314 Mr. E. H. Hall on the new Action of 



sheet about 10 centims. square. The letters attached are in- 

 tended to distinguish different plates constructed from gold of 

 the same number. 



Gold Foil, No. 6 A. 



This strip was, I believe, of the kind called by dentists 

 "hard," or " cohesive." To determine the thickness it was 

 weighed before being attached to the glass. Previous expe- 

 riments having shown the great variation in thickness between 

 different parts of a sheet of gold foil, this strip was cut before 

 weighing into nearly the same shape and size that it was to 

 have on the glass. 



The strip was in general shape a parallelogram with a pro- 

 jection from the middle of each of its longer sides. The use 

 of these projections, which were much reduced in size before 

 making the observations, has been already explained. 



Length of strip when weighed = 8'50 centims. 



Width „ „ = 2-14 „ 



Area, including projections . =20*5 square centims. 



Weight = -0848 grm. 



Taking the specific gravity of gold at 19*36, the value given 

 by Ganot for "gold stamped," we find 



thickness = -000214 centim. 



With this plate many series of experiments were made, 

 yielding most of the time-results, which were very discordant, 

 owing to various disturbing causes, some known and others 

 perhaps unknown, to which allusion has already been made. 

 The results obtained every day, except the last, of my work- 

 ing with this plate are so discordant that, in preparing them 

 for publication, it does not seem worth while to go over again 

 the great mass of figures involved, for the purpose of correct- 

 ing any small errors of calculation. The results obtained 

 were:— Mx y 



February 20th, - 



w 



= 134xl0 1 



j} 



V 



;• 



= 136 „ 



d 



23rd, 



?; 



= 163 „ 



V 



;• 



V 



= 159 „ 



?J 



j j 



J? 



= 166 „ 



JJ 



25th, 



J" 



= 160 „ 



JJ 



« 



J? 



= 149 „ 



>; 



5? 



?? 



= 157 „ 



jj 



27th, 



?J 



= 152 „ 



)) 



V 



V 



= 147 „ 





Mean . 



a 



= 152xl0 1 



