1. Detection of gold b/ means of SnCl₂ solution.
About known quantities of gold in 10 c. c. added 1 drop, of conc.HCl (1. 19) and 3 drops of sat. SnCl₂ solution, detected by special gold brown Cassius reaction being specified its colour of blanc test. By this method, 0.01mg Au is detected.
2. Gold contents in sea water.
1 l sea water is treated by 1g Fe SO₄ thoroughly, alkalified by 6n·NH₄OH being converted Feto Fe and filtered.The ppt.is disso'ved by means of 6n HCl,washed thoroughly to chloride free. The filer paper is ashed,treated by 5 c. c. a uaregia,diluted With 5 c. c. H₂O, evaporated to dryness, dissolved in 10 c. c. H₂O and filtered. About f filtrate, gold is tested by means of theabove method.
3, Gold deposition on the evaporation of sea water.
16 brines of sample were prepared being concentrated from sea water to bittern. By means of the above method, gold contents of each samples were measured containing no gold in the brine sp.gr. 1.096, that is, all gold in sea water deposits when sea water is concentrated to its volume about 1/4 of sea water.
4. Separation of gold by means of cupellation.
(a) With 5g substance ppt.ed on the evaporation of seawater to the degree of sp.gr. 1.096, large bottom. of gold and silver alloy separated.(Au 0.75mg,Ag 2mg)
(b) About scales, separated on common salt manufacture from sea water, only two scales containing mainly carbonate, Au and Ag alloy separated, the other scales consisting of CaSO₄, no bottom separated.
(c) Precipitants in the 1 st and 2 nd evaporating pond at soler salt field, sea: the bottom.
(d) The transporting sand of Japanese salt field, separated the bottom.
5. Absorption of Au in sea water.
By means of three active carbons, Au in sea water abzorbed during 20min,at room temperature. Absorbed Au in carbon extracted about its 40% Au but contained its all quantities when the carbon is ashed.

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