gung eine Menge auf, welche genau so viel Sauerstoff als eine Salz-basis enthält, von der diese Mange Säure gesättigt wird.

Zweitens mit Salzbasen. Das Wasser spielt hier in so fern die Rolle eine Säure, als es ihre Stelle vertritt, enthält aber nur gleiche Theile Sauerstoff mit der Basis, oder ist zuweilen ein submultiplum vom Sauerstoff der Basis."

He uses the term hydrate freely, speaking of "Hydrate der Thonerde" and "Eisen Hydrate. Vauquelin in 1813, repeating an analysis published by Prof. Bruce of New York, confirmed the findings of the American:

49

When water unites with a solid body and preserves with it the solid state, it is in this case, only, that one gives to the combination the name of hydrate.' He refers to soda and potash as hydrates, and mentions the hydrate of lead. None of these authors used the term hydroxide, for, at this time, it had not been generally accepted. Graham, 23 considering water as a constituent of salts, does not employ the term hydroxide, but he had the concept, for he distinguishes carefully between the water combined in acids and that in bases following the hypothesis of Berzelius already quoted. Thus Graham:

"In the hydrates of the caustic alkalies and of the earths, water is retained by a strong affinity, and is generally supposed to be united, like an acid, to the alkali or earth. In such hydrates water discharges an acid function."

"In the case of hydrates of the acids,* the portion of water which is found to be inseparable by heat, or to be very strongly retained, has generally been presumed to be in the place of a base to the acid, although little attention has been paid to the subject.

The most highly concentrated sulphuric acid retains one atom of water, and is supposed to be a sulphate of water."

*It is hardly necessary to remind the reader that at this era the oxy-acids were not regarded as hydrogen compounds, but what we now term the acid anhydrides, or acidic oxides, were termed acids and the combinations of these oxides with water were called hydrates of the acids.

In the "Hand-Book of Chemistry" of Leopold Gmelin,20 published in 1849, we begin to get a more definite statement about water-compounds; he defines oxides:

"The act of combination of oxygen with other bodies is called oxygenation (combustion); also acidification, when the resulting compound is of an acid nature; oxidation in the contrary case. The oxygen is the oxygenizing body (supporter of combustion); also, according to circumstances, the acidifying or the oxidizing body.' v. 2, p. 38.

"Oxygen forms about 136 inorganic. compounds; they are as follows:1. Of acid nature

a. Non-metallic oxygen acids.
b. Metallic oxygen acids

2. Compounds not of acid nature:
Oxides. v. 2, p. 38.

Gmelin does not use the term hydroxide, which, indeed, was not common in Germany, the word hydrate being there used. It is clear, however, that his idea of hydrates was that of the modern concept of basic hydroxides, and there can be no doubt that, had the question been raised, he would not have extended the term hydroxide to include the oxy-acids. Silliman is not so definite:

46

it combines with many substances, forming a large class of hydrates: hydrate of lime and potash are examples. It is also, as we have seen, essential to the acid properties of common sulphuric, phosphoric, and nitric acids, acting here the part of a much more energetic base than in the hydrates. p. 249.

He seems, nevertheless, inclined to limit hydrates to basic compounds. Newth37 unequivocally asumes this position:

'Binary compounds that are formed by the union of elements with oxygen are called the oxides of these elements. C'ertain of these oxides are capable of entering into combination with water, giving rise to substances known as acids; such acids are distinguished as acid-forming oxides, or acidic oxides. They are also sometimes termed anhydrides. All the non-metallic elements, except hydrogen, form oxides of this order, and the acids derived from them are known as the oxy acids.

ments, are brought into contact with acids, chemical union takes place, and a compound termed a salt is formed. Such oxides are distinguished as salt-forming. or basic oxides. There are also oxides which are neither acidic nor basic." p. 17. These quotations serve to present a clear picture of the notion that hydroxides are water compounds and they show in addition the diversity of opinion in respect to the limits of application of the term. will be obserevd that, while the term hydrate is used throughout in most of the citations, the writers clearly had in mind those compounds which to-day would be termed hydroxides. We turn then to the consideration of the view that hydroxides are hydroxyl compounds, and first examine the broadest application of this view.

It

This conception is not of very great age. It appears only a short time before the publication of the theory of ionisation. Fownes, 50 in 1885, and this is the earliest reference to this specific concept that I have found, says:

"Water acts on many oxides, both acid. and basic, with great energy and considerable evolution of heat, producing compounds called hydroxides." p. 159. Underhydrates,' the 1889 edition of Watt's "Dictionary of Chemistry, read the following:

we

"Another way of stating the theoretical difference between hydrates and hydroxides is to say that hydrates contain water as such, and that hydroxides contain the elements of water.' p. 703, v. 2.

"The term hydroxide is sometimes used in a narrower sense than explained above; by some chemists it is applied only to compounds whose reactions are best explained by supposing them to contain the group or radicle OH." p. 704. Remsen42 in 1899 supported this view: the hydroxides form two of the most important classes of compounds, known as acids and bases." p. 61. Goodchild and Tweney" define an hydroxide thus:

..

