EVE VENING CHEMICAL WORK-Laboratory, Clerical, or Teaching-wanted by Lady with B.Sc. training and works experience. Accustomed to library "digging." "- Address, E. W., CHEMICAL NEWS Office, .6, Newcastle Street, Farringdon Street, London, E.C. 4. Lady, B.Sc., seeks Post in Analytical Labora tory.-Ad ress, H. J., CHEMICAL NEWS Office. 16, Newcastle Street, Farringdon Street, London, E C. 4. Young Lad seeks Position in Analytical Lab oratory, Good experience. -- Address, Y. L., CHEMICAL NEWS Office, 16, Newcastle Street, Farringdon Street, London, E.~.4. Young ex-Service Man (21), Matric distinc tion Chemistry, Mathematics, desires opening in Analytical or Testing Department of Manufacturing Chemist (Pharmaceutical or Pho ographic) while training for Technical Examinations.-Address Hammersley, 125, Napier Road, Tottenham, London, N. 15. Blue Serge with Tapes. All the garments which are quite new are made of thick "LASTING CLOTH" with the exception of the Shirts which are in blue serge. The five items form a complete outfit very suitable for use in Factories, Wanted, a young Physicist to take charge of Manufacturing Chemicals, etc., and where clothing of a Department making Steam and other Pressure Gauges. State salary and experience. Address, Cliffe, Great Brook Street, Birmingham. fire resisting nature is worn. They are available in 6 sizes (with the exception of the caps which are in 10 sizes) and are stored at the Royal Army Clothing De LABORATORY BENCH for Sale, 5 ft.partment, Grosvenor Road, Pimlico, S.W.1 3 ins.; solid Teak top; fitted with Cupboards, Drawers, and Gas Fitt ngs. £25.-Apply, 1, Liberia Road, Highbury, N. 5. YOUNG CHEMIST SEEKS To be sold in Lots of not less than 25 Garments of each item. Tender forms containing full particulars can be obtained on application to the Controller, D.B.3.b.2, Ministry of Munitions, Earl's Court Exhibition, Warwick Road, London, S.W.5. (Telephone Hammersmith SITUATION. 2300. Telegraphic address: Textilquip Earls Londou) F. JOST, BERN, Rütlistrasse, Switzerland. TO MANUFACTURING CHEMISTS. and are to be returned not later than 10 a.m. on 24th he Owners of BRITISH PATENT No. Royal Army Clothing Department, Grosvenor Road, 105906, relating to The SAMPLES representative of the bulk may also be at:-The Office of the Controller (D.B.3.b.2), Ministry of Munitions, Block "C," Earl's Court Exhibition, Warwick Road, S.W.5. CITY OFFICE.-M. of M. Disposal Board, Holland House, 32, BELFAST.-Grand Central Hotel, Royal Avenue. Street. BRISTOL.-8, Unity Street, College Green CARDIF.-Ministry of Munitions, Room 25, Principality Build. ings. COVENTRY.-Chamber of Commerce, Masonic Buildings. DUB.IN.-Ministry of Munitions, 121, Lower Baggot Street. DUNDEE.-Flax Office, 10, Victoria Chambers. EXETER.-Labour Exchange, Queen Street. GLASGOW.-Pattern Room, Ministry of Munitions, 250, St. Vincent Street. LEEDS.-Chamber of Commerce, 26, Park Row. LEICESTER.-Chamber of Commerce, 3, Granby Street. LIVERPOOL.-Chamber of Commerce, Liverpool. MANCHESTER.- Cotton Textile Office, Danlee Buildings, Spring Gardens. NOTTINGHAM.-Chamber of Commerce, Eldon Chambers, NEWCASTLE.-Chamber of Commerce. PLYMOUTH.-Labour Exchange, Manor Street. Note For particulars of other Government Property for Sale, THE WATER OF FORT DODGE, IOWA. FORT DODGE, Iowa, is supplied by a system of seven wells There are extensive deposits of gypsum in and around Fort Dodge which affect the quality of the water. These deposits belong to the Mississippian, including the subcarboniferous and carboniferous. We made an analysis of the water of three of the wells, believing them to be representative of the entire series. No. 1, 1827 feet deep. It terminates in the Jordan sandstone of the Cambrian. The water used in the analysis probably came from a depth of 1431 feet, from the Saint Peter Rock above the Ordovician. The last analysis shows that a river water is not necessarily soft, but may be quite hard as in the present instance. The water of this stream may vary considerably in bardness in different seasons of the year, as it is fed by ground water from numerous springs, and this water dissolves notable amounts of calcium carbonate and sulphate with which it comes in contact. In times of flood the gypsum content may appreciably decrease. There would seem to be no advantage in deep wells over the somewhat shallow wells that partly supply the city. Cornell College, Mount Vernon, Iowa, THE DEVELOPMENT OF A GRAPHITE INDUSTRY, AS ILLUSTRATED BY THE HISTORY OF THE QUEBEC Brief History of Graphite. THE mineral now known as graphite has been in commercial use for many years. Its true chemical nature consists only of the element carbon, and was first recognised as such by Scheele, 1742-88. Previous to this it was generally supposed to be "dead," and in those early days, on account of its distinctive marking on paper and porcelain, was shaped into crayons, and was called "lead pencil," hence this erroneous appellation for