364 



NA TURE 



[August 9, 1894 



The First Biennial Report, for the years 1892 and 1S93, 

 of the Maryland State Weather Service, which was organised 

 on May i, 1S91, has been published. As in other States, the 

 observers are voluntary, and the Weather Bureau supplies 

 instruments. &c. The present report is intended to give a 

 geniril view of the climate, so far as conclusions can be drawn 

 from data yet obtainable : it also contains a general summary 

 of the physical features of Maryland, and of the different types 

 of soil, each of which is specially adapted to the cultivation of 

 certain classes of plants. The Director of the service, W. B. 

 Clark, points out that the climate is generally what is known 

 as continental, but is, greatly moJified in the eastern part of 

 the State by the ocean. The average mean temperature of 

 January is 32°'S, and of July 75° S, a mean range of 43°, but 

 the differences in certain localities are very considerable. Rain- 

 fall is fairly equally distributed throughout the year, the ' 

 maximum occurring in the spring ; the mean annual fall is 42*4 

 inches. Snow never fails completely, even with warmest 

 winters. , 



The Reporli of the Dirtclor of the Michigan Mining School 

 for 1890-1892 have just been distributed, and tell of much good | 

 work having been accomplished at this popular institution 

 during the years under review. In the report for 1891-92 men- 

 tion is made of a number of changes which were to come into 

 effect in 1S93, one being the lengthening of the course from 1 

 three to four years, and the raising the age for admittance into | 

 the regular course to twenty years, unless the intending student j 

 shall have completed a regular course in some good high school 

 or academy. The need of some kind of endowment is 

 pointed out, the school being at present entirely dependent 

 upon legislative aid. The report also calls attention to the 

 necessity for the erection of an additional building on grounds 

 belonging to the school. This building would be used for 

 machine shops, testing and electrical laboratories, the mining 

 engineering laboratories, &c. A metallurgical laboratory is 

 much needed, but cannot at present be proceeded with for 

 want of funds. The work in each department has developed so 

 much that an increased expenditure all round is deemed 

 necessary. 



DiAZOMBTHANE, H,C':^ i| , has been isolated by Prof, von 



Pechmann, of Munich, and a preliminary communication con- 

 cerning it is contributed to the current Bcri.hte. This interest- 

 ing substance is a yellow gas at the ordinary lemper.aturc, which 

 condenses when cooled to a yellow liquid. It appears to be 

 odourless, but is extremely poisonous, so much so that Dr. 

 Pechmann finds it very difficult to work with in the gaseous 

 state, owing to its violent action upon the respiratory organs. 

 The principal properties of the substance have therefore been 

 studied with its solution in ether. It is obtained by the action 

 of alkalies under special conditions upon any of the nilrosamines 

 of the type NR . Ac . NO, where R represents an alkyl radical 

 inch as methyl, ethyl or benzyl, and Ac stands for acetyl, 

 benzyl, or the radicals CONH2 and COOCjIIj. The yield of 

 the gas is at least fifty per cent, of the theoretical when 

 nitrosomethylbcnzamide or nitrosomethylurethane are employed. 

 The reaction appears to be a very simple one, represented by 

 the following equation : — 



CIIjN/^^ + NaOH = CH,N, -1- H,0 -t- AcONa. 



The new substance behaves in a characteristic manner towards 

 dilute acids. The yellow solution in ether is instantly decolour- 

 ised upon the a<ldition of the acid at the ordinary temperature, 

 nitrogen being evolved. Water acts in a similar manner and 

 almost as vigorously as when acidified. It is much more stable, 

 however, towards alcohol. Iodine decomposes diazomclhane 

 NO. 1 293, VOL. sol 



with formation of methylene iodide CHjTo and evolution of 

 nitrogen. The reaction may be carried out volumetrically if 

 the iodine is likewise employed dissolved in ether, the comple- 

 tion being indicated by a sudden decolourisalion of the liquid ; 

 the nitrogen can readily be measured by means of the nitro- 

 meter, over mercury. Diazomethane reacts with silver nitrate 

 and Kehling's solution in a similar manner to the diazoacetic 

 ether described by Curtius. Mercuric oxide is reduced in the cold. 

