INTENSITY OF MAGNETIC AND DIAMAGNETIC FORCES. 719 



Weight of the mixture. Quantity of iron. Attraction 



I. 10-70 0-6848 



n. 10-65 0-3408 



III. 10-55 0-1624 6473 



259-95 

 133-60 



IV. 10-35 0-0828 34-65 



V. 10-15 0-0406 15-95 



The numbers in the last vertical column give the attraction of 

 the iron in the different fatty mixtures : they represent the 

 weights requisite for the separation of the watch-glass, minus 

 0-25 grm., whereby, without incurring a perceptible error, we have 

 assumed that the amount of the diamagnetic lard remained the 

 same throughout. 



If we start from the assumption that the attraction of the iron 

 m the different fatty mixtures is in proportion to the mass of 

 iron, we need only divide the numbers in the third vertical 

 column by those in the second to obtain the force with which 

 in the above experiments, a gramme of iron is attracted. In this 

 way we obtain the following numbers :— 



grms. 



I. 379-3 



II. 392-0 



III. 398-5 



IV. 406-5 

 V. 394-8 



As there is ground for believing that the differences do not 

 arise from errors in weighing, we take the mean of these weights 

 which amounts to 



394-2 grms. 

 If we now calculate the attraction of the different fatty mix- 

 tures, we obtain the following numbers instead of those previ- 

 ously obtained : — 



grms. grms. 



I. 269-95 Difference -10-0 

 II. 134-34 - 0-74 



III. 64-02 + 0-71 



IV. 32-64 + l-Oi 

 V. 16-00 _ 0-05 



The differences, which can by no means be attributed to errors 

 in weighing, become less in consequence of the observation, that 

 the intensity of the current at first increased and at last dimi- 

 nished. The increase and decrease was certainly not directly 



3 c 2 



