SCIENTIFIC SUMMARY. 
337 
force air at any pressure whatever, if sufficient steam power be used, without 
any of the friction and loss of power incidental to a blowing cylinder. The 
principle is that of two irregularly-shaped blowers revolving in an oval 
cylinder. These blowers are so arranged that as they revolve, the air which 
enters is pent up between them, and driven with any required force through 
the escape-hole. 
Japanese Alloys , their Nature and Nomenclature. — The Builder gives 
the following abstract of a paper which appeared some time since in an 
American scientific journal: — The first alloy given maybe regarded as a 
weak Japanese imitation of jewellers’ gold. This Shakdo is an interesting 
alloy of copper and gold, the latter metal in proportions varying between 1 
per cent, and 10 per cent. Objects made from this composition, after being 
polished are boiled in a solution of sulphate of copper, alum, and verdigris, 
by which they receive a beautiful bluish-black colour. 1 Gin shi hu icliij 
(‘ quarter silver ’) is an alloy of copper and silver, in which the amount of 
silver varies between 30 per cent, and 50 per cent. Ornamental objects 
made from this composition take, when subjected to the action of the above 
solution, a rich grey colour, much liked by the Japanese. Mokume is a 
mixture of several alloys and metals of different colours associated in such 
manner as to produce an ornamental effect. Beautiful damask work is pro- 
duced by soldering together, one over the other in alternate order, thirty or 
forty sheets of gold, shakdo silver, rose copper, and gin shi hu ichi, and then 
cutting deep into the thick plate thus formed with conical reamers, to pro- 
duce concentric circles, and making troughs of triangular section to produce 
parallel, straight, or contorted lines. The plate is then hammered out until 
the holes disappear, manufactured into the desired shape, scoured with ashes, 
polished, and boiled in the solution already mentioned. The boiling brings 
out the colours of the shakdo, gin shi hu ichi, and rose copper. Of brasses 
(Sin ehu) the finest quality of brass is formed of 10 parts of copper and 5 
parts of zinc. A lower quality, of 10 parts copper and 27 parts zinc. Kara 
kane (bell metal) varies from first quality — copper 10, tin 4, iron f, zinc If, 
to fourth quality — copper 10, tin 2, lead 2. The best small bells are made 
from the former quality, and large bells from the latter. 
Iridium from Blende. — Herr Boettger has pointed out that the flue-dust 
which condenses in the chimneys of the zinc works of Goster contains oxide 
iridium in the proportion ~th per cent. He gives the following directions 
for its extraction. Boil the deposit for half an hour with hydrochloric acid, 
and digest the clear liquid with pieces of zinc for six hours at the ordinary 
temperature. There is then deposited a black metallic powder, which is 
washed with water, and which contains copper, arsenic, cadmium, thallium, 
and iridium. By boiling this with a concentrated solution of oxalic acid, a 
solution of cadmium, thallium, and iridium is obtained ; the latter is precipi- 
tated by ammonia, and the precipitate is then boiled with ammonia and 
afterwards with water, until the washings contain no more thallium. The 
oxide of iridium is then almost pure, and only contains traces of iron. — Vide 
Journal fiir praktische Chemie. 
Motive Power in Mines. — M. Tresca made a recent communication on this 
point to the Society of Encouragement. Works in mines require a motive 
power, either sudden and discontinued or continuous and slow. In the first 
B B 2 
