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verj- considerable size may be formed. Fig. 3 shows a spoon which has been annealed in water g a s and then plunged into t h e tip of a large Bunien flame. T h e figure is of t h e natural size. I t was t h u s made evident t h a t i n order to successfully anneal t h e ware, not only must t h e penetration of oxygen be preveiited but also t h e penetration of reducing gases. Experiment showed that hydrogen, niethane, acetylene, etc. were very active in producing blisters, while nitrogen and -arbon dioxide were entirely inert. Carbon monoxide lay betKeen the two extremes. F u r t h e r work indicated that the most desirable atmosphere from a technical point of view was one which coiitained enough reducing gases such a s hydrogen, methane, o r carbon monoxide, to prevent t h e penetration of t h e sniall amount of oxygen which cannot be e x cluded &hen working with large furnaces, and enough inert gas, such as zarbon dioxide or nitrogen, to prevent, t h e penetration of t h e reducing gases. Such an atmosphere can be prepared in an apparatus such as is m p l o y e d i n making so-called producer gas, when so operated a s to deliver a product consisting approximately of two thirds carbon dioxide and nitrogen and one-third carbon monoxide, w i t h a small amount of hydrogen. Annealing processes based on t h e above observations are iiow employed in practically all t h e large silver producing fac:ories in America. I wish to acknowledge t h e constant interest and support in this work received from Mr. C. E. Cole, President of t h e Towle Manufacturing Company, Silversmiths, Newburyport, blassachusetts, and from Mr. Martin Boyle, sometime chemist of t h e same Erm. T H E RAPID DETERMINATION OF NICKEL I N T H E PRESENCE OF CHROMIUM, IRON AND MANGANESE. BY c i v JOHNSON Recrired May 17,' $ 0 ;
I n applying t h e method of T. Moore' to t h e determination of nickel in steel, t h e directions given on page 183, Analysis of Steel W o r k s Materials by Brearley and Ibbotson were followed : One gram of steel was dissolved in a 150 cc. beaker with ten cc. of concentrated hydrochloric acid diluted with a n equal volume of water. When action ceased ten cc. of nitric acid ( 1 . 2 0 ) were added and t h e contents of t h e beaker were boiled to about one half. 16 cc. of dilute sulphuric acid were poured into t h e solutiou and also three grams of poydered citric acid. T h e solution was stirred until t h e citric acid was dissolved, transferred to a 600 cc. beaker, a n d rendered faintly but distinctly ammoniacal. T h e nickel was titrated with a standard solution of potassium cyanide Chemical S e w s , 72, 92. 3
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using a measured amount of standard silver nitrate and tTyo CC. of a 20 p r r cent. solutioii of potassiuiii iodide a s an indicator. T h e cleep red color of the citrate of iron greatly obscures t h e end poiut. The authors coniplaiii of this color and r e c o ~ n n ~ e ithe ~ d use of a conclensirlg lens to cast a beam of light through t h e darkness. In the presence of chroniiuiii t h e writer found that a still more sombre glooni settled c1on.n over t h e close of the reaction. T h e authors mentioned, also state t h a t this element retards tlie uuiou of the cyanide aiid tlie nickel causing t h e reciirrerice of the cloud of silver iodide. After struggling with t h e process for some time and always carefully separating tlie ciironiiuni, and with i t the iroii, iii chrome steels, :in attempt mas niade to dispel the darkness and also to avoid these tedious separations : Less citric acid per gram of steel was taken and the dark red shaded to blackness. Naturally. the aniouut of citric aciti per g r a m of steel was then increased, that is, six grams of citric acid per gram of steel were used and a marked improvenieut was noted. Still more citric acid caused a cornplete lifting of the shadows. T h e following modified procedure was finally adopted for nickel steels a f t e r having been thoroughly tested with plain carbon steels to which known amoutits of uickel had been added : Dissolve one grain of steel drillings in a I j o cc. beaker with 20 cc. of hydrochloric acid ( I : I ) . W h e n action ceases add ten cc. of nitric acid ( I . 2 0 ) . Reduce t h e volume of the solution to about 15 cc. keepiug the beaker covered during t h e boiling. Remove t h e beaker from t h e fire and pour into i t eight cc. of conc. sulphuric acid diluted with 24 cc. of water. T h e presence of t h e sulphuric acid is essential to a sharp end reaction between t h e cyanide standard and the silver iodide in t h e subsequent titration, T r a n s f e r the contents of t h e beaker to one of 600 cc. capacity contaiiii n g twelve grams of powdered citric acid. Stir until t h e citric acid is dissolved. Render this solution fm'nfb,but disiiiictb~ alkaline with ammonia, using one part of concentrated ammonia diluted with one part of water. A large excess of ammonia causes low results. Staud t h e beaker in running water until i t is cold. T h e volume of the solution should now be about 300 cc. Much larger volumes than 300 cc. should be avoided as g r e a t dilution retards t h e end point causiiig t h e cloud of silver iodide to disappear atid then to reappear again in a few minutes. T h e faintly ammoniacal condition can be easily controlled b y addiug t h e amniouia rather slowly and noting t h e changes of color that ensue : T h e first change is to amber, then to yellon~ish green, then to distinct green, then t o a light shade of greeu, theu to a yellow almost niatching
D E T E R X I S A T I O N O F N I C K E L IK C H R O M I U M , ETC.
