8 Journal of the Asiatic Society of Bengal. [(N.S., XVI, 
¥Y. SuupHuric Acrp. 
Sulphuric acid of density about its maximum, 1-840, cor- 
responding to 90°% of pure’ H,SO, prepared by boiling with 
the usual precautions, is the only desiccant which we have 
found suitable for use with sensitive quadrant electrometers 
and similar instruments, and even with this substance the best 
results can only be obtained when, as in our arrangements, the 
« 
insulators which are to be kept dry by it are enclose 
, soon 
making the sealing of the older type of case used by us 
of the case and dipping into the beaker. By means of a two- 
way tap outside, the acid could be introduced under pressure 
or siphoned off. The acid contained in the beaker could be 
stirred by means of an open spiral, of glass tubing, which 
could be either lowered entirely underneath the surface of the 
period to see the maximum increase of leak possible. The 
leak increased to double the usual value and then began vary- 
