NATURAL PHILOSOPHY. 153 



ELECTRICITY AND THE PULSE. 



At the meeting of the American Association at Salem, after 

 explaining the improvements in the diagnosis of aneurisms which 

 the case had suggested, Dr. Upham proceeded, with the aid of 

 the telegraph and magnesium light, to render audible and visible 

 the pulsations of patients in the City Hospital in Boston ; Mr. 

 Farmer having charge of the telegraph instruments in the lecture- 

 room, Mr. Stearns at the City Hospital, and Dr. Knight, assisted 

 by the internes of the hospital, taking the medical direction. 

 The Franklin Telegraph Company placed their entire line be- 

 tween Salem and New York at the disposal of the Association, 

 and every pulse-click of the magnet was heard simultaneously at 

 every station on the entire line. 



AN IMPROVED BATTERY. 



We have recorded so many improvements (as they are all 

 called) in galvanic batteries, that the number and variety be- 

 come bewildering. The last we meet with is that suggested by 

 Bottger, who proposes to substitute metallic antimony for carbon. 

 An amalgamated zinc plate is immersed in a strong solution of com- 

 mon salt and sulphate of magnesia. The antimony, like the car- 

 bon, is placed in a porous pot, but the liquid used is dilute sul- 

 phuric acid. A combination of this arrangement is said to give a 

 stronger and more lasting current than a cell of Daniell's battery. 

 — Mechanics' Magazine. 



APPLICATION OF LEICHTENBERG'S EXPERIMENT TO THE MIN- 

 ERALOGICAL ANALYSIS OF ROCKS. 



M. S. Meunier proposes to make use of the well-known experi- 

 ment of Leichtenberg's electric figures to separate from each 

 other the divers mineralogical constituents of some kinds of rock. 

 We briefh' remind our readers that the experiment alluded to con- 

 sists in charging with electricity a cake of resin or sealing-wax, 

 by means of a previously charged Leyden jar ; it is thus possible 

 to charge certain portions of the cake with positive, others with 

 negative, electricity. In order to exhibit this to sight it is usual 

 to blow, by moans of a small jDair of bellqws, on to the cake of 

 the resin, a mixture of very finely powdered red lead and sul- 

 phur ; the friction, on leaving the nozzle, causes the powders to 

 become electrified, and the sulphur, being negatively electric, is 

 attracted by the curved figures positivel}^ electric on the cake, 

 while the red lead follows the opposite course. M. Meunier has 

 tried thus to separate sulphur-bearing trachite into its mineral 

 constituents, and succeeded perfectly in getting the sulphide and 

 fieldspar from each other ; he states that he hiis equally well suc- 

 ceeded with rocks made up of two different silicates. — Cosmos. 