the article, which has still remained. The first discovery of its purest form was at Borrowdale in Cumberland, England. Description of Properties. Graphite, or "Plumbago," has a greyish black colour with a metallic lustre, soft and soapy to the touch. It is a perfect conductor of heat and electricity, and is impervious to all acids or alkalies. It also has an extremely low resistance to friction, and on account of its softness will find its way into the minutest pores in a bearing, making it run smooth and sweet. It occurs in the crystalline and amorphous forms. The former has several different forms of occurrence, hexagonal prisms, needle-shaped crystals, in foliated masses (often called "chip plumbago"), or flakes disseminated throughout the rocks of its occurrence. The amorphous variety more resembles a graphite shale, and approaches the true coal series. Thus there are three distinct allotropic forms of pure carbon-diamond, graphite, and coal. The method of occurrence and physical properties of each are entirely different; where one is detrimental to lubrication, as in "carbonised" cylinders and bearings-graphite is used to eliminate it and cause smooth running. Geology. The ores of the Buckingham district are chiefly of the flake variety. The country rock is a crystalline limestone of the Grenville series, interbanded by a complex of pyroxine gneisses, gabbro, pyroxine diorite, proxine syenite and pegmatites composing the Buckingham series. The whole mass is intensely deformed and twisted, and there is a great enrichment of graphite at the contacts of the pegmatite intrusions, the ore occurring in distorted lenticular masses, flakes of graphite can be traced far into the limestone on either side of the ore bodies. These ore Dodies average from 12 per cent to 16 per cent carbon. Graphite was mined from the Buckingham district as far back as 1845, and from then to the present date an enormous amount of money has been spent, much thought and originality has been shown, in trying to solve the problem of graphite concentration in this district. Some extraordinary difficult features are presented, chiefly because the specific gravity of graphite, which is 2.25, is only slightly less than that of its accompanying gangue, which is from 2.5-2.7, and the natural shape also tends to aggravate the problem. Dry methods of concentration, with their accompanying inconveniences from dust losses and difficulties of operation, were always carried on. While all due acknowledgment is to be made to the pioneers of the industry, it must be granted that the commencement of operations by the Quebec Graphite Co., Ltd., who used wet concentration, marks one of the first milestones of progress in this direction. History of Quebec Graphite Co., Ltd. Co., Ltd., are situated about four miles east of Buckingham, Published with the permission of V. Eardley-Wilmot, General P.Q, on lots 1-4. This property was taken over by the British Company from the Natal Company, who obtained it from H. E. Dixon, of Ottawa. During 1910 and 1911 a parcel of graphite ore was sent from lot 3 to the works of Fried Krupp, Magdeburg, Germany, and after a long series of experiments, what was supposed to be a satis factory process of concentration was evolved. This process was on the wet gravity lines, its outstanding features being very careful classification and a unique finishing plant. The Quebec Graphite Co. was thus formed in London to work the contemplated process. Its capital was £100,000, and building and mining operations were begun in 1912. Owing to climatic conditions, non. arrival of parts, and scarcity of labour, installation of the plant, which was entirely under German jurisdiction, was not completed till September, 1913. The machinery was all German, and consisted of initial crushing and grinding units, sixteen gravity tables, classifiers, dewaterers, dryer and finishing plant. Power was supplied by a 160 h.p. Diesel oil engine. It was expected that the rough concentrate would run about 80 per cent carbon, which would then be brought up to go per cent carbon by the finishing plant. No time and money had been spared in the installation, and on September 26, 1913, milling operations were begun. At an early date defects in the initial crushing and grinding installation were noted. A rough 80 per cent concentrate could not be produced, and the recovery also was unsatisfactorily low; furthermore, the plant was designed in a country where labour was cheap, and consequently the enormous amount of man-handling and disregard for labour-saving devices in this mill tended to make milling costs very high. Also the drying apparatus was hopelessly inefficient. Thus the contract of the German firm | was not fulfilled, and the German engineers left the scene of operations before the accomplishment of their task, and with the usual "promises" of better improvements. Had the company known that nation as they do to-day, they would have at once