filver and platina prefent advantages which 
no other metals feem to poffefs. Theory 
would give the preference to platina, from 
its refiftance both to heat and to acids ; 
and practice will juttify this preference, in 
all but a fingle inftance, viz. where a 
quantity of potafh is kept for fome time 
in fufion, inwhich cafe the crucible will be 
found to have loft part of its weight by 
pure chemical decompofition ; for if the 
potafh be faturated with muriatic acid 
and evaporated, a triple falt, tormed by 
a combination of muriatic acid, potath, 
and oxide of platina, will bet! Aone 
Alkalies have no immediate action upon 
filver, but crucibles made of this metal 
are, after long ufe, more brittle aa 
they were before. 
Mr. Chenevix will not admit the pro- 
priety of the term fixed as applied to pot- 
afh and foda: the former by a ftrong heat 
may be totally volatilized ; foda, though 
Jefs volatile, is far from fixed, and the 
volatility of both is” increafed by the ad- 
dition of a little water. This property 
of potafh has been advantageoufly applied 
of late to the art of bleaching. 
In Mr. Smithfon Tenant’s account ‘*Of 
the Compofition of Emery,” a fubftance 
which has long been ufed in our manu- 
. 
New Patents lately enrolled. 
[ Sept. I, 
fagtures, for grinding and polifhing other 
bodies, and which is chiefly brought from 
the iflands of the Archipelago, it appears 
upon analyfis to confit of argillaceous 
earth, filex and iron. In books of mine- 
ralogy, it is confidered as an ore of iron, 
but trom_the refult of fome experiments 
made by Mr. Klaproth, it feems probable 
that emery and diamond fpar are in reality 
the fame fubitance, though the former ts 
ufuaily mixed with a larger proportion of 
irony than the latter. 
ANaTOMY. 
‘The only paper on this fubjet is Mr. 
Everard Home's deicription of the ana- 
tomy of the Orxithorbyachus Hyfirix. 
The characters which diltinguifh this 
animal from all other quadrupeds, give 
the tribe a refemblance in fome refpects to 
birds, in others to amphibia ; fo that it 
may be confidered as an intermediate link 
between the clafies Mammalia, Aves, 
and Amphibia, although the great diffe- 
rence that exits between it and the Myr- 
mecophaga, the nearefi genus we are at 
prefentacquainted with, fhews that the nicer 
gradations towards the more perfe& qua- 
drupeds are not at prefent known. Be- 
tween it and the bird, -no link of impor 
tance feems to be wanting. 
NEW PATENTS LATELY ENROLLED. 
EDWARD WARNER’S, (LITTLE NEW- 
STREET, SHOE-LANE,) jor an 1M- 
PROVEMENT upon the AIR-LAMP, de 
Properties whereof confift in refleding 
a@ more general and ftronger Light, by 
means of certain Valves and a newlly- 
confirucied Burner. 
R. Warner’s lamp appears to bea 
very confiderable improvement upon 
that invented by Argand. In the latter, 
to obtain a clear and ftreng light, it is ne- 
ceffary that the oil ufed fhould be of the 
pureft kind, the expence of which is con- 
fiderable. This is owing to the oil being 
an inch and a half or more below the level . 
of the light ; confequently none but very 
pure oil can be made to afcend that height 
inthe cotton. Mr. Warner has fo con- 
ftructed his lamp, that the burner may be 
raifed to any height, and the oi] is always 
on a level with the light. The glafs- 
chimney to this lamp is in the lower part 
globular, which has the property of throw- 
ing the light perpendicularly downwards, 
as well as throvgh the fides; by this part 
of the invention the-light is equally diftri- 
buted in every direction; of courle the 
glafs-holder, which muft differ from that 
in common-lamps, is made with a {pring 
that holds it firmly at the bottom. By 
means of new-invented valves, the air- 
lamp is eafily cleaned by any fervant, and 
the refervoir is prevented clogzing up in 
the neck. 
The Patentee warrants hislamps to burn 
oil at nearly half the price of that made 
with fpermaceti ; the principles of the 
invention being to fupply the cotton with 
a flow of oil level with the light—to pre- 
vent common-oj} from crufing the cotton, 
and burning dim fo foon as other lamps— 
to raife the light two inches higher in the 
patent giafs-chimney, made of a globular 
thape, the light burning im the centre of 
the globe, in order to magnify it, and, at 
the {ame time, tolet fuch a body of air pals 
through the chimney, as to-render it lefs 
liable to break than other glaffes, “and 
throw down the light in a diablo near 
ly perpendicular. 
MB 
