104 
METHODS IN PLANT HISTOLOGY 
of any low museum jar with tight-fitting cover. The tin cans, with 
tight covers, in which you get your pound of “ Improved Vacuum 
Coffee” make good exsiccators for small amounts of material. You 
may improvise other forms; the essential thing is to provide a small, 
air-tight place in which the soda lime may work. 
Instead of soda lime you may use fused calcium chloride or the 
white sticks of sodium hydroxide. 
We are now ready for the transfer from absolute alcohol to the 
10 per cent Venetian turpentine. Make the transfer quickly. Pour 
off the absolute alcohol and place the dish, with the material, in the 
exsiccator; then pour on the 10 per cent turpentine, and immediately 
put on the cover. This is better than to pour on the turpentine and 
then try to get the dish well placed in the exsiccator. 
The greater the surface of soda lime exposed, the more rapid 
will be the concentration of the Venetian turpentine. The con¬ 
centration must not be too rapid. Not less than 2 days should be 
allowed for the concentration of 30 c.c. of the turpentine in an 
ordinary Minot watch glass. 
Great care must be taken not to let any of the soda lime, or other 
drier, get into the turpentine. 
When the lime has become saturated, it may be heated until 
dry, and then used again. If material is put into an exsiccator with 
nearly saturated lime, the turpentine becomes milky. If the material 
is very valuable, wash in absolute alcohol until entirely free from 
any milky appearance, and start again in 10 per cent turpentine. 
As soon as the turpentine has attained the consistency of pure 
glycerin, it may be exposed to the air without any danger from 
moisture; but the turpentine would soon become too thick for 
mounting. If the turpentine has become too thick, thin it with 
a few drops of absolute alcohol or with 10 per cent or any thin solution 
of Venetian turpentine. 
Mount the material in a few drops of the Venetian turpentine 
and add a cover. Tapping on the cover with the handle of a needle 
or scalpel will often separate the filaments so that they are more 
convenient for examination. Square covers may be used since it is 
entirely unnecessary to seal the mounts, which are as hard and durable 
as those mounted in balsam. 
Material in the thickened Venetian turpentine, when not needed 
for immediate mounting, may be put into small bottles. The corks 
