J30 
EXP 
.—He exploited great matters in his own perfon in Gallia, 
and by his fori in Spain. Camden. 
EX'PLOITS (Bay of), a bay of the Atlantic, on the 
ealt coad of Newfoundland. Lat. 49. 45. N. Ion. 55. 20. 
W. Greenwich. 
To EXPLO'R ATE, v. a. .[exploro, Lat.] To fearch out; 
to try by fearching ; to explore.—Snails exclude their 
horns, and therewith explorate their way. Brown. 
EXPLORA'TION, f. Search; examination.—Ufe 
may be made of the like way of exploration in that enquiry 
which puzzles fo many modern naturalids. Boyle. 
EXPLOR A'TOR, f. One who fearches; a fearcher ; 
an examiner. 
EXPLO'RATORY, adj. Searching; examining. 
To EX'PLORE, v. a ■ [exploro , Lat.] To try; to fearch 
into ; to examine by trial : 
The mighty Stagyrite firft left the fhore, 
Spread all his fails, and durd the deeps explore ; 
He lleet’d fecurely, and difcover’d far, 
Led by the light of the Moeonian dar. Pope. 
EXPLO'REMENT,/. Search; trial.—The frudrated 
fearch of Porta, upon the explorernent of many, could lcarce 
find one. Brown. 
EXPLO'SION, f. A fudden and violent expanfion of 
an eladic fluid, by which it indantaneoufly throws off any 
obllacle that happens to be in the way, with wonderful 
force and rapidity; as the explosion of gun-powder, ful¬ 
minating gold, &c.—Thofe parts which abound with 
ftrata of (lone, or marble, making the ftrongeft oppofition, 
are the moll furioufly ihattered, an event obfervable not 
only in this, but all other explofions whatever. Woodward. 
.—In gunpowder the charcoal and fulphur eafily take fire, 
and fet fire to the nitre; and the fpirit of the nitre being 
thereby rarified into vapour, rulhes out with explofion, af¬ 
ter the manner that the vapour of water rufhes out of an 
aeolipile: the fulphur alfo, being volatile, is converted 
into vapour, and augments the explofion. Newton. 
With explofion vafl 
The thunder raifes his tremendous voice. Thomfon. 
Explofion differs from expanfion, in that the latter is a 
gradual and continued power, adting uniformly for fome 
certain time; whereas the former is always fudden, and 
©nly of momentary or immenfurably fhort duration. The 
expanfions of folid fubflances do not terminate in violent 
explofions, on account of their flownefs, and the fmall 
fpace through which the expanding lubdance moves; 
though their drength may be equally great with that of 
the moll adtive aerial fluids. Thus vve find that though 
wedges of wood, when wetted, will cleave folid blocks of 
Hone, they never throw them to any diffance, as is the 
cafe with gun-powder. On the other hand, it is feldom 
that the expanfion of any elaftic fluid burfts a folid fub- 
ftance without throwing the fragments of it to a confiae- 
rable diffance, with effedts that are often very terrible. 
The mod part of explofive lubflances are either aerial, 
or convertible into fuch, and raifed into an eladic fluid. 
Thus gun-powder, whole effence feems to confift in com¬ 
mon air fixed in the nitre, or at lead an air of fimilarelaf- 
ticity, where it is condenfed into a bulk many hundred 
times lefs than the natural date of the atmofphere; which 
air being fuddenly difengaged by the firing of the gun¬ 
powder, and the decompofition of its parts, it rapidly 
expands itfelf again with a force proportioned to the de¬ 
gree of its condenfation when fixed in the gun-powder, 
and fo explodes, and produces all thofe terrible effects 
that attend tl-.e explofion. The elaftic fluid generated by 
the fired gun-powder expands itfelf with a velocity of 
about ten thouland feet per fecond, and with a force more 
than one thoufand times greater than the preffure of tiie 
atmofphere on the fame bafe. 
