CHEMISTRY. 



a candle, has a central hollow space about half 

 its own length, the "zone of no combustion." 

 Mr. J. Wallace, of Newcastle-on-Tyne, has dis- 

 covered a method of obliterating this hollow 

 space, and of producing a solid flame. While 

 experimenting with a view to ascertain the 

 conditions of safety in the mixture of air with 

 coal-gas, Mr. Wallace observed that as the pro- 

 portion of air was increased the hollow space 

 became smaller, the whole flame contracted, 

 and the heat became more intense. The surface 

 of the space changed from a leaden color to a 

 brilliant emerald green, and finally, as the pro- 

 portion of air was increased, the " zone of no 

 combustion " disappeared altogether and the gas 

 and air exploded in the Bunsen burner. The 

 form of the burner was such as to allow of an 

 intimate mixture of the air and gas. It was 

 thus apparent that the hollow space or "zone 

 of no combustion " depended entirely on the 

 amount of air which was mixed with the gas 

 previous to combustion, and it only remained 

 to construct a burner in which the gas-jet 

 should be able to induce the extra quantity of 

 air, and the burner itsalf be so arranged that 

 the tendency to explode or light within should 

 be prevented. It in\y here be noted that a 

 much greater proportion of air must be pre- 

 admixed to obtain a good flame from a large 

 burner than from a small one, because the area 

 of the flame increases at a much greater rate 

 than its circumference. The remainder of the 

 air, which makes up the total combining quan- 

 tity, is combined with the gas during combus- 

 tion, and appears only to unite at the lower 

 part of the flame; the upper part being en- 

 veloped and cut off, so to speak, by its own 

 products. 



The following account of some of Mr. Wal- 

 lace's experiments is from the Engineering and 

 Mining Journal : 



A cylindrical cap of finely perforated iron plate 

 was fitted on to a burner tube 1 inch in diameter, and 

 made adjustable to various hnglits. When raised 

 to t inch, gas was burned above it at the rate of 20 

 feet per hour, with a flame which was solid to the 

 centre, each hole in the cap being covered by a 

 bright-green bead showing where combustion began. 

 A 2-ine!i tube was next fitted up with 3 jets at tho 

 bottom, capable of passing 40 feet per hour at 11- 

 inch pressure. When lighted and adjusted the flamo 

 proved to be as complete as the previous ones, and 

 the proportion of air pre-admixed, when measured 

 from a test-holder, was 4 f 'o volumes. A platinum 

 wire stretched across the flame inch above the 

 cap became instantly white-hot for a distance of 4 

 inches, 'and the color gave no indication of any dif- 

 erence of temperature in any part enveloped in the 

 flames. When the air was interrupted at the base 

 of the burn?r a large hollow space immediately ap- 

 peared above the cap, and the wire cooled to black- 

 ness. On again admitting the air the wire was once 

 more incandescent. The green beads when exam- 

 ined by the spectroscope give the spectrum of car- 

 bonic oxide, and they only appear in a flame which 

 bums in the most complete manner. 



Absorption of Nitrogen ~by Plants. Berthe- 

 lot has published the results of a series of ex- 

 periments which prove that, under the in- 



fluence of atmospheric electricity, free nitro- 

 gen is absorbed at the ordinary temperatures 

 by the proximate principles of plants. The 

 apparatus used in these experiments consists 

 of a system of tubes in which the organic sub- 

 stances come into contact either with pure 

 nitrogen or with atmospheric air, the whole 

 communicating with a source of electricity at 

 a tension precisely the same as that of atmos- 

 pheric electricity. Under these conditions 

 pure nitrogen, or the nitrogen of the atmos- 

 phere, is invariably fixed by different organic 

 matters, as moist cellulose and dextrin. The 

 amount of nitrogen that is thus fixed is con- 

 siderable. These experiments demonstrate the 

 influence of a natural cause, hitherto scarcely 

 suspected, and nevertheless of great impor- 

 tance for vegetation. Hitherto, when the effects 

 of atmospheric electricity have been studied, 

 its luminous and violent manifestations, such 

 as thunder and lightning, have been chiefly re- 

 garded. Upon whatsoever hypothesis, the for- 

 mation of nitric and nitrous acids or of nitrate 

 of ammonia has been exclusively taken into 

 account. But the author's experiments show 

 a new and hitherto unknown action, which 

 works unceasingly under the most serene sky, 

 and which determines a direct fixation of ni- 

 trogen in the principles of the tissues of plants. 



New Oxide of Manganese. Fre"my has ob- 

 tained a new oxide of manganese, Mn 4 O 5 , aris- 

 ing from the reaction of the sulphate of the 

 sesquioxide of manganese on the sulphate of 

 the protoxide. It is obtained by decomposing 

 permanganate of potassium with an excess of 

 trihydrated sulphuric acid. On mixing the two 

 sulphates of manganese, the liquor takes on a 

 wine-red color, and deposits hexagonal tablets 

 formed by the combination of sulphuric acid 

 with the oxide Mn 4 O 6 . This salt is very un- 

 stable, water decomposing it with a precipitate 

 of hydrated sesquioxide of manganese. The 

 liquor retains in solution a mixture of sulphu- 

 ric acid and sulphate of protoxide of manga- 

 nese. The rose-colored liquid known to chem- 

 ists, obtained in the preparation of oxygen by 

 treating the peroxide of manganese with con- 

 centrated sulphuric acid, owes its coloration 

 to the presence of the new compound discov- 

 ered by M. Fremy. The new oxide, Mn 4 O 6 , 

 takes its place in the following series of ox- 

 ides, sometimes called manganites, true 'saline 

 oxides : Sesquioxide, Mn 2 O 3 = MnOa, MnO ; 

 red oxide, Mn 3 0=MnO2, 2MnO ; new oxide, 

 Mn 4 O 6 =Mn0 2 , 3MnO. The newly-discovered 

 salt is decomposed by potash, and gives a black 

 precipitate, which easily dissolves in sulphuric 

 acid, and which reproduces the primitive salt. 

 Certain specimens of peroxide of manganese, it 

 is thought, contain a certain quantity of the 

 oxide Mn 4 O 8 ; those, probably, which give a 

 rose-colored liquor under the action of concen- 

 trated sulphuric acid. 



The Oxides of Manganese Sources of Ozone. 

 Experiments made by Valmagini indicate that 

 ozone is not only abundantly present in bi- 



