i)() .srnr.M high TEMPERA t» 
accurate forms yet devised. The completed adjustment is well showr 
in Fig. 11a, where /> is the boiling tube, R the ring burner, A the oil 
bath for the cold junction of the thermo-couple, JB the thermometer ol 
the cold junction. The central tube is closed by a piece of asl 
wicking, as shown. Communication with the air-pump takes place 
through C. Mr. Greiner h.i- - succeeded in inserting a second 
tubulnre in the top of the boiling tube, Fig. 11, through which a mer 
cuiy thermometer may be inserted, thus affording additional means ol 
thermal comparison. 
Dr. Cribb.s's ring-burner. — A final reference is to be made to the riug 
burner. This is shown diagrammatically about one-half full size in Fig 
1 2. The burner proper, a b e, is a circularly bent tube of brass or iron, of 
the inner side of which about forty radially disposed hole-, each about 
0.l" u in diameter, have been drilled. The straight tube ef conned 
ring with the injector, the tubedeadmit . the influx of gas, 
tube/o of the injection of air. Both the tubes d e and/o are i rovidec 
with stop cocks. Where only moderate intensity of flam sirabk 
gas may be passed in at /and the tube de left open. Either of the 
tubes de or ef is available for clamping t e burner in t: ring stand] 
In the general case where a blast is necessary Professor Richards 
pneumatic injector is most easily applicable. The pump which can b< 
used equally well either for slight compressions or for exhaustions it 
now in such general laboratory use that special description is unneces 
sary. 
It is probable that for special purposes boiling tubes of larger diam 
eter will be preferable, but such tubes are more fragile and the mania 
illation is of necessity less expeditious. 
APPARATUS FOR HIGH BOILING POINTS. 
Original forms of boiling crucible. — The tubes ji re ni 
longer convenient when the boiling point of the substance exeeeds lov 
redness. Iu such a case bellows have to be used for injecting air aut 
the glass tube itself, becoming more aud more viscous, yields gradual^] 
to the charge of metal it contains. Hence for high temperatures it i 
necessary to replace the glass tube by crucibles of fire-clay or of poroi 
lain. In Fig. 13 I have given the original form of au apparatus of thi 
kind. Ir consists essentially of two French crucibles, a a a a and b b bb 
put together on the rlat open end, which it is well to grind smootl 
Both crucibles are perforated. A porcelain tube, d </, has bet 
men ted into the lower crucible with asbestos cement. This tubf 
1 above, open below, and glazed exteriorly, is to contain the thermc 
element. Through the tube a h above, some I .' _ 
hydrogen, may be introduced, the tube g h bei g g ss or ] 
lain. The lower crucible is partially til!' ther sul 
stauce, fcfc, whose boiling point is to be used, . ken to ir 
