Assaying Gold and Silver

In "NOTES ON ASSAYING AND ASSAY SCHEMES" BY PIERRE DE PEYSTER RICKETTS Published in 1876 there is a list of tools an assayer would need to haul out into the mining areas to set up shop.

That alone is task enough to stop most people. Try to imagine yourself in that milieu.

Trying to get the knowledge to do the job, building a shack to work out of, gathering the needed equipment out in the middle of nowhere, Then facing those desperate (desperate people do desperate things!) rough miners and the thieves preying on them - Gives one the collywobbles!



Here is the list:

quod.lib.umich.edu/cgi/t/text/text-idx?c=moa&cc=moa&view=text&rgn=main&idno=AEK6695.0001.001



CRUCIBLES. A good crucible should stand sudden changes of temperature, be infusible, impermeable, and not attacked by fused substances. The crucibles in use may be arranged in the following order.
1. Black lead, or graphite for melting.
2. French clay. round and triangular. (Fig. 7.)
3. Hessian sand crucibles (Fig. 8.)
4. Charcoal-lined crucibles.
The most refractory crucibles are cut out of quick lime, or can be moulded from magnesia, and chloride of magnesium, but the latter, however, are soft and not very strong.
The composition of the black lead crucibles is generally one part of refractory clay, to three of graphite; but sand is sometimes used. If the crucibles contain too much silicious matter they are liable to be acted upon by the melted charge, or the bases contained in the coal around them when in the fire. These crucibles run in sizes from 1 to 400. The smallest holding from two to three pounds of metal. The next, four to six, and so on. The demand is for two kinds, "steel" and "brass;" but they can be employed for melting all substances which are not oxydizing in their action.
French crucibles are made of Paris clay and fine sand, and rank among the best, but are more expensive than the Hessian. For melting charges which can be poured they are superior as the crucible can be used again. The sizes run from 1 to 20, with covers to match.
The composition of the ordinary Hessian crucible is about three-quarters clay (German), and one-quarter sand. They are round and triangular, and run in regular sizes, viz: Small fives, large do., up to eights. Halves, holding onehalf gallon, and ones, holding one gallon, with covers to match.

The charcoal crucible is made by lining an ordinary clay or Hessian crucible with a mixture of charcoal and molasses. The charcoal employed should be very fine, and only just enough molasses used to hold it together. The mixture is then packed into the crucible as tightly as possible, dried slowly, and bored out to any extent desirable. Sometimes water and gum are substituted for molasses. Fig. 9 represents three kinds of charcoal lined crucibles. Alumina crucibles for some operations are very satisfactory FIG. 9. when intense heat is required, but lime will answer as well. The choice of a crucible depends upon the nature of the substance to be treated in it, the temperature of the fire, and the time it is to remain exposed to the action of heat. If a charge be basic the crucible should be basic also, and vice versa. To test a crucible for fusibility, heat a piece of the crucible and see if the corners are rounded, or it is fused on the edges. For corosive action fuse litharge in the crucible. For permeability fill two crucibles with water and note the time required for it to run out; the one which holds the best being preferable. The action of sudden changes of temperature may be ascertained by heating suddenly, and cooling first in air and afterwards by plunging in cold water.

ROASTING DISHES, (Fig. 10), and SCORIFIERS, (Fig. 11.) Both dishes and scorifiers are made of refractory clay. FIG. 11. They should FIG. 10. resist the action of litharge and not be too deep. Painting with water and oxide of iron prevents the cutting by strong bases, to some extent. Scorifiers may be bought or made, but as a rule it is better to buy them as they will stand transportation and require some care to make properly. A section of a good scorifier is uniform in character. It is close, and should show no flaws or cracks. (Fig. FIG. Ila. 11a.)

