Intelligence and Miscellaneous Articles. 159 



dant liberation of binoxide of nitrogen, which suddenly ceases if 

 the wire be immediately withdrawn, without leaving a gas-bubble, 

 and which recommences as soon as the wire is again immersed. 

 At the same time the water is charged with a fresh quantity of 

 nitric acid. This decomposition can be determined with more acti- 

 vity by the introduction of a little bell containing air, its outer sur- 

 face having been freshly disaerated in the flame of a gas-burner. 

 The bubbles of binoxide then seem to issue from the bell, as in the 

 solution of ammonia. This effect, of a gaseous atmosphere decom- 

 posing nitrous acid, can be observed even at the temperature of zero 

 (Centigrade) ; in this case the liberation of the binoxide of nitrogen 

 is less rapid. 



There is, then, the closest analogy between the emission of a dis- 

 solved gas, effected at the surface of the solution, into a gaseous 

 medium as into a rarefied atmosphere, and that decomposition of 

 explosive bodies which, as I have pointed out in the case of oxyge- 

 nated water, there is no reason to attribute to a peculiar catalytic 

 force. Moreover the evolution of heat which accompanies the de- 

 composition of these bodies, though slight in the case of nitrous acid, 

 explains the rapidity with which the phenomenon proceeds as soon 

 as it has been induced at one point of the body, unless the reaction 

 be arrested at its starting, as I have here shown. — Comptes Rendus 

 de VAcad. des Sciences, Jan. 4, 1875, pp. 44-47. 



ON VENUS AS A LUMINOUS RING. BY PROF. C. S. LYMAN. 



In this Journal*, eight years ago, a brief notice was published 

 of some observations made by the writer on Venus when near her 

 inferior conjunction in 1866. The planet was then (for the first 

 time, so far as appears) seen as a very delicate luminous ring. The 

 cusps of the crescent, as the planet approached the sun, had ex- 

 tended gradually beyond a semicircle, until they at length coalesced 

 and formed a perfect ring of fight. 



No opportunity has since occurred of repeating these observations, 

 until the day of the recent transit. On Tuesday, December 8th, 

 Venus was again in close proximity to the sun ; and the writer had 

 the satisfaction of watching the delicate silvery ring enclosing her 

 disk, even when the planet was only the sun's semidiameter from 

 his limb. This was at 4 p.m., or less than five hours before the 

 beginning of the transit. The ring was brightest on the side 

 towards the sun — the crescent proper. On the opposite side the 

 thread of light was duller and of a slightly yellowish tinge. On 

 the northern limb of the planet, some 60 or 80 degrees from the 

 point opposite the sun, the ring for a small space was fainter and 

 apparently narrower than elsewhere. A similar appearance, but 

 more marked, was observed on the same limb in 1866. 



These observations were made with a five-foot Clark telescope of 

 4| inches aperture, by so placing the instrument as to have the 

 sun cut off by a distant bunding while the planet was still visible. 

 * Silliman's American Journal, vol. xliii. p. 129. 



