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Historical Articles

MONTHLY REVIEW

Published by the
American Electroplaters Society

Publication Editorial Office
3040 Diversey Ave., Chicago

Vol. XIV APRIL, 1927 No. 4


EDITORIAL

The Value of Research on Plating
During the past year the electroplaters have been frequently urged to enlist the support of their employers toward the Research Fund. In such efforts it is safe to say that the platers in turn were asked by their employers such questions as “What use is such research?” “Have you ever gotten any help from it?” “Has our firm ever benefited by it?” How such questions are answered no doubt determines largely the attitude of the firm toward research on plating.

Those who are engaged in these studies at the Bureau of Standards and elsewhere have an equal interest in the answers to such questions. Obviously unless the platers and manufacturers and through them the general public, are benefited by such investigations there is no justification for spending public funds on them, much less for encouraging manufacturers to support them.

Electroplating, like other industries, involves three important kinds of knowledge.
(1) There are certain general laws and principles of physics and chemistry which apply to all electrolysis the study of which constitutes “fundamental research.”
(2) The use of these principles to predict methods of improving or controlling the conductivity, efficiency, throwing power and structure of deposits, in existing or desired processes of plating, may be defined as “industrial research.”
(3) The actual application of such conclusions to any given process, involves “engineering.”

Of these three tasks the first is largely conducted in detached research laboratories, such as in universities, and the results make up most of the literature of the related sciences. Industrial research is usually carried out in laboratories of large firms or in institutions such as the Bureau of Standards, that are cooperating with industry. The third, the practical application, must be done in the plants, in this case by the platers themselves or by chemists associated with them.

The important thing to note is that instead of the plater’s job becoming easier as a result of industrial research it will become harder (but more interesting) because he then has more promising possibilities to try out. All that the plater has a right to expect of industrial research is that it will point out to him the directions in which he can most probably improve his operations. The plater himself must find out whether and how given information may be applied to his work. If he succeeds in thus improving his process, well and good; if not, he should inform the chemist, so the latter may help to explain any apparent discrepancy.

To illustrate, the bureau published in the Review for April, 1925, a paper showing that by adding from one to two pounds per gallon of sodium sulfate to a nickel-plating solution, the conductivity and polarization are increased, and hence the throwing power is improved and brighter deposits are produced. After making tests in a few plants, such solutions were suggested for plating on zinc and die castings, and also for barrel plating or mechanical plating of brass and steel. It was then clearly stated that “for specific purposes modifications may be required.”

From recent plant visits I was somewhat surprised to find how few platers have ever tried the addition of sodium sulfate to their regular nickel solutions. Of these, the definite reports are usually favorable. Indefinite statements that “some one else tried it and could not make it work,” are not of much guidance to the research chemist. If persons who tested it and found difficulty would report their results to the bureau, an explanation and possible remedy might be forthcoming. Thus a specific statement that it is necessary to adjust the pH in such solutions more frequently is constructive. If this is found to be generally true, the plater must decide for himself whether the advantages in saving time, electricity, nickel, and buffing by the use of sodium sulfate more than make up for the additional effort in controlling the pH.

Any such investigation costs the bureau at least $5,000. Is it unreasonable to expect a number of manufacturers, through their platers, to each spend for example $100 to find out if they can apply the results to their own plant, with possibly great savings? Of course if the plater and manufacturer are satisfied that their present practice cannot be improved, there is no necessity for research. The best way to let us know that you want more research, is to use, so far as possible, the results already obtained.

—DR. WM. BLUM,
Associate Editor.



THROWING POWER

(An address before Chicago Branch, American Electroplaters’ Society, Jan. 29, 1927.)
By Oliver P. Watts

The old saying, “The used key is always bright,” applies to other than merely physical things. It applies particularly to our knowledge. Forty years ago I could read Greek, with much difficulty and a dictionary. Today I don’t know the whole of the alphabet, and frequently find myself “stumped” by some one of the two or three letters, which to the more erudite, tell the name of the fraternity or sorority which inhabits the latest addition to the group of magnificent buildings which house so many of my students. At about the same time I was supposed to be extra proficient in the calculus. Today calculus is all Greek to me, and I have merely a bowing acquaintance with the integral sign. It isn’t only the unused tool that rusts. By disuse any power or attribute that we may possess is lost.

So, while I have nothing new to tell you on the subject of throwing power, it may perhaps be profitable that we spend a few minutes on the general principles of this important, but until recently, utterly neglected subject.

