HARDWICKE'S SCIENCE-GOSSIP. 



[Feb. 1, 1867. 



FORAMINIFERA IN CHALK. 



I HAVE for some years past successfully prac- 

 tised a simple method of obtaining Foramini- 

 fera, &c, from chalk. 



Fig. 33. Gravesend Chalk. 



As many persons are desirous of obtaining a 

 good supply of these interesting objects, the fol- 

 lowing directions may prove useful. 



Having procured a lump of fresh chalk, 

 break it into pieces of about the size of a 

 large walnut ; then, with some heavy in- 

 strument, crush, not pound nor grind, 

 these pieces into a coarse powder ; when 

 a sufficient quantity (say one or two 

 pounds) has been thus prepared, either 

 pass it through a sieve, or remove the 

 large pieces, crush them, and return 

 them to the powder; next procure a 

 piece of stout calico, into which place the 

 chalk, and tie it up as a housewife would 

 a pudding. A large vessel of clean water 

 should now be obtained, and the crushed 

 chalk, having been allowed to become 

 saturated with the fluid, the bundle should 

 be kneaded, in the hands only : the con- 

 tents will soon become a thick pasty 

 mass, the milky water gradually ooze 

 through, and the bulk of the chalk be- 

 come considerably diminished. From 

 time to time, after allowing the fluid to 

 drain off, the cloth should be untied, and 

 rctied closer to the mass, and when the 

 contents are reduced to about one-third, or less, 

 of their original bulk, all large pieces of chalk, por- 



tions of spines of Echini, &c, should be removed, 

 as the attrition of these hard bodies would greatly 

 injure the delicate and beautiful little fossils. 



When the greater portion of the chalk has escaped 

 through the cloth, much greater care must be used, 

 and at last the bag should be merely 

 shaken, until the water which flows from 

 it is almost clear; the contents of the 

 cloth may then be transferred to a bottle 

 of clear water, which should be vio- 

 lently shaken, the organisms occasionally 

 allowed to subside, the milky fluid poured 

 off, and fresh added : this operation to be 

 repeated until the water remains clear 

 when agitated. The white powder should 

 be dried and sifted ; the coarser will be 

 found to consist of minute corals of 

 great beauty, sponges, shells, and the 

 larger foraminifera, &c, and the finer of 

 the smaller foraminifera, &c. 



So far from this apparently rough mode 

 of proceeding injuring these delicate or- 

 ganisms, the majority of even the most 

 fragile are quite uninjured : this, no 

 doubt, is owing to the semifluid contents 

 of the bag not being allowed to escape 

 too quickly ; if too coarse a cloth be used, 

 not only do the more minute fossils pass 

 through, but the softer part of the chalk 

 being at the same time removed, the 

 hard pieces of some portions of shells and spines 

 would be brought into a more immediate contact 



Fig. 34." Chalk of Mcndon. 



with these minute bodies, and their inevitable 

 destruction would be the result. The operation is 



