210 J. C. Draper—Preparation of Cylinders of 
the zirconium oxide pencil from its position, as is the case 
with the calcium oxide, it may on the contrary remain 7 situ 
for any length of time, and the apparatus is always ready for 
use whenever it is wanted. 
Though the standard works on chemistry generally mention 
the light-emitting power of zirconium oxide under a high tem- 
perature, the only successful attempt that has been made to 
apply it practically that I am aware of was that of Tessié du 
Motay. Unsatisfactory references to his process for preparing 
zirconia cylinders are to be found in various chemical works 
and journals, the best that I have seen being that given on 
page 47 of “Crooke’s Select Methods in Chemical Analysis.” 
The careful reader of this and other articles on zirconia will be 
prepared to expect difficulties in the way of its preparation, 
and it is to the removal or lessening of these difficulties that I 
now propose to address myself by the minute relation of the 
process I have finally adopted after many weeks of experiment. 
e subject naturally divides itself: Ist, into the preparation 
of zirconium oxide; and, 2d, the preparation of the cylinders 
or pencils. 
Preparation of zirconium oxide. 
2d. Reduce five or six grams in a steel mortar: 
or, by first heating to bright redness and chilling in water 
while very hot the same may be in a porcelain mortar. 
wder. The final yield of zirconia depends on the thorough- 
ness with which this is done. 
4th. Weigh out two grams of the fine zireon powder and 
mix it intimately in a mortar with ten grams of dry sodium 
carbonate, place the mixture in a covered platinum crucible of 
twenty cubic centimeters capacity. 
. Place the crucible over a strong Bunsen flame; the 
burner should be at least fifteen millimeters in diameter; 
about twenty minutes the mass in the crucible will have 
shrunken to one-third of its original volume if the heat 18 
sufficient. To secure uniformity in temperature of the erucible 
