Glass. — \ i , Book - W tt Tke, Electro-Platers Hand-Book By JAMES H. WESTON ILLUSTRATED BY Z. ELLIOTT BROOKES FREDERICK J. DRAKE & CO. PUBLISHEKS CHICAGO COPYRIGHT, 1915 BY FREDERICK J. DRAKE & COMPANY COPYRIGHT, 1905 BY FREDERICK J. DRAKE & COMPANY /Ci- DEC -9 1915 ©CLA416794 This book has been written to meet the require- ments of platers desiring a practical and yet non-technical work on electro-plating. The sub- ject-matter given herein has been obtained from platers of practical experience, and the construc- tion and operation of the different devices used in the electro-deposition of metals are fully described and illustrated. It contains useful information for platers and others who wish to become acquainted with the practical art of the electro-deposition of metals and their alloys, including Electro-deposition of Metals, Electro-deposition of Alloys, Electro-plat- ing Dynamos, Electro-plating Solutions and Elec- tro-plating Apparatus. The Author The Electro-platers Hand-book ELECTRICAL RULES AND FORMULAS In order to enable the operator of an electro- plating plant to intelligently handle the batteries or dynamo and plating vats and turn out work properly, it is almost absolutely necessary that some knowledge of the fundamental principles of electricity should be had. Electricity or electrical energy may be gener- ated in several ways — mechanically, chemically and statically. By whatever means it is pro- duced, there are many properties which are com- mon to all. There are also distinctive properties. The current supplied by a battery is of the direct form and will flow continuously until the battery is practically exhausted. The dynamo current is primarily of an alter- nating nature or one which reverses its direction of flow rapidly. In use, this alternating current is changed into a direct or continuous current flowing in one direction only, by means of a commutator. The cause of a manifestation of energy is force, if of electromotive energy, that is to say of electric energy in the current form, it is called 7 8 THE ELECTRO-PLATERS HAND-BOOR electromotive force. What this condition of excitation may be is a profound mystery, like gravitation and much else in the physical world. The practical unit of electromotive force is the volt. When electromotive force does work a current is produced. The practical unit of current is the ampere. A current of electricity passes through some substances more easily than through others. A current of one ampere is maintained by one volt through a resistance of one practical unit. This unit is called the ohm. The volt, the unit of electromotive force, will generate a current of one ampere in a circuit hav- ing a resistance of one ohm. There are several specified equivalents for estimating the exact value of one volt, but these usually refer to the determined capacity of some given type of dry cell. The ampere, the unit of current strength, has been fixed as the equivalent of a current strength which can deposit .00033 grams of metallic cop- per, by the electro-plating process, in each second of time. In this respect it measures not only the current intensity, or available working energy, but also the rapidity of its work. The work above stated might readily be accomplished by a given current in ten seconds, instead of in one, but such a current would not have the value of one ampere, only of 1-10 ampere — since it would require ten times as long to accomplish the same result. ELECTRICAL RULES AND FORMULAS 9 An analogy for the ampere is the miner's inch, which represents the product of an orifice one inch square, through which water is allowed to escape from a tank, by the height of the column of water in the tank, in inches. The miner's inch is, therefore, in the first place, a measure of rate or velocity, giving inch-seconds, or the number of cubic inches of water passed in each second of time. Thus, while water flows at the rate of so many miner's inches, the electrical current flows at the rate of so many amperes, the rate per second, in both cases, being directly relative to the original pressure at the source. It is inaccurate to speak of an ampere per second, since such an expression means simply a current of one ampere. In speaking of a current of ten amperes, it does not refer to the amount of cur- rent passed in ten seconds, but to that passing in one second. The ohm, the unit of resistance, measures not only the relative resistance of a circuit composed of a conducting wire of a given length and diam- eter, as compared with wires of different length and diameter, composed of the same material, but also the specific resistance, which refers to the variations in resistance found between wires of the same length and cross-section, but of different materials. The different resistance of different metals, as found in circuits, precisely similar in all other dimensions, is demonstrated in the fact that, while a silver wire shows a conductivity of 100, and one of copper, 99, a wire of iron gives only 16.80. 10 THE ELECTRO-PLATERS HAND-BOOK Ohm's Law. This law expresses the relation in an active electric circuit of current, electromo- tive force or voltage and resistance. These three factors are always present in such a circuit. Its general statement is as follows : In an active electric circuit the current is equal to the electromotive force divided by the resist- ance. This law can be expressed in various ways as it is transposed. It may be given as a group of rules, to be referred to under the general title given above. 1. The current is equal to the electromotive force divided by the resistance. B °-R 2. The electromotive force is equal to the cur- rent multiplied by the resistance. E = CxR 3. The resistance is equal to the electromotive force divided by the current. * E 4. The current varies directly with the electro- motive force and inversely with the resistance. 5. The resistance varies directly with the elec- tromotive force and inversely with the current. 6. The electromotive force varies directly with the current and with the resistance. This law is the fundamental principle in most electric calculations. If thoroughly understood ELECTRICAL RULES AND FORMULAS 11 it will apply in some shape to almost all engineer- ing problems. The law will be illustrated by examples. Single Conductor Closed Circuits. These are circuits embracing a continuous conducting path with a source of electromotive force included in it and hence with a current continually circulating through them. Example : A battery of resistance 3 ohms and electromotive force 1.07 volts sends a current through a line of wire of 55 ohms resistance. What is the current? Answer: The resistance is 3 + 55 = 58 ohms. By rule 1 the current is 1.07 + 58, which gives .01845 of an ampere. A point to be noticed here is that whatever is included in a circuit forms a portion of it and its resistance must be included therein. Hence the resistance of the battery has to be taken into account. The resistance of a battery or gener- ator is sometimes called internal resistance to dis- tinguish it from the resistance of the outer circuit, called external resistance. Resistance in general is denoted by R, electromotive force or voltage by E, and current by C. BATTERIES A battery is rated by the resistance and electro- motive force of a single cell. In the case of storage batteries, whose susceptibility to polari- zation is very slight, the resistance is often assumed to be negligible. There are two resistances ordinarily to be con- sidered, the resistance of the battery which is designated by E or by n times K if the number of cells is to be implied and the resistance of the external circuit which is designated by r. The current given by a battery is equal to its electromotive force divided by the sum of the external and internal resistance, that is C- E Example: A battery of 5 cells arranged to give 7*5 volts, with an internal resistance of 10 ohms, sends a current through a conductor of 12 ohms resistance. What is the strength of the current? Answer: Current = 7. 5 -*- (10 -»- 12) = .34 of an ampere. Arrangement of Battery Cells. In practice the cells of a battery are arranged in one of three ways. All may be in series, all may be in paral- lel, some may be in series and some in parallel, so as to represent a rectangle. 12 BATTERIES 13 Other arrangements are possible. Thus the cells may represent a triangle, beginning with one cell, followed by two in parallel and these by three in parallel and so on. This and similar types of arrangement are very unusual and little or nothing is to be gained by them. The electromotive force of a battery is equal to the voltage of a single cell, multiplied by the number of cells in series. The resistance of a battery is equal to the number of its cells in series, multiplied by the resistance of a single cell and divided by the num- ber of its cells in parallel. Example : A battery of 50 gravity cells 1 volt, 3 ohms each is arranged 10 in parallel and 5 in series. What is its resistance and electromotive force? Answer: Resistance = 5x3-*- 10 = 1.5 ohms. Voltage =5x1 = 5 volts. The same battery is arranged all in parallel, what is its resistance and voltage? Answer: This gives one cell in series. Resistance = 1 x 3 -*- 50 = .06 ohm. Voltage =1x1 = 1 volt. The same battery is arranged all in series, what is its resistance and voltage? Answer : This gives one cell in parallel. Eesistance = — - — = 150 ohms. Voltage * 50 x 1 = 50 volts. 14 THE ELECTRO-PLATERS HAND-BOOK The current given by a battery is obtained from these rules and from Ohm's law. As the difference between these arrangements can be more clearly shown by illustrations than by a voluminous description, diagrams are here given to illustrate the different arrangements. At A in Figure 1 the cells are shown arranged in series, the zinc in one cell being connected to the carbon of the next, and so on through the whole line of cells. By this arrangement the electro- motive force or power of each cell is added to that of its neighbor, and the internal resistance of each cell is added in a similar manner. But only the volume of current generated in one cell is had. This is shown by the following figures, calculated according to Ohm's law. Supposing the electromotive force of each cell to be 1.80 volts, and the interal resistance of each cell 0.06 ohms, then, taking three cells in series, the fig- ures will be: 1.80 + 1.80 + 1.80 = 5.40 volts OA 0.06 4-0.06 + 0.06 = 0.18 ohms = 3 ° amp6reS * But, if only one cell is taken, the figures will be: 1.80 volts 0.06 ohms 30 amperes. The difference being, in the first case a current of 30 amperes at a pressure of 5.40 volts, while in the second case the same current of 30 amperes, but at a pressure of only 1.80 volts. At B in Figure 1 the cells are shown arranged in parallel, the zincs being all coupled to one conductor, and BATTERIES 15 the carbons to the other conductor of the circuit. By this arrangement the three cells are in a corn- Fig. 1. Arrangement of Battery Cells. bination equal to one large cell, and get the elec- tromotive force voltage of one cell divided by one-third of its resistance, since there are now 16 THE ELECTRO-PLATERS HAND-BOOK three paths of equal resistance open to the pass- age of the current. The figures therefore are : 0.06.3 = 0.02 = 9 ° am P ereS ' with a voltage of only 1.80 volts. When the external resistance of the circuit is added to the internal resistance of the battery, far different results of a more practical value are given. Sup- posing, for instance, that the resistance of solu- tion, slinging wires, and leading wires amount to the total of 1 ohm, then the figures will be, in the first arrangement : 1.80 x 3 = 5.40 0.06x3 + 1.00=1.18 = 4 '° 7 ampereS ' While in the second arrangement the following result would be given : 1-80 0.02 + 1.00 = ^ amperes. This shows how useless it is to couple up cells in parallel to a high resistance in the outer circuit, such as would be met with in actual plating prac- tice. But, if four cells are coupled, as shown at C in Figure 1, which may be described as coup- ling in parallel series, the following results are given : 1.80x2 = 3.^o on ^3x2 + 1.00 = 1.06 = 3 * 39 ampereS ' Tims, by arranging the cells in groups, in either ifrcies, parallel, or parallel series, the required rolume of current through the work is obtained BATTERIES 17 at the voltage suitable to the deposition of the metal in a proper condition. It is preferable to so arrange the cells, as shown, instead of dividing the circuit, or adding resistances to keep back the current. ELECTRO-PLATING WITH BATTERIES The first experiments in electro-plating were carried out with current derived from galvanic batteries. Its application to commercial uses was also made by the same means. Some good work on a large scale has been done with current from batteries. Al- though, in large work- shops, the battery as a generator has been quite superseded by the dynamo, it still retains its place in small shops and in the home of the amateur electro-plater. When operations in a small way have to be con- ducted at intervals in small shops where power cannot be read- ily obtained to drive a dynamo, the use of a battery becomes a neces- sity, and is a less costly generator than a plating dynamo with its accessories. Batteries used for electro-plating are of two forms, single and double liquid types. In the first-mentioned form the elements, which usually 18 Fig. 2. Single Liquid Type of Plating Battery. ELECTRO-PLATING WITH BATTERIES 19 consist of carbon and zinc plates or cylinders, are immersed in the same solution, while in the double liquid form the carbon element is in one solution in a porous cup in the center of the con- taining vessel or jar and the zinc element sur- rounds the porous cup in another solution. A battery of the single liquid type is shown in Figure 2, in which the carbon and zinc elements are attached on either side of a wooden sup- port. To charge this form of battery, add 1 part (by volume) of sulphuric acid to 8 parts of water, when cool add 2 parts (by weight) of nitrate of soda. Chromic acid or bichromate of soda may be used instead of the nitrate of soda as a depolarizer, but are much more expensive. A double liquid type of battery is shown in Figure 3. To properly charge such a battery, add 1 part of sulphuric acid to 10 parts of water, when cool put in the containing vessel or jar in which the zinc element goes. If chromic acid is used as the depolarizing agent in the porous cup, use 2 parts (by weight) of chromic acid to 10 parts (by volume) of water. When either bi- chromate or nitrate of soda are used, the propor- Fig. 3. Double Liquid Type of Plating Battery. 