112 
The other 70 were now put into water at 70° Fah, 
and this was done chiefly in order that they might be 
broken wet, as those would necessarily be when taken out 
of the freezing mixture. 
The mode of breaking was this : — I put a bar on the 
suspending wedges, then hooked on the weight scale, and 
with a number of weights much under the breaking load, 
raised the loose end of the plank by the screw jack so as to 
bring the weights to bear. I now added single pounds or 
21b. weights till 151b. were put on, these were then taken 
off and a 141b. weight was placed and single pounds again 
put on, thus regularly adding till the bar snapped ; I then 
recorded the breaking weight, my assistant meantime put- 
ting on another bar. I spent nearly eight hours in breaking 
these 70 bars, and every one got an equal amount of care. 
On opening up the freezing mixture 44 hours after 
enclosing it, I found it in perfect condition, little solution 
and no increase of temperature having taken place. The 
bars were taken into the laboratory in small lots and im- 
mersed in another freezing mixture, from which they were 
withdrawn singly with pliers. Having seized one piece with 
too firm a grasp I found that my fingers grew white and 
produced an intense pain as if burned. Some of the freezing- 
mixture was spread on each bar by a spatula while on the 
the machine, so that every one was broken at a temperature 
within one or two degrees of zero. The mode of breaking 
was exactly similar to that employed with the other lot, and 
equal care was given to every bar. This I can affirm, as 
every one of them was broken by myself, and all entries 
made by myself. 
The results are before you, and to me it was a matter of 
surprise, when both sets were completed and added up, to 
find that they almost exactly corroborated my previous 
experiments, which I do not think were fallacious in their 
character, but merely defective in their not covering a suffi- 
