SCIENCE. 



317 



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 1^ 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- 

 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 Giinther'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, absut 12 meters (about 40 feet) to the sala. 

 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 Am/a 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 Annates des Sciences Naturelles, sixth 

 series, V. and VII. 



Ithaca, Dec. 21, 1! 



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 was 

 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. 



WlNNECKE suggests that FJartwig's Comet is identical 

 with the comets of 1382, 1444, 1506, 1569 and that it 

 therefore has a period of 62^ 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 