CUPELS. These vessels are generally made of the ashes of burnt bones free from organic matter, ground and washed, horses or sheep bones are said to be the best. Cupels can be bought or made, but the latter is preferable when they have to be carried some distance. The prepared bone-ash can be obtained in bulk, and is mixed with just sufficient warm water to cause it to hold together without being moist. Sometimes in mixing the bone-ash a little wood ashes is added, or a spoonful of "pearl-ash," (carbonate of potash). Before adding it to the bone-ash it is dissolved in water. Too much bone-ash should not be mixed at once, as it dries quickly.

Page 28 28 LUTES. If the bone-ash is too fine or too coarse it works badly; as in the first case the cupel will crack upon drying, and in the second, be too porous, absorb silver with the litharge and occasion loss. The cupel is formed by filling and driving the prepared bone-ash into a mould for the purpose. The right degree of compression should be used, as otherwise the cupel will be either too hard or too porous. A little experience will tell the operator when he has reached the proper point, when completed it presents the FIG. 12. appearance of Fig. 12. Care should be used in drying, plenty of time being allowed, and all moisture and organic matter expelled previous to using, by heating in a furnace. Sometimes a cupel is made of coarse bone-ash, and the surface finished off with fine washed material. Cupels dried in the sun are better than those dried artificially. They are not so liable to crack. In the Royal Mint, London, England, a very fine form of cupel is in use. It is square, with four depressions for holding the same number of buttons, enabling the operator to run two assays in duplicate in the same cupel. Ironbound cupels are sometimes used when the amount to be cupelled is large, especially in treating sweeps. LUTES, CEMENTS AND WASHES. GOOD FIRE LUTES. 1. Fire clay, two parts. Sharp sand, eight parts. Horse dung, one part. Mix well and temper the same as mortar, until the desired consistency is reached.

Page 29 TOOLS. 29 2. Fire clay, one part. Sand, three parts. Mix with a little hair and borax water. 3. Zinc cement. Dissolve three per cent. of borax in water to about 1.49 specific gravity and then add calcined oxide of zinc to suit. OTHER LUTES. Plaster of paris mixed with water, milk, glue, or starch water makes a good lute, and will stand a red heat. Wax or parafine is useful for bottles, stoppers, etc., also tallow or stearic acid. A fine lute for iron vessels is porcelain clay (kaolin) mixed with a solution of borax in water. A good lute for glass vessels, is quicklime slacked in the air and then beaten into a liquid paste with whites of eggs. Where corrosive vapors are liable to escape a lute made of fire clay, and boiled linseed oil should be applied and covered with slips of linen spread with the lute of lime and egg. To LINE CRUCIBLES. Fine sifted charcoal mixed with gum water, borax water, or molasses enough to hold when pressed together in the hand, without being wet or sticky. It should contain no lumps. WASH FOR CRUCIBLES AND SCORIFIERS. 1st. Finely pulverized chalk and water. 2d. Sesquioxide of iron (hematite) and water. TOOLS. The tools required by the assayer are regulated more or less by the work to be done.



Four balances will be found useful in an assay laboratory.

a.- A rough scales for weighing large samples of ores, metals, fluxes in bulk, &c. An ordinary grocer's scale will do very well.
b. - A balance for weighing out ore for assay, and the buttons of the base metals. (Fig. 1). This balance should FIG. 1. take ten ounces in each pan, turn with one-twentieth of a grain; and be provided with movable pans, level, and set-screws for adjusting. It is generally placed on a box, with drawer for weights.
c. - Hanging scales for fluxes. The pans made of horn, and supported by threads to a brass beam. It should carry at least ten ounces, and turn with one-half grain.
d.- The button or bullion scale, (Fig. 2). This balance should be used for nothing but gold and silver beads, or bullion; and must be accurate and extremely sensitive. When loaded with one gramme, it should turn with one one-hundredth of a millegramme, and requires to be handled with the greatest care. It is provided with steel knives, agate bearings, spirit level, and set-screws. To ADJUST THIS BALANCE.-First turn the set-screws, two at a time, until the bubble is in the centre of the level, and the balance is firm. Then note the number of divisions the needle indicates on the scale when vibrated, counting from the second swing. If it shows equally on both sides of the centre line it is correct. Never leave the rest down, or raise it when the needle is not near the centre line, as the knife edges are likely to be thrown off their bearings and the balance injured. To clean, an artist's blending-brush is very convenient, as it is soft and fine.

