textile industry require grinding wheels for sharpening cards, snagging castings, and maintaining tools, cutters, and dies used extensively in keeping up its equipment.

The leather and shoe industry uses grinding wheels for the buffing of hides and for the sharpening of leather cutting and shaving knives.

The steel-mills use alundum grinding wheels for grinding out seams of high-speed steel billets preparatory to rolling into bar stock. The steel foundries use alundum wheels for snagging steel castings. Crystolon grinding wheels are used in foundries for snagging cast-iron castings, and for cleaning castings of brass, bronze, and aluminium. The railroad industry has extensive use for wheels composed of artificial abrasives.

Such

parts as locomotive piston-rods and valves must be ground on cylindrical grinding machines; guide bars must be surface ground with alundum grinding wheels; steel car-wheel treads and flanges sometimes are ground with alundum wheels, and manganese-steel frogs and switches have to be surfaced and fitted with grinding wheels composed of aluminous abrasive.

The optical industry uses aluminous abrasive wheels for lens grinding, and aluminous abrasive grain for roughing out lens blanks prior to polishing.

The cut-glass industry employs the artificial grinding wheel to a very large extent in curting the intricate designs that go to make up the beauty of this ware.

The marble industry employs silicon carbide abrasives in thin wheels for sawing marble into slabs, and in thick wheels for surfacing or moulding the marble into various shapes and designs.

The final polish on marble slabs used in interior building operations is obtained by means of abrasive blocks composed of very fine grit silicon carbide or alundum abrasive, followed by putty powder.

Selection of Wheels.-The main points to con sider in the selection of grinding wheels are as follows:

Material. High tensile strength (aluminous

abrasive). Low tensile strength (carbide of silicon abrasive). Operation.-Cylindrical; surfacing; internal;

sharpening; off-hand grinding. Bench stands; floor stands; swing frames; portable; electric; pneumatic; flexible shaft. Wheel speed; work speed; contact; condition and type of grinding machine; personal factor.

Material. Whenever a grinding job is presented to you, the first thing to think of is the nature of the material to be ground-whether it is hard or soft, &c. If it falls under the general head of a high tensile-strength material—such a all steels and down as far as the hard grades of bronzes-then an alundum wheel of some kind should be used. If, on the other hand, the material falls in the class of low tensile-strength materials--such as cast-iron, chilled iron, brass, soft bronzes, aluminum, and copper-then you should use crystolon wheels.

Operation. The next thing to consider is the nature of the operation to be performed by grind. ing; that is, whether cylindrical, surface, internal, sharpening, or off-hand grinding is demanded.

If the speeds deviate very much from these, and it is impossible to change them to suit our recommendations, then this must be taken into account in your recommendations. Speeds higher than those recommended call for slightly softer grades to offset the harder cutting action; and speeds lower than those recommended call for slightly harder grades than would be ordinarily supplied.

Work Speed. It is impossible to tell a customer the exact speed at which his work should be done on any given grinding job. It is largely a matter of experiment. The work speed should be suited to the wheel in use and the nature of the material to be ground. On the Norton cylindrical grinder, a speed of from 60 to 80 surface feet per minute is often used for roughing and from 30 to 40 surface feet per minute for finishing. On most types of precision grinding machines, it is customary to rough grind at a higher surface speed of work than on finish grinding.

Contact.-Contact affects grade selection. Broad contact calls for softer grades and narrow contact for harder grades, as the case may be. This is especially true in snagging and off-hand grinding. Where wheels are used for grinding the burr left by welding, or for grinding sharp fins from castings, extremely hard grades, such as S, T and U, are called for. In cylindrical grinding, the contact varies with the diameter of the wheel and the work, increasing with larger work or with a larger wheel, and thus making a softer grade of wheel desirable.