20 THE ELECTRO-PLATERS HAND-BOOK tions should be as follows: Water 8 parts, sulphuric acid 8 parts (by volume), bichromate or nitrate of soda (by weight) 2 parts. The zinc elements should be kept well amalgamated and always removed from the cell when the bat- tery is not in use. The single liquid type of battery has a voltage of from 1.63 to 1.75 volts per cell, while the double liquid battery has a voltage of about 2 volts per cell. The positive pole or carbon of the battery should always be connected to the anodes in the plating solution and the zinc or negative to the cathodes or work being plated. Construction of Batteries. The construction of batteries for electro-plating must be governed by the requirements of the work. These usually demand a full, constant current at a low voltage. To insure the first condition, large cells must be used and have electrodes with a large surface. The cells should be not less than one-half gallon in size, and may be of ten-gallon size with ad- vantage. The electrodes must be large, to cor- respond with the cells, but there should be at least one inch free space below the plates when they are fully immersed. This space being necessary to prevent short circuiting and local action caused by particles of metal falling from the electrodes to the bottom of the cell. It is a well-known rule, that the surface of the plates in a battery should exceed that of the anodes in the depositing solution, and these should present a ELECTRO-PLATING WITH BATTERIES 21 snrface slightly in excess of the surface to be plated. When the cells are arranged in series, only the surface of the electrodes in one cell can be taken into account, all the others being em- ployed in forcing the current through the resist- ance in the circuit. Large cells and large electrodes insure a low internal resistance of the battery, and consequently more force for use in the outer circuit, since the strength of the cur- rent will be equal to the voltage of the battery divided by all the resistances in the circuit. To insure constancy, both the exciting and the de- polarizing liquids must be in a condition to work through the required time. Amalgamation of Zinc. The zinc plates used in batteries are rarely made of pure metal. Even the best rolled zinc contains impurities. The effect of these impurities is seen in local action, in which the impure zinc forms with the purer particles a number of galvanic pairs. By coating the zinc with mercury, this tendency to local action is reduced to a minimum. As the zincs come from the maker, they are coated with a greasy film, unless sent out amalgamated. To remove this film, dip the zincs in hot water in which some washing soda has been dissolved, and rinse them in clean water. Pour some mercury in a shallow dish, such as a baking dish or a porcelain tray, and cover the mercury with a mixture of sulphuric acid and water, made by adding 1 part by measure of sulphuric acid to 3 or 4 parts by measure of water. Some caution is 22 THE ELECTRO-PLATERS HAND-BOOK always required when adding this acid to water, as the acid combines with the water in such a violent manner as to cause great heat and spurt- ing of the mixture. The consequences might be serious damage to skin and to clothing, as the acid is very corrosive and will quickly destroy clothing. Therefore, always add acid to the water slowly, but never add water to the acid. Place the zincs in the dilute acid and brush the mercury all over their surface with a brush made of fine steel wires, until all the surface has been made bright with the mercury. Then set the zincs aside in an empty dish to drain off the sur- plus mercury. Zincs must be reamalgamated in a similar manner when any part of them have lost their coat of mercury, and bare gray patches appear on them whilst being cleaned. A wide bristle brush will be found a very useful article for brushing zincs after use in the battery. When zinc cylinders are used, the insides must receive the most attention, as these are the parts subject to the action of the acid. Set the zincs in empty jars when not in use, to catch the mer- cury draining from them. ELECTRO-PLATING DYNAMOS The evolution of the dynamo may be said to date from the time when it was discovered that an electric current passing through a coil of wire produced an inductive effect on a magnetic needle placed beneath it, or, in other words, an electric current passing through a wire exerted mag- netic effects on iron and steel placed near the wire. This discovery led Michael Faraday, in 1831, to infer that, since a magnetic effect could be produced in iron by a current of electricity, a magnetized piece of steel in motion should pro- duce an electric current. A long spiral or helix of copper wire was therefore procured and its ends connected with a galvanometer. A power- ful bar magnet was then introduced into the spiral of wire. This being done, a deflection of the galvanometer needle took place instantly when the bar magnet was placed in the coil, and an opposite deflection was caused when the mag- net was withdrawn. This discovery led to the construction of a machine in which a disc of cop- per connected by wires to a galvanometer was caused to revolve between the poles of a power- ful horse-shoe magnet, and thus set up a current of electricity in the wire. Other experimenters fol- lowed on the same lines, and in the course of a few years the magneto-electric machine was so far de- 23 24 THE ELECTRO-PLATERS HAND-BOOK veloped as to produce brilliant sparks, give power- ful shocks, and also effect chemical decomposition. Principle of a Dynamo. A dynamo-electric machine is a machine constructed to convert dynamic or mechanical force into electric energy. It has been already shown that a moving bar magnet will induce a current of electricity in a helix of copper wire surrounding the magnet. The influence of a magnet is not only felt in a wire wrapped around its poles, but extends to a considerable distance beyond them. In the case of a horse-shoe magnet the magnetic influence fills the space between the poles, and extends beyond them. This space, thus filled with mag- netic lines of force, is called the magnetic field. If some turns of insulated copper wire are wrapped around a bar of iron, and it is caused to move in this magnetic field so as to cut the lines of force, a current of electricity will be induced in the turns of wire wound on the iron bar, by the cut- ting of the lines of magnetic force through which it moves. If some insulated copper wire be wound around the legs of the magnet, a current of elec- tricity will be set up in the magnet coils as well as in the coils of wire surrounding the iron bar. It may be mentioned that in the field of a horse- shoe magnet there is a neutral zone in which there are few lines of magnetic force to be cut by the moving bar. It follows, therefore, that the electric inductive influence of the magnet on the armature coils will be greatest where the lines of force cut are the most dense. As the armature ELECTRO-PLATING DYNAMOS 25 is made to move in the magnetic field, there will be two strong magnetic impulses and two re- versals. If the ends of the armature coil are connected with the ends of the magnet coil so as to send the strong impulses through this coil in one continuous direction, the effect of this current of electricity flowing through the magnet coils will be an increase of magnetic strength in the magnet. This is done in a dynamo by means of a device known as a commutator. A commu- tator is made in the form of a split ring of brass mounted on an insulated hub, and fixed on the shaft of the armature. The two ends of the armature coils are connected with the two sec- tions of the commutator, and the current is col- lected from these by two strips of metal called brushes. In some armatures there are several coils. When this is the case, the commutator has as many segments as there are coil ends, but the action is the same. As the coil of wire passes out from the most intense part of the magnetic field into the comparatively neutral zone, the impulse given to it is interrupted by a division in the commutator, and diverted by way of the brush to the magnet coil or to the outer field. In this way a current of electricity is generated by the rotation of the armature in the coils of wire wound on it and also on the field magnets, and the machine thus becomes a generator of electricity. Selecting a Plating Dynamo. The resistance of the plating solution, the slinging wires, and the wires conducting the current from the dynamo to 26 THE ELECTRO-PLATERS HAND-BOOK the vat being known, the armature of the dynamo should be wound with wire offering a resistance of one- twentieth the working resistance of the outer circuit. The field magnets should be wound with wire having a total resistance of 400 times that of the armature, or 20 times the total resistance of the outer circuit. The armature coils should be connected in shunt with the coils of the field magnets, to insure uniformity of the current under varying loads, and to prevent re- versal of the magnetism in the dynamo by the current being sent through the field magnet coils in the wrong direction. It should be understood that all solutions, through which a current has been passing, form in themselves a galvanic bat- tery, with the articles being plated and the anodes as elements. The plated articles being the posi- tive elements, and the anodes the negative ele- ments, in this galvanic battery, the current generated is therefore opposite to that employed in the work of electro-plating. If the coils of the field magnets of a dynamo are connected in series with those of the armature and the outer circuit, the back current from the solution will rush around the coils immediately after stopping the dynamo, or on slowing down its speed, and will reverse the poles of the field magnets by inducing in them an opposite condition of mag- netism to that existing while the dynamo is in proper working order. This is prevented by con- necting the field magnet coils in shunt with the armature, and should the back current from the ELECTRO-PLATING DYNAMOS 27 solution become sufficiently powerful to pass round the field magnet coils, it passes through them in the same direction as it is sent by the dynamo itself, and does not reverse the permanent magnetism of the field magnets. In a dynamo wound for electro-plating, with the coils connected in shunt, the magnetism of the field magnet cores will be proportionate to the resistance in the outer circuit. If there are several articles suspended in the solution, and a proportionate surface of anode, the resistance of the outer circuit will be low, and the greater volume of current will flow by the path offering least resistance, which will be, in this case, through the solution. As a consequence, only a small portion of the current will pass around the field magnet coils, and thus the magnetic in- tensity of the fields will be low. If, on the con- trary, the resistance in the plating vat is high, when only a few articles are immersed in the solution, the path of least resistance will be by way of the field magnet coils, the armature cur- rent will flow by this path, increase the intensity of the magnetic field, and raise the tension of the current, thus enabling it to overcome the in- creased resistance in the plating vat. Choice of a Dynamo. In the early days of plat- ing dynamos for electro-deposition, the makers were few and far between. At the present time almost any maker of dynamos can make a ma- chine for electro-deposition. In choosing a new dynamo, see that it is shunt wound, that is, that 28 THE ELECTRO-PLATERS HAND-BOOK the wires from the field magnet coils are con- nected one to each brush, and that the terminals which lead to the outer circuit are also connected one to each brush. Although the series machine is cheaper to operate for a given output, yet it is sure to be subject to reversal sooner or later. Mechanical devices are in use to prevent the in- jurious back flow of the current from the vat, but these are not always reliable. Compound wound machines, which possess both shunt and series coils, are equally liable to reversal, but these machines are very suitable for special work re- quiring a constant low voltage through varying resistances in vats connected in parallel with the dynamo. The output of the dynamo should be expressed in amperes, but some makers express the output by so many square feet of exposed cathode surface, thus giving the plater some idea of the surface of goods he can cover at the same time. The dynamo chosen should have a broad, firm base, so as to stand steady while running. Its bearings should be long, and provided with means to keep them well lubricated, to prevent heating while at work. It must be well ventilated by air spaces between the coils, to keep them cool while the machine is working. Heating of the coils and bearings means a loss of power in the outer circuit, and a loss of driving power, since heat absorbs the force which should be converted into electricity. The driving pulleys should have broad, smooth surfaces, to prevent loss of power 6y slipping belts, and the machine should be ELECTRO-PLATING DYNAMOS 29 driven from a countershaft. All wearing parts should be so arranged as to be easily got at and removed for repair. This applies specially to the brushes, brush-holders, and commutator. The brush-holders should not be fixed to any part of the machine, but should be attached to a rocker arm, pivoted in such a manner as to allow of free movement through an arc of a circle, for the easy Fig. 4. Plating Dynamo of the Weston Type. adjustment of the brushes to any angle. The commutator segments should be of hard copper. The brushes may be of carbon or fine copper gauze. The brush-holders should be pivoted on the rocker arm and furnished with springs to exert an equal pressure on the