If you were required to plate both inside and out a hundred brass tubes three or four inches long and a half inch inside diameter would you choose the sulphate or the cyanide solution for plating, supposing that you had both ready for use? The electrotyper and maker of phonograph records, who deposit ten pounds of copper to one deposited by the average plater, invariably use the sulphate solution; yet you would choose the cyanide solution because of its superior throwing power.

Why should the two solutions behave so differently in this respect? If the cyanide solution is capable of depositing copper way up inside the tube, where we would expect little or no current to flow, why does the sulphate solution utterly fail to do the same? Ohm’s law tells that the current flow varies directly as the em.m.f. or voltage, and inversely as the resistance. But the voltage between the anodes and any part of the cathode is practically the same, and if the composition and concentration of the plating solution is uniform, the resistance to different parts of an object will be proportional to their distances from the anodes. So far it seems as if the flow of current to different objects or to different parts of the same object should always be in inverse proportion to their distances from the anodes, and that all solutions should have exactly the same throwing power—quite contrary to out observations in plating.

G. Gore, in his book on electrodeposition, published a half century ago, notes that in addition to the ohmic resistance of solutions, which varies uniformly with the distance, there is some special obstacle to the passage of current, residing at the contact of electrode and electrolyte. To this he gave the name “transfer resistance.” One factor which contributes to this transfer resistance is the difference in composition between the film in contact with the electrodes and the main body of solution. At the cathode metal is being removed, and consequently the film of solution here is weaker, and at the anode where metal is dissolving the film is more concentrated in metal than the main body of solution. These changes in concentration alter the potentials of both anode and cathode in such a way as to oppose the flow of current, and this opposition increases with rise in current density. Under ten amperes per square foot this change in potential of the cathode seldom exceeds 0.03 volts, so that this change in concentration is not a very important factor in throwing power. A more important factor in altering thepotential of the cathode is the hydrogen often deposited along with metal from many plating solutions. The total alteration of potential or polarization of the cathode at current densities now used may in extreme cases amount to as much as a volt, a considerable portion of the total voltage across the solution.

With certain solutions the cathode polarization changes but slightly, while with others it increases greatly with increase of current density. It is this latter property, the increase in cathode polarization with rise of current density, which imparts throwing power to a plating solution. If the voltage be represented by E, the total polarization at both electrodes by P, the current by I, and the resistance to the part of the cathode under consideration by R, then

E = P + IR

Only that portion of the voltage not offset by polarization is effective in sending current through the solution. Let us consider two portions of cathode surface, one of which is three times as far from the nearest anode as the other. More current flows to the near than to the far surface, but if the polarization is not affected by current density, the voltage effective in sending current to each surface is the same, and since R is proportional to the distances, the currents will be in the same ratio. If, however, P increases considerably with rise in current density, the polarization on the near surface will be much larger than on the far surface, and consequently the voltage remaining to send current to the near surface will be smaller than that acting on the far surface. The result is that the far surface gets a larger share of current than the relative distances warrant.

Another and most important factor in throwing power is current efficiency. If the current efficiency of each particular plating solution were the same at all current densities, the weights of metal deposited on near and on far parts would be proportional to current distribution; but the current efficiency varies, in some cases greatly, with changes in current density. In the cyanide copper solution an increase in current density causes a notable falling off in current efficiency, indicated by a great increase in evolution of hydrogen. This is favorable to throwing power, for at the near surface, where the current is greater, a larger per cent of it is wasted in deposition of hydrogen. In the nickel solution an increase in current density causes a rise in current efficiency, which is unfavorable to throwing power. If you must cover a hollow article with nickel, use a small current for a long time rather than a large current for a short time.

It is evident from the equation that the relative magnitude of polarization and IR-drop across the solution is important. If IR is very large compared to P, the changes in P due to differences in current density will have little effect on current distribution, and hence on throwing power; but if P is large compared to IR its changes will profoundly influence the amounts of current flowing to near and far portions of the cathode.

All other conditions remaining unchanged, throwing power can be increased by increase of polarization or by lowering of resistance. It does not follow, however, that solutions of low resistance have the best, or even good, throwing power. One of the lowest-resistance solutions in use by platers is the acid copper sulphate solution, notable for its poor throwing power. Since hydrogen is not deposited from this solution at currents used in plating, the only polarization at the cathode is that due to removal of copper from the cathode film, and while this is proportional to the current, its total is too small to impart good throwing power. The statement that hydrogen is not deposited from this solution is only another way of saying that its current efficiency does not fall off at current densities used in plating, so its very poor throwing power is accounted for.