THE WEIGHTS employed by the assayer area.
a. Avoirdupois for ores, base metals, and fluxes.
b.-Troy for gold, silver, &c.
c.-The French system based upon the gramme as a unit. These weights can be used for weighing ores, fluxes, and results; and will always be found convenient, as they are on the scale of ten.
d.-The assay weights, which is a system made up from a comparison of the three foregoing, will be found extremely simple and useful, saving a vast amount of calculation and labor (see table, page 136). The unit of the system is the assay ton=29.166 grammes. Its derivation will be seen at a glance.

One lb. avoirdupois=7,000, Troy grains. 2,000 lbs. =one ton. 2,000 X 7, 000=14, 000,000 Troy grains, in one ton avoirdupois. 480 Troy grains1= oz. Troy. 14,000,000. 480=29,166+Troy ozs. in 2,000 lbs. avoirdupois. There are 29,166 millegrammes in one assay ton (A.. T.); hence2,000 lbs. is to 1 A. T. as 1 oz. Troy is to 1 millegramme. EXAMPLE. —Weigh an A. T. of ore, and if on assay it yields one millegramme of gold or silver, the result reads one Troy oz. in 2,000 lbs. avoirdupois, without further calculation.



Should the assayer desire to make quantitative determinations in the wet way, he will require, besides the above, an analytical balance, which will carry 100 grammes in each pan, and turn with one-twentieth of a millegramme. This balance should be provided with apparatus for taking specific gravities, rider, and weighing-tubes.


The following are the principal:



Crucible tongs (Fig. 13.) They should be made with long FIG. 13. handles for taking crucibles out of the fire, etc.
Scorification tongs. (Fig. 14.) The spring should not be FIG. 14. too strong, and the horse shoe part should just fit the scorifier.
Cupel tongs. (Fig. 15.) These should be made of steel FIG. 15. and about two and one-half feet long with an easy spring.
Three hammers are useful. One large for hammering metal, one medium for breaking crucibles and scorifiers, and one small for marking lead buttons.
A set of small steel dies from 0 to 9 inclusive; and large and small alphabet for marking buttons and bullion will be found useful, but are not necessary.
Three pokers are convenient, small, large, and medium.
One or two small hoes or scrapers for cleaning out the bottom of the cupel muffle. (Fig. 16.) FIG. 16.
A pair of cutting shears and wire snippers for cutting wire for lead assay, etc.
A small vice and anvil, medium size, also a suitable bench for the same.
Wooden mallets, light and heavy, for packing crucibles, making cupels, etc.
Files for sampling and cutting, and several cold chisels.
Charcoal saw for blow-pipe charcoal, and crucible tops.
Several iron mortars and pestles.
If much ore is to be pulverized, a grinding plate and rubber, (Buckboard and Muller)as shown in Fig. 17, will be a great convenience and save labor. The plate is a flat iron casting 18 X 24 inches, and 1 inch thick. The surface used being planed smooth. The rubber or grinder is a piece of cast iron, 4 X 6 inches square, 1 inches in the middle, by 7/8 of an inch thick at the ends; thus giving a slightly convex surface, which should be true on the board at all points. To conduct the operation place the left hand upon the rubber, throwing the weight of the body upon it, and then grasping the handle with the right hand, move the iron rubber back and forth, depressing the handle when pushing forward and raising it in drawing back. The operation is much more rapid than in the ordinary mortar and pestle style, and the manipulator after a little practice has complete control over the ore treated.
Should it not be convenient to have the plate and rubber, a long handled pestle coming up to the chest will be found an improvement, as the mortar can be placed on the floor and the pestle worked while the operator is in a standing position.
A series of sieves, from twenty to one hundred mesh, will be useful for sifting ores and fluxes. The box sieve, (Fig. 18), is a simple arrangement, and consists of a round tin box with a sieve fitting into it as represented in the engraving. The sieve is a tin frame with any desired FIG. 18. mesh gauze soldered to it, and fits tightly in the box. The advantage gained by its use is that in sifting the pulverized ore there is no dust. The fine material being passed through the sieve is kept from flying around. The size most convenient is 8 inches in diameter, the box 2 inches deep, and the rim of the sieve 2 inches, fitting about 3/4 inch into the box.
Open and closed ingot moulds for casting lead and silver bars, ingots, etc.
Hand button rolls for gold and silver only. They should be kept covered and free from dust.
Cupel mould, (Fig. 19.). This consists of two parts, an iron ring and a steel pestle or  driver, just fitting into the ring.
A mould for pouring the assay charge in scorification. (Fig. 20.) This should be of sheet iron or copper, and not too thin. It saves much time, and by employing it, the scorifiers can be used again.
Shovels for coke and coal, also a small hatchet for splitting kindling wood. The coke shovel should be ribbed or perforated so that the fine coke or dust may fall through.
Mixing scoops of Russia sheet iron 3 by 5 inches, with straight sides and FIG. 20. back about I inch high. They are convenient for mixing lead or silver crucible charges in, and owing to the high finish of the iron, the assay on being poured out does not cling to the scoop; a few sharp taps detaching everything.
A tin sampler, shown in Fig. 21, will be found very useful. It consists of a series FIG. 21. of troughs arranged in a row and fastened together at equal distances by a tin strip soldered on their ends.