brushes. Plating Dynamo- A plating dynamo of the Weston type is illustrated in Figure 4. These 30 THE ELECTRO-PLATERS HAND-BOOK dynamos may be either shunt or compound wound. The frame and pole pieces are of cast steel. For the frame a special soft grade is used, having a high magnetic permeability. The field coils are made of insulated copper wire wound compactly by machinery, insuring the maximum ampere turns without great bulk. The whole coil is properly insulated and protected from mechanical injury. The armature is of the toothed type and is most carefully constructed. The core is built up of thin soft steel discs. Each disc is insulated on both sides and assembled on a spider con- structed to insure the greatest amount of venti- lation. The armature coils are made in a form and per- fectly insulated. The slots in which the coils rest are also insulated, so there is no chance for a ground. The segments of the commutator are forged from pure copper carefully insulated with the best mica. The radials from the bars are so arranged that a steady current of air is thrown on the com- mutator and brushes. The bearings are self-aligning, and the boxes made of special bronze, and provided with large oil wells and automatic oiling rings. These machines are said to run continuously under full load with a rise of temperature above the surrounding atmosphere not exceeding 8 degrees Centigrade (46 degrees Fahrenheit) in windings, and somewhat less in the commuta- tor. The commercial efficiency is said to be ELECTRO-PLATING DYNAMOS 31 85 per cent, and the electrical efficiency 93 per cent. Compound versus Shunt Wound Plating Dyna- mos. A little information as to the merits of compound as opposed to shunt winding may not be out of place. The shunt wound dynamo has only one winding on its field magnets, in which only a portion of the current generated passes through the field winding and in operation will lower its voltage as the tanks are filled with work, while the brushes have a tendency to spark on the commutator, which necessitates their regula- tion from time to time as the load increases or decreases. These particularly undesirable features are due to the method of winding of a shunt wound dynamo, which permits only a small portion of the current generated by the armature to pass through the field coils, while at the same time the armature reaction is constantly tending to reduce the field magnetism, which in many types of shunt wound machines makes necessary an exciter in the shape of a small dynamo, in order that the fields may be properly charged. This current from the exciter must be regulated as the load on the dynamo is increased or diminished. Under these conditions more time must be con- sumed in plating a given batch of work than would be necessary if the dynamo was of com- pound type, while the sparking of the brushes on the commutator as load is increased or decreased requires frequent renewal of the latter. 32 THE ELECTRO-PLATERS HAND-BOOK In the plating room where there are a number of tanks containing different solutions of varying densities, or of solutions requiring a difference in voltage for the successful production of work, the disadvantage of a shunt machine is apparent for the reason that when a tank is emptied and so much load is taken from the machine, the voltage will increase in all the other tanks, thus making necessary a constant watchfulness on the part of each man in charge of a tank, or work may be burned. There are other disadvantages which always apply to the shunt wound type of dynamo. Compound Wound Plating Dynamo. A com- pound wound dynamo has two distinct windings on its field magnets, one of very many turns of fine wire, called the shunt winding, and another known as the series winding, which latter con- sists of a number of turns of heavier gauge wire. The series winding is in series with the vats or external circuit. The current that is used in the vats, passing through this winding, increases the magnetism of the field as the load increases, and thus the drop in voltage, which would otherwise occur by reason of the increased drop in the armature winding and increased magnetic reac- tion caused by the armature current, is provided for. Speed of Plating Dynamos. Plating dynamos are built to run at lower speeds than electric lighting dynamos, because the voltage of a plat- ing current is lower than that employed for elec- ELECTRO-PLATING DYNAMOS 33 trie lighting. The voltage of the current from a dynamo largely depends upon the speed of its armature. As each yard of active wire on an armature coil is capable of developing one volt when driven at a circumferential velocity of 1,250 feet per minute, the voltage of the current from a dynamo may be readily calculated if the length of the active wire on one of its armature coils and the speed at which the armature is driven be known. The circumferential velocity of the armature may be ascertained by measuring its diameter, multiplying this by 3.14 to find the circumference, and then by the speed of the armature. To increase the voltage of the cur- rent from a machine its speed must be increased, and to lower the voltage the speed must be de- creased. Plating dynamos are usually driven at speeds varying from 700 to 1,500 revolutions per minute. The speed can be ascertained by co ant- ing the revolutions of the driving pulley and cal- culating the speed of the pulley driven by it, or the speed of the armature shaft may be taken direct by means of a speed indicator. Dynamos, Efficiency of. The limit of efficiency of a dynamo is at the point where the voltage or pressure ceases to be strong enough to deposit metal to the best advantage. In shunt wound machines the voltage usually drops below the desired pressure when- from one-half to two-thirds of the ampere capacity is being taken out. Com- pound wound dynamos will maintain the same pressure up to the full rated capacity of their 34 THE ELECTRO-PLATERS HAND-BOOK amperage, and it is for this reason that from compound wound dynamos an efficiency of from one-third to one-half more can be obtained over shunt wound machines of the same rated capacity. Over-Compounding. Although a compound wound dynamo possesses distinct advantages over the shunt wound machine for electro-plating, still better results in the maintenance of a con- stant potential may be obtained by the process known as over-compounding in which the series field winding is given a sufficient number of turns in proportion to the turns in the high re- sistance shunt winding to cause its influence to overbalance that of the shunt winding. The resist- ance of the main circuit between the dynamo and the plating tanks is known, and the drop in volt- age due to that resistance depends upon and varies with the amperes of current (C) made use of. Then by following Ohm's law (See page 10) where E = C X R, the over-compounding of the dynamo may be so regulated with respect to the series and shunt field windings, that when there is an increased demand for current there will also be a corresponding increase in potential, the result being that a constant voltage will be main- tained at the plating tanks. In over-compounding it is advisable to put a somewhat greater number of turns of the series winding in the field coils than is actually needed to overcome armature reactions and lost voltage in order that there may be an increase of four or five per cent more voltage at full load over that at no load. ELECTRO-PLATERS MATERIALS In a well organized electro-plater's shop there are many appliances necessary besides plating bat- teries and dynamos for properly performing the" work. Some of these are necessaries, without which not even the most simple operation may be done, while others may be termed conveniences for facilitating larger operations or work of a more intricate nature. Platers working even in the smallest way with a plating battery must have suitable vessels for holding the plating solutions and the various pickles used in preparing the work. Slinging wires are necessary for holding the articles in the solutions, and suitable brushes for cleaning the work before being plated and finishing its surface afterwards. Among con- veniences may be mentioned a selection of revolv- ing scratch brushes, and a lathe for revolving them, a similar selection of small polishing wheels, made of different materials, and denomi- nated dollies, mops, bobs, etc.. together with a suitable machine for working them, a set of hand brushes for cleaning and polishing, and a set of burnishers if silver and gold plating is to be done. Plating Vats. Although the outer containing box is made of strong wood with well-fitting joints, this material alone is not suitable for pla£- 35 36 THE ELECTRO-PLATERS HAND-BOOK ing solutions, since the wood absorbs a large quantity of the solution, and the salts creep over the sides. The frame must therefore be lined with a material impervious to the speedy action of the cyanide, such as a coating of asphaltum, but better yet is sheet lead, this will resist the action of the cyanide for many years, but all joints must be made by burning instead of solder- Fig. 5. Nickel-plating Tank. ing, as solder will form with lead a galvanic pair, and a galvanic action will soon corrode the joints. The lead-lined tank must then be lined with match-board, to prevent the accidental contact of the articles with the lead lining, and the upper rim of the vat should be framed with strips of wood boiled in paraffine, to prevent the internal absorption and creeping of the salts. ELECTRO-PLATERS MATERIALS 37 Plating vats should be selected with a view to the magnitude of the operations to be performed in them. If the operator desires to plate a few rings, scarfpins, brooches, studs, sleeve-links, solitaires, and similar small articles, a suitable vat is an enameled iron saucepan holding from one to two pints of liquid, or a stoneware salt-jar immersed in hot water in a saucepan, but if Fig. 6. Group of Plating Tanks. watch-chains, watch-cases, and similar longer or more bulky goods are to be plated, a larger pan or vat must be obtained. If the operations are to be extended to a larger trade, a larger enameled iron vat, capable of holding from five to ten gal- lons, will be required, and this must be heated over a suitable furnace, or over an atmospheric gas-burner, or by means of a steam-jacket. The two last means are preferable, as being more 38 THE ELECTRO-PLATERS HAND-BOOK under control than the first. It must be under- stood at first, that the vat for gold-plating solu- tions must be impervious to the attacks of potas- sium cyanide when heated to a temperature of from 150 to 180 degrees Fahrenheit. All metals except platinum are soluble in hot cyanide solu- tions, and nearly all other substances, except glass, vitrified stoneware and enameled iron. Fig. 7. Glazed Stoneware Tank. Figures 5 and 6 show different styles of plating vats. Plating tanks for very large work are usually made of wood and lined with a thick coating of asphaltum. Tanks. Tanks for use with acid should be of glass or glazed stoneware, enameled wrought iron tanks are more suitable for potash and alkaline solutions. A heavy glazed stoneware tank is shown in Figure 7. For small work a good ELECTRO-PLATERS MATERIALS 39 quality of white enameled iron cooking utensil may be used for the potash solution. Heating Tanks. Large tanks for heavy work are usually made of cast iron and heated by a steam coil in the bottom of the tank. Such tanks are used for solutions that must be kept hot, such as lye, rinsing water, cleaning compound and cyanide solutions. These tanks, along with Fig. 8. Steam Tanks with Coils in the Bottom of the Tank. the steam chamber, are cast in one piece. A pair of the tanks are illustrated in Figure 8 in posi- tion and ready for use. Another form of steam tank or kettle is illus- trated in Figure 9. A positive circulation of steam is carried through the channels shown in the drawing in the bottom of the tank. These 40 THE ELECTRO-PLATERS HAND-BOOK are extra tanks and adapted for use wherever lye, cleaning compound, water or alkaline solutions are to be kept constantly hot. Fig. 9. Steam Kettle with Corrugated Steam Passages. Fig. 10. Glazed Stoneware Dipping Baskets. Dipping Baskets. Baskets of glazed stoneware are always used when a number of small articles have to be dipped in acid or cyanide solutions. ELECTRO-PLATERS MATERIALS 41 Fig. 11. Steel or Aluminum Wire Dipping Baskets. 42 THE ELECTRO-PLATERS HAND-BOOK t^ffi;:.:.rr-^^y;:.