ON STANDARDS FOR USE IN ELECTRICAL MEASUREMENTS. 119 
Other series of observations showed that the resistance for 10 seconds’ 
interval was the same as for 5 seconds’; if the interval was prolonged to 
30 seconds a very small increase in capacity was noticeable. Thus the 
effect of absorption is to increase the capacity of the *1 microfarad by 
about 8 in 1,000, or 008 of the whole; of this ‘0065 shows itself in the 
first 2 seconds of charging and ‘0015 afterwards, the increase after 5 
seconds, if any, being extremely small. 
When comparing I. with -5 microfarad the resistances used were 
592,290 and 24,900 respectively. In this case an alteration in the latter 
resistance of 10 ohms, or s;55, was easily seen. The following are the 
results :— ; 
Interval | Resistance | Interval / Resistance 
10 seconds 24,900 2 seconds 24,930 
5 o 24,900 0 - 25,060 
These again show that the absorption effect disappears after 5 seconds, 
and that the effect of absorption in 2 seconds is about -0052, and in 
5 seconds about “0064 of the whole capacity. 
When comparing with 1 microfarad, the resistances were 592,290 and 
12,580, the last number being accurate to about 5 ohms, or about the 
same proportion as before. 
The results of the various observations are given in the following 
table; the observations made with II. have been corrected for the leak, as 
already explained. 
Table giving the Capacities of certain Mica Condensers as compared with 
the Aix Condensers. 
Value found by 
Date Value from I. Value from II. Commutator 
at frequency 64 
August 19 . : “04934 “04938 “04867 
by sie yi . “04934 “04936 
June 17 . : “09772 “09780 “09638 
August 14 . : 09751 
eerlo; : “09773 09786 
a : 09773 “09781 
| August 18(M). “5005 “5008 
me ISGA) “5007 “5009 
mw ol. : 5006 “5010 
August 18 . ‘ 9910 “9912 
te ees : “9913 “9912 
_ It will be noticed that, for either condenser I. or II., the results are in 
very close accordance; with the exception of one observation, on August 
‘14, the differences are barely as great as 1 in 5,000, and the method is 
clearly capable of giving the value of a mica condenser, in terms of the 
air condenser, to this accuracy. 
The reason for the low result on August 14 is to be found in the fact 
_ that on that day the leak was considerable, being, as we have seen, over 
Bs 1 per cent. per minute. Full observations for the correction were not 
, 
