SCIENCE, 



[Vol. XIII. No. 329 



ductor of the current, the effect must be instantaneous ; while, if 

 the phenomenon resulted from some secondary action, it would 

 probably go on increasing up to a certain point with the duration 

 of the illumination, and it would also probably continue for a time 

 after the light had been cut off. His method of making the test 

 was equally simple and ingenious. The light was interrupted at 

 rapid intervals by means of a rotating disk with holes or slits, and 

 he placed a telephone in circuit with the battery. It is, then, ob- 

 V ious, that, if the effect is instantaneous, the telephone will produce 

 a note corresponding in pitch to the velocity of the disk ; if olher- 

 vvise, there will be silence. There was silence. A make and break 

 in any other part of the circuit could be heard, but not in the beam 

 I if light : hence we must seek for some secondary action on the 

 surface of the plates to explain M. Hallwach's e.Kperiments." 



The Electro-Chemical Equivalent of Silver. — A very 

 important electrical constant — one often used in the measurement 

 of electric currents — is the amount of silver deposited in a given 

 lime by a given electric current. Determinations have been made 

 l)y Kohlrausch, Rayleigh, and Mascart, the results of the last 

 differing from those of the first two by as much as one part in 

 four hundred. Recently Pellat and Potier have repeated the ex- 

 periments, using to measure the currents an electro-dynamometer 

 constructed by M. Pellat, and taking every precaution to insure 

 accuracy. The result obtained gives 1.1192 milligrams of silver 

 deposited by one ampere in a second. The previous results are, 

 Kohlrausch, 1.1183; Rayleigh, 1.118; Mascart, 1.1156; Pellat and 

 Potier, 1.1192. The mean is very near to Rayleigh's value. 



The Voltaic Current obtained with Bismuth in a 

 Magnetic Field. — The following experiments are due to Dr. 

 G. P. Grimaldi. A wide U-tube contained a solution of bismuth 

 chloride in hydrochloric acid. In the two limbs of the tube dipped 

 two wires of chemically pure bismuth very carefully polished. One 

 hmb of the tube was placed between the conical pole-pieces of a 

 Faraday electro-magnet of medium size in such a way that the 

 surface of the liquid was in the most intense part of the field. The 

 two wires were joined up to a very sensitive Thomson astatic 

 galvanometer. On closing the galvanometer circuit, a current was 

 observed which at first varied rapidly, but which finally reached a 

 permanent value. This was compensated by means of a shunt 

 containing a standard element, and the galvanometer was brought 

 back to zero. If then the electro-magnet was excited by a power- 

 ful current, a permanent deflection of the galvanometer was ob- 

 served ; if the magnetizing current was broken, the galvanometer 

 returned to zero. The current produced by magnetism, which the 

 author calls the galvano-magnetic current, is independent of the 

 intensity and direction of the current first observed in closing the 

 galvanometer circuit before the magnet circuit is made. The lat- 

 ter is variable ; the former is always in the same direction, — in the 

 galvanometer circuit, from the magnetized bismuth wire to the non- 

 magnetized one ; and in the liquid, from the non-magnetic metal 

 to the magnetic one. The intensity of the galvano-magnetic cur- 

 rent depends on the state of the surface of the metal, and to get 

 regular results it is necessary to carefully polish the bismuth wires. 

 To give an idea of the magnitude of the electro-motive force of the 

 galvano-magnetic current, the author states that in the various ex- 

 periments hitherto made under good conditions' with various wires, 

 and in various modifications, it has varied from t^uisij t° Wou of ^ 

 Daniell cell, the magnetic field being produced by a Faraday mag- 

 net of ordinary size, excited by a current of eight to twelve amperes, 

 and with conical poles seven millimetres apart. With less powerful 

 magnetizing currents, the results are smaller ; and, with a current 

 of two amperes, the galvano-magnetic current is scarcely appreci- 

 able. The direction of the galvano-magnetic current is independ- 

 ent of the direction of the field : its intensity sometimes varied a 

 little when the field was reversed, and sometimes remained con- 

 stant. 



NOTES AND NEWS. 



The fourth annual meeting of the Science Club of the Uni- 

 versity of Kansas, Lawrence, was held Friday, May 17. The fol- 

 lowing is a list of the papers read : " Proximate Analysis of the 

 Mountain Sage," by L. E. Sayre, John Scott, and E. Morris ; " On 



the Action of Various Organic Acids on Calomel," by E. H. S. 

