« 
S. LT. Moreland—Formation of Diffraction Bands. 5 
colloidal, it is indeed very like it, and its behavior toward 
water very similar. 
The continuation of the experiments since, the preparation 
of the paper cited, confirms the conclusions there suggested, 
viz: that clays probably exist as a series of hydrous silicates, 
feebly holding different proportions of water in combination and 
having different properties, so far as their behavior to water is 
concerned. That some of them swell up in water (much as 
boiled starch does) more than others and are diffusible in it 
with different degrees of facility, that this diffusion is in part. 
at least, analogous to that of colloids in water, that the strata 
observed in the suspension represent members of this series of 
chemical compounds which hold their different proportions of 
combined water very feebly and are stable under a very limite 
range of conditions. That they are destroyed or changed in 
the presence of acids, salts and various other compounds, and 
that they are stable only under certain conditions of tempera- 
ture, some which may exist at one temperature being changed 
to others or destroyed at another temperature. 
The special bearing of the experiments and conclusions on 
certain geological phenomena, especially the transportation of 
suspended mud and the formation of bars and deltas, will be 
considered in another paper. 
Art. IL—On a method of illustrating the formation of Diffraction 
Bands; by 8S. T. MorELAND. 
tion phenomena that may be proved, or at least illustrated, by 
_ this piece of apparatus :— 
