134 
NATURE - 
ae 
be) 
iz 
7 S 
salt of the new acid C,N,;H;0,, which he proposes 
to call allantoxanic acid. Various other salts are de- 
scribed. The acid is found to be bibasicz.—On the action 
of sodium-amalgam on dinitrohephtylic acid, by H. A. 
Kullhem. The result of the action appears to be the forma- 
tion of a monobasic acid having the formula C,Hy,) (NO,)O,. 
—On the products of the decomposition of the chlorhydrin of 
glyceric acid, by Messrs. Werigo and Okulitsh.—On a new acid 
from aloes, by P. Weselksy. The body in question was obtained 
from Socotra aloes; its formula is, CyH,.O, when dried in the 
air, and its anhydride has the formula C,,H,,0;. The acid is 
apparently dibasic.—Dr. H. Sprengel communicates a paper on 
the water air-pump.—On liquid carbonic anhydride, by L, Cal- 
litel, is a translation from the author’s late paper in the 
Comptes Rendus—On the addition of cyanamide, by Dr. FE. 
Baumann, is an account of the compounds formed when this 
body is added to various others.—On the combination of 
bromine and ether, by P. Schutzenberger, has already ap- 
peared in the Comptes Rendus.—An examination of a 
new alkaloid, by Prof. Hlasiwetz. The body in question is a 
product of the oxidation of cinchonin.—On the isomers of dini- 
trophenol, by H. Hiibner and W. Schneider.—On the nature of 
sulpho and sulphonitrobibrombenzolic acid, by H. Hiibner and 
R. Douglas Williams.— On the synthesis of carbazo] and on 
phenathren, by C. Graebe.—Contributions to the history of the 
orcins, by J. Stenhouse, has already appeared in the Proceedings | 
of the Royal Society, the present communication, No. III. of 
the series, deals with the amido-derivatives of those bodies.—On 
a new method of preparing carbonic tetrabromide from bromo- 
form, by J. Habermann. The author acted on bromoform in 
the presence of potash with bromine. The mixture exposed to 
direct sunlight for 5-6 days gives a good product of tetra- 
bromide. In the dark, after an exposure of three months, only 
a trace was formed. The reaction occurs as follows :-— 
CHBr, + Br, + KHO = CBr, + KBr + H,O. 
SOCIETIES AND ACADEMIES 
LonbDon 
Royal Society, May 1.—‘‘On the Condensation of a Mix- 
ture of Air and Steam upon Cold Surfaces.” By Prof. Osborne 
Reynolds. 
The object of this investigation is to ascertain how far the 
pressure of a small quantity of air affects the power of a cold 
surface to condense steam. 
The conclusions which the author draws from the experiments 
are as follows :— 
1. That a small quantity of air in steam does very much retard 
its condensation upon a cold surface ; that, in fact, there is no 
limit to the rate at which pure steam will condense but the 
power of the surface to carry off the heat. 
2. That the rate of condensation diminishes rapidly, and 
nearly uniformly as the pressure of air increases from two to ten 
per cent. that of the steam, and then less and less rapidly until 
thirty per cent. is reached, after which the rate of condensation 
remains nearly constant. 
4. That in consequence of this effect of air the necessary size 
of a surface-condenser for a steam-engine increases very rapidly 
with the quantity of air allowed to be present within it. 
5. That by mixing air with the steam before it is used, the 
condensation at the surface of a cylinder may be greatly dimi- 
nished, and consequently the efficiency of the engine increased. 
6. That the maximum effect, or nearly so, will be obtained 
when the pressure of the air is one-tenth that of the steam, or 
when about two cubic feet of air at the pressure of the atmo- 
sphere and the temperature 60° F. are mixed with each pound 
of steam. 
As this investigation was nearly completed, the author's atten- 
tion was called toastatement by Sir W. Armstrong, to the effect 
that Mr. Siemens had sugested as an explanation of the otherwise 
anomalous advantage of forcing air into the boiler of a steam- 
engine, that the air may prevent, in a great measure, the con- 
densation at the surface of the cylinder. It would thus seem 
that Mr. Siemens has already suggested the probability of the 
fact which is proved in this investigation, The author is not aware, 
however, that any previous experiments have been made on the 
subject, and therefore he offers these results as independent testi- 
mony of the correctness of Mr, Siemens’s views as well as of his 
own, 
| ¥une 12, 1873 
‘*On the effect of Pressure on the Character of the Spectra o 
Gases.” By C. H. Stearn and G. H. Lee. 