severed all conrections with them. However, further experiments were initiated at Krupp Works with the object of overcoming these defects, and it was again "supposed" that a satisfactory solution had been found. Meanwhile the plant had run through the winter, but was finally closed down for readjustments on June 17, 1914. Work of dismantling proceeded, some of the new machinery was sent from Germany, arrived, and was installed, but some was not shipped at the outbreak of the war in August, 1914. At this period the company's finances, due to the investigations and alterations, were becoming strained. British Treasury regulations and a moratorium in England, made it difficult to raise further funds, and all work was finally stopped early in Sep. tember, 1914, and the company went into voluntary liquidation early in 1915, and was reconstructed under the name of The New Quebec Graphite Co., Ltd. The new company restarted operations on July 19, 1915, and the work of remodelling the plant was resumed. The old plant, with the missing units still in Germany, was repaired and tuned up as well as possible, and a test was run in the end of September, 1915. This was fairly satisfactory, but the management considered the mining outlook very unpromising, as at that date no deposits of value were developed, and practically no ore was in sight. The works were therefore closed down again until April, 1916; all German superintendents and interests were displaced, and Mr. R. C. Rowe and Mr. C. N. Daly, who had considerable experience in mining and milling graphite in this district, were appointed as works managers, and operations were again resumed. It was felt that defects in recovery would be in some measure offset by the increased price of graphite, and it was the company's policy to return any profits into development of the property and investigations for improving the milling process. For a period of two years under this new manage ment the plant ran steadily and productively. A definite scheme of prospecting was followed, and new and highly promising deposits were uncovered and developed, and indications of almost unlimited quantities of ore were shown to exist. During this period investigations into increasing the efficiency of the plant were also conducted. The impossibility of obtaining spare parts for the German machinery was a heavy strain. Every part, therefore, no matter how small, had to be drawn, patterns made and specially cast, deliveries were bad and irregular, and consequently the efficiency of the plant suffered. Moreover the old inherent defects were still present, in spite of the German "promises," and this, coupled with the ever-increasing cost of supplies and labour, caused cessation of operations in April, 1918. After this date the company turned its attention very seriously to improv. ing the recovery of values in the concentration plant. Investigations in flotation concentration of several different processes were conducted in Canada, U.S.A., and in England. But the strain of these continued investigations was, however, too great, and the company again went into voluntary liquidation. In June, 1919, the British Company again decided to start afresh, with drastic alterations and new ideas; and this new company was called The Quebec Graphite Co., Ltd.; head office at 4, Fenchurch Avenue, London, England. Mr. V. L. Eardley-Wilmot, recently returned from the army, a mining engineer from British Columbia, was appointed general manager, who, after preliminary investigations in England, came over to reorganise and start operations on a new scale. After careful study of the latest methods of ore concentration both in Eastern and Western Canada, and exhaustive tests and experiments, the present and latest method of graphite concentration was decided on, both in consideration of its efficiency and for the reasonable cost of plant and engineer fees. The results of these experiments with this new process have proved that the very highest grades of both coarse and fine flake graphite can be produced from the company's property at Buckingham. The company is very much indebted to the invaluable assistance given to them by the Mines Branch at Ottawa. Remodelling of the mill on these new lines started during August, 1919, directly under the supervision of R. C. Rowe. The old Krupp process has been definitely discarded. The initial crushing and grinding plant has been entirely reconstructed with the latest mills. The dewatering and drying equipment has been altered, and additions have been made to the already highly efficient finishing plant, and it is hoped that the company will be able to sell some of its discarded units. The economic geology of the property in the vicinity of the mill has been investigated, and further exploration has revealed a large ore body of the highest grade that has been milled in recent years. The company's property is very extensive, and is permeated throughout with