6o6 



i\'A TURK 



[October iS, 1894 



Messrs. j. J. Gkikh.n and Sons have recenily published 

 the third edition of their illustrated and descriptive catalogue of 

 chemical apparatus. A few of the new instruments are worthy 

 of notice. For instance, a new pattern of Tate's air-pump, 

 described in the catalogue, has been designed with valves at 

 each end of the barrel so that no air can exist between them 

 and the pistons, hence, at each stroke, all the air contained in 

 the barrel is expelled. Metallurgists will be interested in a 

 new form of gas furnace capable of carrying on operations at a 

 white heat without the aid of a blower ; the power of the 

 furnace may be judged from the fact that one pound of cast iron 

 can be melted in ihirty-five minutes. A cathetometer which 

 enables the operator to turn the telescope in any direction with- 

 out moving the instrument bodily, is another noteworthy feature. 

 Arnold and Hardy's apparatus for the estimation of sulphur in 

 steel and steel-making iron ; benzolme blast furnaces attaining 

 a temperature of 2100° F. ; Prof. Roberts-Austen's electrical 

 pyrometer ; and many other pieces of apparatus, for use in 

 leaching and research, have been introduced into the catalogue. 



A CONSIDEKABLE addition to our knowledge of the chemical 

 history of hydrazine or diamideand its derivatives is contributed 

 by Prof. Curtius, its discoverer, and his assistants, to the current 

 issue of the fournat fiir fraklische Chemif. -Vn interesting 

 account is given of the position ofdiamideasa salt-forming base, 

 and its relations in this respect to ammonia and the fixed alkalies. 



NH, 

 Diamide itself, | , is an extremely unstable substance, so 



NH5 

 much so that it is still doubtful whether the anhydrous gas has 

 yet been obtained, or is even capable of separate existence. On 

 the other hand, the liquid hydrate, N^Hj. H,0, is a very stable 

 substance, as Prof. Curtius has long ago shown. It is interest- 

 ing to note that this is the opposite of what ^is the case with 

 ammonia, where the gas itself is stable and the hydrate par. 

 ticularly unstable. Moreover, while ammonia is a monacid 

 base, diamide isdi-acid ; and just as we accept the idea of a 

 hypothetical ammonium radicle NIIj, so we are bound likewise 



NH3 

 to admit the conception of a divalent radicle { , which Prof. 



NH3 

 Curtius terms diammonium, in the hydrazine salts. Thus the 



XH,|C1 

 normal chloride of hydrazine is | and the sulphate 



NH3CI 



I xSOj . Diammonium would thus seem to be analogous 



nh/ 



10 the divalent metals of the alkaline earth.s and the 

 parallel would appear to be further justified by the sparing 

 solubility of the sulphates and their inability to form alums with 

 sulphates of the alumina group. On the other hand, diammonium 

 exhibits properties which puint to a close similarity to the 

 alkali metals. For the hydrate behaves in by far the greater 

 number of instances as a mon-acid base, like ammonium 

 hydrate. The neutral chloride above mentioned, NjII„Clj, 

 decomposes below 100' into hydrogen chloride and the chloride 

 NjHjHCI, which cannot be made to lose more hydrochloric 

 acid without destruction of the base. Thehydratc N.,IIj.2Ho0.j 

 is only capable of existence in solution ; it passes on evapor- 

 ation into the hydrate N,ll|.II,0, which latter substance boils 

 without decomposition, iJry ammonia gas only displaces half 

 the acid of the sulphate N.^! 1,1 I^SOj, and leaves the stable 

 sulphate (NjIIjl.HjSOi. Moreover, Prof. Curtius has only 

 succeeded in preparing one nitrate, NjTI,. UNO,,, and one 

 thiocyanatc, N,II,SCNH. Hence he concludes that diam- 

 monium is capable of acting both in a monovalent capacity as 

 (N-H-,)', and as a divalent radicle (NjH,,)", (he former resulting 

 in the production of the more stable salts. 



