The weight of gold, as of all substances, it is convenient to estimate relatively, and in comparison with the weight of an equal volume of water. The relative weight, or _specific gravity_, as it is called, of gold, is remarkably high, the lightest varieties being twelve times heavier than water, and pure gold nineteen times. This is expressed by saying that the specific gravity of native gold is 12-19, and the number determined by comparing the weight of the mineral in water and air.

As the value of gold depends almost entirely on its specific gravity, and this test, therefore, is of the greatest practical importance, it will not be out of place if we here explain some very simple apparatus for the determination of this point.

If the specimen then is large enough to be suspended conveniently by a thread, weigh it first in air by a fine balance, expressing the result in grains, and taking care previously to remove dust or loosely adhering particles. Then suspend it by a horsehair from the scale-pan (it is convenient to have a hook attached to it for this purpose,) and thus suspended, immerse it and re-weigh it in water, taking care that it is covered on all sides by at least half an inch of water, and carefully brushing off with a feather any bubbles of air that adhere to the surface. The results may then be noted as follows:--

Weight of substance in the air in grains Deduct weight of ditto in water -------- Difference

This result gives the weight of a bulk of water equal to that of the specimen, and by dividing the weight of the specimen in air by this number, the specific gravity is obtained.

weight of substance in air Specific gravity --------------------------------- weight of equal bulk of water

If, however, the substance is in the form of fine sand, or very small lumps, it is better, after weighing it carefully, to take a small dry phial furnished with a stopper; counterpoise this phial accurately in the weight-scale by shot or strips of lead, then fill it completely with pure water, taking care that no bubbles of air are left in, and weigh the quant.i.ty of water it contains: afterwards empty the bottle and dry it inside.

Next fill the bottle about two-thirds full of the powder to be examined, weigh this and record the weight. Then fill the bottle once more with water, taking care, as before, that all bubbles are expelled and none of the powder washed out. Once more weigh it.

We have then to make the following calculation:

Weight of powder and water in grains = Deduct weight of powder alone = ------- Difference (weight of water left in bottle) =

Weight of bottle full of water in grains = Weight of water left in bottle = ------- Difference (weight of water displaced } = by, and equal in bulk to, powder) } -------

weight of powder in air The specific gravity = -------------------------- weight of water displaced.

It may be useful to know the specific gravity of various substances at all resembling gold in weight or appearance, and we therefore append the following short table. The specific gravity of water is a.s.sumed to be unity:--

Osmium 21-1/5 Platinum 19-1/2 - 22 not hammered.

Iridium 18-7/10 Gold 15-3/4 - 19-1/4 ditto Mercury 13-1/2 Palladium 11-7/10 Lead 11-1/4 Rhodium 10-3/5 Silver 10 Copper 7-3/4 - 8 Bra.s.s 8-1/2 Lead ore (galena) 7-1/2 Copper pyrites 5 Iron pyrites 4 Diamond 3-1/2 Sand 2-3/5 - 3

By the help of this table the value[18] of auriferous sand may also be in some degree estimated, since, as will be seen, the specific gravity of most of the sands is under 3, while that of the most impure gold is 12; so that if the specific gravity of the sands themselves, when experimented on, is much greater than that of ordinary sand, it is likely that the excess will be for the most part gold, in a district otherwise known to be auriferous: the greater the specific gravity, too, the greater probability there is, of this being the cause. It may also be worth while to mention here, that the specific gravity of those pepitas or lumps of gold which present a fine yellow color varies generally from 14-7/10 to 18-8/10; but when much paler they may range as low as 12-1/2, which is that of a mineral called _electrum_, which will be described presently, and which is a mixture of silver and gold.

When a piece of gold is broken (which is not done without difficulty--greater in proportion to its purity,) the fractured edges are very uneven and torn, exhibiting a peculiar fibrous appearance, known to mineralogists as "fine hackly." This fracture indicates that the mineral is _torn asunder_ and not really broken, and is a proof of considerable toughness.

