302 



SCIENCE. 



[Vol. XI. No. 281 



to incandescence. In the Welsbach light, now on exhibition in 

 TSTew Yorlc, the incandescent substance is used in an extremely 

 thin or attenuated form, requiring the minimum heat to produce 

 the maximum of light. The principle of the invention will be 

 understood when it is described as a hood or mantle of finely 

 ■divided but perfectly coherent refractory oxides of lanthanum, 

 zirconium, and yttrium round the flame of a Bunsen burner. The 

 lamp has given satisfactory results so far. 



— We learn from the Engineering and Mining Journal that 

 ■the Alliance Aluminium Company has been formed in London, 

 England, with a capital of ^500,000, for the purpose of manufac- 

 turing aluminium, sodium, and potassium. The company owns 

 the English, German, French, and Belgian patents of Professor 

 Netto for the reduction of aluminium from its compounds, and for 

 the manufacture of sodium and potassium ; the processes of Mr. 

 •Cunningham for the reduction of the above metals ; a process for 

 the manufacture of artificial cryolite by the regeneration of its slags, 

 provisionally protected by the inventor, Mr. Forster, Lonesome 

 ■Chemical Works, Streatham ; a process invented by Professor 

 Netto and Dr. Saloman, of Essen, Germany, by which this metal 

 •can be raised to the highest standards of purity on a commercial 

 -scale. Exhaustive experiments have been made at the works of 

 Krupp at Essen to test the practical value of the processes, and it 

 is stated that he has the means of making the metal in tons. In- 

 stead of beads or marbles, solid chunks of the purest aluminium 

 'inown, weighing from five pounds to one hundred pounds (accord- 

 ing to the size of the converter), are deposited at every fusion of 

 the ingredients, chief among which are sodium and cryolite. The 

 ■company has a contract with the owners of the cryolite-mines in 

 ■Greenland to supply it with practically the entire output. It is 

 ■stated that the patents of the company enable it to manufacture it 

 -at considerably less than one shilling per pound. 



— An interesting fact in the history of I he movement for indus- 

 trial training in the public schools of Washington is its connection 

 with Cooper Union, that unique institution of which New York is 

 so justly proud. As already stated in Science, industrial drawing, 

 including moulding in clay, and construction in card-board, etc., has 

 .long been a feature of the Washington schools. The supervisor of 

 -drawing, Mrs. S. E. W. Fuller, who for fifteen years has guided the 

 work, was trained in the Cooper Union in those early days when, 

 with an enthusiasm and thoroughness not excelled by later institu- 

 tions and a wise prevision of coming demands, it brought art and 

 industry into their proper relation as means and purposes of educa- 

 tion. 



LETTERS TO THE EDITOR. 



•^* Correspondents are requested to be as brief as possible. The -writer's name is 

 -e« all cases reqiiired as proof o/ good faith. 



Twenty copies of the member containing his comjmtnication will be furnished 

 .yree to any correspondent on request. 



The editor will be glad to publish any queries consonant witJi the character of 

 ■ the journal. 



An Unusual Auroral Bo-w. 



I WAS much interested in Mr. D. S. Kellicott's communication in 

 your issue of June i, describing a peculiar form of northern lights ; 

 particularly so, as it was my fortune to witness a similar phenom- 

 ■€non in i88r. On July 2 of that year, the day on which President 

 Garfield was shot, at about 9.20 in the evening, faint streaks of 

 light were observed on the northern horizon. I then observed a 

 streak of cloud-like light ascending at about the east-south-east 

 "horizon. Looking around, I saw a similar streak at an opposite 

 -point. In a short time these streaks blended into one in the zenith, 

 ^forming an arch overhead. There was a bend or crook in this 

 arch ; just at what point I do not remember, as I made no note of 

 it, but I think at or near the middle. Presently the streak began to 

 ;-grow narrower ; then it changed and broadened again, until it be- 

 -came wider than it was at first ; then the southern edge resolved 

 itself into parallel bars at right angles with the arch ; shortly after, 

 the northern edge resolved itself into similar bars, which moved 

 ■rapidly towards the west ; presently the bars at the southern edge 

 ■of the arch either vanished or blended with the others, and they 

 all glided swiftly by towards the west ; the bars gradually became 

 ■fewer and fewer, until they could be seen only here and there 



gliding along; and at last the whole arch faded entirely away. 

