When calcined zinciferous pyrites have to be examined, the estimation of
zinc is similar to that employed in the analysis of zinc ore. The sample
is exhausted with water, filtered, and, to eliminate calcium sulphate and
basic iron sulphate, evaporated to dryness. It is then dissolved in a
small quantity of alcohol and water, refiltered, and the filtrate
decomposed with ammonium carbonate. The original residue is treated with a
solution of ammonium carbonate, which dissolves arsenious acid and basic
zinc sulphate, filtered, and united with the first filtrate. When iron and
manganese are present, the filtrates are treated with bromine. The united
filtrates are boiled or examined volumetrically with sodium sulphide.

* * * * *




PETROLEUM AS FUEL IN LOCOMOTIVE ENGINES.[2]

[Footnote 2: Abstract of paper read before the Institution of Mechanical
Engineers.]

By Mr. THOMAS URQUHART.


Comparing naphtha refuse and anthracite, the former has a theoretical
evaporative power of 16.2 lb. of water per lb. of fuel, and the latter of
12.2 lb., at a pressure of 8 atm. or 120 lb. per square inch; hence
petroleum has, weight for weight, 33 per cent. higher evaporative value
than anthracite. Now in locomotive practice a mean evaporation of from 7
lb. to 7½ lb. of water per lb. of anthracite is about what is generally