Properties of Wood Ashes. 



85 



During my inquiries into this subject, I was induced to com- 

 pare the physical and other properties of various powders. Omit- 

 ting my tables of their specific gravity, porosity, &c. as incom- 

 plete, I give the other results below. The substances were dried 

 at a high temperature, and passed through the same sieve ; the 

 force used in ascertaining the compressibility was sixty pounds. 



The gravity was determined by weighing a given measure, 

 without compression or jar. 



Water, being 1000 



Magnesia, was 



Ashes, 



Chalk, 



Scorified wood ashes, 



Plaster of Paris, . 



Common earth, 



Sand, 



164 

 356 



582 



910 



921 



1035 



1358 



Compressibility. 



The loose measure, being . . . 100 



Ashes were reduced in bulk, to . . 25 



Magnesia, ...... 50 



Chalk, ...... 50 



Plaster of Paris, ..... 69 



Common earth, ..... 69 



Scorified ashes, ..... 86 



Sand, 88 



The sand could be shaken into a less space than it could be 

 pressed by the force employed. 



Conductibility. — I selected neat paper pill-boxes of uniform 

 size, color, &c. and filled them evenly and without jarring, with 

 the several powders tested. On the centre of the surface, T care- 

 fully placed very small squares of tin-foil supporting a particle of 

 phosphorus. Thus prepared, the boxes were at the same instant 

 carefully set upon an equally heated metallic plate, and the time 

 of fusion and of deflagration noted. I give, in the subjoined ta- 

 ble, the average results of several trials, in seconds. 



Macnesia. Ashes. Scorif. ashes. Chalk. I Sand. Coal. Earth. Gvpsuiti. Sugar. 

 42.335 J12.267 125 242. 123 293 125.242 77.420 182.300 154.314 218.407 



When fused, the phosphorus assumed a hemispherical form, 

 and delicate vivid lines shot hke hghtning from the margin ap- 



