430 Mr. W. Brown on the Effects of Percussion and 

 Table VIII. (continued). 



Specimen III. 



Number of 

 magnet. 



Magnetic 

 moment, 

 per gram. 



Percentage loss due to 

 falling 



, Total loss. 



one time. 



three times. 



1 



2. ..... 



3 



4 



5 



4231 

 4345 

 41-11 

 4111 

 39-36 



211 

 1-37 



o-oo 



1-45 

 1-77 



2-16 

 1-38 



o-oo 



1-47 



0-77 



4-22 



2-82 

 000 

 2-90 



2-27 



Mean 



41-46 



1-34 



1-15 



2-44 



From the above Table we find that the relative losses of 

 magnetism in the different specimens due to lying undisturbed, 

 as indicated by the diminished magnetic moments, is in the 

 reverse order to what has taken place throughout the whole 

 series when the magnets were subjected to percussion. 



The total percentage loss all through these experiments due 

 to percussion has been in the order of the number of the spe- 

 cimen. Thus specimen I. has always decreased the least and 

 specimen III. the most ; but, in the case of lying undisturbed 

 for nine months, the decrease in the magnetic moment of spe- 

 cimen I. is 3*5 per cent., and of II. 3*7 per cent., while III. 

 has diminished only 1*6 per cent. Specimen III., however, 

 contains about three times as much manganese as either I. 

 or II. 



In Joule's Scientific Papers, vol. i. page 591, some results 

 are given on the effects of time and temperature on hard mag- 

 nets. The magnets used by him were either one inch long or 

 half an inch, and were made up of a number of thin bars 

 placed side by side so as to form compound magnets of va- 

 riously shaped sections but with plane ends ; the magnetic 

 moments of these magnets diminished about 33 per cent, on 

 lying aside for a period of eighteen years. 



The rate of diminution of magnetism in different kinds of 

 steel, with annealing, time, and temperature, is at present 

 under investigation in this laboratory. In connection with 

 this investigation, further experiments are being made on the 

 same kind of steel as is referred to in this paper, and it is 

 hoped that further results will be ready for publication at an 

 early date. I will now give a tabular view of the results 

 obtained up to this point. 