^{^J^Z^^Q ' Fig. 12. Potash Hand-brush. As successful dipping depends more upon quick and careful handling than upon the nature of the dip itself, the holes in these baskets should be as large as possible, to allow of the rapid escape of the acid or cyanide. Three forms of glazed stoneware dipping baskets are illustrated in Figure 10. Woven wire baskets of round or square shape are also used for dipping purposes. They are made of brass, steel or aluminum. Ten different styles of these baskets are shown in Figure 11. Scouring Brushes. When articles are be- ing cleaned in alkaline solu- tions to remove grease, brushes made of animal fiber cannot be used, as it would be eaten away by the solution. For this purpose brushes known as potash brushes are used. They are made of hard wood backs fitted Fig. 13. Potash Brushes. ELECTRO-PLATERS MATERIALS 43 with knots or tufts of cotton or other vegetable fiber. Some of the many kinds of brushes used for this work are shown in Figures 12 and 13. Brushes used for scouring the work with are illustrated in Figure 14. They are of three forms, as shown, having flat, curved and shoe handles to suit different conditions of work. Fig. 14. Scouring Brushes. They are made with either brass, steel or fiber bristles. Scratch-Brushes. Brushes intended for the general work of cleaning large surfaces are made of brass or steel wire, and of various degrees of softness according to the gauge of the wire used. These brushes are fitted with wooden hubs, with 44 THE ELECTRO-PLATERS HAND-BOOK a hole in the center to fit the spindle of the lathe. Three different forms of scratch-brushes are shown in Figure 15. The one shown in the upper view is for flat work and the two brushes shown in the lower view for cup and goblet work especially. For smaller articles, such as thimbles and rings, the brushes shown in Figure 16 are better adapted, especially for inside work. Scratch-Brush Lathes. A com- bination foot- power lathe for use with either small buffing wheels or scratch -brushes is shown in Figure 17. For small jobs these lathes will be found well adapted. A power combination bench lathe is shown in Figure 18. Fig. 15. Scratch-brushes for Flat, and Goblet Work. Cup ELECTRO-PLATERS MATERIALS 45 Scratch-brushes for Thimbles and Rings. Dust-Brushes. For removing dust from highly- polished gold or silver plated articles, after being dried in hot sawdust, the brushes shown in Figure 19 are well adapted, as they are made of camel ' s hair. Polishing Wheels. Wheels or buffs used for polishing articles may be divided into two classes, those for pre- paring the sur- faces to be plated and those for finish- ing or giving the final polish- ing during the plating opera- tion. Various forms of pol- ishing wheels and buffs are shown in Fig- Fig. 17. Foot-power Scratch-brush ure 20. Lathe. ft if 11 By 46 THE ELECTRO-PLATERS HAND-BOOK Polishing Wheels, Directions for Using. Screw on the spindle only tight enough to hold in place. If there is any flutter or side motion, some- times caused by careless handling or screwing too tight, it can be remedied by side pressure of the hand, or by loosening or tightening the nut on the spin- dle. Always remember to use care the first Fig, 18. Power Bench Scratch-brush time m settin g Lathe. the wheel. Fig. 19. Camel Hair Dust Brushes. ELECTRO-PLATERS MATERIALS 47 Run in direction indicated by the arrow on the face. Soft and medium for silver, nickel work, brass, etc. Medium for stove, axe, or plow work, and saddlery hardware. Hard for gold, brass, emery hard grinding, and for grease or oil work. Fig. 20. Polishing Wheels. Polishing Wheels, Balancing of. All wheels running as fast as they mast in polishing, require to be very carefully balanced or they will pound or chatter, making good work impossible. Balancing is accomplished by placing the wheel 48 THE ELECTRO-PLATERS HAND-BOOK on an arbor and rolling it on two level, knife- edged strips of metal, one on each side of the wheel. Thus suspended the wheel will stop with its heaviest part downward, and with a little chalk to mark the wheel and some small pieces of sheet lead to fasten on the side of the wheel, bal- ancing is quickly and easily performed. It may also be done by hanging the arbor between cone centers, as pulleys are balanced in a machine shop, but the rolling method of balancing en bars, which is precisely the method the watch- maker employs in poising a watch balance, is the quickest and best. Leather wheels are used in polishing and fine grinding, where a flexible wheel is necessary. There are many different kinds of wheels which may be classed under this head. Walrus wheels are made from the tanned hide of the walrus, and are used for work requiring the wheel to be turned up to a thin, moulded edge or curve, as they are thick enough to allow such shapes to be made from a single piece. Bull neck wheels are made from the thickest and toughest portions of hides, and form a harder wheel than walrus. They are much used In stove, bicycle and other steel and iron wcrk. Other leather wheels are similar in their nature, differing only in the mechanical structure and degree of hardness, the desirable quality being the ability to hold the emery up to the work without allowing any lumps or unevenness in the glued emery to cut into or gouge the work. ELECTRO-PLATERS MATERIALS 49 Felt wheels are used with emery and glue, or with polishing compositions. They are of vary- ing degrees of hardness and either white or gray. The higher-priced felt wheels are the cheapest in the end, the extra price being more than made up in the increased durability and uniformity of the white wheels, which wear much longer, and give a superior finish, than do the cheaper gray felt wheels. Cotton buffs are made of discs of muslin and are used with pastes of tripoli, crocus or rouge for finishing or coloring. The hardest buffs are made in sections, from duck, stitched or quilted together, while the soft buffs are muslin stitched only at the center. As many sections as may be necessary to make the desired thickness of wheel are put on the arbor and the flanges set up until the wheel runs properly. Canvas wheels are made of coarse duck or can- vas, cut into discs of the required size and glued or cemented together under pressure, after which they are bored out to receive the arbor, put on the machine and turned up to the required shape. Emery or corundum wheels are used for grind- ing off the imperfections on castings caused by breaks in the moulds. These wheels are of vary- ing thicknesses, grades, sizes and shapes- and should be run at correspondingly varied speeds in order to get the best results out of them. If run too fast th^y will glaze and require frequent dressing to keep them sharp. Too much pressure when grinding will also glaze a wheel. 50 THE ELECTRO-PLATERS HAND-BOOK Polishing Lathes. Polishing lathes are, as a rule, made much heavier and stronger than scratch-brush lathes, and have massive cast iron pedestals and extra long bearings so as to stand heavy work at high speeds. The spindles are fitted at their outer ends with screw threads, col- lars and lock-nuts for clamping the wheels upon ii pi fiflfc' Fig. 21. Extra Heavy Polishing Lathe. them. The work of polishing is best done when the spindle is driven at a high rate of speed, as the greater the surface velocity of the wheel or buff, the better and quicker the finish is imparted to the surface of the work. An extra heavy polishing lathe is shown in Fig- ELECTRO-PLATERS MATERIALS 51 ure 21, and various forms of spindles for use in the same are illustrated in Figure 22. Fig. 22. Spindles for Heavy Polishing Lathe. Polishing Materials. The materials in use for polishing metals to prepare them for plating are: Finely prepared and sifted sand, lime, rotten stone, pumice stone, and various compositions of 52 THE ELECTRO-PLATERS HAND-BOOK emery, crocus, tripoli, and rouge for imparting a high state of finish to the articles. Tripoli, crocus, and rouge, in various grades to suit the work, are made up into cakes or bars. In this form it gives less trouble, and makes less waste than when used in the form of loose powder. The cake of composition is pressed against the wheel or buff whilst it revolves, which then becomes charged with the abrading material and holds it whilst the work of polishing is being done. Tripoli is used in the rough on leather wheels for preparing brass work. The fine tripoli is used on calico buffs for imparting a high finish on brass, copper or steel before it is plated, and in finishing nick el -plated work. Crocus is used for a similar purpose. Rouge composition is used to impart a high state of finish to jewelry, spoons, forks, and electro-plated goods. Pumice stone in fine powder, and rotten stone, are used in scouring goods by hand with brushes in the scouring trough. Pumice stone in lumps, and rotten stone, are both employed as abrading materials to rub down by hand, rough, pitted and corroded surfaces in places difficult to be got at with wheels or buffs. Tripoli comes in three grades: Coarse, for cut- ting down rough or hard brass or bronze on hard buffs. Medium, which is used on medium buffs for smoothing and cutting down softer metals. Fine, which is used, on soft buffs for coloring on cheap work and for use in place of the harder rouges where the color of the latter is ELECTRO-PLATERS MATERIAL 53 objectionable and is difficult to get out of the work. Lime. The lime used for polishing is a pure anhydrous lime, obtained from Vienna, and is ex- tensively used where the red color of rouge is objectionable. It must be used while slacking or it is of no value, so it mast be kept in the airtight tin or bottle in which it was shipped. Rouge. This polishing material is used for coloring brass, gold, silver and the softer metals. It is divided into numerous grades, which are dis- tinguished by the names of the metals for which they are used. Crocus. This substance is an oxide of iron, made by calcining sulphate of iron in great heat and then grading it into polishing powders. The more calcined part is of a bluish purple color, coarser and harder than those portions which have been exposed to a lesser heat, and is called crocus, while the softer and redder portions of the material are called rouge. Pumice Stone. This material is described as a highly porous, light mineral substance of volcanic origin, resulting from the solidification of foam or scum formed by the escape of steam or gas on the surface of molten lava, and is composed of 72 per cent of silica, 17 per cent of alumina, 2 per cent of iron oxide, and 9 per cent of soda and potash. Pumice stone is used in powdered form for scouring the work, to remove all traces of oil, 54 THE ELECTRO-PLATERS HAND-BOOK grease or lye, just before putting the work in the plating solution, also in lumps, for scouring spots that refuse to take the plating, which is a com- mon fault in replating old goblets, cups and trays that have been badly corroded. Speed of Wheels. The peripheral speed or cir- cumferential velocity of a polishing wheel or buff should not exceed a maximum velocity of 100 feet per second, or a minimum velocity of less than 70 feet per second, if good work is expected from the wheel or buff. As the wheels or buffs wear down the work proceeds slower and slower, unless cone pulleys are provided on the line shaft and the countershaft of the polishing lathe. The accompanying table gives the maximum and minimum speeds for wheels from 1 to 36 inches in diameter, in revolutions per minute. Speed of Wheels in Revolutions per Minute. fcs Revolutions per U CO CD £> Revolutions per si Minute. So Minute. C3 r-i u p. 2 Minimum. Maximum. S.a Minimum. Maximum. 1 13,000 18,000 9 1,760 2,460 n 10,000 14,000 10 1,580 2,210 2 7,900 11,000 12 1,320 1,850 2£ 6,330 8,800 14 1,130 1,580 3 5 ; 275 7,400 16 990 1,380 3J 4,500 6,300 18 880 1,230 4 3,950 5,500 20 790 1,100 4* 3,500 4,900 22 720 1,000 5 3,160 4,400 24 660 920 6 2,640 3,700 26 600 850 7 2,260 3,160 30 500 735 8 1,980 2,770 36 400 585 ELECTRO-PLATERS MATERIALS 55 Wheel Truing Device. A wheel truing device for balancing polishing wheels of all kinds, iron pulleys or emery wheels, is shown in the upper view in Figure 23. The cones will take four sizes of arbors, and are usually furnished with the machine. Wheel Clean- ing Machine. A wheel cleaning machine is illus- trated in the lower view in Figure 23. By placing the worn wheel in this Fig. 23. Wheel Truing Device and Wheel Cleaning Machine. machine, and letting it run a few minutes with the water just touching the rollers, all of the glue and emery will be removed without damag- ing or loosening the leather covering. This machine has two rows of movable rods to keep the wheels from falling over. The idle roller also has two positions for different diam- eters of wheels. The speed of the machine should be about 20 revolutions per minute. Belt Straps are made of canvas or duck, from one to two inches wide, glued and set up with 56 THu, ELECTRO-PLATERS HAND-BOOK emery as previously described, and used in polish- ing flat surfaces, such as cutlery, flat springs, large tubes for bicycle frames, etc. They are run on flanged pulleys, one of which is supported on a standard and the other, which is the driver, is sometimes mounted in place of a wheel on one of the polishing heads. Belt Strapping Machine. This belt strapping device shown in Figure 24 is simple in construc- Fig. 24. Belt Strapping Machine. tion and easily operated. It is designed with a view of meeting the require- ments of the large variety of work which experience has shown can be econom- ically and rapidly pol- ished or roughed off by this method. The facility with which this machine can be operated makes it applicable for many small articles heretofore polished on regular wheels. This attachment can be used to great advantage by manufacturers of bicycles and bicycle parts, ELECTRO-PLATERS MATERIALS 57 brass cocks, and other plumbers' fittings, gas fixtures, grate and fender work, while for cutlery- it seems to be indispensable, as with no other Fig. 25. Burnishing Tools. device can the operator reach as well all sorts and conditions of metal surfaces that are inaccessible with the regular polishing wheels. 58 THE ELECTRO-PLATERS HAND-BOOK Burnishing Tools. The work of burnishing is usually performed by means of steel tools, a com- plete set of which are illustrated in Figure 25. Hydrometers. These are glass instruments resembling thermometers in outward appearance, but having a large glass bulb near the bottom, as shown in Figure 26. They are used for testing the specific gravity of liquids, or, in other words, to test their den- sity as compared with that of pure water. The liquid to be tested is placed in a narrow glass jar, Fig- ure 27, from the flask shown in the same figure, together with the hydrometer, or may be put in any other vessel. The instrument floats in the liquid to be tested, with its bulb below the surface and its stem standing above the surface. This stem is graded in degrees similar to that of a ther- mometer, and shows the depth of the bulb beneath the surface. In pure water the bulb sinks down to the degree mark, or to 1000 as marked on some scales, 1000 being taken to represent the density of water at a temperature of 60 degrees Fahrenheit. As the den- sity of the water increases by the addition of salts or of liquids having a greater density than /^ r i i & i w I Fig. 26. Hydrometer. ELECTRO-PLATERS MATERIALS 59 water, the bulb is forced upwards, and the scale then registers so many degrees greater density than water. Two differently graduated hydrometers are in use in this country. These are: hydrometers graded to read direct the spe- cific gravity of liquids in com- parison with that of water, taking this as represented by 1000, and hy- drometers grad- ed by a scale adopted by M. Baume, and called th e Baume densi- meter. The dif- ference between the two gradings is shown in the following table. In some text-books and printed instructions on this art, reference is made to test- ing solutions by means of a hydrometer, and cer- tain figures are given to denote the required den- sity of the solution. These are fallacious unless direct reference is also given to the kind of hydrom- eter to be used. This will be seen on reference to the following table, wherein is shown at a glance the difference between the readings of Baume and the direct reading specific gravity hydrometers. Fig. 27. Testing Jar and Flask for Use with Hydrometer. 