The solution containing the cobalt and manganese is boiled until free from H2S. The iron is oxidised back to the ferric state by the addition of bromine water and boiling until the excess of the latter is expelled. Ten cc. double normal ammonium chloride is added, and the iron and alumina are precipitated by the addition of ammonia, and are filtered off. (The iron alumina may be determined from this precipitate if desired).

The solution still containing the manganese and cobalt is transferred to an Erlenmeyer flask fitted for passing in H2S, as before described, and 3 cc. strong ammonia is added. H2S is passed through for some time, and after precipitation ceases 3 cc. more of ammonia are added, and the flask is filled to the neck (300 cc. flask), is corked, and set aside for twelve hours at least. The precipitate is collected and washed on a small filter with water containing ammonium chloride and sulphide.

Manganese. -The manganese is extracted from the precipitate on the filter by pouring through it strong H2S water acidified with one-fifth its volume hydrochloric acid (sp. gr. 1.11). This solution from the extraction is evaporated to dryness, ammonium salts are destroyed by evaporation with a few drops of sodium carbonate solution, hydrochloric acid and a drop of sulphurous acid are added to decompose excess of carbonate and to dissolve the precipitated manganese, and the latter is re-precipitated at boiling heat by sodium carbonate after evaporating off the hydrochloric acid. The manganese is weighed as Mn304 and calculated to MnO2, in which form it is probably present in the enamel.

The residue of cobalt sulphide left after extracting the manganese is burned in a porcelain crucible, dissolved in aqua regia, and evaporated with hydrochloric acid; the platinum-and copper, if any is present-are thrown down by heating and passing in hydrogen sulphide. The filtrate from the platinum and copper is made ammoniacal, and cobalt is thrown down by hydrogen sulphide. This is filtered off and washed with water containing ammonium sulphide. This is either ignited and weighed as oxide or more accurately determined by dissolving in an ammoniacal solution of ammonium sulphate, containing 10 grms. of ammonium sulphate and 40 cc. of concentrated ammonia for each o 3 grm. of cobalt, and electrolysing in a weighed platinum dish at room temperature with a current of o5 to 15 ampère, and an electromotive force of 2·8 to 3·3 volts. The electrolysis is finished in three hours. The circuit is broken and the liquid poured off, and the platinum dish is washed with water, then with absolute alcohol (distilled one hour), and finally with ether, allowed to dry in oven at 95° for one minute, and then weighed. The metallic cobalt is calculated as CoO, in which form it is present in the enamel.

The Determination of Boric Anhydride in Enamel. The boron is determined in a separate sample of about 0.3 grm. This finely pulverised sample is fused with 3 grms. sodium carbonate for fifteen minutes, is taken up with 30 cc. dilute hydrochloric acid and a few drops of nitric acid. The melt is heated in a 250 cc. round bottomed flask almost to boiling, and dry precipitated calcium carbonate is added in moderate excess. The solution is boiled in the flask after it has been connected with a 6-inch worm reflux condenser. The precipitate is filtered on an 8 cm. Buchner funnel (see method of Wherry and Chapin, Journ. Am. Chem. Soc., xxx., 1688, for "Determination of Boron in Silicates "), and is washed several times with hot water, taking care that the total volume of the liquid does not exceed 100 cc.

The filtrate is returned to the flask, a pinch of calcium carbonate is added, and the solution is heated to boiling to emove the free carbon dioxide. This is best done by connecting the flask to a suction-pump, and the suction is

temperature, filtered if the precipitate has a red colour, and four or five drops of phenolphthalein is added, and N/10 sodium hydroxide solution is run in slowly until liquid has a strongly pink colour. A grm. of mannite (or 150 cc. of neutral glycerol) is added, whereupon the pink colour will disappear. Continue to run in N/10 Sodium hydroxide until end-point is reached. Add more mannite or glycerol, and if necessary more alkali, until a permanent pink colour is obtained: 1 cc. N/10 sodium hydroxide 0.0035 grm. B2O3.

=

Lead. The enamel for cooking utensils should never contain lead. To determine whether a cooking utensil contains lead, E. Adam gives the following simple qualitative method:-A small piece of filter-paper moistened with hydrofluoric acid is placed upon the enamel and allowed to remain for some minutes; the paper, together with any pasty mass adhering to the enamel, is then washed off into a small platinum basin, diluted with water, and tested for lead by passing H2S through the solution. J. Grünwald (Oesterr. Chem. Zeit., viii., 46) gives another quick test for lead:-Wet small portion of surface with HNO3 (conc.), and heat until acid is evaporated. Add several drops of water and a few drops 10 per cent potassium iodide solution, and if even a trace of lead is present yellow lead-iodide will be produced.

