1 00 jDr. Itafe^^ Dejlagrator and Calorimotor. 



ain incandescent iron. A platina wire three sixteenths of an 

 inch in thickness, was made to flow like water. Iron of 

 iike dimensions burned explosively. When the experi- 

 ments were repeated before my class of more than three 

 hundred pupils, and many visitors, there Were very ((^w 

 who conld bear the light with the naked e)e. 



Much attention was excited by the deflagration of a 

 stream of Mercury. This was accomplished in the follow- 

 ing way* A wire proceeding from one pole of the deflagra- 

 tor, was introduced into some mercury held in a glass ba- 

 sin ; and another wire proceeding from the other pole, into 

 some mercury in another vessel, having a capillary orifice 

 wrhich might be closed by the finger or a stopple. This last 

 mentioned vessel with the mercury running from it was sup- 

 ported at such a height above the surface of the mercury in 

 the glass basin, as to permit the discharge to take place 

 through the metallic stream just as the galvanic surfaces 

 Were subjected to the acid. The mercury deflagrated ex- 

 plosively. 



The experiments may be varied, by causing the stream 

 of mercury to fall on iron filings, or card teeth. 



When the phenomena of a scries of 250 pairs o( 7 inches 

 by 3, are such as I have described what would be the pow- 

 er of a deflagrator with plates, as large as Children'sj and as 



liumeroiis as Davy's ? 



Probably the most useful mode of applying such instru- 

 ments to analysis, would be to expose substances to the dis- 

 charge in vac«io on carbon. I observed that after iron and 

 charcoal were ignited between the poles during a few sec- 

 onds, under an exhausted receiver, on admitting the air, a 

 flash took place, and a yellowish red fume appeared which 

 condensed on the glass. It would seem the iron was vola- 

 tilized,* and that the admission of air oxidized the vapour 



A deflagrator of 250 or 300 pairs is found to produce 



torture when applied for a short time to the back of the 

 hand, and it is difficult for the sufTerer to believe, that his 

 skin has not been cauterized. One of mj pupils showed 

 me a slight excoriation, which be considered as arising 

 from it, on the spot where the positive pole had touched him. 

 Between the excitement of acid, and water, the difference 

 df power in aficcting the flesh, is far less than with metalfj 



* Aad possiHy the carbon too? Ed, 