60 THE ELECTRO-PLATERS HAND-BOOK Table Showing Readings of Different Hydrometers. Baume Specific Gravity Baume Specific Gravity Baume Specific Gravity 10° 1 . 0000 37° 0.8395 64° .7423 11° 0.9930 38° .8346 65° .7205 12° .9861 39° .8299 66° .7168 13° .9791 40° .8251 67° .7133 14° .9722 41° .8204 68° .7097 15° .9658 42° .8157 69° .7061 16° .9594 43° .8110 70° .7025 17° .9530 44° .8063 71° .6990 18° .9466 45° .8017 72° .6956 19° .9402 46° .7971 73° .6923 20° .9339 47° .7927 74° .6889 21° .9280 48° .7883 75° .6856 22° .9222 49° .7838 76° .6823 23° .9163 50° .7794 77° .6789 24° .9105 51° .7752 78° .6756 25° .9047 52° .7711 79° .6722 26° .8989 53° .7670 80° .6689 27° .8930 54° .7628 81° .6656 28° .8872 55° .7587 82° .6619 29° .8814 56° .7546 83° .6583 30° .8755 57° .7508 84° ,6547 31° .8702 58° .7470 85° .6511 32° .8650 59° .7432 86° .6481 33° .8597 60° .7394 87° .6451 34° .8544 61° .7357 88° .6422 35° .8492 62° .7319 89° .6392 36° .8443 63° .7281 90° .6363 Thermometers. In electro-gilding operations a thermometer is needed to ascertain the right temperature of the gilding solution. This instrument must be wholly of glass, as any metal- work will dissolve in the hot gilding solution. The best for this purpose are those with a white enameled scale enclosed in a glass tube. The scale may be graded in degrees, Fahrenheit or ELECTRO-PLATERS MATERIALS 61 Centigrade, as may be most convenient to the operator. If the scale is graded in Centigrade degrees, and it is desired to ascertain the value of a reading in degrees Fahrenheit, multiply the reading by 9, divide the product by 5 and add 32. If the reading is in degrees Fahrenheit subtract 32 from the reading, multiply the remainder by 5 and divide the product by 9 to convert the reading into Centigrade degrees. Rheostats, Use of. Rheostats are of the first importance in the plating room. Without them the varying degrees of current necessary for handling different solutions, or for manipulating baths of various sizes, cannot be obtained. A rheostat is necessary in the field of the dynamo where it will control the voltage along the entire line of connection, enabling an initial current strength to be maintained while the tank rheostats further reduce this current to the pro- portions required. The rheostat in the field, while it affects the voltage by setting a fixed resistance in the field of dynamo, does not affect the ampere capacity except in a minor degree. On the other hand the rheostat placed between the main line and the tank affects both the voltage and amperes, reducing the latter in the same proportion as the former is cut down. It is necessary, then, that the rheostat selected for the tank be of ampere carrying capacity sufficient to handle the current used in the tank. If the rheostat has not suffi- cient capacity to handle the ampere current a 62 THE ELECTRO-PLATERS HAND-BOOK Fig. 28. Rheostat. resistance is formed which prevents the proper amount of current from flowing into the tank. The action of a current of elec- tricity can be likened to the passage of water through a pipe, the force with which the water flows from the aperture repre- senting the volt- age, while the quantity discharged may represent the ampere current. If a valve or stop-cock is placed in this pipe the action would be similar to that of the rheostat in an electric circuit. In arranging tanks it is neces- sary that con- ductors be of sufficient size to carry the great- est number of amperes the tank will handle. Different solutions require different amperes per square foot of work surface. Fig. 29. Voltmeter. ELECTRO-PLATERS MATERIALS 63 ' A plain rheostat is illustrated in Figure 28. Voltmeters. The voltmeter shown in Figure 29 has a scale from to 6 volts and upwards. The scale is divided into 120 divisions, so that each division represent one-twentieth of a volt, and when used in connection with the switch boards will enable the plater to study carefully all the requirements that insure good results, and will give the means of accurately reproducing such Fig. 30. Combination Voltmeter and Rheostat. conditions as have been found by experience con- ducive to success. A combination of a voltmeter and a rheostat mounted on a slate base is illustrated in Figure 30. Ammeter. It is a fundamental law of elec- trolysis that a certain number of amperes passing through a plating solution will cause a definite weight of metal to be deposited. As, for instance, one ampere will deposit in one hour 1.106 grammes of nickel, 4.15 grammes of silver. It is evident, therefore, that by means of an accurate 64 THE ELECTRO-PLATERS HAND-BOOK ammeter, such as shown in Figure 31, the amount of metal actually deposited can easily bo de- termined. Time Dial. To denote the time of taking the work out of the tanks, the dials illustrated in Figure 32 will be found to be very useful. They are made very strongly of bronze, oxidized and lacquered, with nickel-plat- ed hands, and bright figures. They are eight inches in diame- ter, and are quite flat, and can be screwed up or suspended over or near tanks. Respirator. Figure 33 shows one of the latest forms of respira- tors. This is one of the best devices for protecting the throat and lungs from dust, Fig. 32. Time Dial. poisOUOUS gases, Fig. 31. Ammeter. 1 PW 1 mWS m! i p 7* ■ v /^H ELECTRO-PLATERS MATERIALS 65 and all other impurities, in places where persons are exposed, and, many times, life endangered. In respiring, the air is inhaled through a thin, wet sponge or cotton, and, in expiring, passes out through an automatic valve in the side, so that breathing with the respir- ator is easy, allowing it to be worn con- stantly, without the least incon- venience. They are manufac- tured of the best white rub- ber, and will last a lifetime. The sponge can be easily taken minute. Steam Generators. Where no outside source or supply of steam is available, the steam generator shown in Figure 34 will be found a very useful adjunct to au electro-plating plant. The generator has a ring below, a water front beneath the fire door, and water tubes surround- ing the fire and steam dome above. Cast iron shields fit in the spaces between and behind the tubes and extend around the heater from the top Respirator. out, rinsed, and replaced in one 66 THE ELECTRO-PLATERS HAND-BOOK of the bottom ring and as high as the bottom of the fire door. These shields prevent the accumulation of Fig. 34. Steam Generator. FU. 35. Rubber Gloves. between the tubes. They also become hot and radiate their heat to parts of the tubes not ex- posed to the fire. There is an air space between them and the outer sheet steel jacket. In the smaller sizes a float and valve to automatically regulate the wa- ter supply is placed inside the steam dome, while in the larger sizes this water-regulat- ing device is con- tained within an iron float box outside of the boiler, but con- nected to it by pipes, as shown. The safe- ty valve is set to blow off at about 12 ELECTRO-PLATERS MATERIALS 67 pounds' pressure and the float has buoyancy enough to shut off the water up to about 30 pounds' pressure. In places, therefore, where there is a water works pressure of from 12 to 30 pounds or so the boiler can be attached at the float valve to a pipe from the hydrant. Where pressure is above or below this or there is no water works a supply barrel or iron supply tank can be used. Rubber Gloves. Figure 35 shows two styles of rubber gloves for platers' use when handling chemicals, lye, acids, etc. Finger Cots. These finger cots, which are very necessary for the protec- tion of fingers against chemi- cals, and also for scratch- brush work, are shown in Fig- ure 36. Wooden Shoes. As wa- ter in abundance is found to be necessary for some plating and pickling operations, which keep the floors constantly wet, the shoes shown in Figures 36 are a very desirable article of wear for the plater. Fig. 36. Finger Cot and Wooden Shoe. 68 THE ELECTRO-PLATERS HAND-BOOK flr^a V J /S mh t l m Ha// /#! ^-yj^=^ H — H ^-rrB ^ — — H : '-^=~~Mi ~>_ w^j ^ss) Fig. 37. Rubber Apron. wife 1 ^'.^V'^ilM fitefr - WPSI^ -',o d t, u d d =: z: o eg • rt s- h d w C, " J -1 ■+J — go e8 >. G 6 2 d Hi O 1 74 THE ELECTRO-PLATERS HAND-BOOK depend upon the number of amperes of current we can get through the solution. The salts of nickel, zinc, tin, and iron appear to need a cur- rent of greater strength to decompose them than those of gold, silver, and copper. Rate of Deposit of Metal. Each metal has its own peculiar qualities which govern the rate at which it can be deposited in a good condition. This condition has been named a reguline state, that is, a state nearly like that of the metal when melted and cast in a mould. Electro-deposited metal, however, is generally so porous, even in its best condition, as to be rarely air-tight and water- tight. The quality of a deposit is governed by the quality of the solution from which it was obtained, the temperature of the solution, and the quantity of electric current passing through the article to be coated, in a stated time. This last is called the density of the current, and it determines the quantity of metal which can be deposited in a given time. The following list shows the quantity of metal which can be de- posited with a current density of one ampere on one-tenth of a square foot of surface in one hour. Aluminium, 52.4977 grains. Silver, 52.1142 Zinc, 18.7240 Copper, 18.1638 Gold, 37.7290 Nickel, 16.9030 CLEANING THE WORK The term cleanliness, when applied to metal surfaces about to receive a coat of electro-de- posited metal, means absolute freedom from the least trace of dust, grease, or other animal mat- ter, rust, corrosion, or any other form of oxidized metal. As an example, a surface made clean by any mechanical means alone will not serve the purpose, because loose metal dust and minute particles of the polishing material may be left on the surface, or the cleaning material may be oily or greasy, and the particles of dirt thus left on would prevent perfect adhesion of the deposited metal. If a perfectly clean surface be handled with the naked hand, the deposited coat will strip off the spots touched with the hand. The surfaces to be plated must therefore be made clean by mechanical means, and then made chemically clean by suitable solutions of acids or of alkalies. Each metal requires a slightly differ- ent treatment to that of others. Cleaning Cast Iron. Iron castings may be coated with copper or with brass in an alkaline bath, or with nickel or zinc, but are rarely coated with silver or with gold. The method of clean- ing is the same for each process. The casting must be first freed from the hard black crust of burnt sand on its surface, and particles of sand 75 76 THE ELECTRO-PLATERS HAND-BOOK from its pores. To do this, immerse the casting in a pickle composed of six fluid ounces of sul- phuric acid to each gallon of water, and let it soak for half an hour. If, at the end of this time, the black crust has become sufficiently loose to be rubbed off with the tip of a finger, the operation of pickling is complete. If there are obstinate scales, re-immerse it in the pickle for a short time, then try the hard spots again. If they are still obstinate, pour a little muriatic acid on them and put the casting again in the pickle. When the black scale is all loosened, rinse the casting in water and take it to the scouring tray, where it must be scoured with wet silver sand and a hard brush until a clean, bright surface has been obtained. If there are any sand-holes, these must be cleaned out with a sharp steel point, and the clean, bright casting rinsed at once in clean water, then transferred without loss of time to a cold potash solution. In this it may remain for a short time whilst getting the bath ready, when it must be again rinsed in clean water, and transferred at once to the bath of copper, nickel, brass, tin, or zinc. If the casting is large, a number of stout slinging wires must be employed, as cast iron itself is an inferior conductor of electricity. If the casting is greasy, or has been used where oil could get on it, the casting must be put in a hot potash dip, scoured, and rinsed before placing in the acid pickle. If it is rusty, the rust spots should be smeared with muriatic acid before being placed in the pickle. CLEANING THE WORK 77 Cleaning Wrought Iron or Steel. Wrought iron should be treated in a similar manner to cast iron, the pickle being the same for both, but it will not be necessary to leave the articles so long in the pickle before scouring them. As a high polish may be desired on wrought iron and steel articles, this is given to them on the polishing lathe by means of emery wheels, and bobs charged with sand, lime, emery, rough cut tripoli, and other abrading substances, to first grind down all roughness, then finish with crocus powder on a leather mop, or with the crocus powder on a cir- cular bristle brush. After being thus brought to a high state of polish they should be passed through the potash dip to free them from the grease contracted in polishing, rinsed in water, and brushed with a soft brush free from grease, then transferred at once to the plating vat. Should there be any delay in finishing the pol- ished steel, or should the article be large, its sur- face will be sure to contract a slight film of rust, and this must be removed by dipping each article for a few moments in a pickle composed of eight fluid ounces of muriatic acid in each gallon of water, then rinsing in water and transferring at once to the plating bath. Celerity in finishing wrought iron and steel is necessary, because of the tendency of these metals to rust when wet and exposed to the air. The slightest film of rust, not to be detected by the eye, will be suffi- cient to cause a loose deposit which will strip whilst being finished or burnished. 