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NATURE 
sd 
[August 26, 18 
given for spinel and corundum by Gaudin. Ebelmen, H. Sainte- 
Claire Deville, and Caron. More recently, MM. Fréuy and 
Feil have prepared the ruby in large crystalline masses unsuitable 
for cutting, although possessing all the properties of the natural 
mineral. 
Fresh essays seem to have led to more practical results, as for 
some time past rubies of fair dimensions are met with in the trade, 
which, although rather less brilliant and transparent, possess the 
hardness, density, and optical properties of this valuable gem. 
Several features of their inner structure show conclusively that 
they were obtained by fusion ; in any case it is well known that, 
unlike silica, which remains vitreous, alumina crystallises by 
fusion. 
The diamond alone appears to have hitherto resisted all 
attempts at reproduction, Although success in this direction 
has been frequently announced, the statement has always proved 
erroneous. The problem is rendered more difficult from the 
fact that the diamond has nowhere been found in its original 
lode. This holds good as well for the Braziliaa itaeotumites 
and quartzites, and for the serpentine breccias of South Africa, 
as for the diamantiferous sands. Nevertheless, in the diamond 
are occasionally embedded some foreign substances, which, while 
depreciating its commercial value, are very interesting as show- 
ing that it must have been formed at a relatively low tempera- 
ture. 
But enough has been said, M. Friedel concluded, to enlist 
your interest in mineralogy, a science whose progress has been 
rapid, whose methods are being constantly renewed, and which 
in every respect deserves the attention of inquiring minds. 
SCIENTIFIC SERIALS 
Anvricar Fournu of Scien-z, Auzast.—Oa hitherto unrecoz- 
nised wave-lengths, by S. P. Langley. The object of the 
laborious and delicate operations here fully described has been, 
not so much to settle the theoretical questions involved in deter- 
mining the relation between dispersion and wave-length, as 
to enable future observers to determine the visible or invisible 
wave-lengths of any heat, whether from a celestial or terrestrial 
source, observed in any prism. A knowledge will thus be 
gained of the intimate constitution of radiant bodies, which an 
acquaintance with the vibratory period of their molecules can 
usually alone afford. These researches into the whole unex- 
plored region of infra-red energy both from celestial and terres- 
trial sources have led to the certain determination of wave- 
lengths greater than o’005 mm. Radiations have also been 
recognised whose wave-length exceeds 0°03 mm., so that, while 
the wave-length known to Newton has been directly measured 
to nearly eight times, there is probable indication of wave-lengths 
far greater. 
and the longest known vibration of the ether has thus in some 
measure been already bridged over.—On the chemical compo- 
sition of herderite and beryl, with note on the precipitation of 
aluminium and separation of beryllium and aluminium, by S. 
L. Penfield and D. N. Harper. The composition of herderite 
is shown to be an isomorphous mixture of CaBeFPO, with 
CaBe(OH)PO,, which may be written CaBe(FOH)PO,, or a 
salt of phosphoric acid, two of whose hydrogen atoms have been 
replaced by a bivalent element, and the third also by a bivalent 
element whose other free affinity has been satisfied by a fluorine 
atom or hydroxyl. Chemically it is closely related to wagnerite, 
triplite, and triploidite, these minerals offering the best illustra- 
tion of the isomorphism of F and OH. In crystallisation, 
herderite is orthorhombic, with a prismatic angle of nearly 120°. 
Regarding water as an essential constituent of beryl, the 
authors add $H,O to its usually accepted formula, writing it 
H,Be,Al,Si,.03;. Its theoretical composition, according to this 
formula, becomes SiO, 65°81 ; Al,O, 18°83; BeO 13°71; H,O 
1°65. Specific gravity, 2°705.—Communications from the U.S. 
