BON 
BON 
covering on the outside of their bodies, 
evidently intended for defence. 
The bones are tire most solid part of ani- 
mals. Their texture is sometimes dense, 
at other times cellular and porous, accord- 
ing to the situation of the bone. They 
are white, of a lamellar structure, and not 
flexible nor softened by heat. Their spe- 
cific gravity differs in different parts. That 
of adults’ teeth is 2.27 : the specific gravity 
of children’s teeth is 2.08. It must have 
been always known that bones are combus- 
tible, and that when sufficiently burnt, 
they leave behind them a white porous sub- 
stance, which is tasteless, absorbs water, 
and has the form of the original bone. The 
nature of this substance embarrassed the 
earlier chemists. But in 1771, Scheele 
mentioned, in his dissertation on fluor spar, 
that the earthy part of bones is phosphate 
of lime. This discovery was the first and 
the great step towards a chemical know- 
ledge of the composition of bones. The 
component parts of bonqs are chiefly four ; 
namely, the earthy salts, fat, gelatine, and 
cartilage. The earthy salts may be ob- 
tained either by calcining the bone to 
whiteness, or by steeping it for a sufficient 
length of time in acids. In the first case 
the salts remain in the state of a brittle 
white substance ; in the second, they are 
dissolved, and may be thrown down by the. 
proper precipitants. These earthy salts 
are four in number : 1. Phosphate of lime, 
which constitutes by far the greatest part 
of the whole. 2. Carbonate of lime. 3. 
Phosphate of magnesia, lately discovered 
by Fourcroy and Vauquelin. It occurs in 
the bones of all the inferior animals exa- 
mined by these indefatigable chemists, but 
could not be detected in human bones. 
4. Sulphate of lime, detected by Mr. 
Hatchett in a very minute proportion. The 
proportion of fat contained in bones is va- 
rious. By breaking bones in small pieces, 
and boiling them for some time in water, 
Mr. Proust obtained their fat swimming 
on the surface of the liquid, It weighed, 
he says, one-fourth of the weight of the 
bones employed. This proportion appears 
excessive, and can scarcely be accounted 
for without supposing that the fat still re- 
tained water. The gelatine is separated by 
the same means as the fat, by breaking the 
bones in pieces and boiling them long enough 
in water. The water dissolves the ge- 
latine, and gelatinizes when sufficiently 
concentrated. Hence the importance of 
bones in making portable soups, the basis 
.of which is concrete gelatine, and likewise 
in making glue. When bones are deprived 
of their gelatine by boiling them in water, 
and of their earthy salts by steeping them 
in diluted acids, there remains a soft white 
elastic substance, possessing the figure of 
the bones, and known by the name of car- 
tilage. From the experiments of Hat- 
chett, it appears that this.substance has the 
properties of coagulated albumen. This 
cartilaginous substance is the portion of 
the bone first formed. Hence the softness 
of these parts at first. The phosphate of 
lime is afterwards gradually deposited, and 
gives the bone the requisite firmness. The 
gelatine and fat, especially the first, gave 
the bone the requisite degree of toughness 
and strength ; for when they are removed, 
the bone becomes brittle. The relative 
proportion of phosphate of lime and carti- 
lage differ exceedingly in different bones 
and in different animals. Ox bones, ac- 
cording to the analysis of Fourcroy and 
Vauquelin, are composed of 
Solid gelatine 51 
Phosphate of lime , ...37,7 
Carbonate of lime ..10 
Phosphate of magnesia... 1.3 
100.0 
See Anatom y. 
BONIS non amovendis, in law, is a writ 
directed to the Sheriffs of London, &c, 
chaiging them, that a person, against whom 
judgment is obtained, and prosecuting a 
writ of error, be hot suffered to remove his 
goods until the error is determined. 
BONNET, in fortification, a small work, 
consisting of two faces, having only a para- 
pet with two rows of palisadoes, of about 
ten or twelve feet distance : it is generally 
raised before the saliant angle of the coun- 
terscarp, and has a communication with the 
covered way, by a trench cut through the 
glacis, and palisadoes on each side. 
Bonnet, in the sea-language, denotes an 
addition to a sail : thus they say, lacc on 
the bonnet, or shake off the bonnet. 
BONNETIA, in botany, so called in 
honour of M. Charles Bonnet, a genus of 
the Polyandria Monogynia class and order. 
Essential character : calyx five-parted, two 
parts larger; corol five-petalled, three 
smaller upright, two longer declinate ; cap- 
sules oblong, three-celled, three-valved, 
many seeded. There is only one species, 
viz. B. mahuria grows in marshy places in 
Cayenne and Guiana, a tree about fifteen 
feet high, branching chiefly towards the 
top. The flowers are borne on terminal 
spikes, and are of a purple colour. 
