472 Notes and Memoranda. 



nebulosities which, in reversing themselves, produced the tail." The periodicity 

 of the jets at first suggested a rotation of the comet about an axis, but the idea 

 was not confirmed by observation. The light of the nucleus and of the aigrettes 

 was only polarized once, on the last day on which such an observation was possible, 

 and then very feebly. The nebulosities, on the contrary, were always strongly 

 polarized. These facts indicate adiffereut molecular condition, and M. Secchi suggests 

 that the nucleus and the aigrettes may have been formed of vapour analogous to 

 our clouds, which do not polarize, while the nebulosities had passed into a state of 

 gas which polarizes like our atmosphere. He adds, " We might also admit that 

 the nucleus and the aigrettes were incandescent, but the supposition is a little 

 difficult. After the perihelion passage there appeared vestiges of paraboloid sur- 

 faces enveloping the sheaves of light, as if the matter was being deposited in layers 

 as the comet cooled." 



Secchi on Mars. — In 1858, M. Secchi found the appearance of Mars differ 

 considerably from the drawings of Maedler and other astronomers. Now, the 

 planet has returned to its former aspect, and, instead of exhibiting large compli- 

 cated solar spots, showed them to be reduced to a small circle, as in Maedler. 

 The great spots had given place to rose-coloured surfaces, traversed by blue canals, 

 as represented in Secchi's picture of 1858. From these changes he thinks no 

 doubt can remain that the polar spots consist of snow, or condensed clouds, which 

 the summer heat of the planet melts. The red surface he regards as land, and 

 the blue canals as water. — Comptes Rendus. 



Volcanic Haie. — M. Ranibosson communicates to the French Academy some 

 facts relating to the volcano in the Isle of Reunion, and states that in the eruption 

 of 1860 as in that of 1812, it poured forth a shower of dark cinders and of long 

 flexible filaments of glass-like golden hair. Similar filaments were seen by Sir W. 

 Hamilton emitted by Vesuvius in 1779. 



Analysis of Air.— In his pamphlet on "Air and Water," Mr. Condy 

 points out the facility with which air may be tested for organic impurities by placing 

 in the required spot four or more small white saucers, each containing an ounce of 

 distilled water, and severally one, two, three, four, or more drops of his Patent 

 Ozonized Water, or Disinfecting Fluid, reduced by addition of two parts of water. 

 The rate at which the pink colour of the permanganate disappears, indicates the 

 proportion of impurity present. If during a night or day the colour vanishes in 

 the saucer containing four drops, he states that the impurity verges on positive 

 pollution. 



New Use op Diamonds. — It was proposed some time ago in Cosmos to employ 

 rough dark diamonds in the perforation of rocks, and that journal now states 

 that M. Leschot has used a perforator formed of a tube terminating in a crown of 

 these diamonds, and succeeded in making a hole in granite in one hour which 

 would have taken two miners two days. The diamonds were not injured in the 

 process. 



Experiment with Sulphuretted Hydrogen. — Cosmos says, "Bring some 

 drops of bromine in contact with sulphuretted hydrogen, and you will see the 

 volume of the gas doubled at the moment the sulphur is deposited." 



A Fowl with Black Periosteum.— Dr. Miche, dining with some friends on 

 a Cochin China fowl, noticed that the covering of its bones was quite black. He 

 accordingly sent the skeleton to M. Flourens, who was able to exhibit to the Academy 

 a similar skeleton of a common fowl. The bones themselves were white. Six 

 chickens out of twelve having the same parents exhibited this peculiarity, and tho 

 flesh of the only one killed was dark and ill-flavoured. 