Condition of Grinding Machine.-This is something which you would really have to observe personally in order to understand how it would affect grinding wheel selection. If the spindle is loose and cannot be put in good condition, a harder grade of wheel must be used than would ordinarily be recommended. This is in order to overcome the tendency to pound the wheel face to pieces. Light, flimsy machines and machines improperly secured to the foundation also call for harder grades than would ordinarily be used. Machines are frequently placed in the middle of a wooden floor which vibrates badly and in this case harder wheels must be used than for a machine on a firm, solid foundation.

Personal Factor. This is extremely important in the operation of grinding wheels, frequently influencing the results obtained as much as 100 per cent. We mean by this that different men working on the same kind of machines and on the same work in the same shop will get one result, say 15 hours' life, whereas other men under exactly the same conditions might get 30 hours. This is based on records obtained and not on impressions, and explains why the same wheels will work differently in different shops.

(In the original, several woodcuts are given, illustrating the various

apparatus, &c.).

NOTE ON BRANNERITE.*

By ROGER C. WELLS, Ph.D., U.S. Geological Survey. THE mineral brannerite described in a recent paper in the JOURNAL OF THE FRANKLIN INSTITUTE and CHEMICAL NEWS, CXX., was carefully tested for helium, as it was expected that a mineral consisting of nearly 50 per cent of the oxides of uranium, and also containing thorium, should show at least a trace of helium. None was found, however, by the method employed. It was found that some sulphur dioxide was produced by reaction of the mineral and sodium bisulphate, and after removing this with a solution of sodium hydroxide, the remaining gas did not show the characteristic yellow line of the helium spectrum. Shortly after the paper was published the advantages of purifying the evolved gases by means of charcoal and liquid air were brought to the attention of the writer by Dr. R. B. Moore, of the Bureau of Mines, and it seemed desirable to repeat the test, using this method. Some highly active charcoal was kindly furnished by Prof. A. B. Lamb, of the Fixed Nitrogen Research Laboratory, American University, for the purpose. The clean-up of the gas by this method gave a decisive result indicating the presence of helium, which places the mineral in the list of uranium minerals in which helium has been identified. The test was conducted as follows:

About 5 grms. of brannerite was powdered and mixed with previously fused sodium bisulphate in a hard glass tube which was connected by a thick rubber tube to the Töpler pump. Between the hard glass tube and the pump were three stopcocks, and between the latter were sealed the tube containing the charcoal and a spectrum tube, respectively. The system was evacuated until a pressure of about o'05mm. was permanently obtained while the charcoal was heated. The spectrum tube and pump were then cut off, leaving the stopcock between the charcoal and mineral open while the bisulphate was gently fused. The tube of charcoal was then allowed to stand in liquid air for about half an hour to effect a clean-up of the gas. Finally the gas was admitted to the spectrum tube and a little later the tube was sealed off.

The yellow helium line showed up strongly in the spectrum, and several other lines believed to belong to helium were noted. These observations were made with a spectroscope having an illuminated scale and the wave-lengths were read from a curve based on some familiar flame spectra. The method does not give more than three *Published by permission of the Director, U.S. Geological Survey

significant figures. The values found ascribed to helium were 6660, 5880 (yellow line), 5030, 4720, and 4470. Two lines, 6545 and 4870, may represent hydrogen, whereas 6070, 5620, and 5200 are believed to belong to carbon. Among other lines noted but not placed are 5470 and 7000. The spectrum may be examined more carefully later if it should appear desirable, but the first object in view was to establish the presence of helium. At the conclusion of the experiment it was found that approximately half of the mineral taken was decomposed by the short fusion with the bisulphate.

PROSPECTS OF CEREAL CROPS AND OF SUPPLY.

ACCORDING to the June Bulletin of Agricultural and Commercial Statistics, just published by the International Institute of Agriculture, the official estimate of the winter wheat crop of the United States of 1920 is for about 13.7 million tons and that of the spring crop for about 75 millions. Hence the aggregate yield of wheat in the United States will be 212 million tons, or 27 per cent below that of last year, though only 49 per cent less than the average of the five years 1914 to 1918. It should, however, be remembered that the actual quantity exported from the United States during the current season falls short of the available surplus, so that stocks at the end of this period will be greater than those held last year.

