164 Miscellaneous Notices by Prof. J. F. Dana. 



ends of the enclosed steel became north, and the middle 

 south ; if on the contrary, the coil began to pass from left to 

 right, on the positive side, both ends of the steel acquired a 

 south polarity and the middle a north polarity. When the 

 jar was charged negatively, and the coil began to pass from 

 right to left on the negative, both ends acquired a south and 

 the middle a north, polarity ; if the coil begin to pass from 

 left to right on the negative side the polarities are reversed. 

 When a wire is bent into the form of a staple (thus ; ) 



and inclosed in a glass tube surrounded by a spiral passing 

 from right to left, the ends acquire a north polarity, and the 

 middle a south polarity, if the ends of the staple be next to 

 the positive. If the situation of the staple be reversed, or 

 if the coil pass from left to right, then the ends become south 

 and the middle north. Circumstances did not permit me to 

 make the experim.ent on a staple surrounded by the coil 

 passing from right to left, and from left to right. We should, 

 a priori expect, that the middle of the staple in such circum- 

 stances, would acquire the same polarity as the ends, while 

 at some intermediate points on both sides of the middle an 

 opposite polarity would be found, so that five poles would be 

 formed in one piece, and if the wire was again doubled on 

 itself, (thus i ^^^^^ ) two additional poles would be 



formed. The above experiments were many times tri- 

 ed with the same result, and have been repeated by myself 

 and my friend Hon. Thos. Whipple, M. C. 



2. Preparation of Euchlorinc Gas. 



I perfectly well recollect, when I had the pleasure to be 

 introduced to you at Cambridge, that the conversation turn- 

 ed on the preparation of euchlorine gas ; we naturally wish 

 to know whether experienced chemists meet with the same 

 accidents as ourselves, in experiments, and it was no small 

 degree of consolation to learn that the laboratory at Yale 

 had also witnessed accidents in the preparation of this ex- 

 plosive gas. For two years past I have prepared it in the 

 following manner; strong phials capable of holding half an 

 ounce or an ounce measure are provided, into which are put 

 a few grains of chlorate of potash, and then, four or five 

 drops of sulphuric acid, j«st sufficient to moisten the salt, 

 are added ; the phials are then inverted over mercury, ma- 



