B I Y 



474 



J3 IX 



ciplet, they are mixed together, the bitumen docs not regain 

 iu elasticity. 



Concentrated sulphuric acid dooi not net upon elastic 

 bitumen; but when long boiled with nitric acid it yields 

 resin, tannin, and a little nilroperic acid. According to 

 the analysis of M. Henry, jun., the elastic bitumen con- 

 sist! of 



Eaflldi. French. 



Carbon . . . 62*250 58'2GO 



Hydrogen . , 7 '496 4-890 



Azoic . . . 0-154 0-104 



Oxygen . . . 40-100 36-740 



100' 100' 



Benelius remarks, that the difference in the quantity of 

 hydrogen in these specimens is so considerable, that it is 

 surprising their properties are not more dissimilar. 



BITUMENS, MEDICAL USES OF. Though the sub- 

 stances popularly termed bitumens, in the most extensive 

 use of the term, differ, jis stated above, yet as in medical 

 writings the term is restricted to certain forms of these, 

 a slight notice of their uses and modes of action may 

 here be most appropriately introduced. In this limited 

 sense bitumens comprise naphtha, petroleum, maltha, and 

 asphaltum, which are all transition states of the samo 

 tiling ; viz., from naphtha the most fluid, to asphaltum the 

 most solid. These appear to be all mixtures in different 

 proportions of naphtha (strictly so called, naphtha montumi), 

 paraffiue, krcosote, acetic acid, and of some substance 

 which easily becomes black by the action of the air. The 

 chief constituent principles are carbon and hydrogen. They 

 may be considered miueral-empyreumatic oils, and in their 

 action on the human system they are similar to balsams 

 and resins. Their sphere of action does not seem to extend 

 beyond the spinal chord and ganglionic system ; they do 

 not affect the brain or its nerves, except indirectly in case 

 of an over-dose, through the vitiated and imperfectly decar- 

 bonized blood. The functions dependent for their perfection 

 on the nerves of organic life are more powerfully affected by 

 these agents than by any other empyreumatic oil. The se- 

 cretions of the mucous membranes, of serous membranes 

 :md glandular structures, as well as the skin, are promoted 

 by their influence. The process of absorption is also in- 

 creased, and a more copious secretion of urine takes place 

 They are better suited for slight and chronic affections ol 

 the nerves of organic life, than for acute or violent disorders 

 of them. They have been employed in loss of power 

 cramps, and chronic affections of a nervous but obscure 

 nature ; also in affections of the mucous membranes of the 

 lungs, when balsamic medicines are proper, such as humic 

 catarrh, and some of the forms of asthma arising from ner- 

 vous debility. 



Likewise in similar affections of the bladder, such as 

 atony of that organ, and loss of power of its sphincter 

 muscle, cutarrhus vesicee, $-c. They have also been usei 

 in gouty and rheumatic affections, especially when these 

 threaten to terminate in stiffness or loss of power. Lastly 

 they have been employed as a remedy against worms, espe- 

 cially the tape-worm, in which their efficacy is increased hi 

 combination with assafuetida. Externally they are used a: 

 embrocations in rheumatic and gouty affections, and also to 

 allay cramps and spasms. They are also serviceable as an 

 external application to chilblains and some other ulcers re 

 suiting from an imperfect circulation and low degree o 

 nervous power. 



Their employment would be very improper during any 

 inflammatory state of the system, or increased sensibility o 

 the nerves. An over-dose is decidedly poisonous, causing 

 general excitement, tremblings of the limbs, cramps, con 

 vulsions, laborious respiration, a venous state of the blood 

 great debility, and death : or recovery may take place, if b) 

 means of respirarhn and a copious secretion of bile anc 

 urine, the blood can be freed from its excess of carbon 

 Even after a favourable issue appears likely to occur, deatl 

 may take place at the end of two or three days. A very 

 large dose may very speedily cause death. [See KREOSOTK 

 PAHAFPINK. PBTROLKUM.J 



BIVOUAC (written also BIHOUAC. BIOUAC), is 

 term in military tactici probably derived from the German 

 verb beteachen, or beyinachrn, signifying to watch over : i 

 WM originally applied to the strong parties of cavalry- whicl 

 were posted beyond the lines of intrenrhment in order l 



watch the motions of the enemy, and prevent any attemp 



to approach the army by surprise ; and, because the soldiers 



bus employed passed tin- m-lu in llieoprii air, the terra 



was subsequently used to denote iiu- condition uf any body 



f troops when in the field, and not regularly encamped 



under tents. 



