COLLECTING AND PREPARING MATERIAL 21 



the bottom. Successive stages will separate most of the cal- 

 careous tests from the sand and the heavier foraminifera. 



One of the most useful methods is that of "floating". The 

 washed material is taken after drying and slightly heated. Then 

 if this heated material is thrown upon cold water those smaller 

 tests, which are filled with air, will float on the surface and can 

 be poured off. In this way beautiful material can be prepared 

 which is very largely pure foraminiferal tests. This last method 

 combined with "decanting" will give the best results. 



By the use of heavy liquids such as bromoform, etc., it is pos- 

 sible to greatly concentrate the tests of foraminifera and separ- 

 ate them from the remainder of the material. It is often possible 

 in this way to save hours of work that would be involved in look- 

 ing over a sample and picking out the individual specimens. All 

 such work should be done with the use of a ventilating hood. 



Storage of Material. It is possible to store washed material in 

 a variety of ways. Bottles or boxes of convenient size may be 

 used. The various sizes of jars with snap covers make one of 

 the very best and most convenient sorts of containers as they 

 may be opened with a simple pressure on the center of the cap 

 and closed tightly by a pressure at the sides. For small samples, 

 the folded papers used by chemists are very convenient. They 

 can have the data written on them before they are filled, and 

 then can be easily filed in a very small space. They are also very 

 light and if carefully packed will stand shipment well. 



Fossil Material may be collected from many kinds of sedi- 

 ments. For the study of free forms, it is best to collect from 

 the shaly or marly partings frequently found alternating with 

 harder beds. Unconsolidated fossil material may be treated as 

 already described for recent collections. 



With harder material various methods may be used. By boil- 

 ing with alkaline solutions, soda or potash, the specimens may 

 frequently be gotten out in clean condition for study. The use 

 of the autoclave has been described by Driver (1928). The 

 use of the oxy-acetylene torch has been described by G. D. 

 Hanna and by F. and H. Hodson. In the case of hard material, 

 it has been found that the use of a grinding machine will often 

 break down the sample in such a way that the individual speci- 

 mens will crack out along the surface, and a considerable per- 