78 THE ELECTRO-PLATERS HAND-BOOK Cleaning Copper, Brass, and German Silver. As brass and German silver are alloys -of copper with zinc and nickel, they may be conveniently classed together for preparatory treatment, this being the same for all of them. There are several other alloys of copper with zinc, nickel, tin, aluminium, and iron, but to the plater they are all brass, and are to be treated in a similar man- ner in preparing them for plating. It must be distinctly understood beforehand that defects in the surfaces of metals cannot be covered up by depositing upon them a coat of another metal. If the surface of the article is scored with scratches, or pitted with corrosion, the scratches and pits, however small, will appear on the plated surface, and cannot afterwards be effectu- ally removed by subsequent polishing and burnish- ing. Even when the surface has been highly- polished, if it should be accidentally marred by a stain, the dull, irregular spot will appear on the plated surface and mar its appearance. This fact points to the necessity of care being taken in removing all scratches and other roughness from the surface by a series of polishings, beginning with rough cutting materials on bobs and buffs made of bull-neck, walrus, and leather, felt, etc., and finishing off with the finer abrading materials on calico and swansdown mops. In large estab- lishments this work is done in the polishing room by men who devote their whole time to this branch of the business, and the polished articles are handed into the plating room on shallow CLEANING THE WORK 79 wooden trays. As they leave the hands of the polisher their surfaces have a bright, lustrous appearance, and it would appear to the uniniti- ated that it would be only necessary to wire the goods and hang them at once in the plating vat, so clean and bright do they appear. As a fact, the smooth, bright surface left by the polisher is covered by a slight film of grease left from the polishing materials, and this must be removed by soaking the goods in a hot potash dip. They must therefore be connected to lengths of wire and suspended in the hot potash solution until wanted at the scouring trough. After the film of grease has been removed in the potash dip, the articles are taken one at a time to the scouring trough and laid on a transverse shelf of wood, whilst briskly brushed -with hogs' bristle brushes dipped in finely-powdered pumice stone, or with a mixture of equal parts pumice and rotten stone. This is done to clear off the last remaining trace of animal matter, and also to impart a slight uni- form roughness to the surface, such being neces- sary to insure perfect adhesion of the deposited coat of metal. To insure this, it is not necessary to scour the surface hard, but to merely brush it briskly to and fro with a wet brush charged with the scouring powder, care being taken to keep the brush well charged with the powder. The brush to bo used for this purpose must be free from grease, but should the presence of grease or oil be suspected, it will be well to take the pre- caution of dipping the hairs for an instant in the 80 THE ELECTRO-PLATERS HAND-BOOK potash solution and rinsing the brush in water before using it. The scouring trough should be divided into two parts, one division being used for scouring and the other containing water for rins- ing the scoured articles. The powdered pumice is held in a box fixed to the inside edge of the scouring division, furthest from the workman, who first dips his brush in the water and shakes out the surplus, then dips it in the box of powder, some of which adheres to the wet hair. This process is repeated as the powder wears off, and, when the article is properly scoured, it is rinsed in the water contained in the rinsing division, wired with the necessary slinging wires, dipped in the final dipping solution, again rinsed in clean water and suspended at once in the plating solution. While German silver, brass, and some other alloys of copper are being scoured, they contract a slight film of oxide. If the cleaned articles are to be nickel-plated, this film is removed by dip- ping in a solution of cyanide of potassium in water, called a cyanide dip, and this is the final dip before placing the goods in the plating vat. If the goods are to be silver-plated, they should receive a final dip in a dilute solution of nitrate of mercury, which coats the surface with a thin film of mercury. This process, named quicken- ing, is adopted to remove the film of oxide already noticed, and to replace it with a film of clean metal to which the silver can closely adhere. It is sometimes used in preparing articles to be CLEANING THE WORK 81 gilded, but quickening is not always necessary to perfect adherence of silver or of gold. If the gilding or plating solutions are properly pre- pared, and the scouring operations conducted with sufficient celerity and care, a perfect adherence of the gold or silver coat can be secured by swill- ing the article in a cyanide dip, as for nickel- plating, or by merely moving it to and fro in the plating bath for a few moments before connecting the slinging wires to the cathode rod. Cleaning Old Articles. Much of the plater's time in jobbing shops will be taken up in plating old articles, or in re-plating those that have formerly been coated with tin, zinc, nickel, silver, brass, or gold. The first consideration should be paid to the nature of the old plated coat, with a view to adopting the proper means for its complete removal, since successful re-plating of articles coated with patches of metal cannot be done. As old articles are generally more or less dis- colored by tarnish and dirt, this coat must be first removed by boiling in potash solution and brushing with the scratch-brush. Gold may be distinguished from brass by dropping on the coat from the tip of a glass rod a single drop of nitric acid. This acid will immediately dissolve the brass and cause a green spot, but on gold it will not have any effect. Silver may be distin- guished from nickel or from German silver by dropping on the coat a mixture of 6 parts nitric acid and 1 part chromic acid, to which has been added 2 parts of water, or 2 parts strong bi- 82 THE ELECTRO-PLATERS HAND-BOOK chromate of potash solution instead of chromic acid. If silver is present, it will be indicated by a blood-red spot where the mixture attacks the metal, while a greenish spot will reveal the pres- ence of German silver or of nickel. Tin and zinc will freely dissolve in a mixture of muriatic acid and water, but this will have no effect on silver and very little effect on nickel. When the outer coat of grease, dirt or plated metal has been re- moved, the surface will be seen to be pitted, scratched and otherwise worn. These marks must be removed on the polishing lathe or by hand if the re-plated article is to have a finished appearance, unless in so doing the metal is worn too thin to be of any use. When the surface is thus polished, it must be further treated as new work to be plated. It sometimes happens that old goods are made up in pieces put together with soft solder. These soldered joints will clearly appear after the dirt and outer coats have been removed, and are likely to cause trouble if not discovered and properly treated before placing the goods in the plating vat. Soldered joints must be coated with copper in the following man- ner after the article has been scoured. A small glue brush or paint brush must first have some fine iron wires twined among its hairs, which must then be dipped in a strong solution of sul- phate of copper and drawn along the soldered seam. This will cause a thin film of copper to be deposited on the solder, and this film will readily take the mercury from the quickening solu- CLEANING THE WORK 83 tion. If there are large patches of solder or lead mounts on the article, it will be best to coat the whole article with copper or with brass in an alkaline coppering or brassing solution before attempting to plate it with silver, gold, or nickel. If old cruet-stands are made up of two or more different kinds of metals or their alloys soldered together, these must be unsoldered and the differ- ent parts treated apart, or the whole must be coated with copper in an alkaline copper bath before plating. It sometimes happens that articles are made up of tinned iron bottoms, cast pewter legs and sides soldered together, German silver or brass wires and steps, and pewter knob or loop at the top. These parts may be detected by scraping some obscure spot with an old knife or a file. As such dissimilar metals will not plate together in the bath at the same time, because they form galvanic pairs in the solution, we must either separate them by unsoldering, and plate them separately, soldering them together again afterwards, or give the whole a coat of copper under a vigorous current, then quicken with mercury and re-plate without loss of time. Cleaning Work by Hand. The use of ma- chinery for polishing metals has, to a certain extent, superseded the old practice of preparing and finishing the articles by hand. As a large quantity of good work has been frequently done by hand in the past, the same quality of work may still be turned out in small shops, where all 84 THE ELECTRO-PLATERS HAND-BOOK the scouring, polishing and brushing must be done by hand. The first thing to be done is to remove all dirt and corrosion. This is effected by means of the acid and other dips, combined with alternate brushings with coarse bristle and wire brushes in the scouring trough. Next is the removal of all corrosion pits, scratches and other damages to the surface. The first part of the process is done with lumps of pumice stone previously faced by rubbing on a flat stone. With these prepared lumps dipped in water, all the corroded and scratched parts of the surface are gone over, grinding them down until they are almost obliterated, then the entire surface is gone over in a similar manner to produce a uniform effect. This done, well rinse the article and dry it. When dry, go over all the surface with a piece of fine emery cloth placed over a bung, and rub out the scratches made by the stoning proc- ess. Scour off all traces of emery with a soft hair brush in water, well rinse the surface and go all over it with rotten stone to rub out all the scratches made by the emery. The stone must be frequently dipped in water and rubbed in one direction, going over all the surface until it appears quite smooth. When this has been ac- complished, the surface may be finished with a piece of buff leather smeared with fine cut crocus, fine cut tripoli, or rotten stone and oil, the leather being glued to a stick or held over a bung. The polished surface may now be scoured and pre- pared for plating. CLEANING THE WORK 85 Polishing Jewelry. Such articles as studs, sleeve links, solitaires, buttons, earrings, finger rings and small brooches become tedious to polish when a large number of them have to be done by hand at one time. In factories where a large number of such things have to be polished, they are all put together in a rumble, that is, a barrel revolved by machinery, and polished by friction against each other. This may be imitated by hand, using a canvas sack instead of a barrel. The small goods are placed in a long canvas bag with some dry sawdust, and well shaken by two persons, one at each end, or one end may be tied to a post and the other shaken up and down until the small goods are polished. DIPS AND DIPPING When articles are in a good state of polish as regards the mere smoothness of the surface, but are coated with a film of oxidized metal, that is, tarnished, and are also free from animal matter, such as grease, the required condition of surface for plating may be imparted by dipping them in an acid solution and then swilling them in an abundance of clean water. This process is called dipping, and the acid solutions are known as dips. Copper, brass, German silver, and all copper alloys, may be dipped in commercial nitric acid, or in a mixture composed of nitric acid, 2 pints — sulphuric acid, 4 pints — water, 1 gallon. If this does not work well on bronze, German silver, and yellow brass, add a little hydrochloric acid, say one fluid ounce at a time, until the desired effect has been obtained. Potash and Cyanide Dips. To free the surfaces of metal from grease left by the polishing proc- esses, it is necessary to steep the articles in a hot potash dip made by dissolving half a pound of caustic potash or Babbit's potash in each gallon of water employed. This solution should be kept in a wrought-iron tank or pot, with means pro- vided for keeping it hot. As its solvent power is impaired quickly by contact with air, it should be covered up when not in use, and as its caustic 86 DIPS AND DIPPING 87 properties are neutralized by the grease dissolved off the articles, the solution must be kept in working order by frequent renewals. Care must be taken in handling the material and its solu- tions, as it has a powerful caustic action on the skin. Cyanide dips are employed to dissolve slight traces of oxide from the surfaces of goods prepared for nickel-plating. The dip is prepared by dissolving half a pound of commercial cyanide of potassium in each gallon of water contained in a stoneware vessel. This dip is used cold. Iron Pickle. A pickle for iron is made by mix- ing in a stone jar or tank, according to quantity, the following solution: Sulphuric acid 1 part, water 15 parts. Muriatic acid may be substituted for the sulphuric if desired. Bright Dip for Iron. A dip which leaves the surface of the metal bright is made by mixing slowly in the following order: Water 240 parts, sulphuric acid 28 parts, zinc 2 parts, nitric acid 12 parts. Copper, Brass and Bronze Pickle. The castings should be pickled in dilute muriatic acid to remove the scale, and then cleaned and brightened by dipping in a solution made up as follows : Sul- phuric acid 50 parts, nitric acid 100 parts, com- mon salt 1 part, lamp black 1 part. Bright Dip for Copper or Brass. Copper or brass work that is not to be buffed or polished should be first dipped in a pickle of nitric acid 200 parts, common salt 1 part, lamp black 2 parts. 