Geological Survey, Division of the Rocky Mountains, by Whitman 
Cross and L. G, Eakins. The present paper deals with ptilolite, 
a new mineral occurring in cavities of a more or less vesicular 
augite-andesite, which is found in fragments in the Tertiary con- 
glomerate beds of Green and Table Mountains, Jefferson County, 
Colorado. It is described as a white substance in extremely 
delicate tufts and spongy masses composed of short hair-like 
needles loo-ely grouped together ; hence its proposed name of 
ptilolite, from the Greek wrfAov = down, in reference to the 
light downy nature of its aggregates. Its empirical formula is 
RO, Al,O;,10SiO, + 5H,O, R representing Ca, K,, and Na, ; it 
The gulf between the shortest vibration of sound | 
| 
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is thus an alumino-silicate of which no previously described | 
hydrate contains so high a percentage of silica. In this respect — 
it may compare with the rare mineral milarite.—Notes on the ' 
peridotite of Elliot County, Kentucky, by J. S. Diller. This — 
formation, described as a dark greenish rock with specific | 
gravity 2°781, appears to be undoubtedly of eruptive origin, — 
traversing many thousand feet of palzeozoic strata to reach the 
surface. Its mineralogical composition shows 40 per cent. of 
olivine, 30°7 serpentine, 14 dolomite, 8 pyrope, 2°2 ilmenite, 
2 magnetite, with smaller quantities of biotite, enstatite, octa- 
hedrite, and apatite.—Temperature observations at the Lakel 
Superior Copper-Mines, by H. A. Wheeler. The unusually — 
low thermal gradients recorded in these mines—about 1° F. to_ 
100 feet as compare with the normal of 1° F. to 50 or'55 feet in 
vertical descent, is attributed to the proximity of the cold wate 
of Lake Superior. The nearer the mines are to this great 
cooling influence, the lower the thermal gradient will be found 
to be.—An application of the copper reduction test to the 
quantitative determination of arsenic, by Henry Carmichael. 
Using a standard square of copper as an indicator, the author 
has been led to adopt the method here described, which, for the 
estimation of small quantities of arsenic in the human system or 
elsewhere, he believes to be quicker, simpler, more delicate, 
and, in the hands of toxicologists, less exposed to fallacy, than — 
any other. A copper square 1 millimetre on a side detects 
*0000025 grm. arsenious oxide, a quantity 400 times less than — 
that necessary for turning the beam of the ordinary chemical 
balance.—On the crystallisation of gold, by Edward S. Dana. — 
The paper deals more especially with the delicate crystalline — 
threads and arborescent forms from the White Bull Mine, 
Oregon, and the specimens of finely crystallised gold from the ; 
| 
Californian mines. The crystals are illustrated and_fully 
described.—Classification of the Cambrian system of North 
America, by Charles D, Walcott. The formations here treated 
are those characterised by the predominance of the types of — 
Barrande’s ‘First Fauna,” and such additional strata, not — 
characterised by the presence of fossils, as are stratigraphically — 
and structurally connected with the Cambrian strata identified by , 
organic remains. These formations, showing a total thickness _ 
of over 18,000 feet, with a known fauna of 92 genera and 393 3 
species, are regarded, not as a subdivision of the Silurian, but | 
rather as a well-defined geological system underlying the Lower 
Silurian (Ordovician) on the North American continent.—Note 
on the spectrum of Comet ¢, 1886, by O. T. Sherman. When 
observed with the equatorial of Yale Observatory in Mayand 
June, this comet presented no less than seven loci of light where } 
three only are usually seen. These showed approximate wave- — 
lengths 618°4, 600°6, 567°6, 553°7, 517°, 468°3, and 433°2, 
besides strongly suspected loci at 545°4, 535°0, 412°9, and 
378°6. These are compared with the low temperature spectrum 
of carbohydrogen, and it is suggested that a chart should be 
prepared for the carbon compounds at successive heat-levels, 
after the manner of that drawn up by Lockyer for the photo- 
graphed spectra of some carbon compounds (Proc. Roy. Soc., 
Xxx. p. 463). 
Annaten der Physik und Chemie, Ba. xxviii., No. 7, July 
1886.—Th. Schroder, experimental investigation of the influence 
of temperature upon elastic reaction. The experiments were 
made with three wires, respectively of silver, iron, and german 
silver. The elastic reaction was greatest with the first, least 
with the last of these, and the change in the elastic reaction 
produced by change of temperature followed the same order.— 
i, Warburg, remarks on the pressure of saturated vapour. Dis- 
cusses relation between vapour-pressure and curvature of liquid 
surface.—W. Fischer, on the pressure of saturated vapours above 
liquid and above solid substances. The substances chosen were 
ice and water. The difference, for ice, between the two differ- 
ential coefficients of pressure with respect to temperature for 
saturated steam over ice and saturated steam over water is 
0'0465, at the melting-point, where the two curves meet, For 
benzol the two curves do not meet at its melting-point.—A. 
Schrauf, on dispersion and axial density in prismatic crystals ; 
and on the properties of trimetric crystals. The latter shows the 
existence of a relation between coefficients of expansion, axial 
density, and the parameters of the crystal—A. Toepler, some 
lecture experiments on waves. A small gas flame is used to 
show the propagation of a wave of compression in a long tube 
filled with air, and provided at one end with an india-rubber 
pear. Several interesting experiments can be shown.— E. Cohn 
inahatiney mnie arumesien: Send ws wes en rk 
