a superficial disintegration or decomposition, but I could not by the microscope or by polarized light detect a difference in its structure. I hope, however, to do so by a more prolonged and varied examination.

It may be well to state that counter experiments were made, such as allowing the plates to remain with the letters between them, but without electrization, in which case no effect was produced; but it is probable, by analogy with Moser's class of phænomena, that a very long period of contact would produce some effect.

THE

IX. On Glyoxal. By Dr. H. DEBUS*.

HE great difficulty of preparing glyoxal quite pure led me to deduce the formula of this substance from the composition of its compounds, and the alterations it undergoes in contact with other bodies. But since the second memoir on this subject was written I have succeeded in analysing pure glyoxal, and find that its composition must be expressed by the formula C202. H2. It is hydruretted oxalyle.

Since acids contain as many atoms of hydrogen and carbon as their corresponding aldehydes, the formula of glyoxylic acid is probably C2 H2 O3.

The common aldehyde is monobasic, and only one acid corresponds to it.

The bibasic glyoxal forms, on addition of oxygen, two acids,glyoxylic and oxalic acids.

C2 H4 O

+ 0

=

C2 H4 O2

Therefore glyoxal is the aldehyde of the alcohol glycol, and of glyoxylic and oxalic acids. From the formula of glyoxal, C2 H4 O3, in my second memoir, one atom of water must be deducted.

Queenwood, December 25.

*Communicated by the Author.

X. Notices respecting New Books.

Elements of Chemical and Physical Geology, Vol. II. By GUSTAV BISCHOF. Translated by B. H. PAUL, F.C.S. (Published by the Cavendish Society.) London, 1855.

COMPA

YOMPARATIVELY few, if any works, certainly none to the same extent, have issued from the English press of the nature and tendency of that of which the one before us is a translation. The study of chemical geology may be said almost essentially to characterize the industry and research of the German schools, as the numerous papers published in the journals of Leonhard and Poggendorff fully testify, and which have been further enriched by the labours of the Swedish and Norwegian chemists. In France it has engaged the attention of Ebelmen, Delanoue, Delesse, and other able chemists. In America, Silliman's Journal contains the results of the researches of Dana, Rogers and others, bearing on this subject. Not that the inquiry has been entirely neglected in England, but the notices have been but few and far between, and chiefly in this Journal, and also in Jameson's Edinburgh Journal. No special work has been devoted to the subject, although much valuable information bearing upon it is contained in the Geological Observer' of Sir Henry De la Beche. That mineralogy* and mineral geology have not received that attention to which they are justly entitled may be partly borne out by the fact, that in the seven volumes of the 2nd series of the Transactions of the London Geological Society, valuable and important as are the papers contained therein, there are but, strictly speaking, one or two communications bearing on the above subjects, nor in the Journal of the same Society can we find but few mineralogical papers, and those of late date, by Haughton, Dick, Tayler, Ansted, and D. Forbes. It is with no spirit of rebuke, but rather of regret, that we allude to these facts, with the hope of a continuance of similar memoirs to those by Phillips, Bournon, and M'Culloch, which more than forty years ago enriched the first series of the Geological Transactions. Lured by the discoveries in Palæontology, and attracted by the varied interesting organisms which reveal the life-periods of the globe and assist us in determining or understanding their succession, geologists have been more interested in the inquiry respecting the nature and relations of these ancient organic beings, rather than in "that daily sacrifice to truth" which the study of chemical geology requires.

The mere possession or cabinet study of a fossil or a mineral does not constitute, as it ought not to satisfy, the requirements of the palæontologist or mineralogist; the place of a fossil shell or crustacean in the zoological scale is simply one thing, but its importance

The latest special work in England on mineralogy, is the edition of Phillips by Brooke and Miller, in which the crystalline forms are carefully worked out; on this subject the Treatise on Crystallography by the Rev. W. Mitchell is a valuable and important contribution to the science, as in explaining his own crystallographic notation, the equivalent symbols of Naumann, Miller, Brooke and Levy are also given.

becomes more manifest when we inquire as to the analogy or dissimilarity to existing forms,-its mode of occurrence-the relative abundance or scarcity-the broken or preserved condition-the organisms with which it is associated-the nature of the rock, mud, sand, gravel, or calcareous matter,—and other circumstances which would lead to the inference respecting the probable depth of the sea, and whether the creature had lived on the spot or been drifted from a distance. So with a mineral, its chemical constitution is one thing, but its mode of occurrence another-the species with which it is associated the composition of the rock in which it is imbedded, whether intimately mixed, occasionally aggregated or in distinct crystals-whether occurring in veins or fissures-the chemical relations of the substance to the containing rock, whether segregated during consolidation of the rock or subsequently elaborated, are some of the points of inquiry in the 'paragenesis' of a mineral species.

Independently of mineralogy, geology has also received important aid from chemistry, in determining the composition of rocks and the changes they have undergone, in suggesting the various processes of fossilization, in explaining the results of volcanic and pseudo-volcanic phænomena, &c. It is well known that Prof. Bischof has devoted a considerable portion of his time to the bearings of chemistry on mineralogy and geology, and his original work evidences a vast amount of labour and research in collecting together so much useful matter. The English edition is translated from a revised copy by the author of the original work; the facts are more condensed, the subjects are arranged in a more systematic order than in the German edition, and treated in such a manner, as to render it not only a useful work of reference, but a standard treatise for some time upon many of the important and interesting questions in chemical and physical geology. The present edition is by no means a mere translation or abridgement of the German, but an independent work, in which the additional chemico-geological facts ascertained since the publication of the latter, have been incorporated and concisely illustrated.