Canada reports an area under wheat 17 per cent above the average from 1914 to 1918 also an excellent crop prospect, and it is therefore permissible to estimate that the yield will be equal to the average of the period mentioned, and much larger than it was in 1919.

On the basis of these statements, it is reasonable to expect that the North American exportable surplus of wheat for the season 1920-21 will be larger than the exports during that of 1919-20.

Government control of wheat ceased in the United States on June 1.

Crop conditions for wheat are favourable in Germany, Bulgaria, France, England, Wales, Ireland, Luxemburg, Sweden, Egypt, and average in Scotland, Italy, Poland, Switzerland, and Czecho Slovakia. In Hungary injury has Occurred owing to the great heat in May. The estimates of the recent wheat crops in British India have been increased from 9.9 million tons to 10.2 millions, and the new season is reported as developing normally.

The rye crops are favourably mentioned in France, Sweden and Switzerland, as in average condition in Germany, Italy, and Luxemburg, and as poor in Poland and Czecho-Slovakia. Vines and olives promise well in Italy. Rome, June, 1920.

NOTICES OF BOOKS.

The Letters of Berzelius. III. (Published in the name of the Swedish Royal Academy of Science). By H. G. SODERBAUM. 1920. Upsala: Almquist and Wiksels.

THIS Collection of letters, written between 1809 and 1847, contains the correspondence of Berzelius

with scholars of different nationalities, as well as their replies to him, wherever it has been possible to find them. But the letters given only deal with subjects of scientific interest. Berzelius, in his youth acquired the habit of speaking and writing in French, which habit was more strongly developed owing to his long sojourn in France, in 1818 1819, and to the fact that he moved with the diplomatic circles in the capital of Sweden. On account of this, Berzelius conducted all his corre spondence in French.

Among those whose letters are included in the above collection are Goethe, Dana, Wollaston Dumas, Gay-Lussac, Fischer, &c.

The editor is to be congratulated on the care that he has taken in gathering these letters, which must have involved considerable labour and patience. The book is interspersed with photo graphs of eminent scientists, whose correspon dence with Berzelius i included.

NOTES.

ROYAL INSTITUTION.-—A General Meeting of the Members of the Royal Institution was held on July 5; Sir James Crichton-Browne, Treasurer and Vice-President in the Chair. The Chairman announced that the Institution had received a legacy of £5,000 from the late Dr. Rudolph Messel, who was a Member for 30 years. death of Professor Auguste Righi, an Honorary Member, was reported and a resolution of condolence with the relatives was passed. Mr. A. E. Butler, Mrs. R. de l'Hopital, and Dr. W. A. M Smart were elected Members.

The

APPOINTMENT.-Professor Sir John Cadman, K.C.M.G., D.Sc., University of Birmingham, Mr. W. B. Hardy, Soc. R. S., Gonville and Caius College, Cambridge, and Professor Sydney Young, D.Sc., F.R.S., Trinity College, Dublin, have been appointed by an Order of Council dated June 24, 1920, to be members of the Advisory Council to the Committee of the Privy Council for Scientific and Industrial Research,

COMMEMORATION DAY AT LIVINGSTONE COLLEGE.❘ A very successful Commemoration Day, the first for five years, was held at Livingstone College, Leyton, on Friday, June 25. A large number of guests were present, including th Lord Bishop of Chelmsford, who occupied the Chair, the Bishop of Bendigo, the Bishop of Honduras, the Chaplain-General of the Forces, Mr. R. L. Barclay (Treasurer of the College), Dr. and Mrs. C. F. Harford (Founders of the College). At the meeting held in the grounds, after prayer led by Bishop Taylor Smith, a short statement was made by the Principal. Speeches were given by three former students of the College, Rev. J. Kerswell, of the Primitive Methodist Missionary Society, Mr. W. H. Soamell, of the Church Missionary Society, and Mr. R. A. Lorrain, of the Lakher Pioneer Mission. With many interesting anecdotes each missionary spoke of the great debt he owed to Livingstone College as regards his own