The eledtric explofions feem to be dill more firong and 
aftonifiling; as in the cafes of lightning, earthquakes, and 
EXP 
volcanoes; and even in the artificial eledlricity produced 
by the ordinary machines. The adonifhing drength of 
eledtric explofions, which is beyond all poflible means of 
meafuring it, manifeds itfelf by the many tremendous ef¬ 
fedts we hear of fire-balls and lightning. In cafes where 
the eledtric matter adls like common fire, the force of the 
explofions, though very great, is capable of meafurement, 
by comparing the didances to which bodies are thrown, 
with their weight. This is moft evident in volcanoes, 
where the projedtions of the burning rocks and lava ma- 
nifed the greatnefs of the power, at the fame time that 
they afford a method of meafuring it: and thefe explo¬ 
fions are owing to the extrication of aerial vapours, and 
their rarefadlion by intenfe heat. 
Next in drength to the aerial vapours, are thofe of 
aqueous and other liquids. Very remarkable effedfs of 
thefe are obferved in fleam-engines ; and there is one cafe 
from which it has been inferred that aqueous deam is 
even vadly flronger than fired gun-powder. This is when 
water is thrown upon melted copper: for here the explo¬ 
fion is fo firong as almoft to exceed imagination; and the 
mod terrible accidents have happened, even from fodight 
a caufe as one of the workmen fpitting in the furnace where 
copper was melting ; arifing probably from a fudden de¬ 
compofition of the water. Explofions happen alfo from 
the application of water to other melted metals, though 
in a lower degree, when the fluid is applied in fmall quan¬ 
tities, and even to common fire itfelf, as every perfon’s 
own experience mud have informed him ; and this feems 
to be occafioned by the fudden rarefadlion of the water 
into deam. Examples of this kind often occur when 
workmen are fadening cramps of iron into Hones; where, 
if there happen to be little water in the hole into which 
the lead is poured, this will fly out in fuch a manner as 
fometimes to burn them feverely. Terrible accidents of 
this kind have fometimes happened in founderies, when 
large quantities of melted metal have been poured into 
wet or damp moulds. In thefe cafes, the fudden expan¬ 
fion of the aqueous deam has thrown out the metal with 
great violence; and if any decompofition has taken place 
at the fame time, fo as to convert the aqueous vapour 
into an aerial one, the explofion mud be dill greater. To 
this lad kind of explofion mud be referred that which 
takes place on pouring cold water into boiling or burning’ 
oil or tallow, or in pouring the latter upon the former; 
the water however being always ufed in a fmall quantity. 
Another remarkable kind of explofion is that produced 
by inflammable and dephlogidicated air, when mixed to¬ 
gether, and fet on fire ; a kind of explofion that often 
happens in coal-mines, &c. This differs from any of the 
cafes before-mentioned; for here is an abfolute condenfa¬ 
tion rather than an expanfion throughout the whole of the 
operation ; and could the airs be made to take fire through¬ 
out their whole fubdance abfolutely at the fame indanf, 
there would be no «xplolion, but only a fudden produc¬ 
tion of heat. 
The effedts of explofions, when violent, are felt at a 
confiderable didance, by reafon of the concudions they 
give to the atmofphere. Sir William Hamilton relates, 
that at the explofions of Vefuvius, in 1767, the doors and 
windows of the houfes at Naples flew open if unbolted, 
and one door was burd open that had been locked, though 
at the didance of lix miles : and the explofion of a pow¬ 
der-magazine, ora powder-mill, it is well known, fpreads 
dedrudlion for many miles round ; and even kills people 
by the mere concullion of the air. A curious eifedt of 
them too is, that they eledtrify the air, and even glafs 
windows, at a confiderable didance. This is always ob¬ 
fervable in firing the guns at the Tower of London: and 
fome years ago, after an explofion of fome powder-mills 
near that city, many people were alarmed by a rattling 
and breaking of their china-ware. In this refpedt, how¬ 
ever, the effedts of eledtrical explofions are. the mod re¬ 
markable, though not in the uncommon way juft men- 
« tionedj 