 Bailey and W. B. Hilton ; " Blue-Printing," " Columns of Uniform 

 Strength," and "Maximum Bending Moment in Beams and Arch- 

 Ribs," by E. C. Murphy ; " Notes on the Lanidce," and " Notes on 

 Bird-Migration, Spring, 1889," by V. L. Kellogg: " On Some Cor- 

 rections on the Thomson Calorimeter," by L. I. Blake; " Develop- 

 ment of the Liiccinea and the Planorbias," and " The Nervous 

 System of Some Invertebrate Types," by Gertrude Crotty ; " The 

 Psychology of Counting." and " A New System of Derived Units," 

 by W. S. Franklin ; " A Case of Atavism," by E. E. Slosson ; " On 

 the Quality of Commercial Potash and Soda," by George F. Weida ; 

 " Coals of Kansas," by E. H. S. Bailey and L. T. Smith ; " Meth- 

 ods of Stating the Results in Water-Analysis," by E. C. Franklin; 

 " The Mallophaga," by V. L, Kellogg ; " The Mode of Respiration 

 of Salamanders," and " Curve of Daily Mean Temperatures for 

 Twenty-one Years," by F. H. Snow ; and " Proximate Analysis of 

 the Fruit of the Pawpaw {Asimma triloba)," by L. E. Sayre and B. 

 L. Hill. 



— At a recent meeting in New York of the American Institute 

 of Mining Engineers, Mr. Oberlin Smith of Bridgeton, N.J., read a 

 paper on the making of nails of good quality from tin-scrap. This 

 process undertakes to use this material just as it is, without trying 

 to separate its constituents at all, and to use it, moreover, for a 

 purpose in which the qualities of both these constituents — namely, 

 the tensile strength and ductility of the iron, and the resistance 

 of the tin to corrosion — are directly employed with advantage. 

 The nail was invented, in its original shape, by Mr. George H. 

 Perkins of Philadelphia, and has been developed, through various 

 forms, until it has almost reached a commercial stage, the machine 

 in which it is to be made in marketable shape being nearly com- 

 pleted. Mr. Smith has been associated with Mr. Perkins in its 

 development. The machine now under construction has been very 

 much simplified, and made enormously strong and heavy. It is 

 adapted to cutting, crushing, griping, and heading the nails at one 

 operation, and can be run as fast as an expert operator can feed 

 the material. Its feed probably varies, with jagged, irregular scrap, 

 from thirty to ninety nails per minute, although straight strips of 

 sheet metal can be fed by hand into a machine running as high as 

 240 strokes per minute. During the course of their experiments, 

 various forms of nails have been tried. Among others were straight 

 cylindrical nails with conical points, straight square nails with 

 pyramidal and with wedge-shaped points, hexagonal nails, etc. 

 The most practical form seems to be the square taper nail with 

 about the same shape as the ordinary cut nail, but is somewhat 

 stronger and a good deal tougher. The economy of this system 

 of nail-making is obvious. The scrap can be bought for about 

 seventeen cents per hundred pounds, and a boy can make perhaps 

 a hundred pounds of nails per day. The most economical system 

 of manufacture will probably be to run one or more nail-machines 

 at each large " tinshop," set as close as possible to the presses 

 which produce the scrap, so as to^ avoid the expense of unnecessary 

 handling, and the extra tangling-up incident thereto. 



— The bearing of chemistry upon construction is thus illustrated 

 by the Lumber Trade Journal : It is safe to say that no two varie- 

 ties of wood possess the same essential chemical characteristics, 

 and, the instant one possessing much alkali is placed near another 

 that gives acid in its re-action, it will invite rapid dissolution and 

 decay. What is true with reference to wood applies with all the 

 force to the other materials used in structures. Two uprights, the 

 main-stay of a quite large country bridge, rotted off at the ends 

 when bolted together with an iron bolt. New ones were put in, 

 and fastened by wooden pins of the same variety ; and ten years 

 have elapsed, and still they stand. In the first instance, beech, 

 which is known to contain much acetate, was used, and the iron 

 soon oxidized, transmitting the rot to the wood, and, though the 

 rest was perfectly sound, the wood about the splice soon rotted off ; 

 while in the latter case the same wood from the same tree was 

 used, but the wooden pins did not rust, and the joint remains firm 

 and sound at this writing, and it is now nearly ten years since the 

 renewal was made. Now, if a wood like ash or oak, having less 

 acetate in its composition, had been used, instead of rotting or oxi- 

 dizing, it would have tended to preserve the iron, hence would last 



