80 
REVIEW. 
another ; a disposition which explains, we may remark en pas- 
sant, why the crust grows lengthwise, and by wear unravels 
itself into fibres resembling hairs, and why the sole grows in 
thickness, and shells off in flakes. 
Having submitted this short account of the structure of certain 
parts of the foot, I now return to my experiments on the propa- 
gation of caloric through the horny tissue, affecting the deli- 
cately organized living parts which this tissue, as we have now 
discovered, incloses. 
From twelve experiments made on dead feet with the view 
of throwing light on this part of our subject, the conclusions we 
have come to are — 
L. That an ordinary shoe, heated to cherry redness and 
applied to a horny sole of an inch in thickness, and kept burn- 
ing for one minute, the carbonised portion not being obliterated 
in paring out the foot, has transmitted from three to four degrees 
of caloric to the villo-papillary and reticular tissue, which how- 
ever remained in their normal state. 
2. That the greatest amount of caloric transmitted in these 
experiments was felt, according to the thermometer, between 
the fourth and sixth minute from the application of the heated 
shoe. 
3. That the sole pared to the thickness of one-third of an inch, 
giving under the pressure of the thumb, and the iron kept 
burning upon it for half-a-minute, exhibited its villo-papillae 
destroyed by the caloric 
4. That when it had but one-eighth of an inch in thickness, 
and readily bent under the thumb, when the heated shoe was 
held upon it burning for half-a-minute, both its villo-papillae 
and the surface of its reticular tissue were destroyed by the 
caloric. 
The conclusions arising from twelve experiments performed 
with the shoe heated to black redness, are — 
1. That, applied to the sole upon which the burnt mark still 
remained, it was found to transmit in the same time more caloric 
to the living tissues than the iron at a cherry red heat . 
2. That the dull heated iron, the thickness of the sole being 
the same, caused a more lively and deeper burn than the bright 
heated one. 
3. That these experiments confirm what was said by the 
elder Lafosse in 1758, viz. that it was not the bright heated 
iron which oftenest occasioned the burning of the fleshy sole, 
but rather the iron brought to a dull or obscure heat. 
A notion has passed current among veterinarians and smiths, 
that, if the burnt part of the sole be pared away with the draw- 
ing knife immediately after the application of the hot shoe, the 