the best Canadian flake, and several years' supply of ore can be obtained from the small portion prospected, while a close study of the geology shows that at least seven-tenths of the property, which has barely been walked over, must contain an almost inexhaustible supply, and there is therefore not the slightest doubt that the company will now reap the benefit of their long continued and persistent enterprise. Commercial Products. From some of the extremely high-grade coarse and fine graphite produced all manner of commercial products are being mangfactured. These to be immediately put on the market are: I. A high-grade coarse crucible flake, 90 per cent 2. Several high grades of powdered lubricants, in cans, NEWS 4. Foundry facings for all purposes. 5. Graphite dust. A complete line of graphite products is also now being experimented on, amongst which may be listed graphite greases of all grades, stove polishes, graphite paints, pipe and boiler compounds. Experiments in the manufacture of electrodes and electric materials are under consideration. The company expects to establish at least one factory in Canada and one in England for manufacturing these products. The management has the advantage over other graphite properties, in that it possesses what is the crux of the situation, in the form of the very highest grade finishing or polishing rolls, and these, in combination with the last word in graphite concentration, enables them to be able to economically produce all the above products at a considerably reduced price on the present imported goods. The company is also fortunate in having a very sound financial backing in their British directors, who are among the best-known business men in London, England. The idea has been prevalent that Canadian flake is not as good as Ceylon, but this has chiefly been in the past a question of purity, and by recent methods of concentration and finishing it has been shown that the Canadian flake in its pure state can hold its own, for any purpose, against all outside grades of this mineral. The managers are all thoroughly experienced in graphite and its concentration, and being alive to their opportunities, the new industry should branch out into almost any proportions. The market will not be confined only to this continent, for negotiations are already under way for disposal of products throughout Europe and the Far East. THE USE OF HALOID CYANIDES FOR THE Degree of Alkalinity.-A further precaution exists in using cyanogen bromide in that no appreciable amount of protective-alkali must be present. This is quite contrary to the usual practice with plain cyanide in the use of which it is customary to keep a good margin of safety as regards protective-alkali. All of the cyanogen haloids are very rapidly decomposed by caustic alkalis, and again in this instance the products of the decomposition are not solvents of gold. CNBr+2NaOH In an experiment to show the rate of destruction a solution was taken containing o:198 per cent KCN and 0.05 per cent CNBr and divided into two portions. To one of these lime was added equivalent to 2 lbs. per ton of solution (o'1 per cent CaO), and to the other none was added. They were allowed to stand for thirty minutes, and their respective strengths were then estimated. The one with. out lime contained o.188 per cent KCN and 0.034 per cent CNBr, whereas the one containing the lime contained 0192 per cent KCN and no CNBr. The lime destroyed practically all the cyanogen bromide, and by so doing prevented the potassium cyanide from being decomposed by it. A further experiment may be given to show the effect which the addition of alkali has on the extraction of gold when used with cyanogen bromide as compared with plain cyanide. A sample of sulpho-telluride ore was taken and crushed to pass through a 60-mesh sieve; it was then placed in a small tube-mill with an equal rate of water and ground until all the pulp could pass through a 150 * Read before the Institution of Mining and Metallurgy, February 19, 1920. From the Bulletin of the Institution of Mining and Metal lurgy, February, 1920. These results show that when sufficient lime is added, to produce protective-alkali, cyanogen bromide does not give any better extraction in the same time than does the plain cyanide, and by far the best extraction is obtained by cyanogen bromide when the lime is reduced to a minimum. In practical work it is necessary to regulate the addition of lime in order that sufficient is present to neutralise the acidity of the ore, yet at the same time an excess which would decompose the cyanogen bromide must be avoided. It will be recognised that a very much closer control of alkalinity is required than when the plain cyanide process is used. Our own experience shows that as long as the solutions contained in the agitators do not show a protective alkalinity in excess of 0.002 per cent CaO as determined by Clennell's method, the dissolving of the gold is