i86 



NA TURE 



\yune 20, 1889 



alloys, are extremely malleable and ductile, can be worked either 

 hot or cold, easily engraved, the higher grades have an elasticity 

 exceeding steel, are easily cast into complicated objects, do not 

 lose in remelting, and are possessed of great strength, dependent, 

 of course, on the purity and percentage of contained aluminium. 

 The 10 per cent, alloy, when cast, has a tensile strength of 

 between 70,000 and 80,000 pounds per square inch, but when 

 hammered or worked, the test exceeds 100,000 pounds. [A 

 sample shown broke at 105,000 pounds.] 



An attempt to enumerate either the present uses or the possible 

 future commercial value of these alloys is beyond my present 

 purpose. I may, however, remark that they are not only adapted 

 to take the place of bronze, brass, and steel, but they so far 

 surpass all of those metals, both physically and chemically, as 

 to make their extended use assured. [Sheets, rods, tubes, wire, 

 and ingots shown.] 



But even a more important use of aluminium seems to be its 

 employment in the iron industry, of which it promises shortly to 

 become an important factor, owing to certain effects which it 

 produces when present, even in the most minute proportions. 

 Experiments are now being carried on at numerous iron and 

 steel works, in England, on the Continent, and in America. 

 'I he results so far attained are greatly at variance, for whilst in 

 the majority of cases the improvements made have encouraged 

 the continuance of the trials, in others the result has not been 

 satisfactory. On this point I would wish to say to those who 

 may contemplate making use of aluminium in this direction, 

 that it would be advisable before trying their experiments to 

 ascertain whether the aluminium alloy they may purchase actually 

 contains any aluminium at all, for some of the so-called aluminium 

 alloys contain little or no aluminium, and this may doubtless 

 account for the negative results obtained. Again, others contain 

 such varying proportions of carbon, silicon, and other impurities, 

 as to render their u^'e highly objectionable. 



It seems to be a prevailing idei with some people, that, be- 

 cause aluminium is so light compared with iron, they cannot 

 be directly alloyed, and, furthermore, that, for the same reason, 

 alloys made by the direct melting together of the two metals would 

 not be equal to an alloy where both metals are reduced together. 

 Now, of course, this is not the case, and the statement has been 

 put forward by those who were only able to make the alloys in 

 one way. 



Aluminium added to molten iron and steel lowers their melting- 

 points, consequently increases the fluidity of the metal, and 

 causes it to run easily into moulds and set there, without en- 

 trapping air and other gases, which serve to form blow-holes 

 and similar imperfections. It is already used by a large num- 

 ber of steel founders, and seems to render the production of 

 sound steel castings more certain and easyjthan is _otherwise 

 possible. 



One of the most remarkable applications of the property 

 which aluminium possesses of lowering the melting-point of iron 

 has been made use of by Mr. Nordenfeldt in the production of 

 castings of wrought iron. 



Aluminium forms alloys with most other metals, and although 

 each possesses peculiar properties which in the future may be 

 utilized, at present they are but little used. 



In conclusion, I beg to call your attention to the wood models 

 on the table, one being representative of aluminium, the. other 

 aluminium bronze. The originals of these models are now in the 

 Paris Exhibition, each weighing iodo pounds. With regard to 

 aluminium bronze, I cannot speak positively, but the block of 

 pure aluminium is undoubtedly the largest casting ever made in 

 this most wonderful metal. I have to thank the Directors of 

 the Aluminium Company, and especially Mr. Castner, for fur- 

 nishing me with the interesting series of specimens of raw and 

 manufactured metal for illustrating my discourse. 



THE PAL.EONTOLOGY OF STURGEONS} 



HTHE palseontological history of the Acipenseroid fishes is at 

 -*• present very imperfectly known. In the existing fauna, 

 only two families are recognizable — that of the Acipenserida;, 

 with series of bony dermal scutes upon the trunk, and that of 

 Polyodontidas, de-titute of any such armour ; both these occupy 

 so low a position in the scale of organization, that considerable 

 evidence of numerous extinct allies might naturally be expected 

 to'occur among the fossils of the older rocks. Such evidence, how- 



' Abstract of a Paper, by A. Smith Woodward, read before the Geologists' 

 Association on January 4. 



ever, cSn as yet be only slightly recognized. Remains of typical 

 members of the two existing families seem to occur as low in the 

 Tertiary series as the Eocene formation. Pectoral spines and 

 dermal scutes, indistinguishable from those of ihe living Acipen- 

 ser, are met with in the Upper Eocene of the Hampshire Basin, 

 and the London Clay (Lower Eocene) of the Isle of Sheppey ; 

 and Prof. E. D. Cope has described a fish {Crossopho/is) from 

 the Eocene Green River Shales of Wyoming, U.S.A., differ- 

 ing only from the typical Polyodontidse in the possession of 

 rudimentary scales upon the sides of the trunk. 



