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THE POPULAR SCIENCE MONTHLY 



Wonders of the Flora. By H. A. Kresken. 

 Dayton, O. 1879. Pp. 204. $1.50. 



The Rosicrucians, their Rites and Mysteries. 

 By Hargrave Jennings. With numerous Illus- 

 trations. Kew York : J. W. Bouton. 1879. 

 Pp. 388. 



Report of the Commissioner of Education for 

 the Year 1877. Washington : Government Print- 

 iDg-Offlce. 1879. Pp. 850. 



First Step in Chemical Principles. By H. 

 Leffmann, M. D. Philadelphia : E. Stern & Co. 

 1879. Pp. 52. 50 cents. 



Ancient Pagan and Modern Christian Sym- 

 bolism. By Thomas Inman, M. D. With Illus- 

 trations. New York : J. W. Boutou. 18i0. 

 Pp. 147. 



Lessons in Inorganic Chemistry. By W. G. 

 Valentin. With Illustrations. New York: Put- 

 nam's Sons. 1879. Pp. 186. $1. 



Report on Copper-Tin Alloys. By R. H. 

 Thurston. Washington: Government Printing- 

 Offlee. 1879. Pp.300. 



Local Government. By R. P. Porter. From 

 " Princeton Review." Pp. 24. 5 cents. 



The Public Library and the Common Schools. 

 By C. F. Adams, Jr. Boston: Estes & Lauriat. 

 1879. Pp. 52. 25 cents. 



The South Pass Jetties. By M. E. Schmidt. 

 From " Transactions of the American Society of 

 Civil Engineers." Pp. 36, with Plates. 



Address to the New Orleans Sanitary Associa- 

 tion. By Dr. J. H. Rauch. Pp. 13. 



Domestic Sanitation. New Orleans : Graham 

 Print. 1879. Pp.20. 



Milk and Dairies in New Orleans. New Or- 

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Tracheotomy with Galvano-Cautery. By Dr. 

 W. A. Byrd. From " St. Louis Clinical Record." 

 Pp.7. 



Shall the Metric System be made compulsory " 

 By H. T. Blake. From " The New-Bnglander." 

 Pp. 22. 



Petroleum. By P. Schweitzer. Columbia, 

 Mo. : " Statesman " Print. 1879. Pp. 64. 



Report of the Entomologist. By C. V. Riley. 

 Washington : Government Printing-Ofllce. 1879. 

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Phenol. By David Cerna. From "Philadel- 

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American Industries and the Proposed Fran- 

 co-American Commercial Treaty. San Francis- 

 co : " Alta California " Print. Pp. 211. 



History of Massage. By D. Graham, M. D. 

 New York : W. Wood & Co. 1879. Pp. 80. 



The Pocasset Tragedy. By W. Denton. Bos- 

 ton: The Author. 1879. Pp.38. 



Biographical Notice of Joseph Henry. By 

 Joseph Levering. Pp. 11. 



Sanitary Condition of Montreal. Bv F. P. 

 Mackelcan, C. E. Montreal: Lovell Print. 1879. 

 Pp. 41. 10 cents. 



The More Common Families of Insects. By 

 L. C. Wooster. Whitewater, Wis. : " Register " 

 Print. 1879. Pp.52. 



POPULAR MISCELLANY. 



Experimeats with Platinum.— A paper 

 by Mr. Edison, on the behavior of plati- 

 num under the influence of the electric cur- 

 rent, was read at the last meeting of the 

 American Association by Professor F. R. 

 Upham, the author being absent. Hav- 



ing found that a platinum wire, heated by 

 the electric current and suspended in the 

 air, loses weight in proportion to its mass, 

 its heat, and the length of time during 

 which the current passes through it, Mr. 

 Edison took a platinum wire ifg-y of an 

 inch in diameter, and wound it in the form 

 of a spiral one eighth of an inch in diameter 

 and one half inch in length. The two ends 

 of the spiral were secured to clamping- 

 posts, and the whole then covered with a 

 small glass shade. After the spiral had 

 been made incandescent for twenty minutes, 

 the shade opposite to the spiral on both 

 sides was slightly darkened, and after five 

 hours was no longer transparent, a film of 

 the metal having been deposited on it. Mr. 

 Edison is convinced that this effect, namely, 

 the loss of weight in the spiral, is due to 

 the washing action of the air, to the wearing 

 away of the surface of the platinum by the 

 impact of the stream of gases upon the 

 highly incandescent surface, and not to vol- 

 atilization. That this supposition is correct 

 is shown by the very different behavior of 

 platinum wire in vacuo. Mr. Edison placed 

 a spiral of platinum in the receiver of a 

 common air-pump, and arranged it so that 

 the current could pass through it while the 

 receiver was being exhausted. At the pres- 

 sure of two millimetres the spiral was kept 

 incandescent for two hours before the de- 

 posit on the glass shade became visible. In 

 another experiment, when the exhaustion 

 was higher, the deposit became visible only 

 after five hours. The same paper contained 

 observations on other phenomena of still 

 greater interest. It has been known for some 

 time that platinum, when long subjected to 

 a high temperature, becomes disintegrated. 

 A platinum wire which has been heated to 

 incandescence for twenty minutes, on being 

 examined under a microscope, is seen to be 

 full of cracks, and appears shrunken. If 

 the current is continued for a considerable 

 time the wire will fall to pieces. Now, Mr. 

 Edison finds that this shrinking and crack- 

 ing of the wire are due entirely to the ex- 

 pansion of the air in the pores of the metal, 

 and its contraction on the escape of the air. 

 If these air-spaces be previously eliminated, 

 the platinum can be heated to incandescence 

 without disintegration. How this is to be 

 done is best told in Mr. Edison's own words : 



