Intelligence and Miscellaneous Articles. 375 



hausted by water and lij-drochloric acid, was ground to the very 

 finest powder upon a plate of agate ; the two solvents now extracted 

 only imperceptible traces of fixed constituents, and after burning the 

 exhausted charred mass I obtained the same large amount of ash as 

 from the non-pulverized charcoal. It may nevertheless be supposed 

 that the extremely minute vesicles were not destroyed and torn by 

 the friction upon the agate plate. The microscope threw no light 

 upon the subject. 



It is known that charcoal is capable, by a weak kind of affinity, 

 of removing certain salts from their solutions ; I have also mentioned 

 above, that when the charred substance has been treated with hy- 

 drochloric acid, it is almost impossible to remove the acid by washing 

 with water ; but the quantity of ash is too considerable for us to 

 ascribe this origin to it, since it is known that the salts which the 

 charcoal has combined with may be entirely separated by long treat- 

 ment with water at diiferent temperatures. I mixed sulphate of 

 potash and phosphate of lime with sugar, and charred the mixtui'e. 

 Water, and after this hydrochloric acid, extracted the two salts so 

 completely from the charred mass, that the latter, after combustion 

 in an atmosphere of oxygen, left not a trace of ash. 



Several acid phosphates (metaphosphates) are insoluble in hydro- 

 chloric acid after ignition ; to this cause might be owing the resi- 

 duary ash of the charred mass ; but although phosphoric acid is 

 almost constantly met with in this ash, it is not always combined 

 with the bases in the form of acid salts ; moreover, the ash itself, 

 •when it does not contain silica, is soluble in hydrochloric acid after the 

 salts have been exposed, in the combustion of the carbon in oxygen, 

 to a far higher temperature than that employed in charring the 

 organic substance. 



Ignited peroxide of iron is, it is true, not insoluble in hydrochloric 

 acid, although very sparingly soluble; its non-extractiou by acid 

 from the charred blood might be attributed to this cause ; but sup- 

 posing it to be contained in the state of peroxide of iron, not only 

 must it be more readily soluble in hydrocldoric acid, owing to its 

 finely divided state, but the oxide of iron which is found in the ash 

 after the combustion of the coal, and w hich has been exposed to a 

 very high temperature, is soluble in hydrochloric acid. 



The alkaline and earthy phosphates which are found in the ash of 

 the exhausted charred mass cannot have been contained in the 

 form of metallic phosphurets of a peculiar kind mixed with coal, 

 like the phospluirot of iron, which is perfectly insoluble in hydro- 

 chloric acid. It might be assumed that they were formed by.the 

 reduction of the alkaline and earthy phosphates by the carbon. It 

 is scai'cely necessary to notice this assumption, for it is well known 

 that the neutral and basic alkaline and earthy phos])liates are not 

 reduced by carbon even at a high temperature, at least not in the 

 presence of silica or any similar fixed acid. But even the excess of 

 phosphoric acid cannot i>e reduced by carI)on from the acid phos- 

 phates at the temperature whicii I employ in charring organic sub- 

 stances. In the case of the blood, however, phosphuret of iron 