NO. 1303. VOL. 50] 



Proi'. Ci;ktius has succeeded in preparing a large number 

 of double salts containing diammonium, and describes them in 

 a separate memoir in conjunction with his assistant, Herr 

 Schrader. Ammonium, as is well known, forms three classc5 

 of double salts containing sulphuric acid, namely, the aluni*, 

 the double sulphates with 6IIjO, and the peculiar and as yet 

 little understood salts usually formulated as R"S04.nNH3 in 

 which the anhydrous gas is assumed to enter into combination 

 with the metallic sulphate. .'\11 efforts to obtain alums con- 

 taining diammonium sulphate, XoHuSOj, have so far failed : 

 but salts of the other two types, containing the more stable 

 sulphate (N.^H-J^SOj, are readily obtained. It is some- 

 what singular, however, that they contain no water of crys- 

 tallisation, a fact which is possibly explained by the diffi- 

 cult solubility of the compounds. The divalent metals present 

 may be copper, nickel, cobalt, iron, mang.mese, cadmium or 

 zinc, but no! magnesium. They are at once precipitated upon 

 mixing concentrated solutions of the metallic sulphate and di- 

 ammonium sulphate. It is furtlier remarkable that the latter 

 may be either of the two sulphates of diammonium ; indeed, the 

 solution m.iy contain free sulphuric acid. Moreover, the sul- 

 phate N,,H^SOj is difficultly soluble, while the more stnlWc 

 sulphate (N;H.-,)jS04 is deliquescent, and yet the sparin:;ly 

 soluble double salts always contain the deliquescent diani 

 monium sulphate. In addition to these, salts of the type 

 R"S04.2N„H4 and R"SOj-3NjH4 have been obtained ; in th.n 

 of the former type R" may be zinc or cadmium, correspon<lint; 

 to the ammonia compounds R"SOi.4NH3, and in those of the 

 latter type nickel or cobalt, these salts being analogous to the 

 well-known compounds NiS0j.6NH., and C0SO4.6NH3. In 

 direct opposition to the ammonia compounds, the salts contain- 

 ing anhydrous hydrazine are almost perfeclly.insohible in water. 



The additions to the Zoological Society's Gardens during the 

 past week include two Pig-tailed Monkeys {Macaciis ncinc' ■ 

 Irinus, i 9) from Java, a Vervet Monkey (Ccrcofilli, :i. 

 lalandii, P ) from South -Vfrica, presented by the Rev. Sidnn 

 Vatcher ; a Rhesus Monkey (.)/a<-i7<r;« rhesus, <i ) from In 

 presented by Mr. E. Logan; a White-backed Piping ti 

 (Gymnorhina leiiconota) from Australia, presented by M^ 

 Vmcent ; a Manx Shearwater {Pi4j)iuus angloriim) fr.iu 

 Cornwall, presented by Mrs. E. S. Smith ; two Rolun^ 

 {E:il/i(uiii nilieciila), South European, presented by Mr. A, 1 

 Binny ; a Chameleon (Chamitlton vuIgatii)Uom North Afn 

 presented by Mr. W. L. Strong; a Deadly Snake (Tri^.,. 

 cepJiatus alrox) from Trinidad, presented by Dr. A. Stradini; : 

 a Vak (Poipltagiis grunniens, i), born in the Gardens. 



i 



OUR ASTRONOMICAL COLUMN. 



The Rio de Janeiro Ouservatory. — The Brazilian 

 National Observatory, situated on the Morro do Caslello, the 

 most easterly hill of Rio de Janeiro, is to be removed. The 

 Amcruitii Mcleorological Journal reports that the unfavoun 

 situation of the Castello for astronomical observations ha^ I 

 to the selection of a site across the bay, near I'elropolis, at .in 

 elevation of about 3500 Icct. .A. road is now being Imilt up' 

 the mountain, and it is ho[ied that the new observatory will I" 

 completed within two years. The sum of live hundred thou 

 dollars has been voted by the Government for the installaii 



Odservations of Mars. — The current number of the 

 servalory contains a short article in which Mr. Stanley Willi.ii: 

 directs attention to certain important features of Mars, which, it 

 will l)C remembered, is in opposition on .Saturday. With 

 regard to the canals or channels, he remarks that a (ew points 

 upon which observations are desirable are : " How far is the 

 visibility of the canals in dilTcrcnt parts of the planet affected by^ 

 seasonal changes:" Their duplication, when <l>ics it occur?' 

 How long does it Last ? How does it nccur ? And ag.iin, how 

 far is It suliject to seasonal changes?" Mr. Williams com- 

 menced observations in the l.itter part of August, and he found 