It often happens that a change which influences favorably one of the three factors, resistance, polarization and current efficiency, may produce in the others a greater change unfavorable to throwing power. For example heating a solution always lowers its resistance, which taken alone improves throwing power; but it also lessens polarization and increases current efficiency, unless this was already 100 per cent, and both of these changes lower throwing power. For a more scientific and detailed discussion of throwing power you are referred to the papers by Dr. Blum, Haring and Thompson in Vol. 44, 46 and 47 of the American Electrochemical Society

In 1917 I began the testing of throwing power by rolling tubes of thin sheet metal and finding how far inside the tube different plating solutions would deposit metal. By using tubes of different diameter and length it was hoped to classify plating solutions according to their throwing power. It was soon found that the ordinary plating solutions fell into two classes: cyanide solutions of good throwing power, and all other solutions tested of relatively poor throwing power, with no connecting link between. This investigation was interrupted by the war, and not resumed until two years ago, when an attempt was made to investigate and improve the throwing power of several solutions.

It was found that the addition of large amounts of aluminum chloride (AlCl36H2O) to nickel sulphate solution imparted surprising throwing power. To prevent the precipitation of aluminum hydrate it is necessary to add citric acid before bringing the pH value to 5.7 by ammonia. In all cases the preliminary testing was done by plating tubes, and only the best solutions were measured on a Bureau of Standards throwing power box, kindly loaned for that purpose by Dr. Blum. As used the ratio of cathode distances was five to one, and the current was 0.5 ampere per square decimeter of cross section of the solution, or 4.9 amperes per square foot.

Some results are:

Single
Sulphate
AlCl3
·6H2O
Citric
Acid
Throwing
G/l
oz/gal
G/l
oz/gal
G/l
oz/gal
Power
25
3.3
63
8.4
22
3
17%
25
3.3
125
16.7
45
6
28
25
3.3
250
33.3
90
12
40
Nickle Chloride
25
3.3
0
0
0
0
-7
25
3.3
65
8.7
32
4.3
18
25
3.3
125
16.7
65
8.7
32.5
25
3.3
250
33.3
125
16.7
35.3
100
7.3
250
33.3
125
16.7
26


At the same current density the special high sodium sulphate nickel solution of M. R. Thompson has a throwing power of only fifteen per cent. Thompson’s solution carries 140 grams of single sulphate per liter, and is intended for rapid plating. It would be expected that a solution containing only 25 grams per liter of single sulphate would be limited to extremely slow plating, but this solution has been used at one ampere per square decimeter cross section of box, and an actual density of 0.96 amperes per square decimeter on the near cathode, for a half hour without a trace of burning. This is not recommended as a practical plating solution, on account of the cost of citric acid and trouble from precipitation of aluminum hydrate; but the facts have been presented to show that it is possible for a nickel solution to have a throwing power fully equal to that of the usual cyanide copper solution. With the knowledge that this is possible, the attainment of a practical solution of equal throwing power should be only a matter of persistent, though perhaps lengthy, experimenting.

In experiments with the zinc sulphate solution, notable for its poor throwing power, aluminum chloride which had proved so beneficial in the nickel solution was of no advantage, but ammonium citrate was a great help to throwing power. A solution containing 120 grams per liter (16 oz. per gallon) of crystallized zinc sulphate and 15 grams (2 oz.) of citric acid had a throwing power of 27.5 percent when neutralized by ammonia to a pH value of 6.0.

A cyanide copper solution which had a resistivity of 16.4 ohms per centimeter cube at 20 degrees centigrade and a throwing power of 32.6, on addition of 50 grams caustic potash and 20 grams per liter of caustic soda, had a resistivity of 5.5 and a throwing power of 56 percent, the highest attained in any of my experiments. In three minutes this solution plated the inside of a tube 6 1/2 inches long and 3/16 inch inside diameter, when one end of the tube was placed against the side of the tank so that current could enter the tube at one end only. Since the term percent is used in expressing throwing power it is but natural to think of any value much below 100 percent as something very inferior. This is not so. In computing, throwing power by the Bureau of Standards formula for a five to one distance ratio a throwing power of 80 percent would necessitate that the same weight of metal be deposited on the far as on the near cathode—an impossibility. It would seem that the maximum throwing power attainable will be well under 80 percent.