88 THE ELECTRO-PLATERS KAND-BOOK After pickling until clean, they should be thoroughly rinsed in boiling water, allowed to dry for a moment and then plunged into the following solution : Nitric acid 75 parts, sulphuric acid 100 parts, common salt 1 part. Cyanide Dip for Brass. Cyanide of potassium in ten times its weight of water should be used as a preliminary dip when plating articles that would otherwise have the polish injured by the acid dips. The work must be allowed to remain longer in this than in the acid solution. Pickle for German Silver. German silver may be cleaned in the bright dip for copper or brass, or in a preliminary pickle of dilute nitric acid and water, 1 part of nitric acid to 12 parts of water, followed by a dip in equal parts of sulphuric and nitric acids to 24 parts of water, and then rinsing in boiling water and drying in sawdust. STRIPPING This term is employed to denote not only an accidental loosening of the deposited metal under the scratch brush or the burnisher, but also a pur- posed loosening of a deposit by means of acid solutions. Silver is stripped from old plated work on copper and its alloys, before they can be re-plated, by immersing the plated article in hot and strong sulphuric acid, and adding from time to time a few crystals of saltpeter. The acid must be made hot, the articles to be stripped must be quite dry before immersing them in the acid, and must be moved about while adding the saltpeter. If this is done as directed, the whole coat of silver may be loosened without serious damage to the metal beneath. The same opera- tion may be performed in a cold mixture, com- posed of 1 part strong nitric acid added to 10 parts of sulphuric acid in a stoneware vessel. The goods to be stripped in these acids should be first attached to stout wires, as they must be fre- quently moved about in the solution, and taken out to be examined from time to time, to prevent overdoing the process and injuring the metal beneath the coat. When all the silver has been stripped off, the article must be at once rinsed in clean water to free it from acid; but should it be necessary to re-immerse the article, it must 89 90 THE ELECTRO-PLATERS HAND-BOOK be first dried, since the presence of water in the acid will cause it to attack the metal beneath the coat of silver. When the plated article is made of iron, steel, zinc, pewter, lead, or white metal, it must not be immersed in the stripping acid, but should be desilvered in a solution of cyanide of potassium by means of a current from a bat- tery or a dynamo. An old disused plating solu- tion will do very well for this purpose if it has plenty of free cyanide. Immerse the article to be stripped, and connect it as an anode to the positive pole of the battery or dynamo, and sus- pend a plate of carbon or a strip of platinum foil in the solution as a cathode. Then pass a strong current until all the deposited coat of silver has been dissolved. Gold may be removed from gilded articles by a similar method in an old gild- ing solution. The gilt in sides of cups and mugs can be removed by filling them with the cyanide solution, connecting them to the positive pole of the battery and passing a strong current from them to platinum cathodes suspended in the solu- tion without touching the sides of the vessels. Gold may also be stripped from base metals by immersing them in hot nitric acid and adding some common salt as required. This operation is similar to the acid process for stripping silver, and needs equal care. Nickel is stripped from nickel-plated articles in a mixture composed of 1 pint of water, 1 pint of strong nitric acid, and 4 p-nt? of strong sulphuric acid. The water must be f ; 'st placed in a lead-lined vessel, or in one of STRIPPING 91 enameled iron, and the sulphuric acid added gradually and carefully, as the addition of this acid to water raises its temperature to a boiling point. When the sulphuric acid has been mixed with the water, the mixture must be poured into a stoneware dipping pan and the nitric acid added. These precautions are necessary, because the mixture of the two acids and water will dissolve lead and enamel, but will not pierce acid-proof stoneware, whilst this in turn will not stand sud- den expansion caused by the heat generated in mixing the sulphuric acid with water. Whenever this acid is to be mixed with water, the acid must be poured slowly into the water, instead of mix- ing them by pouring water into acid. All opera- tions in stripping by acids must be performed in the open air, or under conditions similar to those laid down for dipping processes. The process must be closely watched throughout, and the article removed from the stripping solution imme- diately its coat of metal has been stripped off. The time taken up in this operation may be only a few minutes if the coat is thin, or it may ex- tend to half an hour, or even more when thick coats have to be stripped. Cleaning Zinc. Some highly artistic and orna- mental articles in cast zinc have the appearance of solid silver and solid gold imparted to them by electro-plating. Zinc goods of all kinds should be first immersed for a few minutes in a hot potash solution to free the surface from any trace of grease, then well rinsed and immersed in a 92 THE ELECTRO-PLATERS HAND-BOOK pickle composed of sixteen fluid ounces of sul- phuric acid to each gallon of water for a few min- utes, then rinsed to free the surface from acid and passed on to the scouring trough. Here they must be dealt with at once and scoured with a stiff brush charged with wet silver sand until the surface has been made uniformly bright, then rinsed in water and transferred to a brassing or alkaline copper bath rich in metal. The current should be strong enough to coat the article with brass or with copper in a few seconds, to prevent the surface from being blackened by the solu- tion. When a film of copper or of brass has gone all over the surface, the anode should be raised and deposition allowed to go on more slowly. If the article has been made up in pieces put together with soft solder, or if the zinc casting has been doctored with solder, the soldered seams or patches may not at first receive a deposit of copper or of brass, but will appear black after the rest of the surface has been coated. In this case the article must be taken out, the black spots well scratch-brushed, rinsed with water, and placed again in the brassing or coppering bath with the defective spots close to the anode. By care- fully moving the goods so as to bring the anode close to the defective spots in turn, they may be soon coated with metal. After the zinc has been thus coated with brass or with copper, it may be made to receive an adherent coat of gold or silver, and should be transferred directly from the brass- ing or coppering solutions to the gilding or plat- STRIPPING 93 ing solutions. If the finished gilded surface is to be bright, the article should go direct from the brassing to the gilding solution, but if some parts are to appear dead and others bright, the brassed zinc must be placed in a silvering solution until it gets a dead white coat of silver, then rinsed, and the intended bright parts scratch-brushed and burnished before placing in the gilding bath. Cleaning White Metal and Pewter. These alloys of lead and tin, as well as the metals of which they are composed, require a special course of treatment to fit them for receiving an adherent coat of silver or of gold. The oxides of these metals and their alloys are soluble in hot caustic alkali solution. It is only necessary to immerse them in a hot solution of caustic potash to loosen any dirt or corrosion, brush the surface clean and bright, rinse again in a caustic potash solution, and transfer at once to the silver-plating vat. If they are to be coated with gold or with nickel, they should be transferred to a hot brass- ing or coppering bath and receive a coat of brass or of copper before placing them in the gold or the nickel bath. Cleaning Silver and Gold. Tarnish on silver may be loosened by immersing the article in a hot solution of cyanide of potassium. Disco] ored gold may be cleaned in a similar manner. Strong warm carbonate of ammonia solution will also loosen the tarnish on silver. After being thus loosened, the tarnish must be removed by brush- ing and scouring, or by means of a scratch brush. 94 THE ELECTRO-PLATERS HAND-BOOK A special form of brush is used to prepare the insides of silver vessels about to be electro-gilt. Filigree work, aud similar delicately formed articles in gold and silver, should be first heated on a jeweler's warming pan before plunging them in the hot cyanide solution, as this class of goods cannot be cleaned by brushing or scouring. The articles to be cleaned should be covered with slices of lemon in a vessel for several hours. They are then rinsed in water, boiled in soap- suds, again rinsed, and finally dried on a hot- water bath. Silver may also be cleaned by boil- ing in potato water. Clearing off Corrosion and Rust. Corroded copper, brass, German silver, and similar alloys, must be first immersed in a pickle composed of sulphuric acid 3 pints, nitric acid If pints, water 4 pints. This will loosen and dissolve the cor- rosion. Corroded zinc should be immersed in a pickle composed of sulphuric acid 1 fluid ounce, hydrochloric acid 2 fluid ounces, water 1 gallon. Rusty iron or steel should be first pickled in a solution composed of sulphuric acid 6 fluid ounces, hydrochloric acid 1 fluid ounce, water 1 gallon. When the rust has been removed, im- merse the iron or steel in a pickle composed of sulphuric acid 1 pint, added to 1 gallon of water in which one-quarter of a pound of zinc sulphate has been previously dissolved. Dirty lead, pewter, white metal, and tin, may be cleaned in a hot solution of caustic potash or caustic soda. ELECTRO-PLATING WITH NICKEL Nickel is deposited from its solutions at the rate of .004641 grains per ampere second, or at the rate of 16.756 grains per ampere hour on one- tenth of a square foot of surface. The thickness of a nickel deposit may be ascer- tained by noting the strength of current em- ployed and the exact surface of metal coated with nickel in a given time, then, knowing that 1 square foot of nickel 1,000th of an inch in thick- ness weighs 319.752 grains, the thickness of the whole deposit, together with its weight, may be found by calculation. Voltage Required to Deposit Nickel. To break up the nickel salt in solution and deposit the metal in good condition on an article when first placed in the bath will require an electromotive force of from 5 to 6 volts, or that furnished by from 3 to 4 battery cells in series. If a plating dynamo does not give the necessary voltage to deposit nickel in good condition, it may be made to do so by driving it at a higher rate of speed. As a rule, there should be a flow of hydrogen gas observable from the article being nickeled, but this may be excessive. Therefore the voltage and strength of the current must be regulated until the best results have been obtained by experience. When the articles have been covered with a thin 95 06 THE ELECTRO-PLATERS HAND-BOOK film of this metal, the intensity of the current may be reduced, and deposition allowed to go on more slowly, to insure a tough deposit. The intensity of one cell may then be found sufficient for the purpose. Finishing Nickel Plating. Nickel deposits differ from those of silver in appearance and hardness, and must receive different treatment. Deposition must go on from the start to the fin- ish without interruption. We may not remove the article to see how the deposit will stand brushing, as in the case of silver; if this is done the next layer will be likely to strip from the first. The deposit of nickel may not be white or brilliant, but of a dull yellowish appearance when it leaves the vat. It must then be well rinsed in hot water and dried, then passed over to the fin- isher, who changes the dull yellow surface to the brilliant polish desired by brushing the deposit with mops and dollies charged with lime. This is best done on the polishing lathe, with circular mops and dollies made of felt, calico and swans- down, the final finishing polish being imparted with a jery soft clean mop. The articles should then be brushed with a soft brush to remove all traces of lime left in crevices on the article, and wiped with chamois leather. Nickel deposits should not be scratch -brushed with brass scratch- brushes, because the brass will wear off the brushes, and become embedded in the harder nickel deposit, causing it to have a brassy appear- ance. If there should be any faulty spot from ELECTRO-PLATING WITH NICKEL 97 which the coat strips while being finished, it may- be remedied by applying a small strip of nickel anode bound up in a rag pad dipped in the nickel solution and connected by a wire with the battery or dynamo. Eest this pad on the well-cleaned bare spot, connect a wire from the negative pole of the battery to the article, and pass a current from the pad to the article until the bare spot has been coated with nickel. Experienced plat- ers and finishers can so work this between them as to successfully patch up a spot and render it indistinguishable from the rest of the article, thus avoiding the necessity of having the work re-nickeled. This will do for small faults dis- covered in finishing, but when the coat strips off in large patches, or in several such patches, the whole coat should be stripped and the whole work of preparation gone over again as at the first. Care of Nickel Baths. Nickel baths should be as carefully guarded against contamination with dirt and impurities as those of silver. The anodes should be always left in the bath, but the connecting wires and the sides of the vat should be frequently cleansed from the nickel salts which creep out of the solution and crystallize upon them. When the solution gets contaminated with dirt, and this interferes with the cleanly working of the bath, it should be filtered through a calico filter. If the metal is withdrawn from the bath faster than its equivalent is dissolved from the anodes, the solution will become acid, and this acidity must be neutralized by adding 98 THE ELECTRO-PLATERS HAND-BOOK liquid ammonia to the solution in small quantities at a time, while stirring, until it ceases to redden blue litmus paper. When the solution becomes too dirty to be used, or is otherwise spoiled, all the nickel may be recovered as a double salt of nickel by adding to it