PUM 
PULMONARIA, in botany, hmg ieort, 
& genus of the Pentandvia Monogynia class 
and order. Natural order of Asperifoliae. 
Borragineae, Jussieu. Calyx prismatic, five- 
cornered; corolla, funnel-form, with an 
open throat. There are five species, of 
which P. officinalis, common lung-wort, 
has a perennial, fibrous root, lower leaves 
rough, about six inches long and two and 
a half broad, of a dark green on their upper 
side, marked with many broad whitish spots, 
pale underneath; stalks almost a foot in 
height, having several smaller leaves on 
them, standing alternately ; the flowers are 
produced in small bunches at the top of 
the stalks ; calyx tubnions, hairy, as long 
as the tube of the corolla ; brims of the 
petal spread open, shaped like a cup, red, 
purple and blue in the same bunch. M'^ood- 
ville observes, that the name pulmonaria, 
seen to have arisen rather from the speckled 
appearance of the leaves, resembling that 
of the lungs, than from any intrinsic qua- 
lity which experience has discovered to be 
useful in pulmonary complaints. 
PULSE, in the animal ceconomy, denotes 
the beating or throbbing of the heart and 
arteries. 
PULTENAJA, in botany, so named' in 
honour of William Pulteney, M. D. a genus 
of the Decandria Monogynia class and 
order. Generic character: calyx, five- 
loothed, with an appendage on each side; 
corolla, papilionaceous ; the wings shorter 
than the standard ; legume of one cell, with 
two seeds. There are six species, all natives 
of New Holland. 
PULVERISATION, an operation, com- 
monly employed in the apothecary’s shop, 
by means of pestles and mortars. The 
bottom of the mortars should be concave ; 
and their sides should neither be so inclined 
as not to allow the substances operated on 
to fall to the bottom between each stroke 
of the pestle, nor so perpendicular as to 
collect it too much together, and to retard 
the operation. The materials of which the 
pestles and mortars aye formed, should re- 
sist both the mechanical and chemical ac- 
tion of the substances for which they are 
used. Wood, iron, marble, siliceous stones, 
porcelain, and glass, are all very properly 
employed; but copper, and metals con- 
taining copper, are to be avoided, especially 
where the article operated upon has a ten- 
dency to corrode the metal. 
PUMICE, in mineralogy, is of a greyish 
White colour ; it occurs in mass and disse- 
?ninated, being always more or less carious. 
PUM 
Tt is glistening with a silky Instre ; its frao 
ture is fibrous, its 'fragments are sharp 
edged ; it is opaque, sometimes a little 
translucent on the edges; it is rather soft, 
but its particles in powder are very hard; 
it is fusible without' addition before the 
blow-pipe into a white enamel ; it is re- 
garded as a volcanic product, and is wrought 
in considerable quarries in the Lipari islan ds, 
which are almost entirely composed of this 
mineral. It is found also in Sicily and Ice- 
land. It is composed of 
Silica 77.5 
Alumina 17.5 
Oxide of iron 1.75 
96.75 
Loss 3.S5 
100 
This mineral is employed in the arts for 
grinding down metals, glass, ivory, &c. pre- 
viously to polishing. It is likewise used in 
smoothing leather, and many other purpose* 
of the like kind. 
PUMP, in hydraulics, a machine fonn- 
ed on the model .of a syringe, for raising of 
water. See Hydraulics. 
Pump air. See Pneumatics. 
Pump chain, consists of a long chain 
equipped witli a sufficient number of valves', 
at proper distances, which working upon 
two wheels, one above and the other below, 
passes downward through a wooden tube 
and returns upward through another. It 
is managed by a long winch or roller, 
whereon several men may be employed at 
once, and thus it discharges, in a limited 
time, a much greater quantity of water than , 
the common pump, and with less fatigue.' 
and inconvenience to the labourers. This 
machine was formerly exposed to several 
disagreeable accidents, by nature of its then 
construction. The chain was of too compli- 
cated a fabric, and the sprokel wheels em- 
ployed to wind it up from the ship’s' bot- 
tom, were deficient in a very material cir- 
cumstance, viz. some contrivance to pre- 
vent the chain from sliding or jerking back 
upon the surface of the wheel, which fre- 
quently happened when the valves were 
charged with a considerable weight of 
water, or when the pump was violently 
worked. The links were evidently too 
short, and the unmechanical manner in 
which they were connected, exposed them 
to a great friction in passing round the 
wheels. Hence they were sometimes ant 
Kk 2 ^ 
