jg THE ART OF MAKING MICROSCOPE SLIDES Radiolaria 



any other method. When tests are cleaned blown off to diminish the pressure as 

 in this manner it is essential that they rapidly as possible. The repetition of this 

 should be thoroughly soaked, and prefer- process resu ts m the disintegration of 

 ably also boiled, in a large quantity of materials which resist every other method, 

 distilled water to remove the alkah. The separation of f oramini eral tests 



Methods for the separation of forami- from chalk is a relatively simple process, 

 niferal tests from shale and clay deposits If one is only collecting the tests at ran- 

 vary according to the degree of hardness dom, so that i does not matter if many of 

 of the deposit The first exploratory step the more fragile forms are broken, the old 

 should always be to boil the mass in a 5 % method of brushang under water has much 

 solution of sodium carbonate. If the to recommend it. A piece of chalk is held 

 solution speedily turns cloudy, it is in one hand under he surface water and a 

 evident that the material is being dis- brush (an old tooth brush is excellent) is 

 integrated satisfactorily and it is only scrubbed over the surface. L^^ge numbers 

 necessary to continue boiUng long enough of tests, which fall to the bottom of the 

 for the tests to separate. The cloudy solu- container, are removed by this method 

 tion should be stirred up and poured off while the chalk remains m suspension and 

 from time to time into a large cyhnder of can be poured off. Tests prepared by this 

 distilled water. This should be allowed to method are never clean and must sub- 

 stand for about 10 minutes, to permit all sequently be boiled in alkah to remove 

 the foraminiferal tests to fall to the the adherent chalk. If it is desired to col- 

 bottom and the cloudy supernatant lect the greatest possible number of shells, 

 hauid then poured off. This may be re- chalk can often be disintegrated by boihng 

 neated as often as experience shows to be either in 5% potassium hydroxide or m 

 necessary to collect a mixture of forami- 5% sodium carbonate; this is, however, a 

 niferal tests and fragments of the shale prolonged and messy business Chalk may 

 mass at the bottom of the cyhnder. Sepa- also be disintegrated by the freezing and 

 ration of the tests from the shale frag- thawing process, or by the autoclave proc- 

 ments may either be by hand under a ess already mentioned. ^ ,. . . 



binocular microscope, or the mass may be The sihceous skeletons of radiolarians 



dried in an oven and sprinkled on cold are cleaned altogether differently and it 

 water, or carbon tetrachloride, for the is difficult to improve on the method of 

 flotation method previously described. If Roudabush 1938 {Ward's Bui 9). No 

 the preUminary boiUng in sodium carbon- prehminary treatment is needed for 

 ate does not result in a sufficiently rapid the easily disintegrated Barbados earths 

 disintegration, two possible methods re- though other material may have to be dis- 

 main The old method used to be to soak integrated by one of the methods already 

 the mass thoroughly in water and then to described. The disintegrated pieces are 

 reez^Tt; a household freezer giving tem- then boiled in 10% potassium hydroxide 

 oeratures of -10° or -20°C. is excellent, for about 20 minutes. Throw the whole 

 The frozen piece is then removed and mass into 10 times its own volume of 

 thrown into boiUng water which almost water, stir vigorously, and allow to settle 

 invariably breaks the mass into smaller for 10 minutes. Pour off the milky solu- 

 Dieces This process of alternately freezing tion; refill the beaker with water, btir 

 and boiUng is continued until the pieces vigorously, allow to settle for 15 seconds 

 have become sufficiently smaU to enable and save the supernatant hquid. Repeat 

 one to complete the separation of the tests the process; the two batches of decanted 

 with boiUng alkaU. water will be found to have most of the 



An interesting alternative method for hberated radiolarians. , , ^, . 



shale has been suggested by Driver 1928 The pieces remaining at the bottom ot 

 (J Pal 1 -253) who subjects the pieces to the beaker can be again boiled witti iu /o 

 the action of high pressure steam in a potassium hydroxide and further batches 

 laboratory autoclave. The pressure is run of liberated radiolarians poured off and 

 up to about 20 lbs., maintained at this for accumulated, 

 a few minutes, and the autoclave then The cleaned radiolarians in the ac- 