The throwing power of the nickel, zinc and copper sulphate solutions was unfavorably affected by very slight increases in acidity, so that this will require careful watching if these solutions are to be kept up to the best throwing power of which they are capable.

If a study of throwing power will, as seems likely, produce a more uniform thickness of plating than is at present obtained, this will result in several economies. For the same service now secured a less weight of metal can be used, which means less labor, power and time required for plating. These economies will not be realized, however, without much experimenting and the accumulation of a knowledge of the effects of different conditions and chemicals on the various factors whose combination gives to each solution its particular throwing power. These factors hare been pointed out by Dr. Blum and his assistants at the Bureau of Standards.

For the plater who wishes to keep a check on the throwing -power of his plating solutions, or to try the effect of addition of different chemicals, but who does: not have a throwing power box, the method of plating tubes is recommended. Two, or at most three, steel rods around which to roll the sheet metal is all the equipment needed. By varying the length of tube as well as the diameter, it is possible to differentiate between the throwing power of all solutions. Thin sheet copper is used to make the tubes. For testing copper solutions this should be very lightly nickeled before rolling into a tube. For silver solutions, which deposit their metal on copper “by immersion,” thin sheet iron should be used instead of copper. By stopping one end of the tube excessive length of tube may be avoided even in testing so good a throwing solution as the cyanide copper.


SCIENCE AND COMMON SENSE

By A. P. Munning

Address delivered before open meeting, Newark (N. J.) Branch.

Francis Bacon, probably the first philosopher to distinguish that knowledge unapplied to action was superfluous knowledge, made the statement as far back as 1592 “that crafty men condemn studies, simple men admire them and wise men use them.”

If we will apply these words to our everyday work and play, we will profit much more than in the endeavor which seems to permeate the whole universe of trying to combine into one poor brain all of the scientific data and nostrums and cure-alls which are being urged upon us.

It is with these thoughts in mind that I am going to try and show my appreciation of the honor bestowed upon me by Mr. H. A. Smith, in asking me to say a few words at random to you tonight.

The art or the lack of art of electroplating prior to the beginning of your society is well known to most everyone. At about that time, 1911, the industry began to absorb some of the basic underlying principles of other industries, because men coming into it had the courage to work, not on past history, but on present-day facts and tendencies, which led to co-operation in efforts to increase the knowledge and use of plating and control, and to stimulate its application by a reduction to known facts of the factors which made for good plating.

What formerly was rule of thumb, and handed down haphazardly from one man to another, became an open book, because it was printed, commented upon, adopted or discarded, as it was tested and either proven or rejected.

Witness the following few monumental strides made since 1911 in the plating art:

The adoption of the highest purity nickel and other metal anodes which it was possible to obtain in various forms.

The increase in the density of plating solutions to 10 and sometimes 15 times the normal density used in 1911.

The use of hot solutions and maintenance of uniform temperatures.

The use of moving cathodes and agitated solutions.

The continued improvement and use of more scientific mechanical plating barrels.

The simplification of plating solutions and formulas.

The recognition of cleaner plating solutions.

The introduction into commercial use of large mechanical units for plating masses of material on given time cycles.

The control of solutions and their salts and chemicals and particularly researches into the throwing power of various solutions.

The introduction of modern low voltage electroplating generators, mostly direct driven, which put them on a plane with highly efficient motors and generators used on higher voltage circuits.

The introduction of various finishing and coating metals such as cadmium, chromium, cobalt, in addition to many researches into tin deposition.

The introduction of special machines for polishing and grinding.

All of this is only part of what has been accomplished and any part of the above would of itself be a great step in advance in this art. Such accomplishments as have been recited are only possible by exact knowledge and truth and mostly by co-operation.

Your society is to be congratulated upon its search for such knowledge and upon the co-operation which each branch has shown to the other branch in your monthly pamphlets, in your monthly meetings and in your annual conventions. Such work immeasurably benefits everyone who in any way contributes his little mite, for many atoms make the whole.

It is our hope, therefore, that since your society at the present time is pre-eminently one in this particular line of industry which is in a measure co-operative and makes for collective progress, that you, each and everyone here, resolve yourself into a committee of one to have the good work which has already been accomplished, continued. Also, never allow the point of contact which you have established among yourselves to be broken while any opportunity for progress and better work is possible in the industry.

The contact which you have established with the Bureau of Standards at Washington, the Research Fund which you are collecting to further the interests of the art are all indications of a broad constructive nature which shows the caliber and the character of the men who are members of this body.

