March 28, 1895J 



NATURE 



517 



aciils are di'tinguished from the aromatic analogues by their 

 greater solubility in water. In all cases they are most advan- 

 tageously prepared by reacting with one equivalent of hydrazine 

 hydrate upon the e-ler of the acid rather than upon the free 

 acid itself. The ei.ters of dibasic fatty acids react analogously 

 with two equivalents of hydrazine hydrate, producing hydrazides 

 which contain two NHNH groups. 



Formic hydrazide, HCO.NHNH.^, is produced when mole- 

 cular equivalents of ethyl formate and hydrazine hydrate are 

 mixed, considerable evolution of he.it occurring. When the 

 product is allowed to stand in a vacuum for some days large 

 tubular crystals of the pure compound 'eparate. The crystals 

 are transparent, very hygroscopic, and extremely soluble in 

 water, alcohol, ether, chloroform, and benztne. They melt at 

 54°. Formic hydrazide does not form salts with acids ; even 

 dilute acids at once decompose it in the cold with formation of 

 formic acid and a salt of hydrazine. The solution of the crystals 

 in water reduces Fehling's solution and ammoniacal silver 

 nitrate readdy at the ordinary temperature. Formic hydrazide 

 forms a crystalline compound with benzaldehyde with consider- 

 able rise of temperature and with elimination of water. 

 The crystals of the compound, benzalformyl-hydrazine, 

 HCO.NH.N : CH.CJI;, melt at 134°. When excess of ethyl 

 formate is heated with hydrazine hydrate in a sealed tube to 

 100"- 1 30' for some hours, another formic hjdrazide, diformyl- 

 hydrazine HCO.NH.NII.COH, is produced in the form of 

 brilliant colourless prisms an inch or more in length. In the 

 prep.iration of this beautiful compound care must be taken to 

 strongly cool the tube during the filling with the two compo- 

 nents, as their interaction is otherwise of a dangerously ener- 

 getic character. The crystals of diformyl-hydrazine are very 

 soluble in water, but difticuUly so in alcohol, and practically in- 

 -solubla in ether. They melt at 159°, and reduce ammoniacal 

 silver solution upon warming. Dilute sulphuric acid decom- 

 poses them as readily as those of formic hydrazide into formic 

 acid and hydrazine sulphate. 



.Vcetic hydrazide, CH3.CO.NH.NH.,, is prepared by warm- 

 ing equivalent quantities of acetic ether and hjdrazine hydrate 

 in a sealed tube for a few hours at llie temperature of a water- 

 bath. The product rapidly solidifies in a desiccator to a white 

 mass of crystals. The crystals are colourless needles aggregated 

 in leaves, and melt at di". They deliquesce rapidly on exposure 

 to moist air, and are also very soluble in cold alcohol. The 

 aqueous solution reacts neutial to litmus, and is readily de- 

 composed into the original component substances by either acids 

 or alkalies. The compound cannot be distilled without decom- 

 position. The solution reduces Fehling's solution very vigor- 

 ously on warming. Like the formic compound, acetic hydra?:de 

 reacts with benzaldehyde to produce an analosous crystalline 

 compound, .icetyl-benzal-hydrazine, CH3.CONHN : CHCuH,. 

 CO.NH.NH3 



Oxalic hydrazide, | , is produced by the action 



CO.NH.NH., 

 of two molecular equivalents of hydrazine hydrate upon ethyl 

 oxalate. The reaction is a somewhat violent one, and is best 

 moderated by the addition of a little alcohol. 



The new compound separates as a white crystalline mass, 

 which is much less soluble in water than the hydrazides of the 

 monobasic acids, and is almost insoluble in alcohol and ether. 

 It is deposited from solution in hot water in very long and thick 

 needles, which decompose at 235°. The solution reduces 

 Fehling's or ammoniacal silver solution much less vigorously 

 than the monobasic compounds. Oxalic hydrazide is much 

 more stable towards acids and alkalies than the last-mentioned 

 substances. The compound may be recrystallised unchanged 

 from dilute sulphuric acid, and concentrated sulphuric and 

 hydrochloric acids only decompose it very slowly. If, however, 

 concentrated hydrochloric acid is allowed to drop upon the 

 powdered substance moistened with water, until the acid is in 

 slight excess, a white crystalline powder is obtained which is 

 found to consist of the hydrochloride of the hydrazide, 

 CO.NH.NHj.HCl 



I . Oxalic hydrazide reacts in an interesting 



C0.NII.NH„.IIC1 



manner with nitrous acid (sodium nitrite and glacial acetic 

 acid) ; an energetic evolution of gas occurs, and a white powder 

 separates. The same white substance may be obtained by 

 acting upon oxalic hydrazide suspended in water with mercuric 

 oxide, and decomposing the mercury compound produced with 

 sulphuretted hydrogen, the filtrate depositing the white powder 



NO. 1326, VOL. 5 l] 



