128 
Paper slips were pasted on the edges of the nails, and then- 
distances asunder measured by a microscope with micro- 
meter eyepiece divided by lines corresponding to rbv of an 
inch. Weights were gradually added to the lever of one 
arm of the pincers until fracture took place, which was 
always accompanied with a sharp report. The observed 
deflection or bending of the nails was taken continuously 
as the weights were laid on, and the calculation of what it 
would have been at the moment of rupture taken from the 
immediately preceding observations. The amount of deflec- 
tion was almost exactly proportional to the weight laid on 
in each 
experiment. 
No. of 
Experi- 
ment. 
1 .... 
Length of 
Nail between 
Supports. 
.. 105 ... 
Breadth of 
Nail in 
Fracture. 
... 0-13 ... 
Depth of 
Nail at 
Fracture. 
... 0-127 
Deflection. 
. -0062 ... 
Breaking 
Weight. 
Lbs. 
... 145-5 
2 .... 
.. 1-1 ... 
... 0-114 ... 
... 0-125 
. -0067 ... 
... 141 
3 .... 
.. M ... 
... 0-120 ... 
... 0-115 
. -0090 ... 
... 171 
4 .... 
.. 1-08 ... 
... 0-111 ... 
... 0-106 
. -0073 ... 
... 142-5 
5 .... 
.. M2 ... 
... 0-122 ... 
... 0-145 
. -0098 ... 
... 189 
6 .... 
.. 1-06 ... 
... 0-138 ... 
... 0-120 
. -0087 ... 
... 184-5 
7 .... 
.. 1-08 ... 
... 0-150 ... 
... 0-118 
. -0095 ... 
... 201 
Average 
1-084... 
... 0-1264... 
... 0-1223 
. -0082 ... 
... 167-8 
If we 
compare 
the above 
with Mr. Brockbank’s 
experi- 
ments we shall 
find, approximately, on 
reducing 
them to 
the dimensions he adopted, viz. 3 feet between supports and 
1 inch section — 
Breaking Weight. Deflection. 
Mr. Brockbank’s, with large bars... 860 - 7 - 740 
My own, with nails 2673- T106 
The metal, in the form I used it, was therefore more than 
three times as strong as that of the large bars to resist a 
compressing and tensile force, while its extent of spring at 
the breaking weight was half as much again. Therefore, 
so far from being of inferior quality, it would sustain a very 
much heavier blow without fracture. 
“ On the Action of Sulphurous Acid on Phosphates,” by 
Dr. B. W. Gerland. Communicated by Dr. B. Angus 
Smith, F.B.S., &c. 
The abstract of this paper will appear in the next 
number of Proceedings. 
