68 
TRANSACTIONS OP THE TEXAS ACADEMY OP SCIENCE. 
In Transylvania, in the mountain Paren Dracubis, the lode is ore- 
bearing only where the gangue is silico-ferruginous. 
The phenomena in many lodes of the French central mining district 
seem to point to an origin by ascension in the above mentioned modus, 
with subsequent alterations. 
To be short, the unprejudiced observer may find many cases in nearly 
every mining district of the world where this peculiar ascension process 
may be admitted without laying a great strain on the well established 
laws of nature, and without risk of losing logical equilibrium. 
The hypothesis that many, if not most, of the ore veins in silicious 
gangues are the result of the demonstrable growth of acid metal salts in 
alkaline silica solutions, by no means excludes circulating metal solu¬ 
tions, gases, metallic vapors, etc. It admits also, but only locally, lateral 
secretion, but it helps to explain phenomena which without this hypothe¬ 
sis can be explained only by straining to the utmost chemical, physical, 
and mechanical laws. 
These veins may grow up in the middle of the gangue or along the walls, 
or that they meander from wall to wall; the hypothesis explains the irregu¬ 
larities in shape, size, and contents of vein and gangue matter, the growth 
of pockets and of horizontal and inclined deposits (lager), and that the 
veins invariably terminate in iron cappings or gossan on the surface if 
iron is present, even if the veins themselves contain only little iron. 
We will have to call for the assistance of circulating solutions, of gases 
and vapors to explain chemical changes, and we may admit lateral secre¬ 
tion locally where the capillary force to absorb is stronger in the 
gangue than in the surrounding rock, or where elements and elementary 
combinations may be forced by chemical affinity to combine with those 
contained in gangues and veins. 
If, and how far, continued experiments will throw light on the gene¬ 
sis of other than quartz gangues and on the origin of certain dykes, 
is hard to predict; but I think I should mention here the copper deposits of 
Chessy and Saint Bre, near Lyons, in France. The copper ores of the mine, 
griseand noir there, are imbedded in a whitish-gray gangue, partly chang¬ 
ing into aphanite. The ore bodies are rounded masses, recalling the 
cavities in the quartz of the Comstock lode. The gangue is a wedge be¬ 
tween other crystalline rocks and triassic sandstone. 
At present I shall venture to uphold only the following conclusions: 
1. It is a property of most, if not all, salts of the heavy and earth 
metals, and more so of combinations of these salts, to grow up in alkaline 
silica solutions, and to form in them veins, veinlets, pockets, and other 
shaped deposits, and thus were brought up from greater to (by mining) 
accessible depths the ores in most of the silicious gangues. 
2. In most of the silicious gangues carrying iron with other metals, 