"A compound containing the hydroxyl group OH. Hydroxides may be acid or alkaline in character.". p 298. "Funk and Wagnall's Dictionary" presents this definition:

17

"A compound containing the group hydroxyl, and formed by the union of the moelcules of water, so that a rearrangement of the atoms takes place, yielding hydroxyl." p. 880.

The "Handwörterbuch der Naturwissenschaften," Jena, 1914, is in accord with this view.

"Hydroxyde kennt man Verbindungen welche die einwertige 'Hydroxyl' gruppe -OH enthalten. v. 5, p. 344. The definition given by "Webster's'52 is :

"A compound of an element or radical with hydrogen and oxygen, not regarded as containing water. The term is

usually applied, and by many chemists restricted, to compounds containing the group OH, or hydroxyl. Hydroxides may be basic, neutral, or acid, according to

Dr. Gray's book is evidently an earnest endeavour of an ardent teacher to place before the student and drive home the essential fundamentals upon which the facts of Inorganic Chemistry are based.

At the present time there is urgent need for such a text-book, and in the main the author's attempt at unravelling the tangle has been successful. In doing so he has not hesitated to make use of the latest experimental results and theoretical deductions. He commences with the brief essen-tials of the historical development of the periodic classification of the elements. and including the subject matter and the latest information. Until recently, the periodicity of the elements was usually and most suitably represented by Mendeléef's Table. There are now other schemes (e.g., Loring's Wedge Table, The Chemical News, 1922, CXXV., 387), and the author has incorporated a pyramidal scheme which he states is based on Langmuir's conceptions of atomic structure.

There are several minor points in which the reviewer feels that the volume might be improved to increase its general utility to students. It sometimes seems rather an account of the tangle than its unravelling. Thus, whilst avoiding a catalogue of facts, the author has gone to the extreme of assuming that the student already has a good general knowledge of them in his possession, even though they be in a tangle.

In the chapter entitled Multiplex Anions and Multiplex Cations, reference could be made to a number of bodies of very minor significance, and there is a tendency to coin expressions. Most of the information in the chapter on the Formation of Complex Ions is valuable and important, but the author is wrong in stating (p. 92) that magnesium chloride is the only chloride of group II. A which forms double chlorides. In the same chapter, the presence of water in certain double salts is disregarded.

Except at the end, there are no diagrams, which is a disadvantage, since these are very helpful in visualising various matters.

The author has undoubtedly produced a book which should stimulate a true interest in science in the students' mind, and those who take students through the labyrinths of advanced Inorganic Chemistry would probably profit by a perusal of this work.

J.G.F.D.

Alloys Resistant to Corrosion, a General Discussion held jointly by the Faraday Society and the Sheffield Section of the Institute of Metals, April 1923. Price 5s. 6d. From time to time the Faraday Society for arranges meetings discussions on Physico-Chemical subjects of importance and interest. At these meetings papers are read and discussed by the eminent scientists who are invited and attracted.

Thus, in April last, there was a general discussion on Alloys Resistant to Corrosion, held jointly by the Faraday Society with the Sheffield section of the Institute of Metals, and the Manchester Metallurgical Society (an account of which appeared in The Chemical News, April 20, pp. 246-9). The contributions were subsequently published in the Society's Transactions, but in order to reach a wider public, are now reprinted in book form.

No definite theory of corrosion emanated from the discussion, but much valuable information was gathered together concerning the methods of prevention, etc.

The reprint is not only of interest to academic physicists and chemists, but also to engineers and technicians.

Chemistry, Inorganic and Organic, by CHARLES LOUDON BLOXAM. Eleventh edition, revised by ARTHUR G. BLOXAM, F.I.C., and S. JUDD LEWIS, D.Sc., F.I.C. Pp. IX. + 832. London: J. & A. Churchill, 7, Great Marlborough Street. 1923. Price 36s.

In Bloxam's chemistry, both the Inorganic and the Organic Sections of the science are considered in adequate detail and in one volume. This arrangement certainly has obvious advantages, especially from the point of view of the student who needs a general knowledge of the whole science. It is evident that the present authors had this in mind, since there is a long section on the general principles of Physical Chemistry which has been inserted following the treatment of the non-metals and preceding the chemistry of the metals.

The early chapters deal with water and its elements; the Air and its constituents and the general properties of Gases; hydrogen, occlusion, reduction, oxidation; the halogens; the sulphur, phosphorus, carbon and boron, and argon groups.

The treatment of the metals as based upon the Periodic Classification.

The chapters on organic chemistry follow the usual plan of arrangement, except that

aliphatic and aromatic substances are described together in the same chapter.

By incorporating both branches of the subject in one volume, the authors have been able to describe such organic metallic derivatives as the cyanides, simple and complex, in a chapter in the organic portion of the book. They have, however, given an account of acetylene, ethylene and methane in the inorganic section.