A shovel full of ore emptied by a series of shakes upon them, is just half caught by the troughs; one-half going through the openings between. By repeating this operation, the size of the sample can be reduced to any extent desired.



A laboratory desk, as shown in Figs. 22 and 23, will be III f _ I FIG. 22. Section. FIG. 23. Elevation. Scale Y2 inch to the foot. Scale X inch to the foot. found a very suitable arrangement, and very compact, consisting of four parts, shelves for bottles, closet for ore scales, drawer for cupels and apparatus, and double closet for crucibles, scorifiers, etc. The illustrations being made to a scale, the desk can be constructed from them without trouble. This style of desk has been in use in the School of Mines, New York, for some years, and has been found most convenient. The lower closet should be provided with a shelf and the drawer with partitions.

If gas can be had, each desk in a laboratory should have a burner above for lighting purposes, and two or three large jets to which rubber tubes can be fastened so that Bunsen burners can be employed on the desk. These jets are best placed next the scale closet.

APPARATUS.
The amount and kind of apparatus required by the assayer varies; but the following list will be found about all that will be needed for ordinary work:
About three dozen quart bottles for reagents, glass stoppered.
One dozen parting bottles, glass stoppered for bullion assay. Eight oz. is a good size. The stoppers should be square-topped and fit exactly, so that the bottles will not leak when shaken.
An assortment of corked bottles of different sizes for samples.
Two or three ring stands and the same number of Bunsen burners or alcohol lamps. The former are preferable, if gas can be had, and should be provided with two or three feet of rubber tubing for each burner.
Two wash bottles, one small and one large, say one-half pint and pint.
One half-dozen horn spatulas or spoons for mixing ore.
Some iron pans for roasting. The ordinary long handled frying pan is suitable, and should be about the size of the furnace top. Before roasting it should be lined with chalk or oxide of iron.
One dozen parting flasks, (Fig. 24,) for gold bullion assay; also annealing cups for the same purpose. These are of clay and made thin. (Fig. 25.)
Brushes for ores and fluxes made of FIG. 24. FIG. 25.camel's hair; or a large feather trimmed, makes an excellent substitute.
A few dozen sheets of glazed paper, or stout manila paper when glazed paper cannot be had, for mixing ore upon. Black is preferable, and when held up to the light, there should be no small holes.
Hessian and French crucibles and covers of various sizes and shapes.
Scorifiers, large and small.
Scorification and cupel muffles to suit furnaces.
Cupels from 1 to 11 inches in diameter. These should always weigh more than the button to be cupelled.
Glass beakers and rods.
Funnels for filtering.

