IMPORTANT CONSEQUENCES DEDUCED FROM ANALYSES OF GOLD. 3 
Before the blowpipe, pure gold and pure 
silver are readily distinguished by their fus- 
ing into a transparent and colourless glass, 
with salt of phosphorous in the exterior 
flame. In the interior flame, if the quantity 
of silver is small, the glass is opaline and yel- 
lowish, but if great, altogether yellow and 
opaque. The native allo 5 's ant in the same 
manner, but an alloy which contains only ^ 
per ceut. of silver has no action on salt phos- 
phorous. 
When the quantity of silver is small, which 
can be easily detected by the golden colour 
of the alloy, the metals may be dissolved in a 
covered capsule, in aqua regia. The greatest 
portion is converted into chloride of silver. 
Decant the solution and remove the chloride 
by the aid of a glass rod, and add a new dose 
of acid. If the alloy contains more than 20 
per cent of silver, the chloride sticks to the 
glass, and gives rise to inaccuracy. The two 
acid solutions should then be diluted. The 
first is only slightly muddy ; for, it appears 
that a saturated solution of gold does not dis- 
solve a notable quantity of chloride of silver ; 
the second, on the contrary, deposits a con- 
siderable quantity of this substance. When 
the whole chloride has been deposited it 
should be filtered and weighed, after being 
dried and fused in a porcelain crucible. Eva- 
porate the liquid in a porcelain crucible, to 
drive otf the excess of chlorine, and when 
fumes cease to be given off, treat it with 
oxalic acid. Place the liquid in a glass de- 
fended by convex cover, in order that no gold 
may be mechanically removed with the car- 
bonic acid, and allow the glass to remain for 
24 hours in a warm place. Filter the liquid, 
evaporate to dryness, and pass a stream of 
sulphuretted hydrogen through the solution of 
the residue in muriatic acid. A trace of cop- 
per is thus separated, and the iron may be 
removed by hydro-sulphuret of ammonia. 
When the gold contains more than 20 per 
cent, of silver, the correct plan is to assay the 
alloy in a cupel with lead and silver, and to 
treat the new alloy with nitric acid, which 
takes up the silver only. Gay Lussac shewed 
that a loss of silver i.s sustained to a small ex- 
tent in this way, and G. Rose, to obviate the 
inadequacy of this plan, tried a number of 
others, and at last hit upon one which he con- 
siders better than any other yet devised. 
Fuse the native gold in a small porcelain cru- 
cible with lead, by means of a lamp supplied 
With a double current of air. Digest the 
mass in nitric acid ; detach it from the cru- 
cible, and place it in a glass vessel, adding 
a new portion of nitric acid diluted with 
water, in order to dissolve the nitrate of lead ; 
wash the residue ; dissolve it in aqua regia ; 
precipitate the chloride of silver dissolved, 
diluting the liquid with water ; filter the li- 
quor and evaporte to dryness. Dis.solve in 
water, and precipitate the gold by means of 
muriate of iron. Sulphated protoxide of iron 
does not answer for the precipitation, because 
the gold in solution may still contain a little 
lead. Dilute the nitric acid solution with 
much water ; then treat it with chloride of 
lead, and not with muriatic acid, which may 
drecipitate part of the lead in the state of 
B 3 
chloride. Place the liquid in a warm place, to 
favour the precipitation of the chloride of 
silver, and when the solution has become clear 
collect the chloride upon the filter which was 
used to filter the solution of gold. The mi- 
nute portion of iron cannot be appreciated, on 
account of the quantity of lead. 
Rose has never found platinum and gold 
associated. He deduces from his analyses 
several imoortant consequences. 
1. ■ Native gold does not contain gold and 
silver in definite proportions. 
2. Gold and silver being thus combined 
in indefinite proportions, he concludes that 
they are isomorphous, an inference which can- 
not be deduced with the same certainty from 
the identity of their crystals. 
3. Native gold always contains silver, cop- 
per, or iron. The smallest quantity of silver 
was in a specimen from Schabrouski, which 
contained 16 per cent, of silver, but 35 per 
cent, of copper were present. 
4. The specific gravity is in the inverse 
ratio of the proportion of silver contained in 
the minex"al. 
In general, fused gold has a greater density 
than native gold, which, however, may be 
owing to cavities in the latter. 
5. Different specimens from the same loca- 
lity vary in composition. 
6. Gold found in veins varries in different 
parts of the same mine. 
7. He finds that the gold from sand con- 
tains more silver than that from veins. The 
proportion in the former being 89-7 per cent, 
of silver, and in the latter, 79-1 a fact com- 
pletely contrary to the determination of the 
Russian government, for the mining of gold 
has entirely yielded to the process of pro- 
curing it from sand. (Poggendorff Ann.) 
STATE OF THE GLOBE AT ITS FOR- 
MATiON. 
BY M. BECQUEREL. 
(Continued from j.age \53.) 
TERRESTRIAL HEAT.— The facts with 
which we are at present acquainted tend to 
prove that every place on tlie surface of the 
globe has an invariable mean temperature. 
The mean temperature of the equator is be- 
tween 81.5 and 82°4, being modified by the 
great extent of the equatorial seas. The 
entrepid northern navigators have found a 
great difference, in the same latitude, between 
the temperatures on land and in the open sea. 
A Melville Id. the mean heat was — 18*^50., 
while in the open sea it was — 8° 3. Calcu- 
lating from these data, the temperature of the 
pole would be— 25^ or 30'^. 
It is remakable that those places which are 
situated on the same isothermal line do not 
present the same vegetable productions. 
Hence, some have divided climate into con- 
stant, where the temperature is steady dur- 
ing the year, variable, and excessive, which 
comprehend those where the differences are 
very great. Cassini, in 1671, had remarked 
that under the Observatory of Paris, the tem- 
perature was steady during the whole year 
