[M’GILL] VISCOSITY IN LIQUIDS 101 
For a particuiar set (A) of these nozzles, the times of efflux for water 
at 20° C., were as given in the following table. The numbers are means 
of numerous closely concordant experiments : 














SERIES A. Form I. Foro II. Form III. 
Diameter | | | 
TEMP. 20° C. of | 50 ebe. 100 ebe.} 50 cbe. 100 cbe.} 50 cbc. 100 che. 
| Nozzle. | | | | 
| | | | 
| [Tete Mere) Re EE | au veo" 2 
| inch nd | 159 2483 | 96.5 | 189°5 |. 35-4 | 161°5 
Fa -| | | 
Distilled Water. . Ave | Ist 30°9 | 27°0 =4-7 4°6 | : 
| winch | 5,4] 31-8 | 627] 9.7, 547 95.2 | 499 
| | | | 
est inentil ne. En ae DE] CR Pos ice | 224 

In sizes -L and 2, inch the time of flow was taken for successive 
volumes of 50 cbe.; and it will be noted that the difference due to change 
of head is practically constant for the same size of orifice, being 3°5 sec. 
and 0°8 sec. respectively. 
The nature of the forces producing flow changes with the absolute 
size of the outlet, as well as with its shape. This is evident from the 
following time-ratios, in which the time of flow through Form I is taken 
== hOOs: 
Form I. Form II. Form III. 
SAR re eee 1100 76°3 65:0 
ss 100 872 79°6 
J 100 91-9 90°3 

It appears from this that the influence of the form of the nozzle is 
less as the diameter becomes greater. 
The influence of an increase in diameter upon the time of flow is 
practically a constant whatever form of the nozzle is employed. Thus, 
taking the time of flow for size =, as 100, we have : 
Size 4. Size 3. Size 35. 
HorsHorimee else 7. ae 100 25°3 10°0 
és fe Ta. ey 100 28°8 12°0 
ay So MOMS oho etree 100 30°9 13°9 
From this study it seems that both the form and size of the jet are 
functions of the rate of flow. 
I had hoped to be able to show the relations between the curves of 
true viscosity, and those of viscosity as shown by this instrument, in the 
vases of water, alcohol, chloroform, and some other liquids whose curves — 
\ 