Gum labels, note book, towels, large and small porcelain mortars, balances, scales and weights, as have been described.

For volumetric work, silver bullion, etc., graduated flasks, pipettes and burettes, will also be necessary. See bullion assay, page 102. Should the assayer wish to be prepared for all kinds of work, it would be well for him to provide himself with the complete list on pages 167 and 168, appendix, or at least iron, clay and glass retorts, agate mortar (large), one or two platinum crucibles and dishes, and a couple of Bunsen battery cells.

These may be divided into six classes.
a. Reducing. To this class belong those bodies which have the power of removing oxygen from its combinations.
b. Oxidizing. All bodies which give up oxygen with facility.
c. Desulphurizing. This class includes all substances which possess a strong affinity for sulphur, and will decompose its compounds under the action of heat or in solution.
d. Sulphurizing. Sulphur and such of its compounds as give up their sulphur easily upon elevation of temperature or in solution.
e. Fluxes. Under this head, we include a large class of bodies, but generally they are substances which render others to which they are added more fusible. Either by acting as a solvent or as a decomposing agent. Fluxes are either acid, basic, or neutral in their action.
f. Solvents include solutions which are used in the wet way only. Such as distilled water, nitric, sulphuric and hydrochloric acids, etc.
g. Precipitants in the wet way. As in the salt solution used in the bullion assay.

The following are the principle reagents and chemicals employed by the assayer in his work.
There are, however, many others which might be used, but they can all be classed under the heads just given.

BICARBONATE OF SODA (sodic bicarbonate, Na HCO,) or the corresponding potash salt. These act as desulphurising agents, and in some cases as oxidising agents. The latter action being due to the carbonic acid contained. Sometimes they act as basic fluxes. They should be free from moisture, and lumps. On account of their easy fusibility they can retain in suspension, without losing their fluidity.