health and also in the help it had been in his missionary work; they told of many lives which have been saved through the use of their knowledge gained at Livingstone College, in cases where there was no qualified doctor near, and of the opportunities which this medical work gave for furthering their work as missionaries of the Gospel. They emphasised the necessity of all missionaries receiving such training before being sent abroad. The Bishop of Chelmsford spoke of his long connection with the College in many He felt that there never was a time when it was more important for English people to realise their responsibilities with regard to the mission field; missionary work was a point on which he felt very strongly. When he looked at Livingstone College he thought of it as deserving

ways.

the title of a "Workers' Life Preservation College." "Think," he said, "of the deplorable loss of life on the part of missionaries. Think of the time, cost, and trouble of sending a man out thousands of miles and then perhaps to die within a month or even a week of his arrival, from what could be called largely preventable causes.” He believed that through the knowledge gained at Livingstone College the lives of many missionaries could be saved and they would do much useful work. "The Government realised during the last war the value of proper medical attention being given to our men; the Church must take just as great pains to ensure the preservation of the life of her workers as the Government does of hers." He spoke of the unity in missionary work which the College was instrumental in advancing and said the College might also be called "A Preparation School for Re-union." He referred to the fact which had previously been mentioned, the large number of nations represented amongst the students of the College, in virtue of which the College might also be called "A Preparation School for the League of Nations." He ventured therefore from every point of view to advocate the claims of Livingstone College, which he believed to be worthy of the name of Livingstone, and he appealed to all to support it by sending students, by financial help and by prayer, in order to enable it to efficiently carry on its work, which he felt was so necessary to the missionary cause.

DETERMINATION OF MERCURY.-C. M. Bouton and L. H. Duschak (Journ. Frank. Inst.).—The volumetric methods for the determination of mercury described in the literature permit the selection of a variation of about 1 mgrm. of Hg. or within o per cent on a 1-grm, sample. As much of the world's supply of the metal is obtained from ores carrying less than 1 per cent mercury, a method that will quickly and accurately determine a variation of less than 1 mgrm. Hg is greatly to be desired. Of the numerous methods tested by the investigators of the Berkeley, Calif., stations of the Bureau of Mines in connection with a study of mercury condenser losses, the method of titration with potassium thiocynate, using ferric sulphate or nitrate as an indicator, proved to be the only one capable of the desired refinement. The titration is vitiated by the presence of any halide; therefore, in bringing the sample into solution, a method must be employed which absolutely excludes all halogen compounds. With slight modification, the method can be applied to

the determination of mercury in practically any material, including that containing considerable quantities of organic matter. Details as to the equipment used, analytical procedure, the modifications necessary when organic matter or much sulphur is present, procedure for assaying a filtered precipitate, alternative procedure for refractory samples; and the results of experimental determination of distillation procedure, effects of evolution of gas, possibility of retention of mercury by the charge, trial assay with sulphur and organic matter present, interfering elements, and titration are given in Technical Paper 227 of the Bureau of Mines. With readily provided facilities one operator can make 50 to 60 determinations in an eight-hour day, exclusive of the time reTechnical quired for preparing the sample. Paper 227 also includes a bibliography on analytical methods for the determination of mercury.

NOTICE.

OWING to the greatly increased cost of

printing and paper, and the advance

in the postal rates, we have been compelled to raise the price of the CHEMICAL

On Friday, July 9, 1920, the Publishing and Editorial Offices at 16, Newcastle Street will be closed for the purpose of removing to

97, SHOE LANE, LONDON, E.C. 4,

CHEMICAL DEPARTMENT, now vacant by the appointment of Dr. T. S. PRICE as Director of Research to the British Photographic Research Association.

Full particulars of the appointment can be obtained from the SECRETARY, Municipal Technical School, Suffolk Street, Birming

ham.

