NATURAL PHILOSOPHY. 113 



opposite and certain directions, and so they are ; the curves described 

 by needles in north or south latitudes should be larger in summer 

 and smaller in winter, and so they are ; a night or cold action should 

 grow up in the winter months, and such is the case ; the northern 

 hemisphere ought to have a certain predominance over the southern, 

 because of its superior temperature, and that is so ; the disposition of 

 land and water ought to have an influence, and there is one in the 

 right direction ; so that in the first statement and examination of the 

 hypothesis it appears to be remarkably supported by the facts. The 

 next step will be to ascertain what is the amount of change in the con- 

 ducting power of the air for givj^ changes of temperature, and then 

 to apply that in the endeavor wo ascertain whether the amount of 

 change to be expected is (as well as the direction) accordant with that 

 which really occurs." Jameson's Journal, July, 1851. 



MAGNETISM OF OXYGEN. 



PLUCKER has given the result of a comparison of the magnetism of 

 oxygen with that of iron. A glass globe was filled with oxygen of the 

 same tension as the surrounding air. The amount of attraction exerted 

 by an electro-magnet upon this globe was then determined by means 

 of a very delicate balance. The globe was then emptied and filled 

 with a solution of chloride of iron, and the magnetic attraction again 

 determined in the same manner. The attraction upon the oxygen was 

 found to be to that on the solution of 8.0678 : 1. To determine the 

 attraction exerted, under the same circumstances, upon soft iron, a 

 < glass vessel was filled with a paste, made by grinding pure metallic 

 iron in powder, (reduced from the oxide by hydrogen,) with a mixture 

 of fresh lard and wax. The amount of attraction upon this glass vessel 

 when empty was first measured, then the attraction upon the same 

 vessel when filled with the solution of chloride of iron, and, finally, the 

 attraction upon the glass when filled with the paste of iron. The 

 amount of attraction upon the glass vessel when empty was subtracted 

 from the amount upon the vessel when filled with the solution and with 

 the paste. In this manner, the magnetism of the solution was found 

 to be to that of the iron as 1 : 230.49 ; the diamagnetic action upon the 

 lard and wax was found to be so slight that it could be entirely neglected. 

 By combining the two numerical results obtained above, Plucker found 

 the specific magnetism of oxygen to be to that of iron as 1 : 285.7. If 

 we refer the specific magnetism of the two substances to equivalents 

 instead of to equal Aveights, we find for the equivalent of iron a degree 

 of magnetism 81.8 as great as that for an equivalent of oxygen. By 

 the same method, Plucker found for the magnetism of sesquioxide of 

 iron the number 891, that of iron being taken as 1.000.000. Pogg. 

 Ann. 33, 105. 



ON THE MAGNETIC RELATION OF GASES. 



PLUCKER, has studied the magnetic and diamagnetic relations of 

 various gaseous bodies, in different states of pressure. The apparatus 



10* 



