420 
NATURE 
[Maxcu 4, 1897 
edition. The book contains avery useful account of the natural 
history, habits, food, and treatment of the various species of 
pheasants. —Prof. Strasburger’s standard work, ‘‘ Das Botanische 
Practicum’ (Jena: Gustav Fischer), is known to all botanists 
asan admirable book for the laboratory and the library. It first 
appeared in 1884, and was reviewed in NaTuRE shortly after 
publication (vol. xxx. p. 215). The original volume consisted of six 
hundred pages; the present edition (the third) runs into 739 
pages, the increase of size being made necessary by the many 
additions to the knowledge. of the minute structure of plants 
during the past twelve years. Prof. Strasburger’s ‘* Practicum ” 
became indispensable to the botanical laboratory as soon as it 
appeared, and the third enlarged and revised edition of it will 
maintain the position gained by the first.—The fourth edition 
has been published of Prof. Henry Adams’s ‘‘ Handbook for 
Mechanical Engineers’? (London: E. and F. N. Spon). The 
book is a collection of notes, definitions, and formulze, to which 
ready reference is often required for examination purposes and 
in general practice.—Messrs. John Wiley and Son, New York, 
have issued a third edition of ‘‘ Retaining-Walls for Earth,” by 
Prof. Malverd A. Howe. The book includes the theory of 
earth-pressure as developed from the ellipse of stress, and a 
short treatise on foundations, illustrated with examples from 
practice.—Mr. Edward Stanford has published new editions of 
three little books by Mr. W. Thynne Lynn. The books are 
** Celestial Motions” (ninth edition), ‘*‘ Remarkable Comets” 
(fifth edition), and ‘‘ Remarkable Eclipses” (second edition). 
They are so readable and accurate that they thoroughly deserve 
to be successful. 
THE concluding part of a most valuable collection of physical 
tables has just been issued by the Smithsonian Institution. 
The work has grown out of a series of meteorological tables 
compiled by Dr. Arnold Guyot, and first published in 1852. These 
tables proved so serviceable, and there was such a large demand 
for them, that when the question of revision fora fifth edition 
arose, Prof. Langley decided to have an entirely new publica- 
tion prepared. The first part of the new series (the Meteorological 
Tables) appeared in 1893 ; the second volume (the Geographical 
Tables) was published in 1894 ; and now we have the Physical 
Tables, to complete the work, which forms the concluding part of 
vol. xxxv. of the Smithsonian Miscellaneous Collections. The 
present volume of tables has been prepared by Prof. Thomas 
Gray, of the Rose Polytechnic Institute, Terre Haute, Indiana. 
There are altogether 315 tablesof data, referring to all branches of 
physical inquiry. The tables are well arranged ; they have also 
been carefully selected from the works of well-known investi- 
gators, and, as a result, they are easy of reference and can be 
trusted. One of the many excellent points presented by them 
is that the authorities from which the physical data have been 
derived are quoted as foot-notes to the tables. It is thus easy 
to find the paper or memoir from which the results are taken. 
A few mathematical tables are included, but only those which are 
useful to physicists, and which are not easily found elsewhere. 
Physical chemists may confidently go to the volume for data 
needed by them, and every one engaged in electrical research will 
prove the value of Prof. Gray's work. The volume is, indeed, 
full of facts which investigators often have to spend hours in 
finding ; it is acompendium which no physical laboratory where 
serious work is done can dispense with. Physicists will be 
grateful to Prof. Gray for so carefully compiling these tables, and 
to the Smithsonian Institution for publishing them. The brief 
introduction on units of measurement and conversion factors 
will be of assistance to students using the tables. 
AN experimental study of an interesting case of chemical 
equilibrium is contributed by M. Pélabon to the Contes rendus 
of the Paris Academy of Sciences (February 15). When 
hydrogen and selenium are heated together for some time, 
NO. 1427, VOL. 55] 
hydrogen selenide is formed ; a state of equilibrium being finally 
reached in which the proportions of hydrogen, selenium, and 
hydrogen selenide are unchanged by further heating. Similarly, 
if pure hydrogen selenide is heated, a mixture is finally pro- 
duced containing the same three substances in equilibrium. It 
has been previously shown by M. Ditte, that for tempera- 
tures above 320° C. the same final system is reached, whether 
the initial system consist of hydrogen selenide or of a mixture 
of hydrogen and selenium. At temperatures below 320° C., 
however, M. Pélabon shows that this is not the case, two 
distinct curves being obtained, according as the compound of 
the mixture is used as the starting-point. These curves are 
those called by M. Duhem (‘‘ Traité elémentaire de Mécanique 
chimique”) curves of ‘‘ false equilibrium,” and the hypothesis. 
proposed by him for such systems, especially that part predict- 
ing the gradual coincidence of the curves with rise of tem- 
perature, is well borne out by the experiments of M. Pélabon. 
A CONTRIBUTION to the fascinating problem of the direct 
production of electrical energy by the combination of carbon 
and oxygen, is made by Messrs. Liebenow and Strasser in the 
Zeitschrift fiir Elektrochemie for February 20. They have in- 
vestigated the so-called Jacques cell, which consists essentially 
of rods of carbon and iron immersed in fused caustic alkali 
(see NaTuRE, vol. liv. pp. 298, 353.) The electrical be- 
haviour of several metals towards fused caustic alkali was first 
studied. A normal electrode of mercury, covered with calomel, 
in contact witha solution of potassium chloride, was connected to- 
the fused potash by means of a piece of pipe-stem moistened at 
one end by the potassium chloride solution, and dipping into 
the fused caustic potash at the other. The difference of 
potential between this normal electrode and an iron rod im- 
mersed in the fused alkali was then measured. For about forty 
minutes the potential difference remained almost constant, 
hydrogen being evolved from the iron, and the fused mass 
having a greenish colour; suddenly the colour of the melt 
changed to dark brown, this change being accompanied by a 
fall of temperature and by a large fall (about 1 volt) in the 
potential difference between the iron and the mercury; the 
dissolution of the iron alsoceased. The new potential difference 
remains practically constant for any length of time. Similar 
phenomena were observed with nickel and silver. Only 
one value was found for the potential difference between 
carbon and fused alkali. The differences of potential be- 
tween iron or carbon in fused caustic potash at about 
500° C. and the normal mercury electrode were: active 
iron, —1°5 volts; passive iron, —0°38 volt; carbon, — 1°32 
to 1°12 volts. In accordance with these numbers, it is 
found that a cell consisting of carbon and iron dipping into 
fused caustic potash, has at first a very small negative electro- 
motive force which rises suddenly, when the iron assumes the 
passive condition to about + 1 volt. The cell develops a very 
inconstant current, the iron being very rapidly polarised. This 
may be remedied to some extent by passing a current of air 
through the fused electrolyte. ' 
AN interesting reaction of magnesium nitride is described in 
the current number of the Berichte, by E. Szarvasy. This sub- 
stance readily reacts at the ordinary temperature with absolute 
methyl alcohol, a mixture of ammonia with trimethylamine 
being formed, about 4o per cent. of the nitrogen being found in 
the latter form. It appears that the methyl alcohol acts partly 
as water, and partly as a methoxy-compound, since the solid 
residue consists of magnesium hydroxymethylate OH. Mg.OCHs3, 
a white hygroscopic powder which is dissolved by acids with 
formation of a magnesium salt, methyl alcohol and water. 
When heated it is converted into magnesia, carbonic oxide, 
and hydrogen. It seems possible that this reaction may pro~ 
vide a convenient mode of preparation of the trialkylamines. 