Search far and wide and make truth the one guiding word which dominates every action taken by yourselves individually and the society as a whole. Individuals or corporations never can progress as well singly as they can collectively for the old adage “that two heads are better than one” is just as true today as it was hundreds of years ago, provided always, the collective mind is searching and promulgating truth for truth’s sake.

Now let me talk a little on the question of science and common sense. It is obvious that all of us cannot be scientists or business men or artisans. By choice or force of circumstances, we become one or another of a great mass which in its own particular sphere is endeavoring to make for the betterment of all and as each of us is bettered or progresses more than the other, so this combined knowledge spreads to others and makes for more and more betterment of the whole. I plead, therefore, that you do not try to be both scientists, business men and artisans at the same time, for we cannot be all things in one, but we can more or less be one thing in one and be paramount in the one thing which we have chosen. Let the scientist be a scientist in every sense of the word and tell us in plain language what it has been his good fortune-to find or learn or suggest. Let the artisan use this truth which the scientist has promulgated, and we have the ideal combination of science and practice working hand in hand to the advancement of both, and business in general. It is obvious that the scientist cannot solve the commercial problem or the problem of well being for the masses, unless the business man or artisan reduces the scientist’s ideas to practice and it must also be obvious that the artisan or business man cannot very well progress except as he applies the common sense ideas or inventions promulgated by the scientists.

Therefore, I plead with you to take to heart today the fact that some are scientists and others are artisans and others are business men and in your realm may I say that you are more in the nature of artists and artisans, for what is better and more useful than the art in which you are engaged, namely—that of beautifying metals and woods and other objects, for durability, beauty and utility.

The executive of a plating room also has the function of a production manager, for plating is usually the “neck of the bottle” in the final production of articles which are coated. As a production manager, his responsibility to see that the work goes to him in the proper condition for beautifying and leaves his department in perfect condition for use, places a great deal of responsibility and control on his shoulders. While he works with his hands and his assistants work with their hands to get the actual result, the executive plater’s brains must work out the problem beforehand and provide the materials to get the results which the hands attain.

I like to similize the electroplater with the great painter—RAPHAEL—who painted one of the most famous pictures in the whole world—THE SISTINE MADONNA, about 400 years ago. It hangs in the public gallery at Dresden. No painter of modern times has been able to match this beautiful picture in its expression—in its execution and particularly in its theme, but most of all, no one has yet been able to use the red colors in a picture as they were used at that time. Now haven’t we a simile here for our art—the inspiration for the beautifying and enlarging the sphere of usefulness of the objects which we cover? Isn’t there an incentive there to do the best and give the best there is in us from an artistic point of view, for remember Raphael was not a scientist. He simply used the brushes and the paints and the canvas which others had made and as an artist, created one of the masterpieces of the world.

These thoughts lead me to say to you foremen platers and executives that there is a way of doing your everyday job better and better, with the result that every piece which we create simply enhances its value to science and to the world.

Science provides the formulas and laws. You men providing and operating the tools are, in my opinion, artists, learning and taking unto yourselves the knowledge which the scientist has promulgated and which is applicable to your particular vocation or business.

Beware of the half-baked scientist. Beware of half-baked opinions. Be sure that when you use science or the laws of science, you are correctly informed as to their principles, not in details, but in such a way that you can apply them from an artistic or artisan’s viewpoint.

Common sense means the control in your business of yourself, your assistants, the materials and the apparatus, which you use. When we have learned to control these things, we have mastered our art and when we have mastered our art, we are eminent in our particular line. It is not an easy matter, but ten minutes each day of concentrated good thinking will give us the answer. We will always be ready to do better things and we will do them as we control the materials and the then who are doing this work with us and for us.

In conclusion, let me ask everyone to observe a few business rules, which every foreman plater or executive can carry out to the betterment of himself and his associates, his company and his art:

(1) Be open minded.
(2) Be positive when you have made your decision.
(3) Do better and more work every day.
(4) Control yourself, your position, your assistants and your work.
(5) Concentrate ten minutes a day on your art.
(6) Support your society or any other concern or society which is helping to better your industry, unselfishly, and which has truth as its backbone. Support the truth always, for it is the easiest and most beneficial means to any end.

