BOLE. 
tallic vessel, and at 214° in a elass vessel; when 
the barometer stands at less than 30 inches, water 
boils at a lower temperature than 212°; when 
the barometer stands at more than 30 inches, 
water will. not boil except at a higher than 212° ; 
and when:atmospheric pressure is totally removed 
from a close vessel by means of the air-pump, 
water boils.at so low a temperature as 72°. The 
pressure of the atmosphere on the summit of a 
mountain: or lofty hill at any one moment is al- 
ways-less than in the adjacent plain or valley ; 
and water; in consequence, always requires more 
heat to bring it to ebullition in a valley than on 
a hill. Am elevation of 530 feet makes a differ- 
ence of one degree of Fahrenheit in the boiling 
point of water; and: every subsequent elevation 
of 530 feet: makes a difference of another degree ; 
and so constant is this ratio, that, but for the 
disturbance of pressure occasioned by meteorolo- 
gical vicissitudes, it might be made a facile and 
perfectly exact means of determining the height 
of mountains. All other liquids, as well as water, 
boil at 140° lower temperature in vacuo than in 
the open air. Water in a vacuum, as in the in- 
stance of the common pulse glass, will boil by 
the heat of the hand; and sulphuric ether in a 
vacuum will boil at a temperature low enough to 
freeze mercury. 
The process of boiling is well known to effect 
| great and important changes in both the chemi- 
cal and the mechanical condition of food, and to 
| render many substances suitable for the digestion 
of man and beast, which, in their raw state, are 
| indigestible, or even inedible, or unwholesome. A 
boiling house for the preparing of cattle’s food, 
and for various other purposes requiring the use 
of hot water, is now an indispensable part of 
|| every proper series of farm buildings, and ought 
to be situated in the immediate vicinity of the 
cow-house. Moveable boilers or boiling-machines 
cam serve only for very small establishments ; and 
either fixed boilers of the construction common 
in this country, or caldrons of a semi-conical 
shape suspended on a crane, and loosely inserted 
in an inverted semicone of brickwork, are requi- 
site for all farms which have a large home stock. 
In these vessels, roots may be reduced from hard- 
ness to an eatable condition; chaff, weak corn, 
and other kinds of barn refuse, may be rendered 
palatable and more nutritive; hay-tea may be 
prepared, as an agreeable and nourishing drink 
to sick cattle ; food may be cooked for swine and 
poultry; and water may be boiled for steeping 
harsh articles of food, or for any other of scores 
of useful purposes. But the same kind of chemi- 
cal and mechanical changes which are made on 
the food of cattle by boiling in water, are effected 
also, and generally with greater advantage or in 
a superior degree, by the action of steam; and 
they will afterwards be the subject of a separate 
notice. See the article Srmamina, 
BOKHARA CLOVER. See Grover. 
BOLE. The branchless part of the trunk or 
BOLLING. 469 
stem of a tree. The boles of most kinds of tim- 
ber trees constitute the principal body of a forest. 
The name bollings is applied in some districts of 
Britain to pollards or the stems of young trees 
freed from the tops and the branches. See the 
article Trzx. 
BOLE. A viscid earth, less coherent than. 
clay. A variety of it has. usually a yellow tinge. 
All the kinds of it are recommended as astrin- 
gents and sudorifics. The chief sort used, in me- 
dicine is imported from Turkey, and will be found 
noticed under the head Anmunran Boun. 
BOLETUS. A genus of fungi, having a globu- 
lar form, and taking their name from a word 
which signifies a mass. Hight or nine species, 
besides several varieties, grow wild in Great 
Britain; and about a dozen other species are 
known to botanists. The milk-flowing species, 
of a buff colour, and about 2} inches broad, grows 
in pastures; and the other eight British species 
grow in wocds. ‘Three of these species have a 
cracked form, one has a frosted appearance, four 
have each a breadth of about 3 inches, and the 
other two have a breadth of respectively 25 and 
4 inches; and most may be seen during both 
summer and autumn. 
But the most interesting boletus is one which 
has a place in the British materia medica. “This 
species of fungus,” says Dr. A. T. Thomson, “ is 
found in Britain growing upon decayed trunks 
of the ash and the oak. The pileus or hat is 
scaly and convex, but depressed in the centre 
When young, it is of a light brown colour above, 
and soft like velvet, white underneath, and 
covered with a slimy matter; but when mature, 
it changes to dark brown, approaching to black. 
It is from 6 to 10 inches in diameter; and al- 
though generally stemless, yet it is sometimes 
supported on a footstalk an inch in length. The 
boletus which grows upon the oak is said to be 
the most valuable. It should be gathered in | 
August or September, and be kept ina dry room. 
The way of preparing it is to take off with a 
knife the white and hard part, till you finda 
substance so soft as to yield under the finger like 
shammy leather. This must be divided into 
different pieces, and these beaten with a hammer 
till they become so soft as to be torn with the 
finger.” Boletus, thus prepared, contains resin, 
extractive, several salts, and a principle similar 
to animal gelatine. Its principal use is as an 
external application to bleeding arteries and 
veins; and is the same as that of lint or sponge. 
BOLL. A Scottish measure of grain. It is 
generally understood to contain four bushels. 
But in the old Scottish measures of oats and bar- 
ley, four lippies were equal to one peck, four 
pecks to one firlot, four firlots to one boll, and 
sixteen bolls to one chalder. A boll of oatmeal 
weighs 140 pounds; and three-fourths of a boll 
of oats is equal to a boll of wheat, pease, or rye. 
BOLLING. The rolling inward and amassing 
of the leaves of some of the varieties of Lrassica 