The only Cretaceous fossils yet known, which are at all com- 

 parable with characteristic parts of the Acipenseroid skeleton, 

 are two specimens from the English Chalk. The remains of a 

 tail from Gravesend, in the British Museum, are most satisfac- 

 torily interpreted as belonging to a fish of this type ; and the 

 extremity of a snout from Sussex, in the Willett Collection, 

 Brighton, seems to be more nearly paralleled by the snout of 

 Acipenscr than by that of any other known fish. Other frag- 

 mentary evidence of Acipenseroids in Upper Jurassic rocks 

 will probably soon be recognized, thanks especially to the in- 

 vestigations of Mr. Alfred N. Leeds in the Oxford Clay of 

 Peterborough ; but the most complete and unmistakable fossils 

 occur in the English Lower Jurassic — both in the Upper Lias 

 of Whitby and the I ower Lias of Lyme Re-jis. 



The gigantic Acipenseroid of Whitby was first noticed by 

 Agassiz, under the name of Gyrosfetis iiiinbUis, but it has not 

 hitherto been scientifically investigated and described. The 

 head seems to have been enveloped in few membrane bones, 

 none externally ornamented or covered with ganoine ; the 

 chondrocranium is scarcely ossified ; and the jaws are toothless. 

 The opercular apparatus is incomplete, without branchiostegal 

 rays ; and the membrane bones of the pectoral arch are unorna- 

 mented. There is evidence of a persistent notochord, and a 

 few ossified ribs occur anteriorly. The upper lobe of the tail 

 exhibits the characteristic series of large fulcra, and the trunk 

 seems to have been naked. 



Gyrostcus thus conforms to the normal Acipenseroid type as 

 represented at the present day ; but the genus of the Lower 

 Lias, Choiidrostcus, displays many striking differences. As 

 pointed out especially by Dr. R. H. Traqnair, these differences 

 tend to place the fish half-way between the modern Sturgeons 

 and the typically Paljeozoic group of Palseoniscida}. The roof 

 of the skull exhibits definite frontal, parietal, squamosal, and 

 supra-temporal membrane bones ; in addition to the operculum 

 and sub-operculum there are distinct branchiostegal rays ; and 

 in minor features there are several interesting resemblances to 

 points of Palffioniscid osteology. Dr. Traquair. indeed, places 

 the PaLxoniscidse in the " Acipenseroidei " ; and it may be that, 

 as no typical Acipenseroids of corresponding antiquity are 

 known, the Sturgeons and Polyodons are the somewhat de- 

 generate descendants of Paleozoic fishes upon this biological 

 level. At the same time, it must be remembered that the 

 Palreoniscida: pass by several known gradations into the charac- 

 teristic bony Ganoids of Mesozoic age ; and if the ascertained 

 facts of palreichthyology are already a sufficient basis for phylo- 

 genetic speculation, it thus appears that two diverging series 

 arise from this primitive stock. In his latest classification 

 {American Naturalist, 1887, p. 1018), Prof. Cope admits the 

 origin of the later Ganoids from fishes of a Palxoniscid type ; 

 but, on the,assumption that the basal cartilages (baseosts) of the 

 pelvic fin in Palaioniscidae were minute or absent, the Sturgeons 

 are placed lower in the series than the latter. Under any cir- 

 cumstances, the relative development of a single structural 

 feature is a slight point for the distinction of two "super- 

 orders"; and if " Podopterygia " and " Actinopterygia" are 

 to hold separate rank, the Pak\:oni cidas (so far as all positive 

 evidence is concerned) may be as justly placed in the former as 

 in the latter. 



NITRATE OF SODA, AND THE NITRATE 

 COUNTRY. 

 I. 



'TWILL lately, nitrate of soda has only been known to the few 

 ^ who dealt in manures, or who were engaged in chemical 

 manufactures; but within the last two years the British public 

 have invested vast sums of money in the shares of Nitrate Com- 

 panies, while the presence in society of live millionaires who 

 have made their money in Tarapaca, and the strong personality 

 of a "Nitrate King," have made "nitrates" a household word. 