The aim of all life is to be happy. If we had everything in the world and still wanted more, we could not be happy, for we would be dissatisfied. Let us be happy, therefore, in our everyday work—in the knowledge that we are honestly creating for others and at the same time gaining in knowledge and experience in the everyday work we are doing. Let each of us fill our own particular niche with the commonplace and everyday courtesies which mean so much in the spread of good-will and happiness to others. Work which is congenial is the basis of all happiness and I am reminded of Lincoln’s immortal words—

“THAT NO MAN EVER GOT LOST ON THE STRAIGHT PATH.”


NEWARK BRANCH
Newark Branch held its business meeting on March 18 with 21 members present, President George Onksen in the chair.
The banquet committee reported progress for our “9th annual” which will be held on Saturday, April 30.
Messrs. Smith and Sizelone spoke on the deposition of chromium.

Vice President Chas. Bohler spoke on the deposition of copper from an acid copper solution, which contained 16 oz. of free H2SO4 per gallon, and was excellent in structure. Bronze solutions and the production of the Verde Antique finish will be discussed.

The business meeting for April was held on Friday, the 15th, with 19 members and 3 visitors present, George Onksen the presiding officer in the chair. Minutes approved as read. Communications ordered filed. Banquet committee reported progress.
Subject for discussion was as follows: What effect has the addition of cadmium to a silver solution. Mr. Chas. Proctor being present spoke upon the subject and stated that silver solutions with 50% silver and 50% cadmium have been used for several years with good results on certain classes of articles. 70% silver—30% cadmium was recommended for ordinary work. Articles silver plated in a silver-cadmium solution do not tarnish as readily and can be kept clean easily.

Nickel in a silver solution up to 5% nickel can be used with good results. Ammonium chloride should be added to a silver solution when nickel anodes are used in conjunction with silver anodes in order that the free chlorine will dissolve the nickel anode
Cadmium may be used with gold instead of silver in a green gold solution. Mr. Proctor submitted samples of chromium plating on shoe buckles and a watch case cover, and spoke on chromium plating in general.

Our educational meeting for April was exceedingly interesting. Bronze solution was the subject of discussion. Mr. Hogaboom advised using bronze anodes of 95% copper, 5% zinc or 92% copper, 8% zinc; a low free cyanide content, and 2 oz. of Rochelle salts per gallon of solution will keep the anodes clean and bright. With such a low free cyanide content the deposit will of course be dull. If a green color appears in the deposit lower the free cyanide content. A talk on p. H. of nickel solutions was given by Mr. Hogaboom, who stated that the temperature of the nickel solution being tested is a very important factor, and demonstrated on the blackboard the variation of the p. H. from 40 degrees Fahrenheit to 120 degrees Fahrenheit; the same nickel solution having a p. H. of 6.1 at 40 degrees and decreasing to 5.4 at 120 degrees.

Mr. Wood, chief chemist at Landers, Frary & Clark in Connecticut, was a visitor and spoke on p. H. of nickel solutions.
The Verde antique green finish was discussed and the following formula was suggested for the quick formation of the green. One gal. water, 4 oz. nitrate of copper, 4 oz. calcium chloride, 4 oz. ammonium chloride and a small proportion of glycerine which retards the formation which would otherwise dry too quickly.

—ROYAL F. CLARK, Secy.-Treas.


BRIDGEPORT BRANCH
Meeting opened at 8:20. The roll call of officers was read. Frank Salvaggio was absent. Minutes of last meeting were read and accepted.
The banquet committee reported that they have their speakers for the educational session which will be held in the afternoon. They say it will be one of the finest educational sessions ever held at a Bridgeport banquet. Fred Lancaster, chairman, reported that returns are coming in very good, which goes to show that we will have a good crowd.
It was voted on that the Board of Managers have full power in renting our new rooms, which will be in the same building, but a few doors from where we are now located.
Communication was read from the B. & O. Railroad giving us in detail the fares which will be in effect for those going to the convention.
Motion was made to adjourn and to see us all at the banquet—Stratfield Hotel, April 23. Meeting closed at 10:30.

—WILLIAM EHRENCRONA, Sec.-Treas.


DETROIT BRANCH
The Detroit Branch held its regular meeting April 1 with President J. Flanagan in the chair. Being a nasty night out, it was surprising that we had such a good attendance.
Report from the chemical class committee was heard, but the members were undecided as to what kind of a class was to be started, advanced or beginners’ class, so the matter was dropped for the time being. For the good of the order, general discussions on nickel and chrome plating took up the best part of the evening.
The coming convention was also taken up, and it seems the Detroit Branch is strongly in favor of taking the assistant foreman into the society.
We were about to adjourn when the chemical class was taken up again, but a very few members responded, due to the fact that the summer months will soon be upon us, and members will want to get away on their vacations, etc., so the matter was again dropped until next fall, when another attempt will be made to start a platers’ class of some kind. Meeting was adjourned at a late hour.