upon evaporation. Analysis indicates that the compound 



CO— NH 

 probably possesses the constitution, I | 



CO— NH 

 CHj-CO-NIINHj 

 Succinic hydrazide, | ' , is prepared similarly 



CHJ.CO.NHNH2 

 to oxalic hydrazide, and crystallises in silver-like crystal aggre- 

 gates which melt at 167', and which are more soluble in water 

 than the crystals of oxalic hydrazide. Malonic hydrazide, 



/CONHNHj 

 CHj<^ , is likewise obtained in a similar manner, 



^CONHNII, 

 the reaction between malonic ether and hydrazine hydrate 

 being very vigorous even in the cold. The crystals melt at 

 152°. The aqueous solution reduces Fehling's solution, am- 

 moniacal silver solution, and platinic chloride at the ordinary 

 temperature. Both the succinic and malonic hydrazides are as 

 stable towards acids as the oxalic compound, and each yields a 

 hydrochloride with concentrated hydrochloric acid. Both 

 hydrochlorides are obtained in the form of small crystals, and 

 they melt at 203 and 197° respectively with violent evolution 

 of gas. Succinic hydrazide reacts with nitrous acid to form an 

 interesting compound analogous to that of oxalic hydrazide. 



CH„.CO.NH 

 Its simplest possible constitution is | | . 



CH..CO.NH 

 Several other more complicated hydrazides are described in 

 the memoir, but the above will afford a sufficiently compre- 

 hensive idea of the important addition to our knowledge of the 

 hydrazine compounds which we owe to the la''.ours of Prof. 

 Curtius. A. E. TuTTON. 



THE AURORA OF MARCH 13. 

 A NUMBER of letters referring to an aurora observed on 

 "^ March 13, have reached us. We select from these com- 

 munications a few de'ails of value and interest. 



Writing from \'ork, Mr. J. Edmund Clark says : — 



" I was in a position for observing at 9. 10 ; the display finally 

 ended soon after 10. The latter part was seen, very similarly, at 

 Scarborough, 9.10. Arch, pure white (and so all through) just 

 north of zenith ; east end brighter, with well-defined, beak-like 

 apex upon o Corona; borealis (alt. 17% az. 13° north of 

 cast). Upper edge just grazed t," and tj Ursx majoris, 

 the lower some 3'' below Polaris, a little west of which it 

 became double, the Pleiades lying in the fork, 5^ or 10' from the 

 finish at about altitude 20° or 25°, nearly due west. No auroral 

 glow outside, nor later, except as stated. The outer curves, 

 west end, would have met, if continued, in similar "beak " as 

 at east end. 



"9.15.' Lower edge through 3 Ursae minoris, Polaris, and 

 o Persei. Streamers now traversing rapidly from tatt to -.vest, 

 pointing to magnetic anti-pole ; passed from ij Ursse majoris to 

 Polaris in 25 to 30 seconds by watch. Constant succession, as 

 bars of light, for some minutes ; then temporary cessation, but 

 later intermittent, until 9.45. These were entirely distinct, as 

 is obvious, from the ordinary far more rapid flickering from 

 horizon t(5 magnetic anti-pole. Three rough positions of 

 stationary forms near the Plough, Auriga, and Jupiter, pro- 

 jected on the B.A. Meteor Star Chart, cross at altitude 6S.y', 

 azimuth 35" (\' and 6^ respectively from the true magnetic anti- 

 pole, for York, at 68^ and 18°). 



" 9.25. Streamers, often as curtain-like fringe on lower edge 

 of arch, now less prominent. Otheis still streaming from east 

 to west in the arch show no perceptible efTect as they sweep by 

 these. New set moved slowly westward, about I* or 2° per 

 minute. 



"g. 30. Lower edge again as at 9.25. Upper edge had 

 covered Plough ; arch double more or less entirely ; varies 

 fast ; much fainter to east from 9.25. 



"9.37. Lower edge through handle of Plough, Capella, I* 

 north of M.rrs and % on from Mars to horizon. Fringe below 

 now brilliant, but rapid fluctuations. 



" 9.45. Brilliant short streamers in fringe, from Mars to 

 a Auriga-, and ', on to Polaris. 



" lo.o. All gone but one long faint streamer from 3° to left 



1 If other* have thoueht of recording positions .it the exact quarters, some 

 altitudes migtit t>e obtained from the four given here. 



