Subsequently Mr. Thilmany changed his mode of application to the Bethell
process of injecting solutions under pressure in closed cylinders, and
probably the paving blocks for experiment No. 3 were prepared in that
way. The chemical examination of them by Mr. Tilden, however, showed the
"saturation very uneven; absorptive power, high; block contains soluble
salts of copper, removable by washing."
It was expected that the double solution, by forming an insoluble
compound, would prove an effective protection against the _teredo_.
Experiments Nos. 4, 5, 6, and 8, however, proved the contrary to be the
fact.
The process, when well done, gave moderately satisfactory results
against decay. A pavement laid in the yard of the Schlitz Brewing
Company, in Milwaukee (experiment No. 7), was sound in 1882, after some
six years' exposure. A report by Mr. J.F. Babcock, a chemist of Boston
(experiment No. 9), indicated favorable results, and the planks in a
ropewalk at Charlestown (experiment No. 15), laid in 1879, were yet
sound in 1882.
The experiments on railroad ties (Nos. 10, 11, 12, 13, 14, and 16),
however, did not result satisfactorily. They seemed favorable at first,
and great things were expected of them; but late examinations made on
the Wabash Railroad, on the New York, Pennsylvania, and Ohio, and on the
Cleveland and Pittsburg Railroad, have shown the ties to be decaying,
and the results to be unfavorable.
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