March i8, 1875] 



NA TURE 



593 



ON SOME REMARKABLE CHANGES PRO- 

 DUCED IN IRON AND STEEL BY THE 

 ACTION OF HYDROGEN AND ACIDS 



FOR a long time it has been well known to wire- 

 drawers and other manufacturers, who free the iron 

 or steel they are engaged in working from rust by clean- 

 ing it with sulphuric acid, that after this process the 

 metal becomes much more brittle than before. Further, 

 if a piece of iron wire that has been cleaned in sulphuric 

 acid be bent rapidly to and fro till it is broken, and the 

 fracture be then moistened with the tongue, bubbles of 

 gas arise from it, causing it to froth. If this same wire 

 be now gently heated for a few hours, or left in a dry 

 warm room for some days, it will be found to have 

 regained its original toughness, and not to froth -when 

 broken and the fracture moistened. 



Some experiments made by the writer on this subject 

 during the last three years, have shown that not only sul- 

 phuric, but hydrochloric, acetic, and other acids which 

 give off hydrogen by their action on iron, produce the 

 same effect, making it probable that hydrogen is the cause 

 of the change. This view is confirmed by collecting the 

 gas given off at the surface of the iron and burning it, 

 when the characteristic flame of hydrogen is seen. 



Putting the facts together, it seems probable that a por- 

 tion of the hydrogen generated by the action of the acid 

 on the surface of the iron is occluded and subsequently 

 given off, either rapidly, as when the iron is heated by the 

 effort of breaking it causing the water on the surface of 

 fracture to bubble, or, more slowly, in the cold. 



Perhaps the simplest way of charging a piece of iron 

 with hydrogen is by laying it on a sheet of zinc in a basin 

 of dilute sulphuric acid. An electric current is here set 

 up, and the hydrogen generated by the action of the acid 

 on the zinc is given off at the surface of the iron. In this 

 way two minutes or even less will often suffice to charge 

 a piece of iron with hydrogen and alter its properties as 

 completely as one hour's immersion in dilute acid without 

 the zinc. 



The change in the properties of iron which has occluded 

 hydrogen is not confined to a diminution of toughness, 

 though this may be reduced to one-fourth, but is accom- 

 panied by a remarkable decrease in tensile strain, amount- 

 ing in cast steel to upwards of twenty percent, after twelve 

 hours' immersion in sulphuric acid. With iron wire the 

 decrease in tensile strain was found to be less than with 

 steel ; the reduction amounted however in some cases to 

 six per cent. Some interesting differences are noticeable 

 in the relative effect of occluded hydrogen on mild steel 

 and highly carbonised steel, the diminution of tensile 

 strain after occlusion of hydrogen being greater in the 

 latter case than in the former. 



As with the metal paladium, so with iron, the electrical 

 resistance is increased somewhat by occlusion of hydro- 

 gen ; in fact, it seems probable that eveiy property of 

 iron or steel undergoes a change after the occlusion of 

 hydrogen, and the extent of this change becomes a matter 

 of great interest to the engineer now that iron and steel 

 are so largely used. 



Cases of the deterioration in toughness of iron of excel- 

 lent quality exposed to the action of gas containing acid, 

 as in the upcast shaft of a coal-pit, have come before the 

 writer's notice, in which the change appeared to have 

 resulted more from hydrogen occluded by the iron than 

 its corrosion by the acid vapours. It is also probable 

 that rapidly rusting iron occludes hydrogen, and is thereby 

 weakened in strength and toughness. 



William H. Johnson 



THE SOUTHPORT AQUARIUM 



TH E grounds of the Southport Pavilion, Winter Gardens, 

 and Aquarium Company occupy an area of about 

 nine acres, extending from a portion of the sea-wall and 



parade, on which they have a frontage of i,iio feet, to 

 Lord Street, the chief thoroughfare of the town, which 

 runs in a straight line, roughly parallel to the sea-coast, 

 for nearly a mile. 



