[MORAN] RADIUM STANDARD SOLUTIONS 79 
Below are the solutions with their strengths— 
Solution. (Radium Content in Grams) X10. 
Wiashine tonal serugn acer hit es a Pah rant pe ee Re 1-570 
: 11 Bias A ah RS SE EES MP A ge ne 1-573 
‘ DR RE MR Le a ert SAN nce 1-570 
Rnéhesford=BülwoodeWeak tel"... keel ee 1-570 
f oe $ Dee eae otk hy TE PA eee 1-570 
‘ QE STONE RE PRE RL 1-570 
ss ty PR FD tc Re eR RR PONS nee 1-567 
The radium bromide solutions taken as above were drawn out 
of the standard bottles withaclean pipette, and weighed to the amounts 
stated. They were then carefully washed into a clean new flask of 
500 c.c. capacity, and diluted up to 250 c.c.with distilled water. The 
flasks were then sealed with new rubber stoppers, tap-grease and seal- 
ing-wax, and wired down. The solutions were then allowed to stand 
for a month, at the end of which time the emanation had reached a 
maximum. 
Meanwhile a new leaf had been put on the electroscope used 
previously, and the latter made absolutely air-tight as tested with 
a pressure-guage. The electroscope was then calibrated, and. that 
portion of the scale chosen which on testing with the solid radium 
standard gave the most uniform readings. The first set of results 
however, varied considerably, sometimes eight to ten per cent. A 
new electroscope made in the Physics Building gave no better results, 
and as the natural leak was fairly high, it was decided to make one 
in the Chemistry Building, entirely removed from radioactive in- 
fluences, or as much as possible. A new 750 c.c. filter-flask was sil- 
vered with the following solution :— 
(1) Alkaline AgNO: solution. 
(2) Reducing solution, consisting of— 
(ay @anersigaiiae: 44:05 re ce sear ae 90 grams. 
(DIRCONCAAC Met oe oe ee tal ss Bye 4 ¢.c 
(GE tiv alcohols, 30 he ts ee, ion: 
(daDistlledavarer mets esta Ci 1000 c: 
This gave a beautiful silvering, and when made air-tight and cali- 
brated gave a natural leak of only -07 division per minute. The 
readings obtained in the calibration were also very uniform. When 
the standards were now tested and the results were still unsatisfactory, 
all possible sources of error were gone into and classified. They are— 
(1) Loss of emanation; which may include— 
(a) Failure to boil off all the emanation. 
(b) Leaks in vessels containing the emanation. 
