144 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The next step is to place in a shallow concave glass used by photo- 

 graphers for crystal photographs, size about 4 by 6 in., a shallow 

 layer of tho diatomaccous mud, and, adding water, gently gig tho glass 

 to and fro, making tho waves run from end to end, and tilting tho off or 

 front end. This manipulation forces the large and small sand-grains to 

 densely cake and pack together, and at the same time forces to the sur- 

 face a large percentage of the diatoms, and most of the vegetable debris. 

 After a few moments of gigging, the surface fluid is gently poured off, 

 and caught in a separate settling vessel, and the heavier sand dropped 

 into a waste receptacle. It may here be observed that a very small 

 percentage of matter would be the outcome of the first manipulation, and 

 that the bulk of the material was removed from the crystal glass as 

 rejected sand. It can generally be relied upon that what is left on the 

 gigging-glass would not do to manipulate again, and the diatoms must be 

 looked for in the light, coherent, flocculent, vegetable debris that floated 

 over in the first removal of the surface fluid. Eepeat substantially the 

 same manipulation until the whole of the mud has been gone through, 

 and in the little that is left of the original half-pound the coveted gems 

 will be found, or do not exist. The next step is to deal with what has 

 been saved in the various partial concentrations, transferring all of it to 

 the crystal glass, adding clean water, and gigging it again several times in 

 succession to remove additional sand, and to get a further concentration 

 of the desirable material. An occasional wet test under the Microscope 

 will show whether the indications of diatoms are good. If so, the 

 material is then transferred to a small holder with a spherical bottom, 

 so that it may quickly settle, and with a rubber bulb pipette all water 

 is carefully removed. Should there aj:>pear to be about 1/2 in. deep 

 of material as the result of all previous manipulation, add to it an equal 

 bulk of sulphuric acid, intimately mix, and by the aid of the pipette 

 transfer it to a 1/2 or 3/4 in. diameter glass test-tube of about 

 six inches length ; boil for fifteen minutes over a candle or spirit- 

 lamp : in that time it is probable that all organic matter will be reduced 

 or carbonized. At this juncture add carefully, a drop at a time, several 

 drops of nitric acid, and boil continuously for ten minutes longer, when 

 it will soon be noted that the blackness is discharged, transparency 

 restored to the boiling fluid, a partial or complete bleaching of the 

 material having occurred, together with a remarkable reduction in volume. 

 If there have not been a complete reduction of all vegetable or other 

 organic matter, it may be necessary to add a few drops more of sulphuric 

 acid and boil it a while longer. Should the preparation at any time not 

 yield satisfactorily to the bleaching process, pour out the contents in a 

 spherical-bottom vessel, and allow time to settle ; pipette off the acid, 

 and add a fresh quantity of sulphuric acid, and boil a few moments, and 

 finally add a few more drops of nitric acid to oxidize the remainder of 

 the carbonized substances. 



All acid-boiling processes should be conducted in an open fireplace 

 if practicable, so that the irritating gases may pass up the chimney. 

 The above apparently long or double boiling process is rarely required, 

 but must be resorted to if the organic material to be reduced is refractory. 

 Where boiling first in sulphuric acid, and later adding nitric acid, is 

 applied to the cleaning of all diatom gatherings not badly mixed with 

 sand or vegetable debris, or is applied to pure gatherings, it acts very 

 rapidly, giving promptly a snowy-white cleaning of the diatoms. In 



