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them, to work with entire satisfaction, some months ago I instituted a 

 series of experiments for the purpose of discovering whether a more 

 perfect process could not be contrived. The result was the method to 

 be described here, which I think will be found to answer the pur- 

 pose sought, viz., that of giving a reliable process by means of which 

 all the organic matter may be removed from sub-peat deposits, guanos 

 or tidal muds. 



Guanos should be concentrated as much as possible, by removing 

 all their easily soluble constituents by means of boiling in water, or, 

 when only the coarser Diatoms are wanted, by boiling for a few 

 minutes in a solution, not too strong, of Carbonate of Soda (washing 

 soda). This removes most of the Ammonia, and Lithic acid, and a 

 greater part of the coloring matter. The residue is best boiled for a 

 few minutes in clear water, and then in Chlorohydric acid, to remove 

 lime, and thoroughly washed with water. What is now left is treated 

 in the same manner as sub-peat deposits and tidal, muds, as follows : 

 The residue after washing, with water adhering to it, is transferred to 

 a test tube or flask, and enough Nitric acid poured over it to cover it 

 to about the depth of half an inch; the liquid is then boiled as long as 

 vapors of Hyponitric acid are given off. These vapors range in depth 

 of color from a yellow to a deep ruby-red, the quantity of organic 

 matter in the gathering determining the depth of tint. In this way 

 the Nitric acid is decomposed, a large part of its Oxygen uniting with 

 the Carbon of the organic matter and going off as Carbonic acid. 

 When the red vapors have ceased to be evolved the residuum is well 

 washed with filtered or distilled water, until all acid is removed. The 

 remaining Diatoms, with some undecomposed organic matter still adhe- 

 rent, is transferred to a porcelain dish, covered with Sulphuric acid to 

 the depth of half an inch, and boiled. While in a state of ebullition 

 ground Bichromate of Potassa is introduced in small portions, always 

 allowing the violent action, which results from the introduction of one 

 portion, to subside before another is added. The Bichromate is de- 

 composed by the Sulphuric acid, Chromic acid being set free ; this, 

 coming in contact with the organic matter, is in its turn decomposed 

 into Sesquioxide of Chromium and Oxygen, which latter substance, 

 uniting with the Carbon of the organic matter, is evolved as Carbonic 

 acid. The Sesquioxide of Chromium unites with the Sulphuric acid, 

 and this, with the sulphate of Potassa, forms a double salt, the solution 

 of which is of a deep chrome green color. As soon as all the organic 

 matter is removed no more of the Chromic acid formed is decomposed, 

 and the liquid becomes of a yellowish green tint in place of deep 

 chrome green. The mixture is then permitted to cool, and, when 

 ({uite cold, the remaining Diatoms are washed free of salts and acid 

 with clear water. 



