SCIENCE. 
3i7 
the crucible, is ladled out into moulds. Thence it is taken 
to the refinery, where it is cuppelled in the usual way. The 
block of metallic zinc recovered in the condenser is re- 
moved, and used over again in the first part of the process. 
All the oxide of lead and dross formed in the different pro- 
cesses are taken to the reducing-furnace, mixed with coal- 
dross, and reduced to the metallic state. The refuse 
from this furnace still contains some lead, and is put 
through the slag hearth, a blast furnace fired with coke, 
the fumes of lead oxides from which are condensed in what 
is known as Johnson’s patent condenser, and are all re- 
covered. The lead from the slag hearth, containing a 
number of impurities, as copper, antimony, iron, or sul- 
phur, is taken to the improving furnace — a furnace built 
in exactly the same way as the dezincifying pan. About 
20 tons of this lead are heated for a period generally from 
four or five days, but the time varies according to the 
amount of impurities present. The oxidised impurities, 
as they are formed, float to the surface, and are skimmed 
off by the workman, who is made to keep the lead perfectly 
clean, so as to have a fresh surface always exposed to the 
action of the flame. The dross skimmed off is first of a 
black color, but gradually becomes lighter as the opera- 
tion goes on, until it shows nothing but yellow oxide of 
lead. When this appearance is noted the pan is tapped into 
moulds, or into the desilverizing pot, where it is treated with 
zinc, and the silver extracted as in the manner before de- 
scribed. By this process the lead can be desilverized and 
turned out in the shape of market lead in thirty hours from 
the time it is put in process ; the loss in working being not 
more than per cent., and the amount of oxide of lead 
formed is very much less than that formed in any of the 
other processes, thereby effecting a very considerable saving 
in the working expenses. It makes an excellent quality of 
sheets, pipes, red-lead, and litharge, and has even been used 
for the manufacture of white-lead. There is, however, one 
product it cannot be used for by itself, and that is the man- 
ufacture of chemical lead. Your President gave us a very 
interesting paper on this subject last session, showing that 
the reason of its not being suitable for this was on account 
of its extreme purity. I understand that Mr. James Napier, 
Jr., of this Society, has made a number of experiments in 
the same direction, and found that by adding to it a small 
percentage of copper or antimony, or both, a good chemi- 
cal lead can be obtained. That all the silver is thoroughly 
taken out may be seen from the fact that there is an excess 
of silver obtained on the large scale to the extent of nearly 
2 per cent, over the assays. An analysis of the market lead 
gave — Antimony, 0.0015, and silver 0.0004 per cent., a trace 
of copper, but no iron or zinc ; from which it will be seen 
that the lead refined by the zinc process is almost chemically 
pure, and to this is due the finer quality of the products 
manufactured from it. 
THE TERRESTRIAL PROGRESSION OF THE 
BRAZILIAN “ CAMBOTA,” CALLICHTHYS 
ASPER. 
To the Editor of SCIENCE : — 
Letters from Mr. John C. Branner, who was engaged 
upon the geological survey of Brazil under the late Prof. 
C. F. Hartt of Cornell University, contain extracts from 
letters to him from Mr. Joseph Mawson, Bahia, describ- 1 
ing some habits of the siluroid fish, Callichthys Asper, 
there known as “ Cambota." These habits have proba- 
bly been observed and described already, but as they are 
not referred to in Gunther’s Catalogue of the Fishes in 
the British Museum the account of a recent observer may 
be interesting to the readers of “ SCIENCE.” 
“During the rainy season the fish live in fresh water 
pools. When the pools dry up in the dry season, they 
bury themselves in the mud and remain there until the 
rains return the following year. They are noted for 
overland excursions. It is said that they are often met 
with going from one pool to another. 
I have had six of the fish in a narrow-necked tin of 
water, with some sand and mandioca meal at the bot- 
tom, for five days, and they continue active and vigo- 
rous, especially the smaller ones. These examples 
measure from 5 to 10 cm. in length, and I have seen them 
much larger. I have had them out in the garden several 
times. I find that they move best on smooth damp 
ground, and are embarrased by sticks or other inequali- 
ties. They can jump a little vertically, but their progress 
on land is effected entirely by a quick wriggling motion 
of the body which is nearly flat upon the ground. The 
paired fins (pectorals and ventrals) are extended laterally, 
and seem to bear little if any weight ; but they move 
slightly, and appear to serve to steady the body. 
Last night I heard a peculiar sound, and on looking 
around I saw one of the fish travelling about the room. 
He had escaped from the tin which was in my bed-room, 
had fallen from the table to the floor, and travelled along 
the corridor, about 12 meters (about 40 feet) to the sa/a. 
I watched him travelling for two hours, during which 
time I estimate that he moved at least 90 meters. To- 
ward the end of the two hours he seemed to flag a little, 
but in the earlier part his method and speed were fairly 
seen. He seemed to start with a sudden movement of 
the head or the barbels, then wriggled briskly for 5 to 10 
seconds, advancing about a meter. Then he would rest 
for about 10 seconds, and start as before. This was 
kept up during the whole two hours, and I left him still 
moving. This morning, five hours later, I found him 
dead. While he was moving I spilled some water on 
the floor, but he crossed it ; hence I concluded that it 
was mud rather than water of which he was in search. 
The fish are eaten and considered good food.” 
It may be added that some examples of these fish were 
brought me by Mr. Branner, and found to be the Calli- 
chthys asper. The species of the genus are easily re- 
cognized from the fact that the trunk is covered by only 
two rows of large scales, a dorsal and a ventral series. 
The ability of Callichthys to withstand a somewhat 
protracted deprivation of water, which it shares with 
other fishes of South America and India, with the North 
American Ganoids Amia and Lepidosteus, and with 
some other Ganoids and Dipnoans, is probably accounted 
for by the obseivations of Prof. Jobert of Rio Janeiro, 
published in the Annales des Sciences Naturelles, sixth 
series, V. and VII. 
Ithaca, Dec. 21, 1880. Burt G. Wilder. 
ASTRONOMY. 
A Probable Variable Star. — On Nov. 25, Swift’s 
Comet was compared with the star No. 4339 of Lalande, 
by Mr. Talmage at Mr. Barclay’s Observatory, Leyton, 
the magnitude of the star being estimated 8, as it w*as 
also by Lalande. Argelander in the Durchmusterung 
gives it 6.4 and Heis made it a naked eye star 6.7, but 
erroneously identifies it with Lalande 4359. It escaped 
observation in the Bonn Zones and may be worth occa- 
sional examination as likely to prove an addition to our 
variable star list. — Nature. 
WiNNECKE suggests that Hartwig’s Comet is identical 
with the comets of 1382, 1444, 1506, 1569 and that it 
therefore has a period of 62yJ years. 
The asteroid picked up by Peters on Oct. 10, is identi- 
cal with that discovered by Palisa on Sept. 30. 
M. Tripier is expected to take charge of the Observa- 
tory of Algiers in April, 1881. 
Dr. Copeland at Dunecht, using Prof. Pickering’s 
device of a prism introduced between the eyepiece and 