not interfered with to any serious extent, and no excessive consumption of alkaline cyanide will take place. By using a higher alkalinity cyanide is saved, but the residue value is increased, and, by keeping the solutions acid, the highest extraction is obtained but the consumption of cyanide is necessarily increased. The metallurgist in charge has therefore to arrange conditions which will give no excessive loss of either gold or cyanide with the particular ore which he is treating. All the plants using this process with which we are familiar have been arranged to crush the ore in cyanide solution, and it is customary to add lime with the ore in the battery boxes to such an amount as to maintain the solution in which the ore is crushed and concentrated very slightly alkaline. By so doing the pulp entering the agitators can usually be relied upon to be neutral or slightly acid. In the latter case sufficient crushed lime can be added to make it neutral or just faintly alkaline. It will be seen that we have a very ready means at our disposal of adding alkali to charges during agitation; but in the event of charges being too alkaline we have no means of obtaining acidity beyond that developed by the latent acidity of the ore. After the pulp has been agitated, the treatment of it as regards alkalinity varies at different plants. At one time it was considered essential before filtering a slime pulp to make it strongly alkaline by the addition of lime in order to increase the cyanide strength by decomposing the double zinc cyanide, and at the same time destroy any cyanogen bromide which remained. These precautions were considered necessary to obtain successful results in the subsequent operation of precipitating the gold from the solution in the extractor boxes. This custom has to a great extrent prevailed, but the idea of destroying the remaining cyanogen bromide is erroneous, as none has ever been found to exist in an agitation vat three hours It will be seen when this salt is used three atoms of after it has been added. It has been shown at one plant that it is unnecessary to make solutions alkaline before they are delivered to the precipitation boxes, as the work done in these extractors suffers in no way by omitting this step, whilst the con. sumption of zinc shavings is very much reduced. The degree of alkalinity for precipitation is of little consequence, but if magnesium salts are present in solution any sudden variation must be avoided. If no lime is added to the solutions before precipitation, it is perhaps unneces sary to mention that greater quantities must be added in the battery boxes in order to maintain the neutrality of the plant circulating solution. When the process was first introduced at Kalgoorlie the adjustment of the alkalinity was a comparatively simple matter, as salt water was in use in the plants, and owing to the large amount of magnesium salts which this water contained, it was not possible to get any appreciable degree of protective alkalinity without the addition of such enormous quantities of lime as to make the use of it impracticable. But with this water a low alkalinity, equivalent to o'002 per cent CaO, could be readily obtained owing to the slight solubility of magnesium bydroxide. This was an ideal condition, and was self adjusting, as if any excess of lime was added it was consumed in precipitating magnesium hydroxide, and did not combine with the cyanogen bromide. To show this experimentally we prepared a solution containing 1 per cent MgSO4, 0.2 per cent KCN, and o'05 per cent CNBr, and lime at the rate of 2 lbs. per ton of solution. Another solution was prepared with the same amount of lime but omitting the magnesium sulphate. Both solutions were then tested for cyanogen bromide at intervals of a few minutes. In the one containing the magnesium salt 0'02 per cent of CNBr remained after three hours, but in the other solution all the CNBr had been destroyed in fifteen minutes. The experiment therefore proved that magnesium hydroxide does not decompose cyanogen bromide to any serious extent in the way that lime does. Manufacture of Cyanogen Bromide.-Until this compound was used for the purpose of gold extraction it had no commercial importance, and could only be regarded as a chemical curiosity. It was found, as soon as its use was commenced on a large scale, that owing to its poisonous nature and instability it was impossible to ship it in bulk. This created a need for a method to produce it on the mines from chemicals which were more easily handled. The production of bromine by treating a bromide with an oxidising agent and an acid was well known, and the production of cyanogen bromide by the addition of bromine to an alkaline cyanide was known almost as well, both of these reactions being easily carried out and giving very good yields. It was a simple step to combine the two reactions in one operation and obtain an equally good yield of cyanogen