SCIENTlflC AMERICAN SUPPLEMENT No_ 2053 291 aspect of ionization by bubbling. A large effect due to the latter cause was to be expected, as the bubbles were very small. It could not, indeed, be doubted that in a large number of cases it was this bubbling that was accountable for the whole of the electrification observed. There were, however, other cases to which this ex planation would not apply. One of these (still without any very thorough explanation) was the ionization pro duced when air

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... drawn over phosphorus. If a little phosphorus were placed in a tube through which air was sucked, then, if a collector in the tube were connected up to an electroscope, the latter indicated that the air which had passed over the phosphorus had become con ductive. This might seem as simple a case of chemical action as we could have, but Block had shown that the