Determination of Phosphoric Anhydride in Enamel. Enamels containing bone-ash to give opaqueness are analysed for P2O5 as follows:

To a grm. sample of very finely pulverised enamel in a platinum crucible 1 cc. of sulphuric acid is added and the crucible is filled half full (about 10 cc. are required) with hydrofluoric acid. The crucible is heated on the waterbath until most of the solution is evaporated, and then gently on a hot plate to remove all the fluorine as silicontetrafluoride and as hydrofluoric acid, but no sulphuric acid fumes should evolve, as P2O5 is volatile. The residue is dissolved in nitric acid and taken to dryness, moistened with nitric acid, diluted with water, filtered, and washed with a very little water.

Add aqueous ammonia to the solution from above until the precipitate of calcium phosphate first produced just fails to re-dissolve, and then dissolve this by adding a few drops of nitric acid. Warm the solution to about 70° C., and add 50 cc. ammonium molybdate solution (70 grms. MoO3 per litre). Allow the mixture to digest at 50° for twelve hours. Filter off precipitate, washing by decantation with a solution of ammonium nitrate made acid with nitric acid.

The precipitate on the filter is dissolved by pouring through it dilute ammonia solution (1 volume of 0.96 sp. gr. ammonia to 3 volumes of water).

The solution is received in the beaker containing the bulk of the precipitate, all of which is dissolved in the ammonia solution.

An excess of magnesium ammonium chloride ("magnesia mixture") solution is added very slowly and with constant stirring. Let solution stand over night. Decant clear solution through a filter and wash by decantation with ammonia water (1 : 3). Dissolve the precipitate by pouring a little hydrochloric acid (sp. gr. 112) through the filter, allowing the acid solution to run into the beaker containing most of the precipitate. When all the precipitate on the filter and in the beaker is dissolved, wash the filter-paper with a little hot water. To the solution add 2 cc. magnesia mixture and then strong ammonia, drop by drop, with constant stirring until distinctly ammoniacal. Stir several minutes, then add strong ammonia equal to onethird of the liquid, let stand two hours, and filter off the precipitate of magnesium ammonium phosphate. Wash with dilute ammonia water, dry the precipitate, ignite separately from the filter, first at low temperature, and gradually raise to full blast. Weigh precipitate as Mg2P207 and calculate as P2O5 in sample.

Jan. 20, 1911
FLUXES AS APPLIED TO THE BRASS

FOUNDRY.*

By ERWIN S. SPERRY.

In the early days of brass founding two things were guarded jealously: the mixtures and the fluxes. At that time it was not an uncommon occurrence to hear one say, when speaking of a new proprietor of a brass foundry, "He will get along all right. His father left him all his formulas for mixtures and fluxes." It seemed to be taken for granted that even capital itself was subsidiary to those heirlooms. Soon the chemist began to make serious inroads into the mixtures, and their secrecy faded away gradually but surely. The mystery of the fluxes was more difficult to eliminate, as, unlike the castings themselves, they did not go beyond the foundry. They could not be analysed without obtaining at least a small quantity, and this was difficult to do, as the brass founder carefully guarded them and the materials from which they were made. In the course of time, however, the secret fluxes went the way of the brass mixtures, so that by the process of evolution "secrets" finally became general technical knowledge. Few brass founders are now found who claim to have anything original or remarkable in the flux line. When fluxes are mentioned, it is frequently asked, What is their advantage, and are they actually necessary? To answer this question, I will say that I believe the flux question is greatly overdone and likewise imperfectly understood. It was only a short time ago that I discovered a brass founder using lime in making an 88-10-2 mixture from new metals. He said "somebody" had told him that it was good for bronze. Although cheap substance that it is, he was wasting his lime, as it remained on the metal like so much dirt, and had no more effect than sand. In another instance I found that a brass ingot maker used a couple of handfuls of a mixture of common salt and borax on the top of a pot of yellow brass after it had been skimmed and immediately before pouring. The mixture was thrown on and then at once skimmed off without waiting for the borax even to stop swelling. He, too, would have been equally as well off without the flux. Another, but diametrically opposite case, was a brass founder who attempted to melt his emery grindings in a crucible without a flux and obtained about a pint of metal and half a bushel of dross. In this case a flux was needed. It hardly will be advisable to go into a detailed enumeration of all the fluxes known to mankind and that can be used in brass melting, as it would be of little value. Many substances once used for this purpose have now become obsolete, and many others have proven to be valueless. It seems preferable, therefore, to give a description of those fluxes that the test of time has proved valuable and the manner in which they should be used.

