258 
NATURE 
[ Fan. 26, 187% 


months when the temperature was high. One of them 
occurred on the Lancashire and Yorkshire Railway in the 
summer of last year when the temperature was 50° to 60° 
above freezing. I could enumerate others in which the 
winter frosts had nothing to do with the fractures which 
ensued.” 
After referring to some other experiments, Sir W. Fair- 
bairn proceeded: “The danger arising from broken tires 
does not, according to my opinion, arise so much from 
changes of temperature as from the practice of heating 
them to a dull red heat, and shrinking them on to the rim 
of the wheels. This, I believe, is the general practice, 
and the unequal, and in some cases, the severe strains to 
which they are subject, has a direct tendency to break the 
tires. To show how easily this may be effected, let us 
suppose that a tire, two feet six inches or three feet 
diameter, is shrunk on to a wheel one-tenth of an inch 
larger than the tire, it then follows that the tire in cooling 
must be elongated to that extent, with a strain equivalent 
to the force of the shrinkage, and calculated to produce 
that amount of molecular disturbance. It may be more 
or it may be less, but supposing the strain to be one-half 
or three-fourths of that which would break the tire, it then 
follows that the constant action of its irregular motion on 
the rails must ultimately lead to fracture.* I am not sur- 
prised that this should be the case, as most, if not the 
whole, of railway tires, excepting those on engines and 
tenders, are not turned, but selected by hand, heated and 
shrunk upon the wheels with every degree of tension, as 
suits the convenience of the workman. So long as this 
process is pursued the public will be exposed to the risk 
of broken tires. What is required in this description of 
manufacture is, that the rim of the wheel and the inside 
of the tire should be ¢urned fo a standard gauge, accu- 
rately calculated to give the required amount of tightness 
with a larger margin of strength, and this done we should 
attain greatly increased security to the public, and a great 
saving in wear and tear—to say nothing of the large sums 
expended by companies in the shape of compensation for 
injuries and loss of life.” 
Here, then, is another potential triumph for more 
scientific accuracy and more hope for travellers. 

SCIENTIFIC SERIALS 
Pogeendorff’s Annaien der Physik und Chemie, 1870, No. 
g.—-The contents of this number are :—(1.) ‘* Calorimetric 
Researches,” by R. Bunsen. In the first part of this paper 
Prof. Bunsen describes the construction and method of using 
a new calorimeter, in which quantities of heat are measured by 
the amount of ice at o° which they are capable of converting 
into water at the same temperature. The quantity of ice melted 
is in its turn indicated by the resulting diminution of volume, as 
shown by the movement of a mercury-column ina graduated 
capillary tube communicating with the vessel in which the ice 
is contained. In order to convert the results obtained by this 
method into absolute heat-units, it is necessary, either that the 
motion of the mercury-column produced by a known quantity of 
heat should be ascertained, or that the specific gravity of ice at 
o° and its latent heat of fusion should be known. The first of these 
quantities was found by observing the effect produced by a given 
weight of boiling water, and the second by a process which may 
be described as consisting in the application of the principle of the 
weight-thermometer to measure the change of volume which 
water undergoes on freezing. From these data the third of the 
quantities mentioned, or the latent heat of fusion of ice, is 
readily calculated. Of the numerical results, given in the paper, 
we will quote only the following :— 
Specific gravity of iceato°C . . . 0°91674. 
Latent heat of fusion of ice. . . 80°025 
Speciac heat of indium (.9 3 s- «.-) see. - OlORTO 
Specific: heatvof calctum <=.) =, = = oe O'1704 
* From long-continued action under strain, it has been proved that it is 
only a question of time when rupture takes place, as repeated increased and 
diminished changes with the same load ultimately leads to fracture. 


