The media are used either in a fluid or solid condition, the latter being obtained by a process of coagulation, or by the addition of a gelatinizing agent, and are placed in glass tubes or flasks plugged with cotton-wool.
The media from the store-flasks are placed in glass test-tubes or small flasks, protected from contamination by cotton-wool plugs, and are sterilized by heat.
From 1850 to 1908 California produced a total of 2,052,000 flasks of metal, of 76.5 lb (since June I, 1904, 750 lb net) each.
The production had steadily fallen to 16,984 flasks in 1908, but in the opinion of the United States Geological Survey this reduction is mainly attributable, in recent years at least, to market conditions, and does not truly indicate the exhaustion of the mines, although the ores now available are of low grades, those of New Almaden having shown a decrease in yield from 36.7% in1850-1851to o~74% in 1895-1896, so that only the greatest metallurgical skill and business economy can sustain the mines against a weak market.
To the second century, lastly, belongs in part the evidence of the catacombs, on the walls of which are depicted persons reclining at tables supporting a fish, accompanied by one or more baskets of loaves, and more rarely by flasks of wine or water.