—C. MASCOLA, Secty.


PHILADELPHIA BRANCH
Philadelphia Branch held its monthly meeting April 1 in the Harrison Bldg., U. of P.
This being All Fools’ Day brought out a large gathering of the members who were not fooled but heard a very good talk by Mr. Leo Riess on ornamental lacquering of novelty goods, illustrated with samples of various finishes on glass and iron casting.
Mr. Riess being well versed in this line of work, his talk was very instructive and was much appreciated.
He will lecture soon again on asbestos boards, etc. Watch for the date and let us have a larger attendance.

—PHILIP UHL, Secty.


NEW YORK BRANCH
The March meetings of the New York Branch were held at the World Building, Park Row, New York City. Both meetings were well attended. Three new members were received into the branch during the month and applications for two others were received.
At the first meetings cleaning problems were discussed and some very interesting points were brought to a head.
Mr. Jos. Hass also gave the members a treat on his talk on problems he had met with in silver plating stainless steel table knives.
The second meeting was presided over by our vice president, Mr. Arthur Grinham, and the branch acted on sending a paper by Mr. Loeb to be read at the Toledo Convention.

—RALPH LIGNON, Rec. Sec.


CHICAGO BRANCH
Regular monthly meeting of Chicago Branch, A. E. S., was held April 9, 1927, at the Atlantic Hotel. The meeting was called to order with President Jacob Hay presiding, and good attendance reports were heard from the members who attended the joint meeting of the American Chemical Society and American Electroplaters Society at which meeting Dr. Wm. Blum spoke on Polarization. This meeting was very well attended.
Mr. H. A. Gilbertson, chairman of the Booster Committee on the Toledo convention, reported that they had selected the New York Central Line as the official line to carry our members. Notice as to time schedules and date will be mailed to all our members.
President Hay called upon several of the members who had promised papers for the convention. Several reported progress.
Our next meeting will be election of officers and it is the president’s wish that all members attend.

The balance of the evening was given over to our librarian who had the following questions:
Question 1. What is a good acid to etch stainless steel?
Answer 1. Muriatic acid with an addition of iron chloride.

Question 2. What is a good dip for oxidizing brass that will take the place of black nickel?
Answer 2. Ammonia and carbonate of copper was given.

Question 3. What causes spotting out on cold-rolled sheet steel plated brass?
Answer 3. Solutions too high in carbonates was given as one season. Pores in metal was also stated to cause this condition.

Question 4. What is a good addition agent to a bronze solution to keep anodes from taking on a film and get good results?
Answer 4. Rochelle salts was recommended.

Question 5. Is there any other dip for brightening copper, other than the regular acid dip?
Answer 5. A bright dip which contains a small amount of water was suggested.

—R. Meyers, Secty.


SILVER CYANIDE PLATING SOLUTION

F. H. Nordman (Continued)

OBJECT OF THIS INVESTIGATION
This investigation was undertaken with a view of determining the characteristics of silver cyanide plating solutions made from sodium cyanide and potassium cyanide. It involved:

1. A comparison of the characteristics of deposits of silver plated from solutions made from C.P. sodium cyanide and C.P. potassium cyanide.

2. A determination of the effect of such impurities as chlorides, carbonates and hydroxides on the characteristics of the deposited metal.

3. A study of the rates of decomposition of the solutions made from sodium and potassium cyanides.

4. A determination of the effect of such impurities as chlorides, carbonates, and hydroxides on the rates of decomposition.

5. A determination of the relation, if any, between the free cyanide decomposed and the carbonate formed and in this way check the equations for the decomposition of the solutions.

The first part of the experimental work consisted of making up the various solutions and plating from them to obtain characteristic deposits. The solutions used in the experimental work were made from C.P. chemicals. The analyses of the solutions are given below. Samples No. 1 and No. 2 were intended to represent plating solutions made from C.P. sodium and potassium cyanides. The solutions were made by precipitating silver cyanide from silver nitrate by means of potassium or sodium cyanide and the solution of this silver cyanide in an equivalent amount of potassium or sodium cyanide was filtered. Cyanide, in the quantity desired for the free cyanide content of the solution was then added.

