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but afterwards the spectrum of the haloid salt of copper is distinctly 
visible. 
Observation on the Dip of the Magnetic Needle. — Mr. P. E. Chase gives the 
following as the result of his observations : — 
1. The lines of equal dip are arranged in approximate parallels, around the 
two (principal) magnetic poles. 
2. In consequence of this parallelism, they are convex towards the north in 
the Pacific Ocean, and towards the south in the Atlantic Ocean. 
3. The magnetic parallels also approximate to the isothermal parallels, both 
in direction and in position, but with some important departures. 
4. In South America, the magnetic equator is depressed nearly 30° south 
of the isothermal equator ; it is, however, nearly equidistant from the 
(principal) north and south magnetic poles. 
5. The magnetic parallels near the magnetic poles are more convex than 
the isothermal lines, but they present some interesting instances of parallelism 
to the ocean currents, which are indisputably gravitation currents. 
6. This parallelism is specially observable in the regions of the equatorial 
currents, the Gulf Stream, and the North Pacific and Japan currents. 
7. If a series of waves were propagated through the air, from the magnetic 
poles to the equator, with slight deflections by the continental contours and 
ocean currents, they could be represented with great accuracy by the magnetic 
parallels. — Aide Proceedings of the American Philosophical Society , vol. X. 
No. 73. 
Peculiar Phenomena of Efflorescence. — Herr Pape’s investigations on the 
efflorescence of crystals are continued in Poggendorfps Annalen. The writer’s 
object is to show that this action is not propagated, as might have been sup- 
posed, irregularly, but in spots of a certain determinate form, generally par- 
taking more or less of the ellipsoid. The relative proportions of the diameters 
of these figures are, he states, intimately connected with the form of the 
crystal. He mentions the well-known fact of the difference in the heat- 
conducting powers of a crystal in different directions, which he considers to 
be somewhat akin to the phenomenon he describes. In some substances — 
for example, newly-formed crystals of Glauber’s salt — large elliptical spots 
may be noticed within five or ten minutes after their removal from the 
mother liquor. In sulphate of zinc the same thing may be observed after the 
lapse of a day or so, the isolated spots having a regular and sharply-defined 
outline. The efflorescence takes place with greater rapidity in the direction 
of the shorter axis of the crystal, and slower in that of the longer axis. The 
form, then, of the efflorescence-figure of any particular face of the crystal 
depends on its position with regard to the axis. He suggests that this fact 
may be found useful in determining the system to which a crystal belongs 
when the ordinary method fails to give satisfactory results. The same law 
may probably hold good during the separation of other substances besides 
water, such as carbonic acid or ammonia from crystals containing these 
compounds. — J Reader, Dec. 2. 
A New Mode of Barometric Begistration is proposed by Mr. Edward 
Crossley, in a letter addressed to the Chemical News of November 3rd. 
Without doubting that the photographic registration of the barometer is 
capable of great accuracy, he thinks that there is another method by which 
