UN E 20, 1890.] 



SCIENCE. 



371 



the magnet. It is inferred that all metals would exhibit magnetic 

 properties if cooled below this critical temperature ; but of this, in 

 the words of Dr. Hopkinson, " we have at present no indication." 

 Mr. Bid well also used on this occasion the very delicate apparatus 

 which he has constructed for accurately studying the effects of a 

 varying magnetizing force on bars of iron. He took up the subject 

 where Joule left it in 1845, and showed that the bar lengthens at 

 first, then contracts, becoming ultimately sliorter than its original 

 length. Joule's greatest magnetizing force was 120 C.G S. units; 

 Mr. Bidsvell has carried his to 1000 C.G.S. units. The correspond- 

 ing elongations and contractions were rendered plainly visible to 

 a numerous audience in the usual optical way by the motion of a 

 spot of light upon a distant screen. 



— The Engineering and Mining Journal of June 14 is authority 

 for the statement that small metallic articles, such as buttons, 

 buckles, clasps, etc., have different colored films produced on them 

 by various methods. Some of these are known as oxidized silver. 

 Rainbow colors are produced on brass buttons by stringing them on 

 a copper wire by the eyes, and dipping them in a bath of plumbate 

 of soda freshly prepared by boiling litharge in caustic soda, and 

 pouring it into a porcelain dish. A linen bag of finely pulverized 

 litharge or hydrated oxide of lead is suspended in the solution, so as 

 to keep up the original strength of the solution. While the buttons 

 are in this solution, they are touched one after the other with a plat- 

 inum wire connected with the positive pole of a battery until the de- 

 sired color appears. The galvanic current employed must not be 

 too strong. The colors are more brilliant if they are heated after 

 they have been rinsed and dried. Colored films are more con- 

 veniently produced upon bright brass by different chemicals, by 

 painting with them, or by immersion. For example: golden yel- 

 low is obtained by dipping in a perfectly neutral solution of acetate 

 of copper; dull grayish green, by repeatedly painting with very 

 dilute solution of chloride of copper; purple, by heating hot, and 

 rubbing over with a tuft of cotton saturated with chloride of anti- 

 mony ; golden red, by covering with a paste of four parts of pre- 

 pared chalk and of mosaic gold. In covering an article with any 

 colored bronze in powder, it is first rubbed with a very little lin- 

 seed-oil, and the bronze dusted evenly over it from a dust-bag. It 

 is afterward heated in an iron pan to about 480° F. In recent 

 times, small articles are also roughened by dipping in strong nitric 

 acid; and, after washing and drying, they are coated with a rap- 

 idly drying alcohol varnish that has been colored yellow with 

 picric acid, red with fuchsine, purple with methyl violet, or dark 

 blue with an aniline blue. This gives the desired color with a 

 beautiful metallic lustre. The latter colors are not very durable, 

 and are for inferior goods. 



— The report of Arthur W. Winslow, State geologist of Mis- 

 souri, states that the detailed mapping of the coal-fields has pro- 

 gressed with little interruption. Field-work has now been ex- 

 tended over nearly four hundred square miles, and the results 

 have been plotted on the preliminary sheets, and are now being 

 transferred to the final sheets. On May 3, Mr. Gilbert Van Ingen 

 reported at the office of the Missouri Geological Survej'. He is 

 detailed by the United States Geological Survey to assist in pale- 

 ontologic work in Missouri. He has been at work during the 

 greater part of April in Pettis County. Detailed mapping was 

 prosecuted during the early part of the month in south eastern 

 Missouri, and about seventy square miles have been covered. 

 ,,Work on the building-materials and clays of St. Louis was vigor- 

 ously pushed during the latter half of April. Along with a study 

 of the origin and distribution of the clay deposits and of the eco- 

 nomically important limestones, inquiry has been made into the 

 nature and extent of the dependent industries. About two-thirds 

 of the stone-quarries have been visited, and nearly all of the clay- 

 works. An idea of the magnitude of the interests involved may 

 be gathered from the following approximate statement of the 

 number of works in and about St. Louis: eight fire-brick and 

 sewer-pipe manufactories, forty common and pressed brick manu- 

 factories, six potteries, one terracotta manufactory, two terra- 

 cotta lumber manufactories, forty stone-quarries. The value of 

 the annual output of the clay industries is at present in the vicin- 

 ity of three million dollars, and that of the stone-quarries cannot 



fall far short of one million. In the laboratory nearly all of the 

 samples of mineral waters collected during April have been ana- 

 lyzed, and the results will soon be ready for publication. In ad- 

 dition, some seventeen lots of specimens sent in by outside parties 

 have been identified and reported upon, and a few analyses of 

 coals and iron ores for survey purposes have been made. 