The form in which gold is found is various. It is sometimes crystalline, in eight or twelve-sided regular figures, pa.s.sing into cubes, but the crystals are generally small and rare. In case of such crystals being found, it is well worth knowing that they possess a value as mineral specimens far beyond that of the gold which they contain.

More frequently the metal is found in lumps or grains, called by the Spaniards _pepitas_, varying in size from that of a pin's head to ma.s.ses weighing, as has been already mentioned, nearly one hundred pounds troy. The term _pepita_ is only applied to grains of some magnitude, and the most common limits of size are from that of a small pin's head to that of a nut or gooseberry.

When much smaller and still rounded, they are called _gold dust_, and when flattened, _scales_ or _spangles_. In nature, and when seen in veins of quartz, gold often occurs _foliated_, or in leafy expansions of extreme thinness, or in branchy (_dendritic_) forms, probably made up of minute crystals. It is in the form of very minute grains that the metal is generally disseminated through rocks and auriferous ores of various metals, and these are reduced according to circ.u.mstances in methods that will be alluded to in a future chapter. In pepitas and small grains it is carried down by streams and deposited in their beds, the pepitas being usually most abundant where there is reason to suppose considerable disintegration of the surface, and where the action of denuding causes to a great extent is evident. The coast of Africa and the rivers of Europe are examples of the former case, while the Siberian deposits and those of California would appear to belong to the latter.

The following are examples of the const.i.tuent parts of various specimens of gold obtained from different gold districts, and will form a useful guide for comparison.

_Table showing the Composition of Native Gold.[19]_

------------------------------------------+-------+-------+-------+------ Locality. | Gold. |Silver.|Copper.| Iron.

------------------------------------------+-------+-------+-------+------ Auriferous sand of Schabrowski, near | | | | Katherinenburg, Siberia (G. Rose) | 9876 | 016 | 035 | 006 Boruschka, near Nijny-Tagilsk, Siberia | | | | (Rose) | 9441 | 523 | 039 | 004 Brazil (Darcet) | 9400 | 685 | | Beresovsk, Siberia (Rose) | 9378 | 594 | 008 | Sand near Miask, Siberia (Rose) | 9247 | 727 | 006 | 008 Bogota (Boussingault) | 9200 | 800 | | Washings near Miask, Siberia (Rose) | 8935 | 1065 | | Gold of Senegal (Darcet) | 8697 | 1053 | | Auriferous sand, Nijny-Tagilsk, Siberia | | | | (Rose) | 8385 | 1615 | | Trinidad gold, (Boussingault) | 8240 | 1760 | | Transylvanian gold (Ditto) | 6452 | 3548 | | Mine of Sinarowski in the Altai (Rose) | 6008 | 3838 | 033 | ------------------------------------------+-------+-------+-------+------

The gold from California, according to the a.s.say of Mr. Warwick of New York, yields 8958 per cent, pure gold, and is therefore, about equal to that obtained from the washings of Miask (the richest district in Western Siberia, and that producing the largest pepitas,) and superior, as the a.s.sayer remarks, to the gold dust from Senegal.

There is a remarkable mixture of native gold with silver occasionally found in Siberia, and known under the name of _electrum_. Its color is pale bra.s.s-yellow, pa.s.sing into silver-white. It occurs in small plates and imperfect cubes, and possesses many of the characters of gold, but it consists only of 64 per cent. of that metal, and 36 per cent. silver. It is at once known by its low specific gravity, which does not exceed 12.

Other mixtures of gold are (1) a _rhodium-gold_ found in Mexico, and containing 34 to 43 per cent. of rhodium, having a specific gravity of 15-168, and a clear, dirty yellow color; and (2) a _palladium-gold_ (containing 985 per cent. palladium, and 417 per cent. silver) found in Brazil and elsewhere in South America, in small crystalline grains of pale yellow color. The auriferous ores of tellurium, including silver, have hitherto only been found in Transylvania. Their color is steel-gray, and they tarnish on exposure. The variety called graphic-gold, or graphic tellurium, consists of about 60 per cent. of tellurium, 30 per cent. gold, and 10 per cent. silver, and is worked chiefly as an ore of gold. Another variety, "yellow gold glance,"

yields somewhat less tellurium, gold and silver, and as much as 20 per cent. of lead.