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the yellow color of t h e acid solution. T h e reappearance of t h e yellow Lint indicates t h a t alkalinity is nearly attained. A little inore amnionia now causes a brownish shade which is evidence :hat t h e ammonia is in slight excess. T h e moderately alkaline citrate 3f iron obtained in t h e proportion of one gram of iron to 1 2 grams of the 3tric acid yields a bright greenish yellow solution in plain nickel steels Instead of being of a deiise dark red shade ! To t h e cold solution, two cc. of a 20 per cent. solution of potassium iodide are added. From a 50 cc. burette a staiidard solution of silver nitrate is dropped into t h e same beaker producing with the iodide a white :urbiclity. T h e standard potassium cycinide is added with constant stirring until t h e cloud of silver iodide just disappears which it does on being converted into silver cyanide. Kickel cyanide is first formed and then the silver cyanide is produced : ( L) X i ( K O L j )+24 K C N = N i ( C S ) ? . z K C N -L 2KN0,; AgNO, T z K C S = X g C N . K C N -,- KNO,. ( 2 ) If t h e directious a r e followed as given, the titiation can be accomplished at almost the full speed of the burette. If the titrated solutions are permitted to reniain in the open beakers for a time a film usually xppears on t h e surface of t h e liquid. No account is taken of i t a s its presence is niost likely d u e to a superficial loss of ammonia. T h e reactions are always found to be conipleted wlieii t h e body of t h e solution is freed of t h e iodide precipitate. Sinizduaru’s-From t h e equations as given, j 85 g. of silver nitrate are 2quivalent to 4.4868 g. of potassinni cyanide. Thi.; weight of cyanide dissolved in one liter of water gives a value of one cc. equals about o.001014 grams of nickel. As comparatively little silver nitrate is needed with each analysis, it is not advisable to prepare more than a half liter of t h e mater solution of this salt tising 2.925 grams per 5 0 0 cc. of distilled water. T h e potassium cyanide standard should contain about five grains of potassium hydroxide to the liter, which renders it quite permanent. T h e solutions are readily standardized by applying them to a plain steel to which a known amount of nickel has been added. T h e chemically pure Jouble sulphate of nickel aiid ammonium is a convenient standardizing medium. For example 0 . 2 grams and 0 . 2 j grams of t h e double sulphate x n be weighed irito I j o cc. beakers together with one grani of plain x r b o n steel drillings. T h i s mixture is then put through all of t h e foregoing manipulations m d titrated with the cyanide solution t h a t is to be standardized. T h e number of cc. o f t h e silver nitrate and of t h e potassium cyanide .EOlution usecl iii this titration are noted. An excess of I O cc. of t h e c! anide is no‘x added atid i n turn titrated with t h e silver nitrate solution
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until a distinct cloud of silver iodide is produced. T h i s second titr:ltioli gives tlie relation betiweti tlie s i l i w so1ntio:i and the cyanide. An actual case will illustrate the calculations : 111 saiiiple S O .34;:. 1 . 7 cc. of standard silver nitrate solution :vcre required lo 11rodace a (',iatinct turbidity and also to coiiiljiiie wit11 any excess of pota standard. In a11 3j cc. of tiir c!.anide were corisiinieci i l l TTlicn tlie cloud of bilver iodide h a d j,ust bcei! dispelieti :in cc. of cyanide w a s allowed to flon- iiito tlie clear w l i i c i o : i . ;uct I O . I CC. of silver nitrate staiidarti \yri*c :iectlcti t o product: :I re:cppear:ii:ce of the cloudiness. Therefore 9.8 : I O . 1 = 0.97 or o.';;w. of cJ-anidr :;tatidaid tlcc!ucti:i::- I .7 solution equals I cc. of silver iiitrate, 1-ieiic-. i!is\cn>, CC. \ v u e deiitlcti.:l le:>\.ili# 3 3 , s j CC. CC. from 3j cc., 1,: :< 0.97 or 1.~15 of cyanidc combined ivitli t h e iiickd i n this steel. T o a plain carhoii steel 0.200 g r n i i i of tloul~le sulphate of nickel and :ini!iioiiiuiii irere ncltled p u t tlirougii all o f the steps of n regular analysis. This iiiixture required 2 8 . 7 5 cc. of c y L cic. T!ie nickel salt cu!itains 14.S6 p v r cent. of nickel or 0 . 2 m . _ o . r + ~ 61: o.o~y7zgrain of nickel irere present. iieiice 0 . 0 2 9 ; ~ : ~ ' : ' . ; j: o.ooi(13(,r I ci:. oi ,staiidartl cyavide so:utioii is equiralriit to o.ccro3 .c, I: of' iiickel. SO.3 4 j j ii i di. .st ni id a r d , a 11(1 t 11ere lias lieeii stated reqiiircd :,3,3j cc. o l ti:? fore, contain,< o.ooro:,\< 3 3 . 3 j . o.O343
