64 
TRANSACTIONS OF THE TEXAS ACADEMY OF SCIENCE. 
tions, filled by and by the whole tube, thus forming a miniature silicious 
gangue with ore veins and iron outcrop. 
Up to this time I had observed that temperature, also light, had 
strong influence on the growth of my experimental veins, and I began 
now to introduce electrical currents into my experiments, which, as ex¬ 
pected, caused interesting modifications, but in many cases not as far- 
reaching ones as I had anticipated. For this purpose I substituted f-incli 
glass tubes for the test tubes, of which I closed one end with corks soaked 
in paraffin, with pieces of copper or platinum wires inserted through the 
corks, in order to have conductors for the currents. Numerous experi¬ 
ments carried on for about three years I regarded a sufficiently strong 
foundation for a tenable hypothesis; and to secure the priority of the 
idea I hurried a short essay, “On the Genesis of Certain Ore Deposits,” 
into the School of Mines Quarterly, No. 3, vol. XII. 
The conclusions published there, based on the above-mentioned experi¬ 
ments, require some modifications on the strength of observations made 
on a number of more recent experiments, though I hold them tenable in 
principle. 
After having worked with salts of most of the heavy metals, I began 
to experiment with alkalies and their salts, up to date without satisfac¬ 
tory results. 
Of the salts of earth metals, I tried only sulfate of magnesia, result¬ 
ing in a satisfactory growth. Lime salts, as far as tested till now, inva¬ 
riably gelatinized the silica, and I found a number of well developed 
azurite crystals in a test tube containing copper, silica solution and 
lime, after eight months. 
Aluminum and alumina salts gave highly satisfactory results regard¬ 
ing their growth and their capacity to carry on with them other metal 
solutions, or to absorb them after the alumina vein is fully grown. 
Now I introduced also gases into my work, and have experimented up 
to date with sulfurated li 3 T drogen, chlorine and carbonic acid. I con¬ 
structed for this purpose an inexpensive apparatus, by which the influx 
of gas or liquid saturated with gases can be reliably regulated. 
But most of the veins are very delicate in their structure, and there¬ 
fore easily destroyed by the commotion of the mother liquid, and it is in 
such cases important not to admit more gas than can easily be ab¬ 
sorbed, though it may take a long time to change the character of a 
vein; in a tube two years old, the veinlets were only partly changed. 
Larger quantities of gas may be admitted if the object of the experiment 
is not so much to change the character of the vein, as to study the 
effect of the gases or liquids on the silica solution, which in these experi¬ 
ments must be regarded as the matrix, the material in which the veins 
will be formed. 
