Abstract
1. The author has experimentally proved that the hygroscopic nature of volcanic ashes mainly depends upon their water soluble sublimates.
The chemical compositions of the water soluble sublimates are as follows.
2. There is a distinct group distribution on the size of ashes, for example Mt. Asama of which the larger one consists the main part of the ash. When we observe the fresh samples, we can see that the smaller ashes adhere on the larger particles, as if they are small magnets and iron powder. The force between these particles is perhaps the adhesion force, and not the electrical or magnetic force.
