122 THE ANALYST. AC!i?ION OF OONCENTRATED SULPHURXU AaDt AT looo C., ON LEAD AND ITS ALLOYS, BY L. PITICIN. THE only work of my importance done, in the estimation of &e effect produced upon lead by hot concentrated dphurio mid, is that of Bauer. Tho acid used by him was 170° T. (sp. gr. 1,848), the amount of lead or alloy taken 0.2 gramme, and the amount of acid used 50 C.C. A brief absircrct of his work, so far as it relates to alloy8 used by me, is here given. 1. . h r 6 i k d . - ~ e f h t sensible evolution of gas was at 1 7 5 O c., a stronger action taring p l w at 1900 C., while at 250"-240' C. all of the lead was suddenly changed to sdphate. n. h d bi8?&h &4J8.= (a.) Pb. 90 per oent., Bi. 10 per cent. Action begins at 150" C., continues quietly to 190" U., when dl of the metal is decomposed.(5.) Pb. 96 per cent., Bi. 4 per oent. This alloy decomposes more quickly than (a), the aotion terminating at 130'- 140' 0, (u.) Pb. 99-27 per Bi. 0.78 per oent. Rapid and mdden decomposition at 160' 0. I]a.-.kd d tZ&hOoly dh348.- (6.1 Pb. 90 per oent., Sb. 10 per cent,THE ANALYEIT. 123 A dow and even decompoition tltkee plaoe, beginning at 190" U1, terminating at 240 0. (8.) Pb. 96 per oent., Sb. 4 per cent. (0.) Pb. 99 per wnt. Sb. 1 per oent, Decompodtion be@ at; 180" CI., terminating at 225" c1, Adon begins at %09, ends at 280" C. m. Lwd mad td:n n&g&-fhdden deoomposition at 200' 0. The a3loysr used by me in determining the effeot of hot acid were the same as those anployed in edimating the adion of cold wid, namely, lead with afimony, tin, bismuth, cadmium, dver, andhc.The amount of acid was as before 10 C.C. and the fluxface expoBed 2 aq, in., but the time of exposure WM 1 hour, instead of 24 hourB, as in testing with cold acid, The &mount of g w given off per square foot was not odouhted, as that facfor would be esaenfi&l only in the employment of lead for cases. The aznount of lead or dloy converted into sulphate per sguaxe foot is given in grammes. for one hour, gwve very conoordant results, as follows :- The four samples of pure lead, exposed to the actionof concentrated acid at 100" (1. 41. Pure lead.. .................... 1.308 Clmmmes. 43. p y ...................... 1*224 $# 44. $ 3 ...................... 1.080 9 ) 42. 1) ......................1*162 )) Tho effeot of antimony in composition with lead ia shown in the following experiments :- 46. Pb. 100 parts, Sb. +part.. .. 2.962 Gb.asunee. 48. $9 ,, 3 ,, .... 3*096 ), 49. 9 9 ,, B ,) .... P736 $, 40. SY y, 1 y p em.. 3.672 $ 9 41. Y 9 $9 2 9 ) . . m . 3.528 9 , 60. Y S 3, 10 ,) .... 2.962 ,) Upon immerdng the doy, very little gas waa given off, and for 40 minutes the acid remained dear. It &en commenced to cloud, and the alloy taken out at the end of the hour wtw oovered with blacik dime. It will be men that at 100" 0. the action of antimony ia not that of a presem&ive of the l e d , a B ie the case with cold acid; while from the experiments of Bauer, quoted above, it seems quite likely that at elevated temperatures tihe d o y with antimony may be more re&ingt&mpurelesd. The relative rrolirbilities of the alloys at ordinary temperatures and at 100" 0.are by no means constant, and thie fomm one of the most interesting features of the investiga- tion; thus, if at common temperatures the doya with antimony are found more inso- luble than lhose with zinc? we cannot predicate the same relation with acid at 100' G. In regard to the &ion of tin upon lead, tu &e&ing its solubility, the foUowing results were obtained :- 61. Pb. 100 pa&, 54. 9 s ,, 3 ,) .... 0-192 ,, 66. 99 ,, 6 ,? .... 0.864 s9 8n. & part,. . 1*008 Gcramme~ 52. 9, ,, 1 9 ) . a 1*?92 y) 63. 1 , ,, 2 $ 9 em a . OM4 yp 66. ?I ,, 10 $ 9 0.864_--_- -.--. -I--"- 124 THE ANUYBT. It will be remembered that one of the general results obtained from the experi- ments with cold acid was that at ordinarg temperatures the alloys of lead and tin were more easily attacked than thoso with antimony or pure lead itself, and yet at this ternu perahre we see the cam revermd.It is, however, in regad to bismuth that the most curiom effects were found to be produced by the composition of the alIoy. The following figures mill fully explain the peculiar action of the bifimuth :- 67. Pb. 100 psrts, Bi. $part.. . , 24-840 (hunmm. 68. 9 , ,, 1 ,, .... 