997 



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 heat 

 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 less 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 v/as 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 

 contained. 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. 

 The air-pump vacuums of all the gases were alike, including that 

 of oxygen. 



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 distinguishes the two classes of magnetic bodies 

 into paramagnetic and diamagnetic substances. 



There is no other gas like oxygen : its paramagnetic character is 

 very high. A solution of protosulphate of iron in distilled water 

 was prepared, of which a certain bulk in a glaj^s bubble was of the 

 same paramagnetic force as an equal volume of oxygen ; the solution 

 was then of such strength as to contain of crystallized protosulphate 

 of iron seventeen times the weight of the oxygen which could coun- 

 terbalance it. In another case, a glass bubble, containing one-third 

 of a cubic inch of oxygen, was opposed to a corresponding bubble 

 having within only an oxygen vacuum. As soon as the magnetic 

 power was on, the oxygen passed inwards, and it required a force 

 equal to one-tenth of a grain to hold it out at the equidistant position. 



The author then refers generally to the air as a paramagnetic 

 medium, because of the oxygen it contains, and in the next, or 

 Twenty-sixth Series of Researches, he proposes to enter, after some 

 preliminary inquiries, into the great subjectof atmospheric magnetism. 



