CHEMISTRY. 



91 



od gold for about an hour and a half, as it lies 

 in a crucible heated in uii ordinary inolting-fur- 

 Tlif chlorine is at first rapidly absorll, 

 e process is completed when a brownMi- 

 . \apor appears. The chlorine is con- 

 iilv evolved from a self-acting generator, 

 and -J.OOO ounces of gold are readily refined in 

 ...urs, by throe melting-furnaces,. 98 per 

 f the gold being delivered ready for 

 n'in.i:_v on the same day. The gold thus ro- 

 tiiK-il is perfectly tough, and contains only about 

 i. ne-h:ilf |>or cent, of alloy. The ultimate loss 

 1 is found to be only 19 parts in 100,000 ; 

 ss of silver is 240 in 100,000. The cost 

 of retinago, including the above loss, but ex- 

 cluding rent of premises and expenditure, is 

 , rthings per ounce. The silver is obtained 

 in tiio form of fused chloride, and is reduced to 

 the metallic state by plates of zinc combined 

 with slabs of the chloride into a galvanic ar- 

 rangement, devised by Dr. Loibriss. In twen- 

 ty-lour hours the chloride is completely re- 

 duced to the state of spongy silver, and 1,400 

 or 1,500 ounces could thus be readily treated 

 in a day. No acid is required, and the zinc 

 consumed is only 25 per cent, of the chloride 

 reduced. The whole process, having been 

 thoroughly tested at the time, is to be brought 

 into active operation at once. It is already 

 employed by some of the banks in Australia 

 and New Zealand. 



Anhydrous Fluoride of Silver. George 

 Gore, F. R. S., read before the Royal Society a 

 paper on the preparation and chemical behavior 

 of this salt of silver. He says that it is not 

 decomposed by sunlight. It melts below a 

 visible red heat, and forms a highly-lustrous, 

 mobile, and jet-black fluid. In a state of semi- 

 fusion or complete fusion it is rapidly decom- 

 posed by the moisture of the air, with- separa- 

 tion of metallic silver, but not by dry air. In 

 such a state, with platinum electrodes, it con- 

 ducts electricity freely, apparently with the 

 facility of a metal, and without visible evolu- 

 tion of gas, or corrosion of the anode. 



Hydrogen does not decompose the dry salt, even 

 with the aid of sunlight ; nor does a stream of that 

 gas decompose an aqueous solution of the salt ; but 

 the dry salt is rapidly and perfectly decomposed by 

 that gas at an incipient red heat, its metal being 

 liberated. 



Nitrogen has no chemical effect upon the salt, even 

 at a red heat, nor upon its aqueous solution. Dry 

 ammonia gas is copiously absorbed by the dry salt. 

 In one experiment, the salt absorbed about 844 times 

 its volume of the gas. The salt, in a fused state, is 

 rapiilly and perfectly decomposed by dry ammonia 

 gas, and its silver set free. A saturated solution of 

 It is also instantly and violently decomposed by 

 strong aqueous ammonia. 



Oxygen has effect neither upon the dry salt at 

 15 C., or at a red heat, nor upon its aqueous solution. 

 Steam perfectly and rapidly decomposes the salt at an 

 incipient rod heat, setting free all its silver. No 

 chemical change took place on passing either of the 

 oxides of nitrogen over the salt in a state of fusion. 



By passing anhydrous hydrofluoric-acid vapor over 

 perfectly anhydrous and previously-used fluoride 

 of silver, at about 60 Fahr., distinct evidence of the 

 existence of an acid salt was obtained. This noid 



salt is decomposed by a slight elevation of tempera- 

 ture. 



Numerous experiments were made to ascertain the 

 liflmvior of argentic fluoride in a state of fusion, with 

 i-lilt.riiu- ; and great dillioulties were nOOOBtttvd. in 

 consequence of the extremely corrosive action of the 

 substances when brought together in a heated state. 

 Vessels of glass, platinum, gold, charcoal, gas car- 

 bon, and purified graphite, were employed. By 

 heating the salt in chlorine, contained in closed ves- 

 sels, formed partly of glass and partly of platinum, 

 more or less corrosion of the glass took place, the 

 chlorine united with the platinum and fluorine of 

 silver to form a double salt, and a vacuum was pro- 

 duced. By similarly heating it in vessels composed 

 wholly or platinum, the same disappearance of 

 chlorine, the same double salt, and a similar vacuum 

 resulted. Also, by heating it in vessels composed 

 partly of gold, an analogous double salt, the same 

 absorption of chlorine, and production of rarefaction, 

 was produced. And, by employing vessels partly 

 composed of purified graphite, a new compound of 

 fluorine and carbon was obtained. 



Artificial Alizarine. Mr. J. "Wallace Young 

 has laid before the Glasgow Philosophical 

 Society the results of experiments upon two 

 kinds of artificial alizarine (the genuine arti- 

 cle being the well-known extract from mad- 

 der), one of Continental and the other of 

 English manufacture. The former contained 

 a large amount of colored matter, but further 

 purification was necessary before it could be 

 used as a madder-substitute. When mordanted 

 cloth dyed with it was boiled with solution 

 of soap, the colors were found to be rather 

 fugitive. Cloth prepared for Turkey-red ab- 

 sorbed the dye-stuff readily, but the same 

 want of fastness was observed. "When mixed 

 with iron and albuminous mordants, and.print- 

 ed on in the way in which madder extract is 

 used, the colors were found to be dull and not 

 sufficiently fast. A sublimate obtained from 

 the dried paste closely resembled natural aliza- 

 rine, but was rather lighter in color. It dyed 

 mordanted cloth well, and withstood treatment 

 with soap. The English-made madder-substi- 

 tute yielded a red rather yellower than that 

 yielded by natural alizarine, a black of equal 

 if not superior quality to madder-black, but 

 the chief difference was in the purple, which 

 was rather slate-colored than any thing else, 

 contrasting most unfavorably with the fine 

 shade of color given by madder. The yellow- 

 ness of the red seemed to depend pretty much 

 on the proportion of tin salt used in the clear- 

 ing. As with madder and its preparations, the 

 development of the coloring matter of the 

 artificial alizarine is increased by tanning ma- 

 terials, as sumac, and deteriorated by chalk. 

 The dried residue of the brown artificial aliza- 

 rine liquid yielded by sublimation a crystalline 

 body of a yellower shade than that of the 

 crystals of the natural alizarine. In order to 

 compare the artificial alizarine with the natural 

 substance, and with purpurine, which is anoth- 

 er madder extract, the author dissolved each 

 of them in weak ammonia, and added barium- 

 chloride ; they all yielded purplish precipitates. 

 The natural alizarine precipitate was of a fine 

 bluish-purple color, and the supernatant liquor 



