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GOLD AND SILVER IN SEA-WATER. 343 
All six samples of northern sea-waters also gave the reaction 
for gold; the details are omitted for brevity. As in the case of 
the southern samples, some gave the reaction readily, others 
required from one to several weeks. I should not however, like 
to say that this is a sufficient indication of some being richer than 
others, for the test appears to be wanting in precision. 
QUANTITATIVE TESTS. 
Unfortunately all the samples had been used up in making 
qualitative tests for gold, but, in default of more water, the 
chlorine-water solutions and precipitates yielded by the stannous 
chloride from each batch of tests were mixed together and evapor- 
ated to dryness and then scorified and cupelled so as to determine 
the amount of gold. The assays were not done separately on 
each test, as it was thought that the gold beads, if any, would be 
too small to weigh. 
Southern Sea-waters.—The first batch of tests, Nos. 1 to 6, 2.¢.s 
the extracts from six litres, gave ‘003 grain of gold, 2.¢., 508 
grain of gold per ton, or ‘38 grain per cubic yard, or ‘032 mgm. 
per litre. 
Second batch.—The precipitate from twelve litres used for the 
second set of tests gave -009 grain, i.e., “76 grain of gold per ton, 
or ‘57 grain per cubic yard, or ‘048 mgm. per litre. The film was 
treated twice with chlorine water, and the two extracts added 
together. 
Third batch.—9-025 litres gave ‘0069 grain of gold, 2.¢., 1:09 
grain per ton, or -58 grain per cubic yard, or ‘049 mgm. per litre. 
Northern Sea- Waters. 
8100 litres gave 0060 grain of gold equal to ‘75 grain per ton, 
or “56 grain per cubic yard, or 048 mgm. per litre. 
In calculating the amount of gold per ton or cubic et the 
Specific gravity was in each case corrected to 1-026, i.¢., the mean 
results obtained by the “Challenger ” Expedition, corrected to 
155° ©. for Sea-water off the coast of New South Wales. : 
