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THE AMERICAN NATURALIST. [Vol. XXXVII. 



of the oxalic acid solution, which probably takes place according 

 to following reaction : 



C,0 4 H, + (X = 2 CO., + H 2 0, and it is perhaps this peroxide 

 of hydrogen that, in combination with some other compounds, 1 

 effects the bleaching. 



According to Richardson, the total amount <>t hydrogen per- 

 oxide formed in the solution increases with the concentration of 

 the acid, while at the same time the proportion of peroxide to 

 acid formed decomposed decreases simultaneously, and since the 

 described action of the head occurs with greater rapidity if con- 

 siderably diluted, only a very weak solution should be used. 



If the fossils, especially leaves, are wanted almost colorless, 

 the following method of bleaching is recommended. A solution 

 (not too strong) of potassium permanganate, is employed where 

 they are allowed to lie for some time, and then transferred 

 directly into the oxalic acid solution. 



To extricate fossils from calcareous peat it is necessary to 

 remove the carbonate of lime, and this is best done with hydro- 

 chloric acid. If, however, the material contains lime in a small 



very slowly and unevenly. In order to prevent this, the peat- 

 particles are thoroughly saturated with strong alcohol, and the 

 hydrochloric acid is applied afterwards. The separation will 

 now proceed easily and uniformly, and the gas-bubbles are 

 bursting so soon, that no undesirable foaming is caused. Should 

 this occur, the mass is again treated with alcohol. The sepa- 

 rated peat-material can then be preserved in the alcoholic cal- 

 cium-chloride liquid. 



Whatever method is employed for bleaching, this process has 

 to be done very carefully, so as to prevent the fossils from being 

 destroyed by the acids. The next step is the "slumming," or 

 washing of the macerated mass. For this purpose there are 

 different devices for slumming vessels. These are all constructed 

 on the plan of creating a rising current of water through the 

 mass, which is poured over a sieve of brass netting with meshes 

 not smaller than 1.5 mm. in diameter. 



1 Hydrogen peroxide alone does not bleach peat. 



