least about eight vent channels 238 the relatively small cross sectional area of each vent channel 238 minimizes the probability that the larger solid particles will enter while the relatively large number of channels 238 minimizes the probability that any significant number of channels 238 will become plugged with the finer powdery particles if any vent channels 238 become plugged gas will be released through the remaining vent channels 238 vent channels 238 extend longitudinally along the outside surface of the cap body 240 change direction to extend radially along the lower surface of the flange 242 of cap 212 change direction again to extend longitudinally along the outside cylindrical surface of flange 242 and change direction again to extend radially along the upper surface of flange 242 it should be noted that the lower surface of flange 242 is not oriented perpendicularly with respect to the outside surface of cap body 240 but rather at an acute angle of about 45 55 degrees resulting in a portion of vent channel 238 that is zig zag or 34 z 34 shaped this zig zag shape of channels 238 functions as a baffle to inhibit the escape of very fine or powdery solid particles that may be small enough to enter channels 238 but too large to become lodged in them and plug them although in the illustrated embodiment ring 218 retains cap 212 in container body 210 because cap 212 and container body 210 are both made of plastic they may alternatively be.