One special advantage of this method of calorimetry is that — 
it allows good results to be obtained with very small quantities — 
of material ; for instance, for specific heat determinations, from 
0'3 gramme to, at the most, 4 grammes is sufficient. 
“* On the relations between the crystalline form and chemical con - 
stitution of some organic compounds,” by P. Groth. 
1 
4 
(2.) 5 
(3-) — 
‘*Experimental and theoretical investigation of the figures of © 
Equilibrium of a liquid mass without weight” (Eighth series), 
by J. Plateau. A translation of this paper, which relates to the 
conditions of the ready production and of the persistency of 
liquid films, to the superficial tension of liquids, and to their 
superficial viscosity, was printed in the Frilosophical Magazine 
vol. xxxviii. p. 445 [1869.] (4.) “‘ On the Absorption of Light,” 
by Paul Glan. Among other results, the author finds that the 
absorbing power of a substance, when it is employed in solu- 
tions of different degrees of concentration, increases in a greater 
ratio than the concentration ; also, that the absorbing power of 
a body in solution is affected by the nature of the medium in 
which it is dissolved. The experimental results are followed by 
a mathematical discussion of the mechanism of the absorption 
of light. (5.) ‘‘Additional researches into the behaviour of 
Vapours in relation to the Laws of Mariotte and Gay-Lussac,”’ 
by Dr. Hermann Herwig. This paper has reference to an 
earlier one published in vol. cxxxvii. of Poggendorff’s Annalen. 
The author finds that, when the pressure upon a vapour at a 
given temperature is diminished so far that the vapour obeys 
Mariotte’s law, that is to say, so far that the product of the 
pressure into the corresponding volume becomes constant, this 
product bears to the similar product, when the pressure is great 
enough to cause the vapour to be saturated at the same tempera- 
ture, a constant ratio which is proportional to the square root of 
the absolute temperature. In the present paper it is shown that 
ethylic bromide and carbonic sulphide conform to this law. 
(6.) ‘* Some analogous Theorems in Photometry and in the Laws 
of Attraction,” by Wilhelm von Bezold. The mathematical 
law of the inverse square of the distance applying equally to the 
illumination produced by a luminous point, and to the force 
exerted by an attracting particle, it follows that the mathematical 
expressions by which photometrical relations are expressed, will 
also admit of an interpretation in relation to the action of 
attracting particles. In this paper the double interpretation of 
the same formula is pointed out in several important cases. For 
example :—The author shows that the photometrical analogue 
of an equipotential surface drawn about several attracting par- 
ticles, is a surface so placed, relatively to luminous points, whose 
luminosity is proportional to the masses of the particles, that the 
illumination of each element of the surface is greater than that 
of any other element passing through the same point. (7.) ‘‘On 
the Luminosity of Phosphorus,” by W. Miiller. The author 
finds that phosphorus vapour is not luminous in the absence of 
free oxygen; that it is not luminous at ordinary atmospheric 
temperatures when in contact with pure oxygen of atmospheric 
pressure, but that it becomes luminous, and at the same time 
absorbs oxygen, when the pressure is diminished to a certain 
amount, depending on the temperature, the necessary reduction 
of pressure being greater when the temperature is lower; and 
that phosphorus which has been for some time in contact with 
certain vapours, (notably hydrocarbons), is deprived by them of 
the property of becoming luminous on the admission of air, 
although air, mixed with the same vapours, is not thereby de- 
prived of the power of exciting (temporary) luminosity in phos- 
phorus. (8.) ‘‘Onthe Superoxides that can be prepared by 
Electrolysis,” by W. Wernicke. (9.) “Ona mechanical theorem 
applicable to Heat,” by R. Clausius. (10) ‘‘On the Spectra of 
negative Electrodes, and of long-used Geissler’sT ubes,” by Prof. 
Edm. Reitlinger and Prof. Moriz Kuhn. (11.) ‘On the 
Meissner Lignite modified by contact with Basalt,” by Dr, A. 
von Lasaulx. (12.) ‘*On the analysis of Silicates,” by E. 
Ludwig. Refers chiefly to the precautions required for 
the accurate separation of silica and alumina. (13.) ‘‘On 
the absorption-spectrum of liquid peroxide of Nitrogen,” by 
August Kundt. On comparing the absorption-spectra of liquid 
and gaseous peroxide of nitrogen, the author found that the 
ill-defined black bands in the spectrum of the former co- 
incided in position with strongly-marked groups of lines in 
the spectrum of the latter. (14.) ‘‘On the work done by 
Gases in Motion, or remarks on the paper so entitled,” by 
Dr. A. Kurz. This is a reply to a criticism by Dr. Boltz- 
man (noticed in NATURE, vol. ii, p. 364) of a previous paper 
by the author, 