Formerly, no army served during a campaign without 

 >cing well provided with every material necessary fur its 

 >rotcctioii from the inclemency of the weather; but, since 

 he Revolution, the French soldiers have, except uii u I. 

 occasions, dispensed with tents. At the periods iu which 

 military operations were suspended, they were quartered in 

 towns and villages; and while on active service, they hud 

 only the occasional cover afforded by such buildings as hap- 

 iened to be situated in the district which they occupied. In 

 ill their great expeditions they remained au bir-muc, as it was 

 called ; and the rapidity of their motions was due, iu a . 

 measure, to their freedom from the impedimenta with which 

 armies were formerly encumbered. The important suc- 

 cesses which so long attended the armies of Franca 

 no doubt, the cause of their example, in this respect, being 

 followed by their opponents. 



The carriage of an extensive tent equipage is necessarily 

 attended with serious inconvenience on any change ol 

 lion, but the removal of this evil must, it is !' uivd, 

 complished at the expense of the comfort ami health 

 soldier. During the summer season, and in tho south of 

 Europe, it may be indifferent whether or not the nu i. 

 the night under a roof; and indeed in those dmiuu- 

 in the summer season the open air may be pn 1'crrcd : but 

 the cold winds and rains which are so frequently Htparianced 

 in the spring and autumn in northern climates must induce 

 painful and dangerous diseases, which render the men at 

 an early period of their service unfit for the active duties 

 of war. 



To lessen the severity of the bivouac, fires are kept \\\> 

 during the night with wood obtained 1'rom the neighbouring 

 forests or villages : the arms being piled along the line, the 

 troops place themselves in their rear in groups, each about 

 its proper fire, which is lighted in any convenient situation, 

 the men sitting or lying upon straw if it can be procured, 

 and endeavouring to shelter themselves from wind or rain 

 by means of boughs planted in the ground, or by boards 

 formed into a roof, according to circumstances. The bivouac 

 of an army making a rapid retreat before an enemy is that 

 in which the most disastrous consequences follow, both to 

 the soldier and to the people of the country along the line 

 of march ; a complete disorganization of the army too often 

 takes place, and lamentable excesses are committed by 

 men suffering the severest distresses from hunger and fa- 

 tigue. In this state the soldier not only takes from the 

 peasant what is requisite to satisfy his own necessities, but 

 wantonly destroys every article of property which he cannot 

 carry away ; fruit trees are cut down, growing corn trampled 

 under foot, and houses are demolished or set on fire to give 

 cover or warmth by night. The retreat of the French army 

 from Moscow will be for ever remembered as an example 

 exhibiting every species of misery which can be inflicted 

 and suffered under the consequences of a rash and ill- 

 planned expedition. 



When a position is to be occupied for several days, it may 

 happen that the men find means to construct rude huts for 

 their protection with such materials as are at hand : and, in 

 an extremely inclement season, they are usually cantoned 

 in such towns or villages as arc in their neighbourhood. 

 They then light their fires in the streets, in gardens, or in 

 barns; certain spots having been previously appoint 

 alarm posts, about which, on signals being given, the dif- 

 ferent corps may assemble in order to form the line of battle, 

 and act immediately as circumstances may require. Per- 

 manent cantonments for the winter are of this nature, and 

 they are secured against surprise by outposts constantly 

 maintained at proper distances about them. 



BIXA, a West Indian genus of plants, which pi 

 substance called Arnotto, and gives its name to the natural 

 order BIXINE* ; a small group in the vegetable kingdom, 

 principally characterized by having numerous lr 

 stamens, "fruit with parietal placenta-, and leaves marked 

 with transparent dots. The only species of any general 

 interest cither in the genus or natural order is the /f/.ra 

 'tin, a native of the Malayan Archipelago, but now 

 i xtremuly common in the West Indies, where it is cultivated 

 in rieh moist soil by the sides of rivers. 



This plant forms a small tree with deep-green, shining, 



