered by that act, that the natural day 

 next following the 2nd of September 

 should be accounted the 14th ; omitting 

 the intermediate 11 days of the common 

 calendar. The supernumerary day in leap 

 years being added at the end of the month 

 February, and called the 29th of that 

 month, 



BISTOURY, in surgery, an instrument 

 for making incisions, of which there are 

 different kinds, some being of the form of 

 a lancet, others straight and fixed in the 

 handle like a knife, and others crooked 

 with the sharp edge on the inside. 



BISTRE, or BISTER, among painters, 

 denotes glossy soot, pulverised and made 

 into a kind of cakes with gum-water. 



BIT, or BITTS, in ship-building, the 

 name of two great timbers usually placed 

 abaft the manger in the ship's loof, 

 through which the cross-piece goes ; the 

 use of it is to belay the cable thereto 

 while the ship is at anchor. 



BITCH, the female of the dog kind. 

 See CA>-IS. 



BITTER, a sea term, signifying any 

 turn of the cable about the bits, so as that 

 the cable may be let out by little and lit- 

 tle. And when a ship is stopped by a ca- 

 ble, she is said to be brought up by a bit- 

 ter. Also that end of the cable which is 

 wound about the bits is called the bitter 

 end of the cables. 



BITTER principle. The bitter taste of 

 certain vegetables appears to be owing to 

 the presence of a peculiar substance, dif- 

 fering from every other in its chemical 

 properties. It may be extracted from the 

 wood of quassia, the root of gentian, the 

 leaves of the hop, and several other 

 plants, by infusing them for some time in 

 cold water. The characters of this sub- 

 stance, originally described by Wether, 

 have been attentively examined by Dr. 

 Thompson, who enumerates them as fol- 



low*?.. 1. When water thus impregnated 

 is evaporated to dryness by a very gentle 

 heat, it leaves a brownish yellow sub- 

 stance, which retains a certain degree of 

 transparency. For some time it con- 

 tinues ductile, but at last becomes brittle. 

 Its taste is intensely bitter. 2. When 

 heated it softens, swells, and blackens ; 

 then burns away without flaming much, 

 and leaves a small quantity of ashes. 3. 

 It is very soluble in water and in alcohol. 

 4. It does not affect blue vegetable co- 

 lours. 5. It is not precipitated by the 

 watery solution of lime, barytes, or stron- 

 tites ; nor is it changed by alkalies. 6. 

 Tincture of galls, infusion of nut-galls, 

 and gallic acid, produce no effect. 7. Of 

 the metallic salts, nitrate of silver and 

 acetate of lead are the only ones that 

 throw it down. The precipitate by ace- 

 tate of lead is very abundant ; and that 

 salt, therefore, affords the best test for 

 discovering the bitter principle, when no 

 other substances are present, by which 

 also it is decomposed. From recent ex- 

 periments of Mr. Hatchett, it appears that 

 the bitter principle is formed, along with 

 tan, by the action of nitric acid on indigo. 



BITTER salt, native, in mineralogy, is of 

 a greenish white, or smoke-grey colour. 

 It occurs sometimes in earthy, sometimes 

 in mass, and often in capillary crystals. 

 When earthy it is without lustre, but when 

 crystallized its lustre is between silky and 

 vitreous. It consists of sulphate of mag- 

 nesia, -more or less mixed with iron and 

 alumina, and probably some sulphate of 

 alumina. It is found on the surface of 

 decomposing argillaceous schistus, and 

 sometimes of limestone. 



BITTERN. See ARDEA. 



BITTERX, in salt-works, the brine re- 

 maining after the salt is concreted : this 

 they ladle off, that the salt may be taken 

 out of the pan, and afterwards put in 

 again ; when being farther boiled it yields 

 more salt. 



BITTERSPATH, in mineralogy, is 

 greyish, or greenish white, passing into 

 asparagus green. It occurs : 1. dissemi- 

 nated or crystallized in rhomboids, or per- 

 fect or truncated at the solid angles ; 2. 

 short, somewhat oblique, tetrahedral 

 prisms, often bevelled at the edges ; 3. 

 compressed hexaedrons. It is composed 

 of 



Carbonate of lime , 52 



magnesia 



Oxide of iron and manganese 3 

 100 



BITUMEN, in chemistry. The tevm 