Having now explained at some length the more manifest characteristics of gold, namely, its color, hardness, and specific gravity, it is necessary, before explaining the mode of separating it from a.s.sociated minerals, that we should here give some account of the behavior of this metal under the blowpipe, and when exposed to simple chemical tests. The a.s.say of gold and its accurate a.n.a.lysis, we postpone for the present.

The method of blowpipe a.n.a.lysis, although exceedingly useful, is not absolutely necessary in the case of gold, because of the many readier ways of determining the metal, but it seems advisable to state the appearances presented. All the varieties are readily fusible into a globule, which when the gold is pure, is unaltered by the continuance of the heat. In this respect it differs entirely from iron and copper pyrites, which, on being exposed to the flame, give off sulphur fumes and undergo considerable change. In the case of gold containing other metals, these, with the exception of silver; may generally be got rid of by continuing the heat in the exterior flame with the addition of a little nitre. Before the oxy-hydrogen blowpipe, the metal is volatilized in the form of a purple oxide.

Gold is not acted on by any of the acids alone. When exposed to the mixture of nitric with hydrochloric acid (in the proportion of one part nitric to four of hydrochloric) called _aqua regia_, it dissolves without residue, the solution giving a purple precipitate with protochloride of tin, and a brown precipitate with protosulphate of iron. Electrum, the mixture of silver with gold above alluded to, is only partially soluble in aqua regia, giving a residue of chloride of silver. The solution is acted on by protosulphate of iron, as already explained.

The following simple mode of detecting attempts at imposition in gold dust is worthy of being recorded in this place.

Place a little gold dust in a gla.s.s tube or earthenware saucer, and pour nitric acid upon it; then hold the gla.s.s or saucer over a flame, or upon a few embers, until red flames (nitric vapors) arise; if it be pure gold, the liquid will not become discolored; but if pyrites or bra.s.s-filings should have been mixed with it, the acid will become turbid, green, and black, discharging bubbles of gas. After the ebullition has ceased, the residue should be washed with water, and acid again poured upon it, when the same effect may be observed, but in a less degree; and if the experiment be repeated till all effervescence ceases, it will finally leave the gold dust pure.

FOOTNOTES:

[17] Mohs' Mineralogy, by Haidinger, vol. ii. p. 438.

[18] A _very rough_ estimate of the value of specimens of native gold may be obtained by multiplying the specific gravity by 4; the result gives the value in shillings nearly.

[19] Abridged from Dufresnoy's "Mineralogie."

CHAPTER XIV.

ADDITIONAL RECENT EVENTS.

The history of the laws of a State affords the best idea of its social condition--present and prospective; for they are framed from the necessity of circ.u.mstances and the demands of the inhabitants. We may, therefore, see the condition and the progress of the Californians in their legislative transactions.

The California Legislature adjourned on the 22d April. They have pa.s.sed a law creating a State a.s.sayer, until a mint be established in California. Among the one hundred and forty-three acts and joint resolutions pa.s.sed, we notice the following:

To incorporate the cities of Benecia, San Diego, San Jose, Los Angeles, San Francisco, Sonoma, and Santa Barbara, and a general act for the incorporation of cities; concerning the State revenue, etc., and its management; creating loans temporarily, appropriations, and other fiscal acts; relating to the appointment of pilots, regulating the duties of harbor masters, declaring certain rivers, etc., navigable, creating health officers for San Francisco, creating a marine hospital, regulating quarantine at San Francisco, providing for the inspection of steamboats; subdividing the State into counties, establishing county seats and providing for the complete organization of all the counties; organizing the supreme court, providing for the early publication of the laws, organizing district courts throughout the State, establishing a munic.i.p.al court in San Francisco, abolishing all laws in force in the State, except such as were pa.s.sed by this Legislature, adopting the common law, regulating the interest of money, public ferries, notaries public, jails and jailers, limited partnerships, roads and highways, public elections, volunteer companies, wills, militia, liens of mechanics and others, descents and distributions, bills of exchange and promissory notes, constables, coroners, guardians, fraudulent conveyances and contracts, the rights of husband and wife, incorporation of colleges, marriages, auctioneers, government and protection of the Indians, settlement of the estates of deceased persons, proceedings against debtor by attachment; creating the office of State a.s.sayer, melter and refiner of gold, to regulate Senatorial and a.s.sembly districts, prescribing the mode of maintaining and defending possessory actions on lands belonging to the United States; to prevent the importation of convicts; for the better regulation of the mines and the government of foreign miners, the national Washington monument, pay of chaplain, the Pacific railway, and concerning grants of land by the General Government to commissioned officers who served in the late war with Mexico.

Here we have all the machinery necessary for the full regulation of a large, commercial, agricultural, manufacturing, and mining community.

The session of the Legislature must have been laborious, indeed; but the members have acquitted themselves of their arduous duties rapidly and well. One great measure adapted by the Legislature was the subst.i.tution of the common law for the uncertain civil law which existed in California when ceded to the United States. The whole legal administration will now conform to that of most of the other States of the Union. The provisions in the Const.i.tution for the purpose of education, have been n.o.bly carried out by an act for the incorporation of colleges.

Agriculture in California appears to be improving, and as it is getting to be as profitable as any thing else, it is attracting increased attention. Boxes of garden seeds which had cost nine dollars, have been sold for one hundred dollars, and scythes which cost three dollars, sold for forty-five dollars. The seeds which were sent around Cape Horn, were almost useless, while those which went over the Isthmus, hermetically sealed, came up first. One man near San Jose, has made fifty thousand dollars by raising potatoes. What toil in digging and washing gold would be necessary to realize that amount!

Among the recent mining incidents, the following is remarkable:--Last winter, three men accidentally struck upon a rich deposit of gold, in a gulch about twelve miles from Knight's Ferry, on the Stanislaus River, and four or five miles back from it. They worked this vein with great success, managing to keep it a secret, until an Indian, wandering through the locality, discovered the secret, and communicated it to his tribe. The next day, several hundred Indians fell to work, with the same success; but as they spent their earnings in gambling and drinking at night, they incautiously let out the secret, and it spread among the whites. The latter, without scruple, took possession of the ground, and set the Indians adrift. An alcalde was elected, the ground staked off, and allotted to the several claimants. This gulch, although rifled of its richest treasures, afforded good digging for a large number of persons, for some weeks, many carrying away, when the water failed, a thousand dollars and upwards, as the result of their labors. The three discoverers of the gulch, took away with them about forty pounds of gold to each man, all sc.r.a.ped up in the short s.p.a.ce of seven weeks.

Imitation lumps of gold have been made and brought into circulation in California. The State a.s.sayer states that above forty specimens have been brought to his notice. They are generally in size from four to five ounces to a pound in weight--quartz, and every thing else necessary to make them look right, properly intermixed.

It has been definitely settled that gold does exist in the vicinity of San Jose. Specimens have been taken to San Francisco.

Several artesian wells have been constructed at San Francisco, since the second great fire, and it is thought that others will soon add to the comfort and convenience of the people of that city. The want of good water for drinking purposes, has been the most serious objection to San Francisco as a place of residence; and additional incentive to exertion in the matter is furnished by the constant apprehension of destructive fires.[20]

Coal has been discovered in California, in various places, and is reported to abound in considerable quant.i.ties in the neighborhood of San Francisco. Every day developes some new wealth of this land of treasure, and we regard the discovery of the abundance of coal as in the highest degree important to the residents of California. Even amid the news of the extraordinary yield of the gold region during the present year, 1850, when a single vessel, in one trip, brings $2,000,000 worth of gold dust to the United States we can pause to notice the discovery of the more useful substances.