54>6 Intelligence and Miscellaneous Articles. 



of a magnetic core or keeper cut into the shape of an hour- 

 glass, they would compensate each other, both for their own dia- 

 magnetic matter and for the air which they would displace; and 

 that only the contents of the bulbs would be virtually in a differ- 

 ential relation to each other, the author passed from bubbles of 

 soapy water to others of glass ; and then constructed a differential 

 torsion balance to which these could be attached, of the following 

 nature : — A horizontal lever was suspended by cocoon silk, and at 

 right angles to the end of one arm was attached a horizontal cross- 

 bar, on which, at about lj inch apart, and equidistant from the 

 horizontal lever, were suspended the glass bubbles ; and then the 

 whole being adjusted so that one bubble should be on one side of 

 the iron core and the other on the other side, any difference in their 

 tendency to set inwards or outwards from the axial line causes them to 

 take up their places of rest at different distances from the magnetic 

 axis; and the power necessary to bring them to an equidistant position 

 becomes a measure of their relative magnetic or diamagnetic force. 



In the first place, different gases were tried against each other, and 

 when oxygen was one of them it went inwards, driving every other 

 outwards. The other gases, when compared together, gave nearly 

 equal results, and require a more delicate and finished balance to 

 measure and determine the amount of their respective forces. 



The author now conceived that he had attained to the long-sought 

 power of examining gaseous bodies in relation to the effects of beat 

 and the effects of expansion separately ; and proceeded to an investi- 

 gation of the latter point. For this purpose he prepared glass bubbles 

 containing a full atmosphere, or half an atmosphere, or any other 

 proportion of a given gas ; having thus the power of diluting it 

 without the addition of any other body. The effect was most stri- 

 king. When nitrogen and oxygen bubbles were put into the balance, 

 each at one atmosphere, the oxygen drove the nitrogen out power- 

 fully. When the oxygen bubble was replaced by other bubbles 

 containing oxygen, the tendency inwards of the oxygen was less 

 powerful ; and when what may be called an oxygen vacuum (being 

 a bulb filled with oxygen, exhausted, and then hermetically sealed) 

 was put up, it simply balanced the nitrogen bubble. Oxygen at 

 half an atmosphere was less magnetic than that at one atmosphere, 

 but more magnetic than other oxygen at one-third of an atmosphere ; 

 and that at one-third surpassed the vacuum. In fact, the bubble with 

 its contents was more magnetic in proportion to the oxygen it con- 

 tained. On the other hand, nitrogen showed no difference of this 

 kind; whether a bubble contained that gas more or less condensed, its 

 power was the same. Other gases (excepting olefiant and cyanogen) 

 seemed in this first rough apparatus to be in the same condition. 



Hence the author decides upon the place for zero, and concludes 

 that simple space presents that case. When matter is added to 

 space it carries its own property with it there, adding either magnetic 

 or diamagnetic force to the space so occupied in proportion to the 

 quantity of matter employed ; and now thinking that the point of 

 zero is well determined, he concludes to use the word magnetic as a 

 general term, and distinguish the two classes of magnetic bodies into 

 paramagnetic and diamagnetic substances. 



* m * This notice has been substituted for two articles which are noticed 

 in the table of contents. 



