Transactions of the Royal Society of Edinburgh, 9. köide;11. köideThe Society, 1831 List of fellows in v. 1-5, 7-16, 20-30, 32-33, 35-41, 45; continued since 1908 in the Proceedings, v. 28- |
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alcoate alcohol alumina amianthus analysis animal appearance Argand burners atom protoxide atoms magnesia atoms silica atoms water barometer Bart baryta calcareous spar carbonic acid cavities cent Cetacea chabasite chemical chloride of calcium cleavage colour composed compound constituents contains copper crystals decomposition deutoxide diameter dissolved distance dugong Edinburgh experiments F. R. S. Lond gallactin glass grains hydrogen inches inductive lens lenses light lighthouses lime liquid lustre magnesia magnet manganese manganese-ore mass of iron metallic mineral muriatic acid nearly observed obtained oxide oxygen parallel Peroxide of iron plane Plate poles portion potash precipitate prehnite prismatoidal prisms Professor protoxide of iron Psilomelane pyrolusite quantity red heat red oxide reflectors refracted result rhombohedral Royal salt shew shewn Society soda soluble solution species specific gravity specimen Sternbergite stomach Strontian substance sulphate sulphuret sulphuric acid surface teeth temperature tion variety weight zinc
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Page 37 - If impurities exist in the glass of any of the spherical segments, or if an accident happens to any of them, it can be easily replaced at a very trifling expence. Hence the spherical segments may be made of glass much more pure and free from flaws and veins than the corresponding portions of a solid lens. " 3. From the spherical aberration of a convex lens, the focus of the outer portion is nearer the lens than the focus of the central parts, and therefore the solar light is not concentrated in the...
Page 37 - ... 5. If it should be thought advisable to grind the segments separately, or two by two, a much smaller tool will be necessary than if they formed one continuous lens. But, if it should be reckoned more accurate to grind each zone by itself, then the various segments may be easily held together by a firm cement 6. Each zone may have a different focal length, and may, therefore, be placed at different distances from the local point, if it is thought proper.
Page 37 - ... lens. 3. From the spherical aberration of a convex lens, the focus of the outer portion is nearer the lens than the focus of the central parts, and, therefore, the solar light is not concentrated in the same point of the axis. This evil may, in a great measure, be removed in the present construction, by placing the different zones in such a manner that their foci may coincide. 4. A lens of this construction may be formed by degrees, according to the convenience and means of the artist. One zone,...
Page 39 - 2. In the solid lens, a great diminution of light arises from the thickness of the central portions, and from the obliquity of the parts at the circumference; which, we conceive, will be fully equal to the light lost by reflection in the burning sphere.
Page 154 - When it comes in contact with concentrated sulphuric acid, an intense heat is instantly evolved ; and the same phenomenon .is produced, though in a less degree, by .strong muriatic acid. This oxide is likewise the base of the salts which are. formed when. sulphuric or muriatic acid is heated with the peroxide, deutoxide, or red. oxide of manganese. As the accuracy of this statement, as respects sulphuric acid, has been denied by an acute chemist and good observer, I have been induced to examine the...
Page 84 - Dark grey crystals of copper-glance are often deposited on low six-sided prisms, which, in respect to form entirely agree with that species. Their surface, however, is never perfectly smooth. On breaking them they do not present a uniform appearance ; generally the portions nearest the surface consist of the reddish metallic substance of variegated copper, whilst the rest possess the grey colour and conchoidal fracture of copper-glance. £ * £ On breaking the sixsided prisms here alluded to, I...
Page 47 - I further considered that every irregularity in a reflecting superficies makes the rays stray five or six times more out of their due course than the like irregularities in a refracting one; so that a much greater curiosity would be here requisite than in figuring glasses for refraction.
Page 224 - They exist at the mouth of a vein of solid iron (barra), half a yard wide, situated at the foot of a mountain. The opposite plain is strewed with similar fragments. The Indian who brought these, calls them " Reventazones," supposing them to be produced by explosions from the mines. He had been charged to bring a piece of the vein itself, and some of the rock in which it is imbedded ; but this he says he could not effect for want of tools. He therefore contented himself with picking up some pieces...
Page 140 - German ones, found in similar repositories, occurs at the mine of Antonio Pereira near Villa Ricca in Brazil, along with brown hematite and psilomelane, in beds in clay-slate, produced according to Dr POHL'S account, from the decomposition of sparry iron. Small granular pyrolusite occurs at Skidberget in the parish of Lepand in Dalecarlia, Sweden. But the individuals are often much smaller, and appear in the form of a black sooty substance. Such are frequently found in the...
Page 126 - I have much pleasure in adding here, that the observation of this peculiar character, which I gave an account of from a rather limited number of crystals, has since been repeated, and perfectly confirmed, by Dr CHARLES HARTMANN of Blankenburg. The faces marked c, if sufficiently enlarged, would give rise to a form resembling a tetrahedron, like Fig. 11, the planes of which are equal and similar scalene triangles. Among the remaining species whose forms belong to the prismatic system, only the sulphates...