May 8.—‘‘Contributions to the Study of the Errant Anne- 
lides of the Older Paleozoic Rocks.” By Prof. H. Alleyne 
Nicholson, M.D., F.R.S.E. 
In this communication the author endeavoured to elucidate 
the abundant and obscure organic remains which are found so 
commonly in the Paleozoic Rocks, an@ especially in the Silu- 
rian strata of Britain, and which are generally known by the 
vague and convenient names of ‘‘ Fucoids,” ** Annelide bur- 
rows,” and ‘‘Tracks.” After expressing his opinion that the first 
step towards the study of these obscure fossils lay in the pro- 
visional grouping and naming of the more marked forms which 
are already known to exist, the author proceeded to divide the 
remains under consideration into two great groups. In the first 
cf these groups are those fossils which are truly the durrows of 
marine worms, as distinguished from mere trails and surface- 
tracks. Some of these burrows (Scolithus) are more or less 
nearly vertical in direction as regards the strata in which they 
are found; and they are to be looked upon as being true 
burrows of habitation. In this section are placed the genera 
Scolithus, Arenicolites, and Histioderma. 
The second great group of Annelide remains comprises 
genuine surface-trails or ‘*tracks,” which of necessity never 
pass below the surface of the bed on which they occur. 
‘The Action of Light on the Electrical Resistance of Sele 
nium.” By Lieut. Sale, R.E. Communicated by J. N. Lock- 
yer, F.R.S. 
The following were the general results of the experiments : — 
I. That the resistance of selenium is largely affected by ex- 
posure to light. : ‘ 
2. That this effect is not produced by the actinic rays, but is 
at a maximum at, or just outside the red rays, at a place nearly 
coincident with the locus of the maximum of the heat-rays. 
3. That the effect of varying resistances is certainly not due to 
any change of temperature in the bar of selenium. 
4. That the effect produced on exposure to light is sensibly 
instantaneous, but that on cutting off the light the return to the 
normal resistance is not so rapid. 
{t would seem that there exists a power in rays, nearly coinci- 
dent with the heat-rays of high intensity, of altering instantaneously 
and without change of temperature the molecular condition of 
this particular element. 
May 15.—‘On Jeypoorite, a Sulph-antimonial Arsenide of 
Cobalt.” By Major W. A. Ross, R.A. Communicated by 
Prof. H. Miller, Foreign Sec. R.S, 
‘Determination of the Number of Electrostatic Units in the 
Electromagnetic Unit made in the Physical Laboratory of 
Glasgow University.” By Dugald M‘Kichan, M,A. 
The object of this paper is to describe experiments made at 
intervals from 1870 to 1872 in the Physical Laboratory of Glas- 
gow University to determine the relation between the funda- 
mental units in the two systems of absolute electrical measure- 
ment, the electromagnetic and the electrostatic. A summary is 
also given of the results of similar observations made by W. F. 
King in 1867 and 1868, 
The two systems of electrical measurement, or the units 
which they employ, are founded on the fundamental units of 
time, mass, and space applied to the observed effects of elec- 
tricity at rest and electricity in motion, The dimensions of 
quantity in the two systems are such that the ratio of the 
electromagnetic and the electrostatic unit of quantity is ex- 
pressible as a velocity. ; 
This velocity, usually known as v, is not only of great im- 
portance in all combinations of electromagnetic and electrostatic 
| action, but it is also of great scientific importance in the theory 
of the propagation of electromagnetic disturbances through a 
dielectric medium. It occupies a very important place in the 
development of the electromagnetic theory of light by Professor 
Clerk Maxwell, according to whose theory this velocity w is the 
same as the velocity of light. 
The first experimental determination of vy was made by Weber 
from a common electrostatic and electromagnetic measure of 
capacity. The result of Weber’s experiments was that v was 
310°74 x 108 centims, per second. 
Another determination was made by Pro® Clerk Maxwell in 
1868, by means of a direct comparison of el<ctrostatic at- 
traction with electromagnetic repulsion, His experiments gave 
v=288'0 x 10° centims, per second, ; 
