36 8 C. G. Wheeler on a Process of Elementary Analysis. 
by means of a thick piece of gutta percha tubing, about four 
inches in length, with a glass tube bent at one end so as to ad- 
scribed, is placed in a suitable vesse 
position as shown in fig. 2, directly before the potash bulbs and 
ascertained at the anterior end of the apparatus by the inflaming 
of a taper; for which purpose, about ten minutes are required. 
Heat is now applied to the mixture of oxalate of lead and oxyd 
of copper, and the necessary carbonic acid evolved to displace 
the oxygen, at least as far as to the anterior portion of the com- 
bustion tube. In order to be certain that the metallic copper is 
surrounded by an atmosphere of carbonic acid gas, the heating 
ef the oxalate of lead is proceeded with until an absorption, 
usually occurring in from five to eight minutes, is clearly percepti- 
ble in the potash bulbs. At this stage of the process it 1s neces- 
sary that the bent tube at the extremity of the apparatus be 
immersed in the mercury contained in the mortar, in order that 
during the absorption of the carbonic acid by the potassa there 
may no air again enter the apparatus. Fire is now applied to 
he metallic copper; then the oxyd of copper is heated, and the 
analysis is thenceforward performed precisely as by the ordinary 
method. When the pant is reached where the substance under 
analysis is situated, the tube at the anterior end of the appara- 
tus is introduced into the tubulure of the gasometer, care being 