 During all this time the lights in the north had been shining, and 

 when I retired for the night they were still to be seen. 



I have copied this description from notes which I took at the 

 time. I have seen other interesting auroras, but never have seen 

 the arch overhead since. Fr.\ncis H. Allen. 



West Roxbury, Mass , June 13. 



Concerning the Montville Serpentine. 



The statement made by your correspondent in your issue of June 

 15, regarding work done by me on the Montville, N.J., serpentine, 

 induces me to add a few additional particulars on the subject. 

 This I am the more inclined to do, since the paper giving the full 

 results ot my work is as yet unpublished, but is awaiting its turn in 

 the Government Printing-Ofiice. 



The origin of serpentinous rocks, by a process of metasomatosis, 

 from the various members of the pyroxene group, is a matter by 

 no means new to petrographers in general, and has been noted by 

 Dana in the limestone-beds of Westchester County, N.Y., as well 

 as by Emmons and Cross in those of the Leadville region. None 

 of the cases, however, can compare in point of beauty with that at 

 Montville. Here, in a coarsely crystalline, highly magnesian 

 limestone, were originally embedded numerous large and small 

 spheroidal and lenticular masses of a gray or pure white mono- 

 clinic pyroxene approaching diopside in composition. These, through 

 a process of metasomatosis commencing on the outer surface, have 

 become converted wholly or in part into a very pure, though highly 

 hydrated, translucent green and light amber-yellow serpentine. In 

 the process of quarrying the limestone for flux, these nodules are 

 thrown out ; and from the quarry dump have been gathered 

 samples showing most beautifully every stage of the change, from 

 that in which the serpentine exists as merely a thin coating, to that 

 in which all traces of the diopside have disappeared, and a solid 

 block of compact serpentine alone remains. The nodules vary in 

 size from the fraction of an inch to two or more feet in diameter. 

 I have as yet, however, never seen blocks of the serpentine more 

 than six or eight inches in greatest diameter. The process of 

 change must have been exceedingly slow and gradual, as the line 

 of demarcation is very sharp ; so sharp, indeed, that at first glance 

 such an origin as I have attributed appears impossible. On ex- 

 posure to the weather, the serpentinous coating undergoes a 

 shrinkage, and breaks away from the unchanged nodule almost as 

 clean as the burr from a chestnut. Nodules in the museum col- 

 lections, which have been freed from their serpentinous coating, 

 have the appearance of some easily soluble substance, like lime- 

 stone, that has been suspended freely in a dilute acid until all its 

 angles and irregularities of surface have disappeared. 



In my paper which is shortly to appear in the Proceedings of the 

 United States National Museum are plates showing the nodules 

 and the transition stages from diopside to serpentine, as shown in 

 thin sections under the microscope. I have gone into consider- 

 able detail in my description, not merely on account of the beauty 

 of the resultant serpentine, but because this is an unusually fine 

 illustration of the process of metasomatosis. The beautifully 

 slickensided surfaces, and other indications of the expansive force 

 generated during the process, are also very suggestive. 



The readiness with which samples can be procured which show 

 in a single small specimen all stages, from perfectly fresh and un- 

 changed diopside to beautiful compact serpentine, makes the 

 material particularly valuable to teachers. The small size of the 

 serpentine blocks obtainable, together with the invariably fractured 

 condition of the mineral, renders it of practically no importance as 

 an ornamental stone. George P. Merrill. 



U.S. Nat. Mus., Washington, June 16. 



Queries. 



33. Diphtheria carried by Turkeys. — Referring to the 

 paragraph ' Diphtheria carried by Turkeys,' in Science for May 

 II, I beg to inquire if the disease among barnyard fowls known as 

 ' roup ' has been investigated as a germ disease, and its relations 

 with other animal orders (if it have any) made out or sought. 



J. T. W. 