ASSISTANT CHEMISTS wanted at once

for the Admiralty Inspection Laboratories at Holton Heath. Candidates must have a qualification equivalent to that of the Associateship of the Institute of Chemistry, and must possess a sound knowledge of Technical Analysis, preferably explosives.

The posts are non-pensionable and the salary is subject to bonus, the present value of the commencing salary being £319, rising by £16 annually to £412.

Applications, stating qualifications and experience, should be made by letter to the INSPECTOR OF NAVAL ORDNANCE, Holton Heath, near Wareham, Dorset.

Wanted, well-trained LABORATORY AND

LECTURE ROOM ASSISTANT to take charge in the Chemical Department, McGill University, Montreal, Canada. Duties: Distribution and ordering of Supplies and Apparatus, setting up Lecture Apparatus, simple Repairs. &c. Must be experienced, steady, and have mechanical ability. Wages

30 dollars per week Duties begin September 15.-Apply, with

references and qualifications, to G. S. WHITBY, 8, Victoria Avenue,

Hull, Yorkshire, before August 10.

A JUNIOR of either sex with some know

Tedge of Chemistry, and commercial experience in chen ical analysis, is required for a junior position in the Laboratory of a large Chemical Works. Kindly state salary required to Box 103, c/o SCOTT & SON, 63, Ludgate Hill, London,E.C.4.

10 a.m. on Monday, July 12.

wanted for laboratory in Newcastle-on-Tyne. Those having experience in analysis of non-ferrous metals and alloys referred. Reply stating age, experience, and salary required to Box 804, c/o Scott & Son, 63, Ludgate Hill, London, E.C. 4.

THE water here described is from a well in the town of Sangerfield, Oneida County, New York, about a mile-and-a-half south of the village of Waterville. It is on the flat land in the bottom of the Sangerfield valley, near the head waters of the Chenango River.

The well is forty-three feet in depth and was sunk in the early '80's. The top soil of the land in the locality is a clay loam, and in boring the well the first twenty-seven feet encountered was hard clay, underneath which was a dark coarse sand, entirely different from any other formation in the neighbourhood. It is an artesian well and flows continuously. The summer and winter temperature of the water is practically constant. The figures express the amounts of the different sub stances in a million parts of the water.

The water is pure and likewise unusually soft for the particular locality.

Dr. A. P. Brigham, Professor of Geology in Colgate University, in a private communication says: "The bedrocks in Sangerfield at any moderate depth would be sandstone or possibly shaly sandstone of the Hamilton group; but the fact is that most of the well waters and pond waters of the region are very hard owing to the amount of limestone flour which has been incorporated in the local materials of the glacial drift by moving from limestone formations that lie to the northward. However, water of a softer character is sometimes obtained from the valley bottoms under thick beds of clay."

This water affords another good illustration of how the character of the soil determines the quality of the water in the region.

Our thanks are due to Dr. Nelson O. Brooks, Physician of the Board of Health of the City of Oneida, New York, for his interest in sending us the sample of water for the analysis.

2. This is a shallow well, only twelve feet deep, also in Oneida County, New York, near Fish Creek, on the premises of James L. Bentley. It is located possibly eighteen or twenty miles from the well described in 1. The analysis is as follows:

NaCl and KCl

Free ammonia

Albuminoid ammonia

Nitrogen in nitrates Nitrogen in nitrites

...

186.40

2.60

...

0'00 1.80

...

99.60 27.00

47'40

11.80

0'00

0'00

0.002

The water is also pure and soft, as would be expected from the locality in which the well is located. It is in the pure white sand about a half mile distant from Oneida Lake. The water doubtless comes from the lake and so has a half mile of pure sand filter. This would easily account for its freedom from organic contamination and the absence of much material in solution. We desire to express our thanks to J. L. Bentley for sending us this sample of water. Cornell College, Mount Vernon, Iowa, June 12, 1920.