The section on physical chemistry gives a good account of the present position in that subject and, as might be expected, the chapter on spectroscopy is particularly good.

Whilst such a comprehensive volume as this lends itself to criticism on the grounds that some sections must receive better treatment than others, it must be admitted that this edition fully maintains the traditions of the previous ones.

BOOKS RECEIVED.

From Determinant to Tensor, by W. F. SHEPPARD, Sc.D., L.L.M. Pp. VIII. + 127. 1923. The Clarendon Press, Amen Corner, Paternoster Row, E.C.4. 8s. 6d. net.

Radio-Activity, by K. FAJANS, Professor of Physical Chemistry in the University of Munich. Pp. XII. + 138. 1923. Messrs. Methuen & Co., Ltd., 36, Essex Street, W.C.2. 8s. 6d. net.

Kolloide in der Technik, von DR. RAPHAEL ED. LIESEGANG. Pp. 157. 1923. Herr Theodor Steinkopff, Residenzstrasse 12b, Dresden & Leipzig.

We have received a copy of the Year Book of the Michigan College of Mines, 1922-23, which also contains announcements of the courses of instruction for the session 1923-24.

We have received a copy of the Prospectus of University courses in the Municipal College of Technology. It gives particulars concerning the College and its courses and examinations.

PAMPHLETS ISSUED BY THE UNION OF SOUTH AFRICA, DEPARTMENT OF AGRICULTURE.

Notes on the Chemical Control of CattleDipping Tanks, by C. O. WILLIAMS, B.Sc. Pp. 137 + 141.

The Estimation of Fineness in Basic Slag, by DR. CHAS. F. JURITZ. Pp. 5.

Some Analytical Methods, by H. F. L. BISCHOFF and B. DE C. MARCHAND, B.A., D.Sc. Pp. 8.

Some Observations on the SulphateMolydate Method of Determining Phosphoric Oxide, by V. A. BECKLEY and A. MARAIS. PP. 5.

Investigation of Different Methods of Testing Babcock Milk Bottles, by C. 0. WILLIAMS, B.Sc., A.R.C.S. Pp. 132 + 136. Representative Transvaal Soils. The High Veld Sandy Soil, by B. DE C. MARCHANT, B.A., D.Sc. Pp. 6.

The Composition of Some Indigenous Grasses, by ALEXANDER J. TAYLOR, B.A. Pp. 218 + 232.

New Patents.

THIS list is specially compiled for The Chemical News, by Messrs. Rayner & Co., Registered Patent Agents, of 5. Chancery Lane, London, from whom all information relating to Patents, Trade Marks, and Designs can be obtained gratuitously.

Latest Patent Applications. 23557-Casale, L.-Production of catalysts for synthesis of ammonia. Sept. 20.

23570-Casale, L.-Apparatus for catalytic production of synthetic ammonia. Sept. 20. 23424-Dreyfus, H.-Manufacture of aliphatic compounds. Sept. 10.

23565-Fraymouth, W. A.-Recovery of calcium oxalate, &c., from trees. Sept. 20. 23231-Badische Anilin & Soda-Fabrik.-Manufacture of active carbon. Sept. 17. 23348-Badische Anilin & Soda-Fabrik.-Production of vat colouring-matters. Sept. 18. 203533-Badische Anilin and Soda-Fabrik-Manufacture and production of dyestuffs and intermediate products therefor. 203551-Hovey, R. B., and Hovel, F. L.-Nitrate of lime.

Specifications Published this Week. 203352-Weizmann, C., and Blumenfeld, J.-Production of titanic acid.

203383-Perkins, W. G., and Beasley, W. H.-Production of refined copper from copper oxide.

186329-Parodi, P. Distilling apparatus for continuous operation.

Abstract Published this Week. 201786-Dyes.-Kalle & Co., Akt Ges., 23, Rheinstrasse, Biebrich-on-Rhine, Germany. Perylene derivatives.-By treating perylene3:49:10-tetracarboxylic acid, or a substitution product thereof, with ammonia or primary aromatic or aliphatic amines, it is converted into difficultly soluble imides which dye animal and vegetable fibre in fast red to blue-violet shades from the vat. In examples the acid or its ammonium salt is heated with ammonium carbonate, methylamine hydrochloride, or aniline; cther suitable amines are p-chloraniline,a or B -naph thylamine, a or B-amino-anthraquinone, also diamines such as o-, m-, and p-phenylene-diamines, 1: 8-naphthylenediamine, and benzidine. perylene 3:4:9:10-tetracarboxylic acid may be prepared by oxidizing with hypochlorite, chromic acid or other oxidizing agent, the vat dyes made by alkali fusion of perinaphthindanone or perinaphthindandione.

The

Messrs. Rayner & Co. will obtain printed copies of the published specifications and abstract only. and forward on post free for the price of 1s. 6d. each.