OcToBER 16, 1902] 
NATURE 
613 
Rationalist Press Association, Ltd., in paper covers at sixpence, 
by Messrs. Watts and Co. 
A NEW medical and scientific circulating library has been 
opened by Mr. T. H. Prince, who was for many years with 
Mr. H. K. Lewis, and has just started as a medical and scientific 
bookseller at Praed Street, Paddington. It is promised that all 
standard works in the various branches of science will be 
available to subscribers. 
WE have received the concluding part of the Boletim Mensal of 
the Qbservatory of Rio de Janeiro for the year 1901. In 
addition to the meteorological observations taken eight times 
daily at that observatory, the Budletin contains monthly and 
yearly results for various parts of Brazil, and a valuable 
summary for twenty years (ending March, 1901) for Bahia, from 
observations made by Dr. Guimaraes. 
SEVERAL new forms of apparatus for the physical laboratory 
have lately been produced by Messrs. W. G. Pye and Co., 
Cambridge. Among the instruments are a table cathetometer and 
areading microscope, constructed on the geometric slide principle, 
an improved pattern storage cell, five hundred of which have 
been in use at the Cavendish Laboratory for several months 
and have proved ‘‘ very convenient and thoroughly satisfactory,” 
and sets of patent resistance coils, in which the coils themselves 
take the place of the usual plugs and can be easily removed to 
show the wire and method of construction. 
A NOTEWORTHY paper on the decomposition of urea is con- 
tributed by Mr. C. E. Fawsitt to the fifth number of the 
Zeitschrift fiir physikalische Chemie, vol. xli. When a pure 
aqueous solution of urea is heated at 100° C. for a considerable 
time, the urea is completely transformed into ammonium car- 
bonate. This decomposition takes place also under the influence 
or acids and bases, the velocity under these circumstances being 
much greater. If strongly alkaline solutions are excepted, the 
decomposition takes place in all cases according to the simple 
equation for a unimolecular reaction, a result which does not 
accord with the ordinary method of representing the reaction. 
The author finds that the facts can only be satisfactorily ex- 
plained by assuming that the urea is in the first place trans- 
formed into ammonium cyanate and that a state of equilibrium is 
set up between these two substances. The cyanate, however, is 
gradually decomposed with the formation of ammonium car- 
bonate, the equilibrium being thus disturbed, and a further 
quantity of urea undergoes transformation into the cyanate. This 
decomposition of ammonium cyanate into ammonium carbonate 
takes place very quickly under the influence of acids. A large 
amount of experimental evidence is found to support the theory 
advanced, and the author concludes that urea is not directly 
attacked either by water, acids or moderately concentrated 
alkalis, Concentrated solutions of the alkalis have probably 
however a direct saponifying action upon the urea, in addition 
to the indirect action described, 
AN investigation of the rate of bromination of carbon com- 
pounds by L. Bruner, which will be of considerable interest to 
organic chemists, is published in the current number of the 
Zeitschrift fiir physikalische Chemie. The catalytic action of 
iodine on the bromination of benzene has been carefully studied 
in a quantitative manner, and it is shown that this action is very 
probably due to the formation of iodine monobromide, which 
by its dissociation gives rise to free bromine atoms. These free 
bromine atoms are the active agents in the bromination process, 
and the catalytic influence of the iodine is due to the much 
greater dissociation of the iodine bromide as compared with 
that of bromine itself. The author shows that the substitution 
NO. 1720, VOL. 66] 
of bromine is a quadrimolecular reaction taking place according 
to the equation 
C,H, + 4Br=C,H5Br + HBrzs—Bry. 
The action of other carriers has also been investigated, the most 
active in the case of the bromination of benzene and bromobenzene 
being aluminium bromide. This compound has, ho wever, no 
influence on the bromination of nitrobenzene. From the con- 
centrated nitrobenzene solution, a compound of the formula 
AIBr,.2C,H;NO, has been crystallised out, a fact of some 
interest in view of Gustavson’s theory of the mode of action 
of AlBrg in the bromination of benzene, toluene and other 
compounds, The author has finally investigated the relative 
velocities of some so-called instantaneous reactions. Itis found 
that the bromination of aniline takes place more rapidly than 
that of phenol, and that the velocity of the latter reaction is about 
one-fifth of that at which iodine is separated by bromine from 
potassium iodide solution. 
Tue additions to the Zoolozical Society’s Gardens during the 
past week include a Vervet Monkey (Cercopithecus lalandiz) 
from South Africa, presented by Mrs. Chas. Lisle Hacket ; two 
Mozambique Monkeys (Cercopithecus pygerythrus) from East 
Africa, presented respectively by Mr. J. M. Creasey and Mrs. G. 
Ord; a Common Marmoset (Aafale jacchus) from South-east 
Brazil, presented by Mrs. Murray Simpson; a Gannet (Sz/a 
bassana) from Scotland, presented by Lord Ribblesdale ; six 
Carolina Anolis (Avolis carolinensis) from Florida, two Tarantula 
Spiders, from Arizona, presented by Miss Ilda Orme; two 
Entellus Monkeys (Semnopithecus entellus), two Sambur Deer 
(Cervus aristotelis), tno Nylghaies (Boselaphus tragocamelus), 
two Tigers (Fees tigrés), two Gadwells (Chaslelasmus streperus), 
an Indian Adjutant (Zeptoptilus argala) from India, two Nutmeg 
Fruit Pigeons (Myristicivora bicolor) from Moluccas, received in 
exchange ; eight Saddle-backed Tortoises (Zestudo ephippium), 
two Thin-shelled Tortoises (Zestudo miécrophys), twenty-four 
South Albemarle Tortoises (Zestedo viczna), one Tortoise 
( Testado ), seven —— Iguanas ( Conolophus subcristatus) from 
the Galapagos, four Indian Porphyrios (Porphyrio calvus) from 
Eastern Asia, a Brindled Gnu (Connochaeles taurina) from 
South Africa, deposited. 
QUR ASTRONOMICAL COLUMN. 
A New TransitinG Device.—An article by Mr. M. B. 
Snyder, of the Philadelphia Observatory, in Popudar Astronomy, 
No. 97, discusses a new device for transiting stars, in which the 
micrometer thread is moved, with a regular speed, across the 
field by means of an electric motor. 
The fundamental idea of getting rid of the personal equation 
in transit observations by using mechanical transiters was first 
suggested by Braun in 1865 and since then has been persistently 
developed by Repsold. After discussing the various methods 
suggested by these and other inventors, Mr. Snyder gives some 
details of his own device, although full details are withheld for 
a future communication when circumstances have permitted of 
more time being spent on the subject. 
In Mr. Snyder's instrument, the micrometer screw, and 
thereby the micrometer thread, is driven across the field of the 
instrument by an electric motor, at a speed depending on the 
declination of the object observed, whilst at the same time the 
observer, by using a secondary adjustment, keeps the star 
image accurately bisected, and the various positions of the thread 
are automatically recorded, by means of an ordinary chronograph, 
at the end of each revolution of the screw. Then at the moment 
of meridian passage an automatic electrical arrangement records 
the instant of transit. The micrometer in its fundamentals is of 
the ordinary type, and is at present attached to the 4-inch 
meridian circle of the Philadelphia Observatory ; itis so arranged 
that, with the motor driving regularly, visual observations may 
be made, and recorded by any one of the usual methods, 
synchronously, thus forming a ready means of determining the 
personal equations existing between the various individuals of 
any group of observers. 
