6 PREPARATION AND MOUNTING 
Concentrated sulphuric and hydrochloric acids, used cold, 
cause epidermic structures to swell up, so that their cells 
may be easily separated. 
Tannin, dissolved in water or rectified spirit of wine, 
hardens gelatinous and albuminoid tissues: it also makes 
them shrink. Its solution in water has been used, as men- 
tioned in another part of this treatise, as an injection pre- 
liminary to one of coloured gelatine, to prevent extravasation 
through the walls of the blood-vessels. It also colours the 
tissues a fawn-colour, or a very faint brown. | 
Lime water and baryta water, especially the latter, will, 
according to Rollet, dissolve the animal cement by which the 
fibres of connective tissue are held together. After a few 
days’ soaking such tissue, as well as tendon, may easily be 
teased out by needles. 
Oxalic acid, in a cold saturated solution (1 acid, 15 
water), according to Schultze, “ causes connective tissues to 
swell up and become transparent, while those formed of al- 
buminous substances become hardened and isolated. Hx- 
tremely delicate elements of the body, such as the rods of 
the retina, &c., are thus well preserved.” 
Strong nitric acid mixed with chlorate of potash destroys 
connective tissue in a short time, and is therefore a good 
medium for isolating muscular fibres (Kihne). 
Sulphurie acid, highly diluted (1 to 1,000 parts of water), 
used warm, gelatinizes connective tissue, and is also useful 
for the isolation of muscular fibres. 
Strong hydrochloric acid dissolves the intercellular sub- 
stances of organs abounding in connective tissue. ; 
Ammonia acts on animal matters much in the same way 
as potash and soda. | 
Alcohol coagulates albuminous tissues, and makes them 
opaque. It corrugates most transparent sansa. and, 
thus renders them more visible. 
Finally, it may be affirmed that there often exists a an 
of making objects which are too dark more transparent by 
means of a fluid which permeates them wnequally, so that. 
