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BJoocl Stains. By J. G. Richardson. 
examination, I have made the subjects of repeated experiment, 
the results of which may be useful to future observers. 
First, as to the action of freezing upon the red disks, I find 
that drops of blood from my finger exposed upon pine wood for 
twelve hours to a temperature of about 15° F. so as to be frozen 
into solid lumps, and then thawed and dried in a moderately warm 
room, present their corpuscles as distinct and uninjured as do 
ordinary blood stains. 
Second, similar drops of blood dried in about fifteen minutes 
by mere exposure in my office upon a hemlock chip, and also upon 
a fragment of oak hark, such as is used for tanning leather, like- 
wise exhibited the corpuscles with exactly the same characters, 
usually seen in those from common blood stains on paper or muslin ; 
and I therefore conclude that the amount of tannic acid taken up 
by the serum from the hark, and a fortiori from any kind of wood, 
under analogous circumstances is insufficient to alter these red 
blood disks. 
