i6^ Dr. Pearson on the colouring Matter 



6. On treating the coaly powder by exposing it to fire, and 

 with the pneumatic apparatus, the products were always char- 

 coal acid, hydro-carbonate gas, and much water, with gene- 

 rally a little empyreumatic oil, and sometimes a trace of prussic 

 atid, leaving a residue varying in weight as just stated. 



From the properties above manifested, I conceive I am en^ 

 titled to declare the black matter, obtained from the bronchial 

 glands, and from the lungs, to be animal charcoal in the un- 

 combined state ; /. e. not existing as a constituent ingredient 

 of organized animal solids or fluids. 



I mean by the term animal charcoal, what is popularly un- 

 derstood. Of course, I do not mean pure charcoal. Such a 

 state of this substance cannot here be reasonably expected, 

 either from a consideration of the state of it, as inspired from 

 the atmosphere, or from its necessary impregnation with animal 

 matter during its long residence in the lungs. I imagine, no 

 person would hesitate to consider such a coaly substance as 

 the present to be charcoal, if derived from other sources be- 

 sides the animal economy ; it being, as shewn by the preceding 

 experiments, a black, tasteless, infusible powder, indissoluble 

 in muriatic acid, nitric acids, and perhaps all common acids, 

 except the sulphuric; affording as large a proportion of char- 

 coal acid as animal and vegetable charcoal which has been 

 exsiccated at the same temperature, and equally resisting fire 

 in close vessels. 



For the purposes of physiology, a few theoretical remarks 

 may, perhaps, be useful. I think the charcoal, in the pulmo- 

 nary organs, is introduced with the air in breathing. In the 

 air, it is suspended in invisibly small particles, derived from 

 the burning of coal, wood, and other inflammable materials in 



