MISCELLANEOUS ECONOMIC PRODUCTS. 377 



use as lithographic plates. There are not a few to-day who believe in this 

 rock as a future source of profit, thus employed. This material is the com- 

 pact grey or dove-colored Burnet marble, previously described under the 

 head of Building Stones and elsewhere in this Report. The abundance of the 

 material, its good exposures for working, the proper thickness of many of 

 the layers, and the good general appearance of the stone, are all favorable; 

 the small specimen pieces exhibited by interested persons often show well in 

 grain, in their reception of inks, and even in the quality of the lithographic 

 prints obtained from them. Were this rock of late geologic age, so as to be 

 free from structural and textural alterations due to upheavals and infiltra- 

 tions, it might be very well adapted to use by the lithographer. But, unfor- 

 tunately, practical tests do not bear out the promise of superficial examina- 

 tions. Upon surfacing the stone, minute seams, flaws, or cracks are always 

 developed, so as to make it unfit for this purpose. Since the deposition of 

 the material in the Silurian Sea there has been too much disturbance and 

 too much alteration to leave a uniform texture except in very small pieces, 

 and the uncertainty of the positions of the defective spots before grinding is 

 an effectual bar to the employment of such a product. Often in working out 

 one defect several others are made apparent. After much study of the out- 

 crops of the Hoover Beds, I am reluctantly compelled to report that there is 

 little chance of obtaining any slabs of lithographic stone of a large enough 

 size for the building up of a profitable industry. 



There are no other rocks in Central Texas which are of any value for lith- 

 ographic plates. 



2. SALT. 



I have not yet made a detailed examination of the salt spring in Llano 

 County a few miles northwest of Bluffton. Under the stimulus of an unu- 

 sual demand, or for other reasons, the brine at this locality was formerly 

 evaporated with some success; but nothing has been done in 'this way of 

 late. Preparations for the work were made upon a somewhat extensive 

 scale, and the cause for abandoning the enterprise is not evident; although 

 it is also difficult to understand, without much study, what could have given 

 rise to a really valuable brine or salt deposit in such a situation. The locality 

 is in the midst of the Archaean outcrops, but Silurian beds are not far dis- 

 tant, and it may be that some of them are the sources of supply. It is diffi- 

 cult to believe in any mere local deposit, however, if such is the origin. 

 Especial attention will be given in 1890 to the district in which the Silurian 

 Beds outcrop in this region. 