Flux for Aluminium. -For years those who melted aluminium used no fluxes at all on it, not even charcoal, as it was soon found that this material did more harm than

good. On account of the lightness of aluminium, charcoal does not readily free itself, and is apt to become entangled in the metal and produce small black spots in the casting. It is within the past few years that a flux has become used. For aluminium the flux that is most extensively used, and which has proved to be so valuable, is chloride of zinc. It seems to react with the aluminium, forming chloride of aluminium and metallic zinc, which alloys with the alumiinium. When this takes place the dross is changed to a fine granular condition, which is readily skimmed off. When aluminium is melted, the surface is covered with a rather thick mass, but the chloride of zinc will change it to a perfectly clear one closely resembling in appearance molten tin or lead. It is needless to say that such clean metal gives better castings.

The method of using chloride of zinc as a flux in melting

• Paper read before the American Brass Founders' Association.From the Chemical Engineer, xii., No. 6.

31

aluminium is simple. Small pieces are thrown on the surface after the melting has been completed. Enough has been added when the surface is clear. A very small amount usually suffices, and for 50 lbs. of aluminium a piece of the size of a walnut is generally enough. The metal is stirred immediately after the addition, and then skimmed. Those who have not used chloride of zinc should try it, as it is an excellent material.

Flux for Nickel-The flux used by makers of nickel anodes has proved to be a good one. It was first used by A. M. Hill, of New Haven, Conn., one of the first in the United States to make nickel anodes and the inventor of the well known "Hill-Barrel" for grinding brass furnace ashes. Mr. Hill has retired from the anode business, but for many years he used this flux with the best results. It is not only good but cheap. It is composed of the following:3 parts I part

..

Lime Fluor-spar

The manner of making it is to take the lime and slake it as though mortar were to be made. Then stir in 1: fluor-spar and allow it to become solid. It is then broken up into small pieces for use.

While fluor-spar alone is a good flux, it becomes very fluid when melted, and rapidly attacks a crucible. I have seen a new plumbago crucible ruined in one heat when fluor-spar was used alone. It seemed to soak in and dissolve out the clay from the crucible mixture and leave nothing but the graphite. The crucible collapsed like an egg shell when grasped with the tongs. The use of the lime with the fluor-spar is to increase the melting-point so that it will not so readily attack the crucible. The proportions previously mentioned have been found satisfactory for nickel. Less lime will render it more fusible.

This flux has been found particularly serviceable in melting old anodes, as it dissolves any earthy matter that may be on them. It is used for both new and old material, however, and may be called the standard flux for nickel. The proportions used are about a pint or a good handful for a new nickel, and twice this quantity for old material.

It must not be imagined because the fluor-spar is toned down with lime that the flux will not act on the crucible, for it certainly will. The crucibles last only five or six heats. In this connection it should be borne in mind that

all fluxes act on the crucible to a greater or less extent, otherwise they would not be of value as a flux.

Flux for Copper.-There probably have been more fluxes proposed or used for copper than for any other metal or its alloys. The fact that copper cannot be melted alone and obtain sound castings from it has brought about this fact. Practically every known chemical has been tried. In the selection of a flux for copper it should be known whether pure copper castings are to be made, or whether it is to be alloyed to make brass or bronze.

To make sound copper castings with a flux alone, and without the use of " physic" like silicon-copper, magnesium, or similar materials (which strictly speaking are not fluxes) is a difficult matter. For this purpose I have found that yellow prussiate of potassium (potassium ferrocyanide) is excellent. With it sound copper castings can be made, but I do not advise it, as far better results may be obtained by the usual deoxidising agents, such as silicon-copper, magnesium, phosphorus, &c.

Its

In melting copper for producing brass or bronze, the For this question is different from the preceding one. purpose there is nothing better than common salt. value lies in the fact that it possesses the property of reducing any oxide of copper which may form during the melting. It has been used for years in the brass industry, and the memory of the "oldest inhabitant "fails to indicate the date of its inception.

Common salt is so efficacious in reducing oxide of copper that, as far back as 1882, R. Monger in the CHEMICAL NEWS proposed it as a means for determining the quantity of oxide that copper contains. His method

was to melt salt in a clay crucible and then drop in the weighed sample of copper. After allowing it to remain for a short time, the crucible was cooled and broken, when the button of pure copper was obtained. The difference in weight gave the amount of oxygen (or its equivalent of oxide of copper). Some very satisfactory results were cited.

In melting the copper for making brass or bronze, about a handful of salt is used and is preferably put in after it has begun to melt. If introduced with the copper, it melts before it, and is apt to volatilise and waste. The action on the crucible is also greater. Too much salt produces a liquid that is apt to penetrate the crucible, like fluor-spar, although not as violently or as rapidly. The amount of salt previously given is used for a pot of metal holding about 150 lbs. The quantity need not be exact, as a variation either way does no harm as long as a sufficient quantity is used to do the work.

