37 
If not, dig a shallow trench, a couple of inches wide and 
deep, around the print and several inches distant from it, 
and flow the water glass into the trench, until it has been 
soaked up by the soil so that it shows on the surface of 
the print. Then let it stand for a day. The print can not 
be pried out, but must be carefully freed by digging the 
soil away from around and under it. It must also be 
handled with much care thereafter, and this reduces the 
value of the method when conditions, such as transpor¬ 
tation, are not favorable. 
In this and many other cases a more desirable method 
is to make a cast of the track with plaster of Paris, or neat 
Portland cement. Plaster of Paris sets more quickly. 
The builder’s finish plaster is seldom good enough. 
Cement is often more available to a forest officer. From 
the cast a replica of the track can then be made, or not, 
as desired. 
When the soil composing the print is firm enough, the 
plaster or cement can be wet mixed by stirring carefully 
into water (sifting it in preferably, to avoid lumps) to the 
consistency of thick cream, and flowed directly into the 
impression, either by pouring, or, if greater care is desir- 
bale, from a spoon. Pure plaster of Paris sets in about five 
minutes and, therefore, requires rapid work; its setting 
can be retarded, however, if desired, by adding a little 
vinegar. When about one-half inch depth has been 
flowed in, reinforce the cast by laying in it, crossed at 
right angles, several thin water-soaked strips of wood. In 
the absence of these, small green twigs, or even stout 
string, will help. After adding another one-half inch of 
plaster the cast can again be reinforced, if desired. This 
is hardly necessary with cement. The finished cast should 
be at least one inch thick. If this is greater than the depth 
of the track, a wooden box or earthen dam can be built 
around the track to hold the liquid. 
In dry sand, ashes, or dust a cast can be secured by sift¬ 
ing in very carefully dry plaster of Paris, then sprinkling 
water slowly on to the plaster until it has become moistened 
thoroughly. When a one-quarter inch layer of cast has 
thus been set. the remaining thickness may be built up^ 