Entering the pile of buildings, which occupy about the 

 centre of the grounds, by the chief portico on the Lord 

 Street side, and ascending a wide flight of steps, the 

 Promenade Hall is i-eached, which is constructed of pitch 

 pine, and is over the principal corridor of the aquarium, 

 to which access is obtained by descending a flight of 

 steps, or an incline, placed on either side of the staircase 

 leading up to the hall, which, like the con-idor beneath it, 

 is 160 feet in length by 42. To the right of the hall, and 

 separated from it by glass doors, is the Band Pavilion, 

 which is said to be capable of holding 2,00c people ; 

 round it is a gallery used as a promenade, and in which 

 pictures are exhibited, and beneath it is the refreshment 

 department, which is on the basement level. Likethe aqua- 

 rium,* the Pavilion is oval in shape, the longest axis being 

 136 feet, the shortest 76. To the left of the great hall, 

 glass doors give admittance to a glass conservatory, 174 

 feet in length by 74, stocked with tropical and subtropical 

 plants and birds ; beneath it are the remaining corridors 

 of the aquarium. 



The first corridor of the aquarium contains twenty-three 

 tanks, the front of each consisting of three sheets of plate 

 glass, as at Brighton ; and the light, as there, is all trans- 

 mitted either through the water in the tanks or through 

 plates of opaque glass placed in the floor above. The 

 roof consists of double groined arches, supported on 

 moulded columns, made of concrete, which has been 

 largely used in various parts of ^the building with good 

 results. 



Tanks i to 23 contain : Sea Anemones, Nos. 7 and 23 ; 

 Octopi, II and 21 ; Crabs, Spiny and Common Lobsters, 

 10, 16, 19, and 22 ; four specimens of King Crabs, 20 ; 

 Conger and Common Eels ; Salmon Trout ; Ballan 

 Wrasse, 6 ; Rough Hound and other dog-fish ; Cod and 

 Rock Cod ; Grey, Streaked, and other Gurnards ; Whiting, 

 Soles, Plaice, Bret, &c. ; Father Lasher {Cottus scorpais), 

 4 ; two specimens of the Angel or Monk Fish, 15. 



By the side of the tanks, plates of fishes from Yarrel's 

 work are hung, which, not always having any connection 

 with the living fish exhibited, rather distract attention, 

 and would be better collected together with various 

 stuffed fish placed at the top of the tanks, and placed in a 

 small museum. Amongst the plates are some original 

 coloured drawings of Mr. Jonathan Couch, of seven 

 species of sharks, signed "J. C, 1825"; also eight 

 drawings of flying-fish, by the same. 



Corridor No. 2 has a flat ceiling supported on iron 

 columns, is lighted by windows looking on to the garden 

 on the Lord Street side, and contains table tanks, rectan- 

 gular and octagonal, the former being filled with fresh 

 water, the latter with salt, containing, amongst other 

 things, several species of Scrpiila, SabcUa, Tcrebclla, 

 Amphrititc, Aphrodita aculcata, and other annclides ; 

 Sea Anemones of various species ; TJiyone papulosa, and 

 other Hololhnriada ; Asciciia- and other tunicatcd mol- 

 luscs ; various species of Starfish, Cidaris ; Norwegian 

 Lobsters ; Blennys, fifteen and three spined Sticklebacks, 

 and large numbers of living zoophytes. Several of these 

 tanks, both in the beauty of their varied contents and the 

 care with which they have been selected and arranged, 

 afford a good example of what can be done by art to 

 reproduce a portion of the richness of effect of the actual 

 sea-bottom. 



On the right or seaward end of this corridor there is a 

 Seal Tank, five seals living in it and in the Seal Pond 

 in the garden between the entrance lodges and the portico 

 of the Promenade Hall. On the opposite end of the corri- 



• The ground slopes from the sea touarJs Lord Street, so that the 

 aquarium is underground on the seaw.ird side. In my "Notes on the 

 Geology of Liverpool," Natibe, vol. ii. p. yr>, I have described the sand 

 cuncs. &€., of this coast. 