Our space will scarcely permit any details of the numerous valuable facts contained in the work, but the following are some of the principal subjects treated in the first and second volumes. The laws of combination in the mineral kingdom as regards the decomposition, conversion and formation of minerals and rocks; and pseudomorphism, which affords such important aid, and is in a great measure the storehouse out of which the knowledge of these laws are chiefly to be drawn, is fully considered, as described from the labours of Rose, Haidinger, Blum, Breithaupt, and the author.

The waters on the earth, by which the greatest part of its surface has been formed or modified, the deposition of chemical and mechanical sediments and those from organic agency, the share which the mineral kingdom takes in the change of the constituents of atmospheric air, are successively treated; the later chapters of the first volume are devoted to the consideration of the simple salts, according to their distribution and importance. The second volume is more useful to

the mineralogist, as it contains the chemical reactions relating to the alteration of minerals, and describes in detail the characters, occurrence, formation, and decomposition of many of the more important minerals which either enter into the composition of rocks or are essentially connected with them, as the silicates, quartz and other siliceous minerals, zeolites, felspar, tourmaline, garnet, augite and analogous compounds, mica, chlorite, serpentine, steatite, talc, and magnetic iron-ore. Under the last subject the magnetic influence of rocks is treated, but no allusion is made to the important paper by M. Delesse, published in the Annales des Mines for 1848.

Wernerian tendencies are strongly exhibited throughout the work, for Prof. Bischof considers that the origin of many minerals may be explained by the aqueous agency, although he does not doubt that their formation may have also taken place by fusion. How far geologists will be inclined to agree with him, that, "with the exception of lava, scoriæ, and other volcanic products, there is no rock whose igneous origin can be proved with equal certainty," is a question. That the igneous theory per se has been too hastily or generally adopted for the explanation of some of the phænomena attributed to it, may require further investigation. The combination of both agencies, assisted by thermo-electric action, acting upon masses of rock, may have induced an alteration in their molecular arrangement and brought into play new chemical affinities, thereby eliminating fresh mineral compounds, and which have again been altered by the influence of other processes, perhaps more gradual in their operation.

The study therefore of the conditions under which minerals occur in nature is more important than their mere chemical composition; for, as remarked by Prof. Bischof, "chemical analyses of minerals acquire a much higher value when their object is not merely the establishment of chemical formulæ, but also the elucidation of their genetic origin. Mineralogists have established the important fact, that one mineral may appear in the form of another, and it is the business of chemists to point out by what processes alterations or displacements may be effected. It is but rarely that the chemist is able to produce artificially the changes observed in nature; and in order to trace the various stages of these natural processes, there remains no other course for him to pursue than to ascertain by analysis the increase of the non-essential and the decrease of the essential constituents, and from the nature of the former to draw conclusions as to the processes which were going on in the mineral when found." While we feel indebted to the Cavendish Society for the publi cation of this work, we cannot but congratulate Prof. Bischof in the translation having been entrusted to Mr. Paul*, whose chemical knowledge and acquirements are a sufficient guarantee for the care with which the spirit of the original manuscript is rendered, and who has thus contributed towards the production of a treatise which ought to be acceptable as well as interesting to a large class of scientific readers.

* The first volume is the joint translation of Dr. Drummond and B. H. Paul, F.C.S.; the second volume is entirely translated by Mr. Paul.

`An Introduction to the Use of the Mouth-Blowpipe. By Dr. T. SCHEERER. Translated, with additions, by H. T. BLANFORd. Leipsic and London, 1856.

It is unnecessary here to remark on the advantages of the blowpipe in the investigation of mineral substances. From the time of Swab to that of Gahn, it was an instrument more or less applied in chemical research; to Berzelius, however, we are indebted for extending and improving its application, and his work, The Use of the Blowpipe,' 1821, was translated into most of the European languages, and was long considered a standard work on the subject. C. F. Plattner, continuing the researches of Harkhort, and having devoted some years to the use of this instrument, published about twenty years since, Die Probirkunst mit dem Löthrohre, of which, two much extended editions have subsequently appeared, and have been translated into English by Dr. Muspratt.

The Löthrohrbuch of Scheerer is intended as an introduction to the use of the blowpipe; the first part of that work, containing the use of the mouth-blowpipe, being only translated by Mr. Blanford, This part includes a short description of the apparatus for researches with the blowpipe, and instructions for the qualitative examination of substances so as to ascertain the presence or absence of certain bodies; and to which is appended two Tables, the first containing the various metallic oxides arranged according to the colours they impart to borax and microcosmic salt respectively; the second on the behaviour of metallic oxides and certain metallic acids, with the same reagents, this table being extracted from Plattner's larger work. To this has been added by the compiler a second part, and which occupies more than half of the remainder of the book, containing the characters presented before the blowpipe of many of the most important and frequently occurring mineral species, these being arranged according to the basic system; their chemical formulæ are also given from Rammelsberg. The various minerals are usefully tabulated under the different bases, the blowpipe characters being arranged in eight columns, according to the phænomena presented either alone, or by the action of different reagents. This part is principally compiled from the work of Plattner, with additions from those of von Kobell and Rammelsberg. With these additions the work forms a useful and concise hand-book for the student, and is also valuable to those who cannot readily consult the larger and more important volume of Plattner.

Some slight typographical errors occur, as Epromite for Epsomite, MO3 for TO; and at p. 129, under Silica, "Nickel is present in the green anhydrous variety Chlorophane," instead, we presume, of Chrysoprase. The reactions with nitrate of cobalt might have been more usefully extended, according to colour, than that given at p. 91. The compiler has verified many of the statements, and has supplied details (where in some cases deficient) from personal experiment; circumstances prevented him from examining the metallic minerals; but we do not see why on that account Mr. Blanford should regret being" obliged to rely principally on the authority of Professor Plattner," the first of assayists, instead of his own observations.