115 



carefully pour off the upper three-fourths of it. Again fill 

 with water, and in twentv-five-ininutes decant as before; 

 repeating this at twenty-five-niinute intervals until the 

 upper three-fourths of the waiter in the bottle, after a 

 tweuty-five-minute rest, will be nearly clear. A large amount 

 of the fine sand, clay, and soda has by this process been 

 washed, and the action of the soda has broken up fhe clay 

 and removed most of the adhering material from the fossils. 

 Now mount a few microscopic slides from the residua i-y 

 sands, etc., at the bottom of the l)Ottle. by taking up with 

 a y)ipette (a piece of small glass Tubing makes the best 

 pipette) a small amount of the material ; scatter very thinly 

 over the middle of the slides; dry them thoroughly ovei- an 

 alcohol lamp, or in some better way, and. while hot. cover 

 the dry material with a few drops of Canada balsam, kee})- 

 ing the slides cpiite warm until the l)alsam will l)e hard when 

 cold. As these 'trial slides'" are seldom of any value, it is 

 not necessary to use cover glasses if the balsam is hardened 

 as above directed. A careful examination of these slides 

 under the microscope, with a good cpiarter- or half-inch 

 objective, will decide as to the value of the material undei- 

 observation; and if it proves to be onh' sand, pour it all 

 out, wash the bottle, and again try the same process with 

 another sample of clay. But if the slides show a few good 

 fossils, the next step is to separate them as much as possible 

 from the mass of sand, etc., with which they ai-e associated. 

 In this, as in the first washing, specific gravity will do most 

 of the work. Pour off most of the watei' and put the shells, 

 sand, etc., into a four-ounce beaker (or glass tund)ler ), wash 

 out the bottle, fill the beaker about three-fourths full of 

 water, and, after it has rested ten minutes, pour three- 

 fourths off the top through a glass funnel into the bottle, 

 re])eating this five or six times. As in the first washing, 

 mount and examine a few slides from the material at the 

 l)ottom of the bottle, mounting and ])reserving slides, if 

 found to be of value. If nothing of value is foimd, pour out 

 the contents of the l)ottle and fill up again as befoi'e from 



