v.x i ■ •• • i ok. 



often suffered to stand after BtirriDg, so as to leave behind the 

 insoluble constituents, among which, of course, are the objects 



of our search. 



The sediment will be materially lessened in bulk bya good 

 boiling in a solution of carbonate of soda, one ounce to the 

 pint, which dissolves much organic as well as some inorganic 

 matter, and, besides, sets free adherent Diatoms without in- 

 juring their structure. Carbonate of potash, however, is not so 

 free from objection. 



The residuum, being drained upon a filter, ought noiv to be 

 boiled in an equal-part dilution of nitric acid for about ten 

 minutes in a beaker glass, the quantity of the fluid being a 

 couple of inches in height above a half-inch of the matter upon 

 which it is destined to act. Lime not in the form of sulphate, 

 and some other elements, are dissolved out as nitrates, and must 

 be poured off in the solution when cold after standing. Hot 

 water should now be added freely to the sediment and poured 

 off after its subsidence, until all acid shall have been removed, 

 whereupon the residuum is to be once more drained upon a 

 filter. 



The matter remaining is now ready for pure nitric acid, in 

 which it is to be boiled for five or even ten minutes; after which 

 treatment, and before cooling, the whole must be deluged with 

 hot water. After standing, the supernatant liquor is to be 

 poured off, and the refractory deposit washed clean with cold 

 filtered water, and drained as before stated. 



The sediment now, much reduced in quantity, is prepared for 

 ehlorhydric acid, in which it is to be boiled for the removal of 

 sulphate of lime if in moderate quantity, perhaps of a small 

 percentage of other matter, and of such metallic stains as have 



resisted the action of the aquafortis. Besides, the chlorii. 



bleached such vegetable organic debris as h.\ \ 1 destruc- 



tion, so thai the sediment, now composed of Diatoms, fine sand 

 and siliceous dust, and extraneous vegetable remains, appears 

 of a pale gray color. 



When thoroughly washed in filtered or distilled water, and 

 then rendered as tree from moisture as p tssible, either by 

 means of a filter or by gravitation, the deposit must be sub- 

 jected to the action of sulphuric acid, O. P., which, heated to 