A large proportion of finely powdered infusible substances.
LITHARGE (PbO), is a basic flux, oxydizing and desulphurizing agent, and supplies the lead in the gold and silver crucible assay. It should be dry, and free from red oxide of lead, as the latter has the power of oxydizing silver, and thus causing loss of that metal during the assay. To free litharge from the red oxide, fuse the same in a crucible, and pour the mass into a cold ingot-mould, keeping it from the air while cooling. All litharge before using should be well sampled, and assayed for silver. To do this, charge in a crucible Litharge............ 4 A.T. Soda............... 2 " Charcoal........... 1 gm. and cover with a layer of dried salt, one-quarter of an inch thick. Fuse in a hot fire until completely liquid, then withdraw, and proceed as in the assay of a silver ore (p. 66).
White lead (carbonate of lead-plumbic carbonate PbCO,), is sometimes employed instead of litharge; also, acetate of lead for delicate experiments.
BORAX, CRYSTALLIZED (2NaBO,.B,0+10H,O).-This acts as an acid flux; but, on account of the water contained, it is generally employed in a vitrified condition, or borax glass (2NaBO2.B2,), which has a more intensified effect. It has neither an oxydizing or desulphurizing action. To prepare-Fuse the commercial borax in a chalk lined crucible, pouring the fused mass out on a clean surface to cool. Pulverize, and keep in a glass-stoppered bottle as borax, when heated, loses its water of crystallization, and undergoes an immense increase in volume, only a little should be added at a time in fusing.
Boracic acid (HBO,) is also sometimes used.
SILICA (SiO,), acts as a good acid flux, and can often be used with advantage.
A good substitute is glass (NaSi, O,+CaSi,07+SiO,), as it is easily fusible, and forms a good slag. It should be powdered and free from moisture. Lime glass is the best.
BLACK FLUX, SUBSTITUTE.-A mixture of three parts flour and ten parts of bi-carbonate of soda acts as a flux and reducing agent, and is especially useful in the lead assay. Black Flux, proper-1 of nitre and 3 of argol-deflagrated.
CYANIDE OF POTASSIUM (potassic cyanide KCy-KCN), as a flux for reducing and desulphurizing is invaluable. It should be prepared with care and kept in a tight bottle, as it absorbs moisture. Take the ordinary commercial article and pulverize in an iron mortar as fine as possible. Never sift, as the dust is poisonous. To protect yourself, cover the mortar with a towel, or a board having a hole in the centre for the pestle.
FERRO-CYANIDE OF POTASSIUM (yellow prussiate of potash)(potassic ferro-cyanide K,Cfy=4KCY,FeCy2), will often be found useful as a flux for reducing and desulphurizing. The crystallized material should be powdered in a porcelain mortar, and dried over a slow fire until it is almost white. If the heat is too high it will carbonize and turn brown.
ARGOL (KHCHO46), crude bitartrate of potash, acts as a basic flux and reducing agent. It should be pulverized and dry, and its reducing power determined. For this purpose we charge Argol............... 2 gms Litharge............ A.T. Soda................ " in a crucible, fuse in a hot fire, cool, extract the button and weigh in grammes. Dividing by two gives the amount of lead one gramme of argol will reduce from litharge.
CHARCOAL, acts as a reducing agent and desulphurizer. It should be finely powdered and its reducing power determined, as in the case of argol. Using one gramme instead of two as in that assay. Ordinary wood charcoal will reduce twenty-eight grammes of lead from litharge.
STARCH n(C6H1,O,)(C,,H,,012 ), sugar, and gum, may also be used for reducing agents, but are not so convenient. Dried starch reduces thirteen parts of lead. Common starch about eleven and one-half parts. Sugar fourteen and one-half, and gum arabic eleven parts.

For some purposes pure hydrogen gas will be found essential as in the assay of oxide of tin. It is the strongest and best reducing agent, but requires care in its preparation. It is made by dissolving zinc in dilute sulphuric acid, and passing the gas evolved through oil of vitrol, to dry it before using. One part of hydrogen will reduce about one hundred and four parts of lead from litharge.

METALLIC IRON (Fe), is a desulphurizing agent, and is indispensable, especially in the assay of lead ores. The best form is iron wire about - inch in diameter. Nails and filings may also be used.
PURE LEAD (Pb), in sheet or granulated form, is used principally in the assay of silver ores. It acts as a basic flux, and a solvent or wash for the precious metals. The sheet form is useful in cupelling gold and silver beads, and in the bullion assay. The granulated is essential in the scorification assay. It can be obtained pure by decomposing the best white lead by charcoal, and granulating or fusing in bars, as the case may require. In sections where granulated lead free from silver, or white lead, cannot be obtained, the assayer can make his own granulated lead from bar lead, poor in silver, by the following method:-Melt about fifty pounds of bar lead in an iron pot or crucible, and keep it just at the melting point. Then pour a ladleful of the melted lead into a wooden bread-tray which has been well chalked on the inside. Keep this agitated by gently rocking the tray to prevent solidification, and when the mass begins to get pasty, throw it into the air and catch it again repeatedly until cold, when the metal will be found to be nearly all granulated. Sift through a twenty-mesh sieve, and what does not go through re-melt. The whole fifty pounds can be granulated in this way in two hours. After granulation sample well and test about thirty to fifty grammes for silver, by the scorification assay. In using the lead, the silver contained in it must be deducted from the results in assaying an ore.
NITRE (potassic nitrate KNOS), acts as a basic flux and oxydizing agent. It should be finely powdered, dry, and assayed for its oxydizing power. Charge: Nitre.............. 3 gms. Charcol............1 " Litharge........... A.T. Soda............... 1 " Place in a Hessian crucible and cover with salt. Fuse in a hot fire, remove, cool and weigh. The difference between the weight of the button obtained and that given in the assay of charcoal, divided by three, gives the oxydizing power of nitre per gramme.
POWDERED LIME (CaO), (dry), and fluor spar (Ca F2), will often be found useful as basic fluxes, especially in the assay of iron ores. Magnesia (Mgo), and alumina (A120,) or kaolin (Al, 0.2SiO,)-are also used, and cryolite (3NaF. Al1F) for tin ores.