The theory of the action of the common salt seems to be that, at the temperature of the molten copper, it breaks up or dissociates into metallic sodium and chlorine gas. The latter escapes and the sodium performs the work in deoxidising.

minute spots in his metal. Tradition states that he gave the matter much thought, and finally believed it was caused by carbon in the metal. More "thought" indicated to him that the only method of removing it was to use a nitrate of some kind which would evolve oxygen and oxidise the carbon. Nitrate of soda, therefore, was used, and upon its use in the German silver he obtained a patent (U.S. Patent No. 96,524, Nov. 2, 1869). As this material was found to work better with black oxide of manganese, the two afterwards were used together and now constitute the flux of the aforesaid concern.

Personally, I doubt whether this flux has much value, and the fact that it is possible to make good German silver without it would seem to indicate it. I feel quite sure that there is no oxidation of carbon, as nitrate of soda, when allowed to melt on copper, will not oxidise it; but instead will actually render it sounder. It is also a singular fact, which I have already demonstrated in practice, that a mixture of nitrate of soda or the nitrate of potash (nitre), mixed with black oxide of manganese and used as a flux on copper, will actually introduce metallic manganese into the copper, showing that there is a reducing action. This explains, I believe, the reason for the action of the flux. A slight amount of manganese is introduced. This is also borne out by the fact that, within the last few years, metallic manganese has come into use as a deoxidising agent for German silver and similar nickel alloys. It use is preflux, as the results are then positive and certain and predetermined amounts of manganese always can be added. Its use has been attended with excellent results, and it seems to be the natural deoxidising agent for nickel and nickel alloys.

The quantity used is about a handful to the crucible. One concern uses one handful, while another believes that double this quantity should be used. A good-sized handful, however, seems to be sufficient. It is added after the copper begins to melt, as this appears to be the best time to introduce it. When the right conditions have been produced, there will be a little slag on the top of the brass when it is skimmed.

I

It is worthy of note that, although every brass rolling mill uses salt in brass melting, few brass founders who make sand castings employ it. Many of them never have heard of it, and others seem to think it is a waste of time. advocate its use under all conditions, and as it is theoretically correct, has been found by actual practice to improve the quality of the brass, and is so cheap that the cost of the brass is not appreciably increased, it seems to me that every brass founder should use it, whether he makes new metal or melts scrap, as the character of his castings will be improved.

Flux for Bronze and Composition.—What has been said about the use of common salt in melting yellow brass, applies equally well to composition or bronze, and it is used in identically the same manner and in the same quantities. It makes no difference whether phosphorus or other deoxidising agents are employed, the salt is used just the same.

Flux for German Silver.-German silver is such a reractory material in the rolling mill that much time and thought have been given the subject of a suitable flux for it. It is a singular fact that the bulk of the German silver manufactured in the United States is made by two conOne uses a flux in making it, while the other uses none. In justice to the concern which uses no flux at all, I will say that their German silver has a little better reputation and they have the more particular trade. I cite these examples simply to indicate that fluxes do not constitute the "secret" of making German silver by any means.

cerns.

The use of the flux by the other concern dates back to 1869, when Frederic Wilcox, a brass caster, who was engaged in making German silver, had trouble with black

In making German silver common salt is used in the same manner, and with the same results, as those obtained in brass and bronze.

Fluxes for Washings, Grindings, &c.-In the melting of washings from the reclaiming of brass foundry ashes, a flux must be used in the majority of instances, unless they have been washed very clean, and this is rarely done. Even with clean washings a flux is advisable. The same rule applies to grindings, skimmings, and similar waste materials. Unless a flux is used when they are melted, a union of the particles of metal is prevented by the presence of so much foreign matter, and instead of fluid metal there usually is obtained a small quantity in the bottom of the crucible, and a large mass of pasty material fritted together. When a flux is used the foreign matter is dissolved, and clean metal is left.

For use in melting brass, bronze, or composition washings, grindings, skimmings, and similar material, I have found nothing better than plaster of Paris. It is a cheap and excellent flux for this purpose. How far back it was employed for this purpose I cannot say, but it was first called to my attention in 1890 by the late C. S. Moore.

With due respect to the late C. S. Moore, I believe he can really be called the father of the present scrap metal industry in the United States, as he was responsible for many innovations (like the "transmutation" of yellow washings into red), and I firmly believe he was the first to use plaster of Paris as a flux. He informed me to this effect, and I have no reason to doubt his word.

The value of plaster of Paris as a flux in melting washings, grindings, and similar material is that it possesses the property of dissolving what foreign matter may be present in the shape of sand, slag, or oxide, and it has practically no action on the crucible. In addition it is quite cheap. On account of the fact that it has no action on the crucible, any desired quantity can be used. It melts readily and forms a thin slag.

To melt washings or grindings with plaster of Paris, mix about 5 lbs. of it with the washings when they are placed in the crucible. Then melt in the usual manner. If the slag at the conclusion of the melt is not sufficiently fluid, more should be added. When the metal is com.