 Cork is bleached and eventually destroyed by the gas, so that the 

 ethereal solution cannot be preserved in vessels closed with cork 

 stoppers. The best proof of its composition and constitution 

 is considered by Prof. Pechmann to be afforded by its reaction 

 with the methyl ether of fumaric acid. The yellow ethereal 

 solution of diazomethane is instantly decolourised upon ad- 

 mixture with the fumaric methyl ether ; the substance produced 

 is a direct addition product which has been obtained in crystals, 

 and which upon boiling with dilute hydrochloric acid evolves 

 carbon dioxide and yields crystals of hydrazine hydrochloride. 

 Moreover, the silver s.ilt of this compound is stable, and has 

 been analysed. In concluding his preliminary notice, Prof. 

 Pechmann states that he has likewise isolated diazoethane in a 

 similar manner, employing, of course, an ethyl inste<id of a 

 methyl nitrosamine. Further particulars of these compounds 

 will doubtless be awaited with considerable interest. 



The additions to the Zoological Society's Gardens during the 

 past week include a Mozambique Monkey (Cercofit/iecus 

 pygerylhrus) from East Africa, presented by Mrs. Keirnander ; 

 a Blotched Genei (Genetla tigrina) from Lamoo, East Africa, 

 presented by Miss M. Clode ; a Grey Ichneumon (Herfestes 

 griseiis) from India, presented by Miss Sullivan : a Four-horned 

 Sheep iOt'is aries, var. ) presented by Mr. Frank C. Strick ; a 

 Blackcap (Sylvia atricapilla) British, presented by Captain 

 John Richardson ; a .Smooth Snake (Coronclla htvis) British, 

 presented by Mr. John Gray ; a Common Viper {Vifiera herus) 

 from Scotland, presented by Mr. J. Anderson ; a Red and 

 Blue Macaw {Ara macao) from South America, deposited. 



OUR ASTRONOAflCAL COLUMN. 



The Mac.nesium Spectrum as a Criti-.rion of StellaR' 

 Temperature.— The vari.itions undergone by the spectrum of 

 magnesium when the element is subjected to different tempera- 

 tures were studied some years ago, and their use in estimating 

 the comparative temperatures of celestial bodies have been 

 pointed out. Prof. J. K. Keeler contributes a note on 

 the matter to the .tslronamische Nachrichteii, No. 3245, 

 his remarks referring especially to some obscrv.itions recently 

 published by Prof. Scheiner on the behaviour, under dif- 

 ferent temperatures, of the lines at A 4482 .ind A 4352. 

 The former line is strong and broad in the spectrum 

 of magnesium, when luminosity is produced by means 

 of the electric spark with I.eyden jar in the circuit, but it docs 

 not appear in the arc spectrum ; on the other liaml, the line at 

 A 4352 is strong in the arc spectrum, but faint in the spark 

 spectrum. Similar differences of relative intensity are found to 

 exist in stellar spectra, and Prof. Scheiner is not alone in think- 

 ing that they afford a means of estimating the approximate tem- 

 peratures of the absorptive atmospheres of celestial bodies ex- 

 hibiting them. In connection with this subject. Prof. Keeler) 

 comments upon the absence of the magnesium triplet /' from 

 the spectrum of Kigel, while the line at A 4482 is conspicuous. 

 He suggests that the star is at too high .1 temperature for the 

 production of the/' group, anil uses the relative strength of the 

 group in different spectra as a criterion of stellar temperature. 

 It is pointed out that Kayser and Kunge have shown that the 

 group is characteristic of a molecular structure which cannot 

 exist at a very high temperature, whereas the lines at A 4482 and 

 A 4352 do not represent the same molecular slate. These con 

 sidcrations lead to the conclusion that the aspect of the /'line- 

 stellar spectra may be used as an index to the temperature in Hi 

 same way as the two lines selected by Prof. .Scheiner. 

 And since the 1/ group is absent from the spectra of Rigel and 



