Properties of Wood Ashes. 87v. 



stirred in a large quantity of water, and allowed to subside. In a 

 short time the insoluble parts settled at the bottom, and most of 

 the coal with them, very few particles of it floating on the water. 

 Hence the porosity of the coal must have been sufficiently de- 

 stroyed to render the fragments specifically heavier than this fluid. 

 3. The washed ashes used in the foregoing experiments, were 

 examined by a microscope, and particles of coal clearly seen in 

 them. Specimens of well burnt and sifted ashes from the stove, 

 exhibited the same appearance. 4. Several hundred grains of 

 sifted ashes were treated with nitric acid, and after long diges- 

 tion, the residue was washed, dried, and weighed ; the quantity 

 was six per cent, of the original weight of the ashes. Under the 

 microscope this residue was found to consist of particles of coal, 

 a greater proportion of black vitrified grains, and transparent par- 

 ticles which scratched glass, and appeared to have undergone par- 

 tial fusion. 5. One hundred grains of sifted ashes were in like 

 manner submitted to the action of hydrochloric acid. On dilu- 

 ting the solution with water, a black matter was immediately 

 deposited with gray particles beneath it. The black sediment, 

 washed and dried, assumed a black-brown color, and weighed a 

 fraction over six grains. This powder scintillated in the blaze of 

 a candle like coal-dust ; under the action of the blowpipe it be- 

 came gray, but the principal part remained unconsumed. 



Having by these means convinced myself of the presence of 

 coal-dust in ashes, it followed that an ordinary fire did not always 

 consume all the carbon of wood ; and to arrive at an approxima- 

 tion to the degree of heat necessary to burn it out of ashes, I 

 tried the next experiments. 6. Sifted ashes were pressed firmly 

 into a crucible, and to expel moisture I subjected them to a tem- 

 perature of at least 440° for an hour. The temperature was as- 

 certained by the fusion of tin. The ashes were then weighed, 

 and subjected to a red heat for half an hour. On weighing again, 

 there was no appreciable loss. Sulphuric acid and the micro- 

 scope detected, as before, particles of coal in these crvcihulated 

 ashes. 7. Most of the ashes of the last experiment were placed 

 loosely in the crucible, and again heated to redness for half an 

 hour. The result was as before — no loss of weight. 8. Inti- 

 mately mixing thirteen grains of coal-dust with four hundred and 

 sixty seven grains of the crucibulated ashes of the seventh ex- 

 periment, and pressing them together, they were heated to red- 