AS SULPHURIZING AGENTS: powdered sulphur (S), pure galena (PbS), or sulphide of antimony (SbS,), are employed. CARBONATE OF AMMONIA (ammonic carbonate (NH4),CO,), as a desulphurizing agent, is used in the decomposition of some sulphates, as sulphate of copper, in roasting. It should be powdered and kept in a close vessel. COMMON SALT (sodic chloride NaCl), as a cover and wash, and as a reagent in the bullion assay, should be always kept on hand. The purer it is the better, and it must also be fine and dry.

AS SOLVENTS AND PRECIPITANTS - distilled water (H,0), sulphuric acid (H,SO0), nitric acid (HNO,), hydrochloric acid (HC1), chloride of sodium, nitrate of silver (argentic nitrate AgNO,), and sulphuretted hydrogen (HS), are most frequently employed. The acids may be purchased pure. Nitric acid should be free from chlorine, which can be separated by the addition of nitrate of silver, drop by drop, until a precipitate ceases to form. The clear acid, after settling, being drawn off with a syphon. Nitrate of silver may be made by dissolving pure silver in nitric acid free from chlorine; evaporate to dryness and dissolve one part of the salt in twenty parts of distilled water.

Sulphuretted hydrogen is best prepared from powdered sulphide of iron (ferrous sulphide FeS) and dilute sulphuric acid. The gas being passed through a second bottle filled with water to wash it. Fig. 26 shows the apparatus in position for use The glass tubes are connected with small pieces of rubber tubing. The gas may be passed into a solution to be precipitated, or a water solution may be saturated and used at pleasure.

The sulphide of iron can be made by heating scrap iron or borings to a red FIG. 26. heat in a crucible and throwing in sulphur. The sulphide produced may be then fused or broken up, still-fusion is unnecessary. OTHER CHEMICALS and reagents will often be found necessary if assays in the wet way are to be made, but the reader must be referred to page 168. The most important are arsenic (As), arsenide of iron (ferrous arsenide Fe2As), hyposulphite (NaiH,S,0,) and sulphide of sodium (Na2S).

Interesting. After reading about the importance of the sample, it makes me wonder how many prospectors were bringing in reliable samples. It seems like it would be easy enough to skew a sample and make your claim worth a fortune, which, of course, you could sell with a favorable assayers certificate. As in statistics, your conclusion is only as good as your sample.

Great information Dave,thank you for posting!!

In addition to the OCR I was able to download the original book this morning so I now have access to the drawings. Here are the Assayers Furnaces.







The above will have to be corrected from the book. - 1dave

Geology must have bought a heavy dose of technology to the west.
Looks like a whole pile of knowledge required to make analysis.
Where did these guys get educated at ? Assayer's school in early colleges ?

Nothing more interesting than getting rich on a mineral/metal claim. A thing of dreams.

Imagine being the first to walk the jewel rich beaches of Sri Lanka.

"Residual deposits are mainly found in flood plains of rivers and streams. The metamorphic types of gems constitute 90% of the gem deposits in Sri Lanka. Sri Lanka has the highest density of gem deposits compared to its landmass. Ratnapura contains the most gem deposits and derived its name from the gem industry. Ratnapura means “city of gems”."

Enjoying reading this thread. A few years ago I had a piece assayed that was over 4k oz Ag.

EDIT: Replacing lost pictures










Have you ever seen a happier girl?