1919.] The Sixth Indian Science Congress. Cxxi 
the work. al first object was to get ica 1 values of the ioni- 
sation of the in India, as only very little is ‘known 
of the air in pelle climates. My second object was to yeehorrs se in- 
fluence of the nature of po Bits on the rit od a the a My pla 
of observation were chos o as to suit this double object. Gearenions 
were made in the following Tocalit ties :— 
1. Bombay and Khandala, in at aust Trap (basalt), 
2. Mt. rele in the Ascneeet S 
3. Tumrikop, in the Dharw ag 9 sediments), 
4, Anand, in the Alluvium (Pleis tocene), 
I consider my work to be still Sotpudane and I intend to continue it 
in some more places. 
Summary of Results. 
1. E has been ie in 5 different places 
2. Asarule E> Hor _E= E nearly, only comannee: 4B< _ E. 
3. In certain places as at certain times in fi ame place Ham. 7 
Ep.m,, in other pl aces Eam. < The ine tity depends much on 
the ake of the air as to smoke, Saat; Riera pier et of the wind in 
ee and in the afternoon. 
s more affected be — of the air ea +E. 
5, Great and rapid changes were obse 
bgoieey of the difierenies in Sern ae on ‘E has been observed 
ndala 
in Boinba t Kha a. 
"Be the air coming from the peager seems to possess a 
ye Bot okey 
Beane clot charge than that coming from t 
The © of the humidity of ee air on —G is obliterated in 
boos b other “uncontrollable factors. 
the the rock and soil in a district seems to affect E 
considerably. 
A new form of ae plate interferometer —By H. Para- 
MESWARA IYE 
hort account is given of experiments made with a eee — 
Fa a Sacra formed by a seis of liquid on top of a layer of mercur 
A scientific definition of the consistence of mortar.—By 
R. S. CREE Brown. 
Nebo on whic e crushing strength very rede epen odift 
cation of the Vicat needle is describ reby a cone, weig ated with 
mmes, i wered into a of the mortar m. thick. The 
gr S, 1 1 
distance from the point of the cone to the base of the specimen, when 
equilibrium is estab ished, is read e eall 
sistence Number. It is shown to vary inversely with the quantity of 
mortar. 
he meaning of this number is further analysed, and its connection 
with the ‘* Hardness Number” of Brinell and arrvigarterr is shown. navapalben ith = 
apparatus the Hardness Number of fres angie made mortar can 
tained to the same scale as the hardness number for steel. The ree 
meaning of this number is discu 
Mutual potential —By D. N. Matrix. 
for mutual 
In a former Pepet the — oie se n expression 
tential in the form of an al involving surface elements with 
pon ener da The present caaete deals pur further vere ares of the 
same formula. 
