PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 553 



distances and room for an isolation with glass, girtta percha, silk, 

 &c. It is equally the reverse of all the magneto electric ma- 

 chines, which all consist of an accumulation of small, weak, de- 

 ficient ones, united on a single axis, and the work I am occupied 

 with for some time is to make a magneto-electric machine, simi- 

 lar to the galvano-electro of Rumhkorf. Those magneto electric 

 apparatus, may be used with the most perfect safety for blasting 

 purposes, which is not the case with the galvanic batteries used 

 thus far exclusively, because with the last an ignition by simple 

 contact of the wire leading to the blast and to the battery, has 

 often happened, and produced a premature discharge and dread- 

 ful accidents. With my apparatus, the wire may be all connected, 

 no electric current being possible before the apparatus is set in 

 motion with a certain velocity, and consequently no discharge 

 can take place before it is desired, and the motion actually is 

 produced. An additional guard may be added by placing some 

 obstruction in the rotary wheels, or taking out the handle, or 

 simply locking the apparatus up in a small box. 



A very weak, almost invisible spark, may ignite gunpowder, if 

 the points producing the spark be separated by a piece of very 

 thin paper covered by a mixture of two parts of sulphuret of 

 antimonium with one part of chlorate of potash ; this, or a very 

 similarly prepared mixture, is now sold under the name of magic 

 wafers. 



This mixture is exceedingly explosive by weak electrical cur- 

 rents, and safe against rubbing, just the opposite of the common 

 matches. I am able to ignite it Avith my smallest magneto-elec- 

 tric batteries, made for medical purposes, producing only very 

 moderate shocks, and scarcely any sparks. The distance at which 

 it is made to work is of no account. It explodes at 5,000 feet*as 

 readily as at five. Some of these batteries are so small that they 

 are enclosed in a box two inches high, three wide and six long. 



As I never made a secret of most of these investigations, but 

 communicated them freely, more than a year ago, to several per- 

 sons, also to my class in my quality as teacher, to post them up 

 in the newest branches of investigation, I have been brought in 

 the necessity to have them published, with the remark that "I 

 reserve for myself tlie right to take out a patent for the improve- 

 ment of the magneto-electro apparatus, as mentioned under No. 

 10, and for the invention of the apparatus under Nos. 12 and 13 

 above; also for igniting gas, gunpowder, &c., by means of heated 



