S2G J. H. MAIDEN AND H. G. SMITH. 
of like material, to the importance, from a scientific point of view, 
of submitting for investigation earthy-looking deposits which may 
be found in timber. 
Physical Description. 
The material is quite soft and almost white in colour, except 
on the exterior of the lumps, where they are slightly stained 
brown in places, by some organic substance. It has a sourish, 
rather unpleasant odour, arising most probably from the presence 
_ of acetic acid. The whole of the cavity appears to have been 
filled with the material ; the largest lump measures in the thickest 
part 2 cm. or about three quarters of an inch, and impressions of : 
the tissue of the wood can be easily seen. 
The original material is crystalline in part, minute acicular 
crystals being seen between crossed nicols with a quarter inch 
objective. The harder and more solid portion appears to contain 
the crystals in very small quantity. © The very soft portion col- 
tains them in abundance. The best method to observe them, is 
to mount a portion on a slide under a cover glass with water, 10 
other material answering so well for this purpose. These acicular 
crystals were found to polarize when revolved between crossed 
nicols, but were altogether too minute to determine their mode ot 4 
crystallization. The material is thus not quite amorphous. 
Determination of the Base. 
The organic matter is with difficulty entirely removed from : 
the original substance by burning, the last traces of carbon 
requiring the heat of the blowpipe before being entirely removed: : 
The residue is perfectly white in appearance, and shows 10 signs 
of fusion with the greatest heat obtainable with the gas-blowpipe: : 
The residue is, when thus ignited, insoluble in acids, and requires ; 
fusion with bisulphate of potassium or other suitable substance — 
before solution can be obtained. This residue contains no OMe — 
— than alumina ; absolutely no trace of lime could be detecte 
im several determinations, and only the slightest trace was obtaine 
when testing for magnesia. Quantitative determination aie a 