Samples No. 3 and No. 4 were intended to represent the solutions made from cyanides containing approximately 15 per cent of chlorides. In the case of sodium cyanide this represents the cyanide that is commonly sold as sodium cyanide equivalent to 100 per cent potassium cyanide. These solutions were made as above, the chloride being added as C.P. potassium chloride or C.P. sodium chloride.

TABLE 1
Analysis of Experimental Plating Solutions
Grams per liter
Free
Combined
Sample
(CN)
(CN02
Cl
CO3
OH
CNO
Salt
1
9.5635
9.6635
trace
.5925
.3024
trace
K
2
10.0360
10.0606
trace
.3675
.5481
trace
Na
3
10.3276
10.3774
3.6212
.4645
.3011
trace
K
4
10.3395
10.8435
3.2160
.2450
trace
trace
Na
5
10.2000
10.5271
trace
.6820
1.6291
trace
K
6
11.8972
10.9792
trace
.4907
1.5416
trace
Na
7
11.8156
11.6297
trace
1.5190
.2196
trace
K
8
11.8156
11.7102
trace
1.5925
.2031
trace
Na


Sample No. 5 and No. 6 were solutions to which were added C.P. sodium and potassium hydroxides equivalent to about 10 per cent hydroxide in the cyanides.

Samples No. 7 and No. 8 were made to represent solutions in which cyanide, containing about 10 per cent carbonate, was used in the preparation. These solutions were prepared as above, the carbonate being added as C.P. sodium and potassium carbonates.

The method of analysis of these solutions for the constituents noted above was that suggested by Paterno and Pannain (5). It is as follows:

“1. To a 10 c.c. sample add a known excess of standard silver nitrate solution. Dilute to 100 cubic centimeters. In 50 c.c. of the filtrate determine the excess silver nitrate by Volhard’s method. The silver nitrate added minus that found in the filtrate gives the amount consumed by the cyanide, cyanate, carbonate, hydroxide and chlorides.

“2. To a second 10 c.c. sample add a known excess of silver nitrate and an excess of acetic acid. Dilute to 100 c.c. and filter. In 50 c.c. of the filtrate determine the excess silver nitrate as above. The difference between the silver nitrate used in each case is consumed by the precipitation of the cyanide, cyanate and chloride.

“3. To a third sample (10 c.c.) add a known excess of silver nitrate and an excess of dilute nitric acid. Dilute to 100 c.c. In 50 c.c. of the filtrate determine the excess silver nitrate as above. The difference between the silver nitrate consumed in each case is used in the precipitation of the cyanide and chloride. The silver nitrate consumed in (2) minus that consumed in (3) is the amount of silver nitrate used in precipitating the cyanate.

“4. To a 50 c.c. sample add an excess of barium nitrate. Dilute to 100 c.c. and filter rapidly. To 20 c.c. of the filtrate, corresponding to a 10 c.c. sample of the original solution add a known excess of silver nitrate. Dilute to 100 c.c. and determine the excess silver nitrate in 50 c.c. of the filtrate. The AgNO3 consumed precipitates silver cyanide, silver cyanate, silver chloride and silver oxide. Subtract this amount from (1) and there remains the silver nitrate used by the carbonate in solution. Subtract (2) from (4) and the silver nitrate used by the hydroxide is obtained.”

The chloride determination used was as follows:

Ten c.c. of the plating bath are diluted to 100 c.c. and N/2 nitric acid is added until acid to methyl orange. Heat just to boiling in hood, and again add N/2 nitric acid until neutral. Heat just to boiling 15 minutes and filter. Wash precipitate with water. Add 5 c.c. N/2 nitric acid to filtrate and heat just at boiling 30 minutes, keeping the volume of the solution at about 125 c.c. Add silver nitrate to precipitate the chloride, stir until precipitate is coagulated, filter on Gooch and dry at 105° C. for one hour.

The free cyanide content of the solution was determined by the method suggested by G. E. F. Lundell (6).

“The sample taken from analysis should contain 0.2 to 0.5 gram of free cyanide. The sample is diluted to about 100 c.c., 1 c.c. of ammonium hydroxide is added, 1 c.c. of 1 per cent dimethy gloxime solution is added and the solution is titrated to a permanent red precipitate with standard nickel ammonium sulfate solution, containing about 15.3 gms. of sulfate per liter.

(To be Concluded in May Issue)



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