bromide. The most satisfactory oxidising agent to use is the alkaline bromate, and it came into very general use. Not only does this salt act as an oxidising agent, but it also contains bromine which can be utilised in the reaction. Another advantage is that when the bromate is used there is no possibility of complicating the subsequent cyanide treatment by the introduction of other elements as there is when such oxidising agents as potassium bichromate, potassium permanganate, or potassium nitrate are used. Also when using a bromate the reaction will take place at atmospheric temperatures, whereas most other oxidising agents require the aid of heat. bromine go to form sodium bromide instead of cyanogen bromide and are consequently wasted, and it is better, therefore, to use a salt of a higher oxidising nature by manufacturing an artificial mixture of a bromide and a bromate corresponding to the formula 2NaBr+NaBrO3. With this salt all of the bromine contained in it is converted into cyanogen bromide according to the following equation : 2NaBr+NaBIO3+3NaCN+3H2SO4 = =3BrCN+3Na2SO,+3H20. According to the above formula the theoretical charge to manufacture 100 lbs. of cyanogen bromide is 112.3 lbs. of the mixed salts, 46.2 lbs. of sodium cyanide, and 92'4 lbs. of sulphuric acid. In practice the weights actually used naturally vary with the purity of the chemicals obtainable. When starting to mix the "brew" as it is commonly called, the acid is first diluted by adding it to about 100 gallons of cold water which is contained in a leadlined vat with wooden stirring gear; the top of the vat is covered, with the exception of a small hole through which the chemicals can be introduced. There is no necessity to allow the diluted acid to cool before the other chemicals are added. The cyanide is dissolved in sufficient water to make a 10 per cent solution; this is contained in a separate tank situated above the mixing vat. The bromide salts are not dissolved, but are added gradually to the acid a few pounds at a time, and as soon as the bromine is set free as shown by the reddish colour, sufficient of the cyanide solution is run in nearly to bleach it. Care is taken during the addition of the salts and cyanide that there is always a small amount of free bromine present in the mixer. That is, the bromine salts are always added slightly in excess of the cyanide. If this is not done and the alkaline cyanide is allowed to be in excess, mutual destruction of cyanogen bromide and alkaline cyanide will take place with the production of brown paracyanogen. The time taken to add the given quantity of bromine salt would be about twenty minutes. When reasonable care is taken, a very high percentage of the theoretical yield of cyanogen bromide can be obtained, and it is not uncommon to reach over 90 per cent. The usual solution prepared on the mines contain about 2 per cent CNBr, but if required, strengths up to 5 per cent CNBr may be prepared without reducing the yield. With solutions above 5 per cent the loss of volatilisation begins to be excessive owing to heating of the charge. The reaction is a rapid one with all concentrations which yield a solution of over o'5 per cent CNBr, and in order to show the rapidity of the reaction we will quote an experimental "brew" which yielded a 1'77 per cent CN Br solution. With this concentration we found that 899 per cent of the theoretical yield was obtained as soon as the bromine salt had been added, and after stirring for one hour, the yield had increased to 93'9 per cent.; continued stirring did not show any further increase. The rate of decomposition of solutions prepared in this manner is very slow, and they will maintain their strength for some days provided they are kept in a closed vessel. It is usual to add cyanogen bromide to the slime charges on a basis of 100 per cent yield from the bromine salt; that is to say, it is not considered necessary to make any allowance for the bromine which is not converted into cyanogen bromide during the process of manufacture. The method of testing a solution of cyanogen bromide by titrating the amount of iodine set free after the addition of potassium iodide and acid with a N/10 solu tion of Na2S2O3 is well known, but the mention of two points which have come to our notice may be useful. When preparing a N/10 solution of Na2S2O3 it is customary for metallurgists to standardise it against pure copper in the same way as they do when making a copper determination. (See "Rand Metallurgical Practice," vol. i., p. 364). This is accurate enough, but a very =3CNBr+3NaBr+3Na2SO4+3H2O. simpler method is to standardise against a N/10 solution If bromine is added to a solution of caustic alkali and the liquor is evaporated to dryness at a temperature of 100° C. a salt corresponding to the formula 5NaBr+NaBiO3 is produced, and this may be used for the production of cyanogen bromine according to the following equation: 5NaBr+NaBiO3+3NaCN+3H2SO4 = |