[NHCOLL-L:4912] Isopropanol as a preservative

[Richard Rosenblatt]

Amplifying HJ walkers brief comment, the Scripps Institution of 
Oceanography Marine Vertebrate Collection and  UCLA fish collections 
converted  to 50% Isopropanol in 1952. I came from UCLA and became 
curator in 1958 and continued the policy. The SIO collection now 
contains more than two million specimens, many of them delicate 
deep-sea fishes. We soon learned of the relative immiscibility of iso 
in water and the necessity to stir and bring preservative up to 
strength after washing out formalin. One advantage not often 
mentioned about iso is that when working with specimens it is not 
necessary to keep dipping them in water or spraying nearly as often 
as with alcohol specimens. When working with alcohol specimens you 
can see the scales curling and the fin-rays rapidly drying out under 
the microscope. I attribute this to the 50% water content as well as 
the lower vapor pressure of iso.
Without belaboring the point, or entering controversies over possible 
chemical reactions, I can say that we have maintained our collection 
for more than 50 years in 50% isopropanol  with excellent results.