22'2448 ,* 69. ,9 ,) 2 ), ..I. 1-000 $1 62. 9 , ,, 10 ,) ...# 2.160 s t 60. 99 ,, 3 ,, .... 1*008 ,, 61. 9, ,, 5 ,, .... 1*008 ,@ The results given in 57 and 58 appear so exceptional, not only in compazison with other alloys, but in regaxd to the sudden change shown in 59 and 60, that it was dectided to make experiments 57,58, and 60 in duplictt&e. 57.@npEa+e) Pb. 100 paxts, Bi. Qb8 23920 68. Y9 99 Bi. 1.. 22*760 60. 9 , 2, Bi. 3 . . 1-224 We here have 8 case in which not only the relative solubility in hot and cold acid is changed as regards other alloys, but one in which an exceas of the deleterious sub- stance seem to a d as a corndive. The alloys mntaining Q and 1 part of b h u t h to 100 of lead gave off gas very plentifullys not only at the start, but tbroughout the whole hour? while the acid beame opaque almost immediately, and the lead sulphate formed oould be removed in s d e s at the end of the experiment. The experiments with cadmium alloy gave very constant results, and in general it may be said that, with the exception of bismuth doy, the figurerJ obtained from the same doy varied muohless than in the corresponding trial8 with cold acid.63. Pb. 100 part9, Cd. Q part .. . . 1.440 Grammes. 64. 99 ), 1 ,, .. .. 1.224 1 ) 66. ?, ,) 3 ,, .. .. 1-080 ,, 67* ¶ 9 ), 6 ,, .. .. 1'368 9 s 68- 9 9 ,, 10 )) .. .. 1.152 )) The aofion of oadmiuzn at this temperature Beems to be neither inmasing nor In the case of silver combined with the lead, we have the same general behaviour, 65. ,, 9 , 2 j) m e 1.296 - 9 diminishing the action of the H,BO, on the lead. eix determinations with varying quantities of silver giving the following result6 :- 69. Pb. 100 parts, Ag. + part , . b e 1*296 Cxmnma. 72. 9 , 9 9 3 9, .. 0*792 #, 70. 9 , s t 1 9 , .. .. 1*080 9) 51.,, 9) 2 $9 0 . 0.864 y) 73. 9 , 9 ) 3 $ 9 a 8 me 0.936 $9 74- J , 2 9 10 ), .. .e 1.440 )) The action of zinc in det;ermining the solubility of lead in hot add is in accordance with its effwt on cold mncentr&ed Ibcid-that is, haeasea the effedi of the aoid, but the!l!HE ANALYST. 125 action ie not so marked as at ordinary temperatures. The figures for fie experiments are :- 75. Pb. 100 parts, Zn. 3 part . . . . 1*800 Gmmmes. 76- $9 y) 1 y3 * * e m 1.296 9 , 77. 9, )) 2 )) 1 0 .b 1.162 y) 78. 1, .. 3 . . . . . . 1.080 .. 79. YY y j 6 $ 9 . b 1.296 y, 80. 9 ) y s 10 9 ) 0. . e 1*080 $ 9 We can easily Bee from the resulb we have obtained the importance of testing the lead employed in &go4 working, and for this no extended analysis is required. The operation ctonl3ists aimply in immersing the lead in acid, more or less concentrated according to the strength of the acid with which it will be brought into contact in actual working, and at the temperature to which it will be subjected in the manufadme of alcid.Mr. McTear says :-“The simpIest safeguard against risk to pans, eta, giving way would be a careful testing of the lead previous to being made into sbeets. For this purpose it will not ’be necessary to make an analysis, but simply to put clean, thin tihaving8 of lead into a tesst-tube and cover with pure, cold vitriol ; the amount of action would then be elearly visible,” It i s however, clear that the adion of cold aoid ie no sure miterion of the effect that hot acid will have upon the lead ; so, to avoid error, it is much safer to test %he lead under the conditions of its aotual emplogment. In order to briefly mm up the results of experiment, it mill be advantageous to compme tho avemge of the d o y ~ with pure lead a8 Unity both at ordinary tempera- tures and at looo 0. The following table mill therefore express the average solubility or liability to formation of sulphate of the alloys in terms of lead. In each case the total of the relative solubilities is divided by six (the number of members in the class), €or the average mlubility of the alloys : Pureled . . . . . . . . . . . . . . . . 1*00 1.00 Pb. 100, 8b. 1 to 10 pmts . . . . . . . . . . 0*81 2% Pb.100,Sn. 1f010 . . . . . . . . . . . . . . 1*42 0.75 Pb. 100,Bi. lto 10 . . . . . . . . . . . . . . 1.10 7.69 pb. l0OYAg.1to1O . . . . . . . . . . . . . . 0.87 0.93 2060. loooc. Pb. 104 Cd. It010 . . . . . . . . . . . . . . 0*86 1-10 pb0100,& 1f010 . . . . . . . . . . . . . . 1-63 1-10 4ottmd of t h A4nem’capc ChmiwZ iYo&&.