1804.] 
lofs which the gold. coin-of this kingdom 
is faid to have fwltained within a certain 
limited time, cannot be attributed to any 
important defect in the compofition or 
quality of the ftandard gold. . This is 
Rrongly corroborated by the obfervations 
of bankers and others, who are in the ha- 
bit of fending or receiving large quanti- 
ties of gold coin from confiderable dif- 
tances. When anumber of guineas, ra- 
ther loofely packed, have been long fhaken 
together by the motion of a carriage, the 
effe&ts of friion are obferved chiefly to 
fall only on a few pieces. And although 
thefe are often reduced nearly or quite to 
the ftate of plain pieces of metal, or 
blanks, yet, upon being weighed, they 
are found to have fuftained little or no 
lofs : from this it appears thar the im- 
preffions have been obliterated, not by an 
actual abrafion of the metal, but by the 
depreflion of the prominent parts, which 
have been forced inio the mafs, and be- 
come reduced toa level with the ground 
of the coin, 
Upon the whole our gold coin fuffers 
but little from every {pécies of friction to 
which it may be fubjected, fairly and un- 
avoidably, during circulation; which can- 
not produce any other wear than that 
which is extremely gradual and flow, and 
fuch as will by no means account for the 
great and rapid diminution which has been 
ohferved in the gold coin of this country. 
As general refults of each part of this 
inquiry, it may be obferved, that the ex- 
periments on the various alloys of ftandard 
gold concur with eftablifhed practice and 
opinion to prove, that only two of the 
metais, viz. filver and copper, are proper 
to be employed in the reduction of fine 
gold to ftandard, for the purpole of coin: 
that numerous.caules influence the {pecific 
gravity of metals ; in fome cafes metals 
added to others produce a contraction in 
the bulk of the mafs, or an increafe of {pe- 
#ific gravity, but in others the effects pro- 
duced are exactly the reverfe: that gold of 
moderate duétility is the beft adapted to 
the purpofe of coin, and that the real wear 
of fuch coin is very flowly effected ; fo 
that a long period of time muft elapfe be- 
fore any confiderable diminution in weight 
can be perceived. 
After all, fays Mr. H. “ Our aétual 
knowledge of the properties of metallic 
mixtures | is certainly very imperfect, and 
has by no means kept pace with the rapid 
progrefs of modern chemitiry. Dew addi- 
tions have been made to the compound 
metals employed by the ancients. ‘The 
Various mixtures of gold and filyer, called 
- 
ca 
Proceedings of Learned Societies. 
ele@rum* ; thofe of the Corinthian + me- 
tal; the varieties of bronzet; the com. 
pound of copper and zinc now called 
brafs$; the metal for {peculal]; the metal 
called argentarium**, in fome mealure 
anfivering to our pewter ; the art of plat- 
ing and of tinning} + 5) and the proce(s of 
amalgamationf{{ ; evince how great a 
progrefs had been made by the ancients 
in the mixing and working of metals.” 
** Much, however, remains to be done, 
and much may be expected from a regular 
and fyftematical feries of experiments on 
the properties of compound metals. . For 
exclulively of the immediate application 
of many of the alloys to economical pur- 
pofes, it cannot be doubted that {cience 
will derive confiderable advantages ;-our 
ideas concerning the properties of metals 
whether fimple or mixed, will be much 
enlarged, and clouds of errors, with the 
traditionary prejudices which as yet 
thade this branch of human knowledge, 
will be difperted.”’ 
SURGERY. 
In Mr. Everard Home’s Obfervatione | 
on the Structure of the Tongue, is offered a 
fafe and effectual means of removing a 
portion of the tongue when that organ is 
fo much difeafed as not to be within the 
reach of medicine, A gentleman, by ac- 
cident, had his tongue bitten with great 
violence, which occafioned great local 
painy and the point of it Joft its fenfi- 
bility, and was deprived of the power 
of tafte. It was like a piece of board in his 
mouth, which rendered the act of eating 
a very unpleafant operation. From this 
cafe Mr. Home concludes that the tongue 
itfelf is not particularly isvitable; but 
the nerves pafling through the fubftance 
to fupply the tip, which forms the organs 
of tafte, are very readily deprived of their 
natural action, which probably arifes from 
their being fofter in texture. than nerves 
in general, and, in that re{peét, relembling 
thofe belonging to the other organs of 
fenfe. 
Another curieus circumftance is, that a 
bruife upon the nerves of the tongue, fuf- 
ficient to deprive them of the power of 
communicating: fenfation, was produftive 
pT aay SORA, Sad rN ES Seal SOP EP Se SUE nti 
* Plinius, 1. xxxill.-cap. 4. *y 
T > 1. xxiv. cap. 2. , 
~ ———, |, xxxiii, cap. 4 and 9. 
XXXIV. cap. Io. 
xxxlii. cap. g. 1. xxxive Caps 
et 
|| -————-, }. 
yies 
¥ , Ibid. 
+t- , Lbid. 
Pp} Vitruvius, 1. vii. cap. 3, 
of 