 Preliminary inspections have been made in Platte, Clinton, 

 Crawford, and Morgan Counties. In Platte and Clinton Counties 

 are coal-beds of economic value, but their mineral waters 

 and clays also deserve attention. There is every probability 

 that the 32 inch coal-bed mined at different points in the vicinity 

 of Leavenworth, Kan., as well as others found at different 

 depths, extends under these counties. Its depth below the sur- 

 face at Leavenworth isabout seven hundred feet, but eastward into 

 Missouri it must rise progressively towards the surface. The ex- 

 act determination of these points,- as well as the definition of the 

 limits of the bed, cannot be made until systematic and detailed 

 work is done in these counties. In view of the extensive devel- 

 opuient of the coal industry at Leavenworth close to the Missouri 

 line, and in view of the probable establishment in the future of a 

 similar industry in Missouri near the Kansas line, provisions 

 should be made in the near future whereby encroachment of 

 mining operations from a property in one State upon a property 

 in the other State shall be prevented. In Crawford County iron 

 ore still occupies a prominent place among its mineral products. 

 Some of the deposits of this ore are, however, exhausted, and 

 others are approaching that condition. The demand will before 

 very long be urgent for new sources of supply. The conditions 

 are such, in this and adjoining counties, as to justify the expecta- 

 tion that systematic and thorough geologic work may lead to the 

 discovery of other deposits; and it is the intention to institute 

 such work as soon as the means and the demands upon the force 

 of the survey will permit. Operations looking to the develop- 

 ment of zinc and lead mining are also in progress. In Morgan 

 County there are prospects of a revival in lead-mining, and this 

 in a more thorough manner than has been the case in past years. 

 A profitable industry may be built up there if the developments 

 are made cautiously and under competent direction, such as will 

 lead to a knowledge of the origin of the ore, and such as will 

 guide one in selecting localities for prospecting. The survey is 

 not at present in a position to give specific advice on such mat- 

 ters, however, and cannot do so until detailed local work is fin- 

 ished. Zinc-mining is also being started in Morgan County, 

 notably at the ''Big Three Shaft," about five miles south-west of 

 Versailles. 



— A petition was lately presented to the Medical Assembly of 

 the Grand Duchy of Baden by the German Women's Association 

 of Leipzig, pra.ving that women might be admitted to study medi- 

 cine. The assembly passed a resolution declining to take any 

 step in the matter, on the ground that women are tmfit for the 

 learned professions, and especially for that of medicine, and, 

 moreover, that the latter is already overcrowded. Herr Arnsber- 

 ger, the ministerial councillor representing the government, said 

 the question was not yet ripe for solution. He also pointed out 

 that the matter was one for the decision of the imperial authori- 

 ties, not for that of the individual states. A similar petition has 

 recently been presented by the same association to the Weimar 

 Landtag, in which the ladies ask to be admitted to the University 

 of Jena, not only to study medicine, but with the view of qualify- 

 ing for appointment as scientific teachers. 



— Duffield Osborne, author of "The Spell of Ashtaroth," has 

 written an article on surf-bathing for the July Scrihner, which 

 will contain practical directions and sketches showing how to 

 avoid the dangers of the surf, and how to get the most pleasure 

 out of it. 



— Messrs. John Wiley & Sons announce as in preparation 

 "Mechanics of the Machinery of Transmission," being Vol. IH. , 

 Part I., Section IT., of "Mechanics of Engineering and Ma- 

 chinery," by Dr. Julius Weisbach, edited by Professor Gustav 

 Hermann, and translated by Professor J. F. Klem, Lehigh Uni- 

 versity, Bethlehem, Penn. 



