overseas, experience goes to show that resonance does not occur.

The static condenser, as built in Great Britain, is essentially a medium-pressure apparatus, the most economical voltage being about 600, but condensers have been, and are, built for direct connection to supplies up to 3,300 volts. It should be noted that only in exceptional cases is it cheaper to supply a high-tension condenser, and that the saving is not even then very material, usually not more than 10 to 15 per cent. of the overall cost of the equip

ment.

Undoubtedly, the right place to put the condenser is on the low-tension circuit, as by so doing the improvement will be effected as far as possible out on the distribution network, and it has been found in practice that the call for high-tension condensers is very small compared with that for low-tension ones.

A case has been reported from overseas of a British-made 100 kVA 3,300 volt outdoor condenser, which, for the purpose of test and experience generally, is connected direct across the high-tension overhead transmission line without any protection whatever, and is therefore subject to every kick and surge on the system. Nearly 12 months have now elapsed since the condenser was first connected and it continues to give every satisfaction. This should be sufficient evidence to show that the static condenser does not in reality possess the attributes of frailty so frequently ascribed to it.

A comparatively new development is the low-tension pole-type condenser connected direct across pole-type step-down transformers, this application being particularly useful in the case of rural distribution. A number of British-made condensers of this type have been working for some considerable time in New Zealand, and it is reported by the engineer of one Power Board that, from the point of view of improved regulation only, the installation was worth while. In this case, however, the annual saving effected is sufficient to repay about 70 per cent. of the cost of the equipment, and to this has to be added the increase in the useful output of the transformer, as the condenser being connected on the low-tension side of the step-down transformer unloads the transformer of wattless current, and for every 2 kVA of condenser capacity under industrial conditions, the load on the trans

former will be reduced by approximately 1 kVA.

The efficiency of the static condenser is very high, about 99.7 per cent., so that the losses are almost negligible. A bank of

direct-connected condensers having an output of 1,000 kVA would have a loss of only 3 kW. Where auto-transformers are used for stepping up the voltage from that of the supply to the most economical voltage for the condenser, the auto-transformer losses have to be added, but the overall losses of large complete equipments for the usual industrial voltages may be taken to be between 1 and 1.5 per cent. of the output in kilo-volt-amperes.

It is well known that the output of a condenser is directly proportional to the plate area, and inversely proportional to the thickness of the dielectric, which latter is mainly dependent upon the applied voltage across the plates.

NOTICES OF BOOKS.

The Laboratory Book of Mineral Oil Testing. By JAS. A. HICKS (late Chief Chemist to Sir Boverton Redwood). VIII +128 pp. Price 5s. net. London: Charles Griffin and Co., Ltd.

This work, which has been revised by Arthur W. Cox, F.C.S., and which has an excellent introduction by the late Sir Boverton Redwood, D.Sc. (Adviser on petroleum to the Admiralty and the Home Office), is clear and concise, and of the practical kind. Considering the great part which mineral oil plays in the commercial life of the world, it will be welcome, and goes a long way towards placing the testing of the commodity on a satisfactory basis. The author has given a useful manual which must be welcome to all connected with the mineral oil laboratory, and will be read with interest by all connected with the great mineral oil industry.

Allen's Commercial Organic Analysis. (A Treatise on the Properties, Modes of Assaying, and Proximate Analytical Examination of the Various Organic Chemicals and Products employed in the Arts, Manufactures, Medicine, etc.) Edited by Samuel S. Sadtler,, S.B., Elbert C. Lathrop, Ph.D. and C. Ainsworth Mitchell, M.A., F.I.C. X + 648 pp. 30s. net. London: J. and A. Churchill.

With such competent editors and the help of several eminent contributors, one will very naturally expect a work of outstand

ing merit, and these expectations are amply fulfilled. Essential oils are dealt with very fully by E. K. Nelson, G. A. Rusell, Ernest J. Perry, B.Sc., and others. Essential oils of all kinds are exhaustively dealt with, and so (though to a lesser degree, obviously) are resins, indiarubber, guttapercha, etc. It is a standard work, which will be appreciated by all concerned with or interested in the matters dealt with, and analytical chemists generally.

