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POPULAE SCIENCE REVIEW. 
these cases the lead is found below the liquid iron according to its greater 
specific gravity. — Vide Chemical Neios, January 24. 
Extraction of Indium from Zinc . — A method for effecting this has been 
published by Herr Kichter. The zinc is dissolved in sulphuric or hydro- 
chloric acid^ and the residue, which is composed of zinc, indium, and other 
metals, is treated with nitric acid. The solution is evaporated with sul- 
phuric acid, diluted, and a current of sulphuretted hydrogen gas passed 
through. The indium is almost completely precipitated with the cadmium 
and copper. The precipitate is dissolved in hydrochloric acid, and preci- 
pitated by ammonia. By repeating the process several times the whole of 
the zinc and cadmium is separated. Finally, the small quantity of iron still 
mixed with the indium is removed by a partial precipitation with ammonia 
and carbonate of soda. Indium is obtained by reducing the oxide; this 
may be effected by heating in a current of hydrogen gas, or by the power of 
a voltaic battery. 
Amher in Australia . — The Ballarat Evening Post states that amber has 
been found of good quality, and in considerable abundance, at Rokewood, 
near Ballarat. 
Petroleum for Locomotives . — On one of the Pennsylvania railroads, an 
attempt was made to work an ordinary locomotive with petroleum instead 
of coal for fuel. The experiment was suspended only on account of the de- 
fectiveness of the mechanical appliances for the new fuel. A later trial was 
made on the Hudson River railroad ; but in consequence of some blunder 
on the part of one of the operatives, the result was not as satisfactory as it 
might have been, although the indications were exceedingly favourable for 
a final success. An ordinary locomotive consumes, on an average, about one 
ton of coal in three hours, or its equivalent in wood. A vast saving in 
transportation of fuel will be made on the great continental road, in passing 
over those portions of the line destitute of wood or coal — a distance of 
about 800 miles — if oil is found an economical fuel for making steam. Ex- 
periments thus far tend to prove that a pound of oil will make as much 
steam as two pounds of coal. — Vide The AHizan, January. 
MICROSCOPY. 
Microscopic Crystals . — As doubtless many of our readers are interested in 
the examination of minute crystals under the microscope, it will be of in- 
terest to give a short account of some recent experiments on this subject, 
which were narrated in a paper lately read before the Pharmaceutical 
Society, by Mr. W. S. Waddington. Mr. Waddington gives good practical 
advice to those about to study “ microscopic crystallography.” He states 
that he has obtained better results by allowing the crystals to be deposited 
from a hot and concentrated solution, than by placing a few drops of a cold 
saturated solution on a clean slide, and allowing it to evaporate spontaneously. 
When crystals are pretty soluble in water, the way of procedure is as fol- 
lows : — A solution is made in hot distilled water, the liquid filtered, and a 
few drops poured on to a clean slide just before the crystals begin to form 
