98 ROYAL SOCIETY OF CANADA 
time the experiment lasts, since the large horizontal area of the vessel 
makes the variation of rate due to gravity to be insignificant. The oil is 
withdrawn from the middle of the whole quantity contained in the vessel, 
and although the outer layers of oil may slightly change their tempera- 
ture, the middle portion is sensibly constant during the time of the test, 
The tubulure (I used at first the agate tube from the Redwood instru- 
ment, but now it is replaced by nozzles of phosphor-bronze bored to 34, 
2s, à, inch respectively) is not placed at the bottom of the vessel ; conse- 
quently particles of dust, sand, etc., which may be accidentally present, 
do not interfere with the working. Finally, the shape of the conical tube 
carrying the agate makes it very convenient to insert the receiving flask, 
whose neck fitting somewhat closely into the hollow cone prevents the 
cooling effect of air currents upon the mouthpiece, a very important con- 
sideration, since they constitute an unascertainable and a varying factor 
in the results obtained with other instruments. I employ a ring burner 
in heating the oil, and a wooden spatula for stirring it. It is convenient 
to use two flasks, so that one may be draining while the other is in use. 
In this way a very large number of experiments may be made, even at 
high temperatures, in a short time. 
The following results illustrate the working of this instrument using 
a cylinder oil : 
Temp. No. of Tests. Max. Min. Mean. 
250° F. 11 34° 0 sec. 33 0 sec. 35°5 sec. 
200° F. 16 159 AAS 5 iat AUS ES 
In order to determine the change in the rate of flow due to lowering 
of the level, I made series of tests taking, in each case, three successive 
portions of 50 cc. The initial level is always 23 inches above the upper 
surface of the nozzle: 
1. Temp. 250° F. (means)— 


Ist, 50 ce. 2nd, 50 ce. Sra HOVE: 
33°5 sec. 34°7 sec. 36°0 sec. 
At 200° F.— 
44°8 see. 47°2 sec. 50°6 sec. 
The withdrawal of 150 cc. causes the level to fall about three-eighths 
of an inch, corresponding to an increase in time of about 2 seconds at 
250° F., and about 54 seconds at 200° F., a guarantee that any slight error 
in the adjustment of original level can have but a very trifling effect on 
the rate of flow. The following experiments were made with a sample 
of glycerine diluted to the density of Redwood's standard rape oil, viz., 
1°226 at 15-5° C. 
The temperature of the laboratory was 68° F., and I found it quite 