OFFICIAL AND OTHER
PUBLICATIONS.

Canada To-day. The Annual Reference Book about Canada.

This is a profusely illustrated book of some 212 pages on the industries, resources, and progress of Canada. It is issued by the Canada Newspaper Company, Ltd., London, price 2s. 6d., a price which could not possibly pay for its production.

Canada.-Descriptive Atlas.

This is a quarto book of some 80 pages, giving maps of the various provinces, etc., composing Canada,also letterpress shewing the population of cities, towns and villages, resources, industries, etc. It is issued by the Ministry of Immigration and Colonisation at Ottawa, and very naturally dresses the window attractively.

The Canadian Patent Office Record. The Phillipine Journal of Science. (Bureau of Science, Manilla.)

Scientific Papers of the Institute of Physical and Chemical Research, Hongo, Tokyo.

Japanese Journal of Chemistry. ional Research Council of Japan.) Mineral Resources of Alaska.

ment of the Interior, U.S.A.)

(Nat

(Depart

The Copper Deposits of the Near Salmon, Idaho. (U.S.A. Department of the Interior.)

Ore Deposits of the Saddle Mountain and Banner Mining Districts, Arizona, U.S.A. Geology and Water Resources of the Mud Lake Basin, Idaho.

Surface Water Supply of the U.S.A., Part VII. Lower Mississippi River Basin.

We have received a copy of the "Grassendale " Diet Chart, compiled by Dr. S. G. The Chart Millimott and Mr. F. Wokes. summarises a vast amount of research on

SOCIETY OF GLASS TECHNOLOGY. Applied Science Dept., The University, St. George's Square, Sheffield. Wednesday, February 17, at 2.30 p.m.

ROYAL INSTITUTION.

21, Albemarle Street, London, W.1. Tuesday, February 16, at 5.15 p.m... Prof. J. Barcroft, "The Egg." (1).

Thursday, February 18, at 5.15 p.m. Dr. J. L. Myres, "Who were the Greeks? (3).

Friday, February 19, at 9 p.m. Hon. J. W. Fortescue, "George III. in his Papers." Saturday, February 20, at 3 p.m. Dr. G. Macdonald, "Roman Britain."

(1).

be read :

"On the Hyperbola Method for the Measurement of Surface Tension," by A. Ferguson, M.A., D.Sc., and I. Vogel, B.Sc.

"The Application of Radiography to the Study of Capillarity," by E. A. Owen, M.A., D.Sc., and A. F. Dufton, M.A., D.I.C.

A demonstration of "The Application of the Piezo-Electric Properties of a Rochelle Salt Crystal and the Tri-Electrode Valve to the Determination of Impact Stresses in Granular Material," will be given by J. J. Hartley, M.Eng.M.Sc., A.M.I.C.E., and R. H. Rinaldi.

ROYAL SOCIETY OF ARTS. Wednesday, February 17, at 8 p.m. James Edward Taylor, M.I.E.E., Superintending Engineer, Post Office Telegraphs. etc., South Midland District, "The Propagation of Electric Waves," Admiral of the

243,990.-Alkali carbonates and hydrates. -Meyerhofer, A. F., 10, Goethestrasse, Zurich, Switzerland.

Alkali, alkaline earth, and titanium fluorides; sodium titanium fluoride; alkali carbonates and hydrates.-The process of the parent Specification is modified by using salts of other complex hydrofluoric acids instead of salts of hydrofluo-silicic acid. In an example sodium fluoride is reacted with calcium fluoride, and the sodium carbonate solution is separated from the calcium fluoride. The calcium fluoride in weak hydrochloric acid solution is treated with sodium chloride and titanium fluoride to obtain sodium titanium fluoride, which is heated to obtain sodium fluoride and titanium fluoride which are both used again,