a saturated solution of ammonium sulphate until the double salt falls and the solution loses its green color. The crys- tals thus obtained may be dissolved in hot water, the solution filtered and purified by crystalliza- tion to form a new bath. If an old- nickel solution fails to give a satisfac- tory deposit of metal, it may be improved by add- ing some common salt to the extent of from 1 to 10 per cent of the nickel salt in solution. The addition of common salt increases the conduc- tivity of the solution, and gives a whiter deposit of nickel than that obtained from an impure solu- tion of double sulphate of nickel and ammonia. If a nickel solution becomes too alkaline, as shown by a yellow deposit, and its power to turn red litmus paper to blue, add sulphuric acid until it shows a slightly acid reaction. Nickel-plating Cycle Fittings. It is not neces- sary to coat cycle fittings with copper previous to coating them with nickel, but it is advisable to do so for several reasons. A coat of copper will adhere firmly to iron and steel and other metals if these are properly prepared, and will ohow defects in the preparation, readily, by not coat- ing the defective parts. These defects can be at once remedied without loss of time and nickel. ELECTRO-PLATING WITH NICKEL 99 Nickel will also firmly adhere to copper, and the two together form a better protecting coat than that of nickel alone. Some platers not only- deposit a good coat of copper on high class work, but also polish this, and re-copper the surface before depositing nickel on the fittings. Which- ever method is adopted, it must be borne in mind that success not only depends on a good coat of copper, but also on absolute cleanliness in the preparation, for only a touch with the bare hand on the prepared article will cause the nickel to strip from the spot whilst being polished. In a good coppering solution a sufficiently durable coat of copper should be obtained in from fifteen to twenty minutes. Re-plating Old Cycle Fittings. Much of the work of a cycje plater consists of old fittings sent to be re-plated. All of the old nickel must be stripped from these, to get surfaces capable of adhering firmly to the new coat. This is best done on the polishing lathe, as in preparing new fittings. First wipe off all excess of dirt, grease or oil with a rag or cotton waste, then give the fittings to the polisher. Rusty fittings must re- ceive similar treatment. Old nickel may be removed from copper and brass fittings by strip- ping in acid. They must then be rinsed, dried and turned over to the polisher to be prepared. Old tinned fittings are scarcely worth the labor and expense of being re-nickeled, as they rarely look well after being stripped of their coat of nickel and tin. 100 THE ELECTRO-PLATERS HAND-BOOK Working Nickel Solutions. Nickel solutions work best in large volumes of from 100 gallons upward, and these are contained in large tanks constructed to suit the work to be done in them. For instance, if long pieces of iron and steel, such as the shafting of machines or harness chains, have to be nickeled, the nickel solution may be contained in a long, narrow and shallow trough. If sheets of iron or such articles as stove-fronts form the bulk of the business, a thin and deep vat will be preferable. In such a vat a large number of small articles strung together on wires may be nickeled, such as screws or bicycle spokes, which can be wired by taking a turn of a long wire around each screw head, and thus mak- ing a long string of them. Double Salts of Nickel. The most important double salt of nickel is that of the double sulphate of nickel and ammonium. To prepare this, first make up a mixture of 1 part sulphuric acid, 2 parts distilled water, and one-third part of nitric acid. Make this warm in a stoneware vessel on a fire furnished with a good flue to carry off the nitrous fumes, and add pure nickel until the acid ceases to dissolve any more of the metal. Drive off the excess acid, if any remains, by boil- ing the solution for a short time, dilute it with one-fourth its bulk of boiling water, and set aside to cool. When cool enough to filter, pass it through a linen filter into a vessel capable of holding double the bulk of liquid. Next dissolve some sulphate of ammonium in hot water until it ELECTRO-PLATING WITH NICKEL 101 will not take up any of the ammonium salt, and set it aside to cool. Add the cold ammonium sulphate solution to the cold nickel sulphate solu- tion while stirring, until the nickel solution loses all its color and a copious precipitate of the double sulphate of nickel and ammonium has been thrown down to the bottom of the vessel. Pour off the supernatant liquid, and wash the crystals with a little more of the ammonium solu- tion. The crystals may now be dissolved in hot water and filtered. The resulting solution may be employed as the nickel bath, or may be evapo- rated down and set aside to cool, when the double salt will crystallize out. Table Showing Rate of Nickel Deposition. Amperes of Square Feet Grains per Grains per 10 Current. of Surface. Hour Hours. Lbs. Ozs. Drms. 1 .1 16.756 167.56 6 2 .2 33.512 335.12 12 3 .3 50.268 502.68 1 2 4 .4 67 . 024 670 . 24 1 8 5 .5 83 . 780 837.80 1 14 6 .6 100.536 1005.36 2 4 7 .7 117.292 1172.92 2 10 8 .8 134.048 1340.48 3 1 9 .9 150.804 1508.04 3 7 10 1.0 167.560 1675.60 3 12 20 2.0 335.120 3351.20 7 10 30 3.0 502 . 680 5026 . 80 11 7 40 4.0 670 . 240 6702 . 40 15 5 50 5.0 837 . 800 8378 . 00 1 3 2 60 6.0 1005.360 10053.60 1 6 15 70 7.0 1172.920 11729.20 1 10 13 80 8.0 1340.480 13404.80 1 14 10 90 9.0 1508.040 15080.40 2 2 7 100 10.0 1675.600 16756.00 2 6 4 102 THE ELECTRO-PLATERS HAND-BOOK Black Nickel-plating. It is possible to deposit a coating of nickel which will be a deep velvety black and equally as hard and as thick as the ordinary nickel plating. The solution to pro- duce this result is as follows : Double sulphate of nickel acid 12 parts, aqua ammonia 16 parts, carbonate of ammonia 2 parts, arsenic 2 parts, cyanide of potassium (quantum sufficit) and suffi- cient water to make one gallon of solution. The water should not be added until all the chemicals are thoroughly dissolved. Boracic Acid. This is of use when the nickel- plating solution becomes muddy and dense, from becoming alkaline, so that the deposit is no longer white and tough. The acid should be used in the proportion of two ounces to the gallon of solution, and has the effect of clearing up the solution and whitening the deposit. ELECTRO-PLATING WITH SILVER To clean the work before plating, dissolve two ounces of lye to each gallon of boiling water, and dip the articles in hot, then scrub with a hard brush and fine powdered pumice stone, or pow- dered bath brick, or powdered Vienna lime, then wash in clean hot water, then in cold water. If the water adheres evenly all over, it is ready to plate, if it does not, then repeat the cleaning and scrubbing. After getting a slight coat of silver on the article it can be removed from the solution and scratch-brushed with the revolving scratch-brush, on which should be allowed to drip a little stale beer or soap suds, this lays down the grain of the silver, after which wash in clean hot and then cold water, and plate again. When sufficiently plated it can be scratch-brushed and buffed with the cotton flannel wheel, to which is applied a little powdered gold rouge mixed with alcohol into a paste. This gives the high color which takes the place of the more expensive hand bur- nishing. For plating silver on articles of iron or steel, it is well to give the articles a slight coat of copper from a cyanide of copper solution, which is very inexpensive. Another plan is to take, say 1 quart of silver solution, when ready for use, and add 3 quarts of water to it and 6 ounces of 103 104 THE ELECTRO-PLATERS HAND-BOOK C. P. Cyanide of potash. Put in a large surface of silver and only a small surface of work at a time. The article will give off gas freely from this solution, before which it should be thor- oughly cleaned and pumiced, and a yellowish coat of silver will be deposited, which is very adhesive. From this put it in the regular silver solution to plate slowly until a sufficient deposit is obtained. From the work in the regular silver solution no gas should escape, otherwise a sandy, hard de- posit will be the result. This can be regulated by the amount of anode immersed, distance between the anode and the work being plated, and the size of the wire, which can be reduced until sufficient resistance is introduced to prevent the escape of gas. Silver-plated Articles, Finishing of. When the articles have received a sufficiently thick deposit of silver, disconnect each from the connecting rod, one at a time, swill them in the plating solu- tion for a moment, drain off the solution taken by them from the bath, rinse each article well in clean hot water, and place at once in clean hot box-wood sawdust to dry. In this they should dry quite white. If they dry yellow or spotty, the cause may be traced to imperfect rinsing, or the use of soiled sawdust. When they are dry they should be taken to the scratch-brush and brushed until all the white burr or matt has been worked down. The brushes must not be worked dry, or they will stain the silver with brass, but must be kept wet with stale beer. This is best ELECTRO-PLATING WITH SILVER 105 applied by means of a small drip-cock over the brush, attached to a lead pipe leading to a small cistern of stale beer placed over the lathe. Very little will be required to keep the brush moist, and the drips may be used over again if caught in a tray beneath the brush. The brush should either be made to revolve away from the work, or from left to right, to prevent splashing of the beer and snatching of the wcrk out of the oper- ator's hands by the brush. Only a very moderate pressure is required on the article to get its sur- face well brushed, slightly more pressure being necessary to force the wires of the brush into crevices. The brushes, as they come from the maker, are usually very stiff and the ends of the wires very sharp. In this condition they are apt to tear off some of the silver when first used. It is therefore advisable to break down the points by holding a piece of steel or cast iron to the revolving brush for a few minutes before using it on the silver-plated article. This wears down the sharpness of the freshly cut ends, and breaks the brush into a working condition. Brushes should, however, be selected to suit the class of work being done, the softer wires for thin coated goods and stiffer wires for more heavily coated and larger articles. When the articles have been scratch-brushed, they must be rinsed in clean water and again dried in sawdust preparatory to the next operations of polishing or burnishing. Polishing Silver Plate and Silver. The degree of brightness or luster imparted to the surface 106 THE ELECTRO-PLATERS HAND-BOOK of silver-plated articles is insured by the number of processes through which it passes. A dull whiteness is left on the surface after scratch- brushing. A better finish is given by the process of polishing. This is usually done on a polishing lathe, with similar buffs, bobs and circular- brushes to those employed in polishing the metal before plating. The lathe may be driven by foot power. A good lathe for this purpose is shown in Figure 17. Silver-plating Solutions. Never add anything to the solution except distilled water and cyanide of potassium when required. If the solution is too rich in silver for a given purpose, take out some of it and dilute the rest with distilled water. If it is not rich enough, do not add any other salt of silver except silver cyanide. Keep the solution covered up when not in use, to keep out dust and insects, and filter it through a filter made of well-washed linen. Shade the solution from direct sunlight, as this decomposes some of the silver salt and wastes the solution. Keep it as near as possible to a regular metal pitch, that is, with an approved quantity of silver in each gallon of solution, by working it with a sufficient anode surface and a sufficient quantity of free cyanide to dissolve the anodes freely. When the anode surface exposed to the action of the solu- tion exceeds slightly the surface of goods to be plated, and the solution contains a sufficient quantity of free cyanide, the current will dissolve from the anode as much silver as it deposits on ELECTRO-PLATING WITH SILVER 107 the articles being plated. If, however, the con- trary conditions are present, the solution will be gradually impoverished, and the deposit show, sooner or later, the bad effects. It is quite pos- sible to err on the contrary side, and get a solu- tion too rich in silver from having too much free cyanide, or exposing too much anode surface to the solution. A lack of free cyanide is shown when the anode plates assume a hard, close-grained appearance, and are more or less coated with a dark, slimy deposit of silver oxide. An excess of free cyanide is shown on the anodes by their very white frosted surfaces being pitted and their edges ragged. It is also shown on the deposit by a soft, loosely deposited coat which strips under the scratch-brush and the burnisher. The odor of cyanide is also strongly pronounced, and this is mingled with an odor of ammonia in hot weather if much work is being done. In adding free cyanide, it is best to dissolve it in distilled water and filter the solution into the bath to remove any loose dirt held in the cyanide of potassium. Never swill freshly cleaned articles in the plat- ing solution, nor allow them to remain in the solution unless they form part of the plating cir- cuit and are receiving a deposit of silver, because the free cyanide will dissolve copper, brass, and other metals, and .thus contaminate the solution with base metal. Solutions thus contaminated will not yield a pure white deposit of silver. Owing to such a large bulk of liquid being con- tained in a wooden vat, its temperature cannot 108 THE ELECTRO-PLATERS HAND-BOOK be regulated, but the best results are obtained between 50 and 60 degrees Fahrenheit. Character of Silver Deposit. Electro-deposited silver is pure, if the silver employed in making up the solution is pure and the anodes are also pure. As the articles leave the solution coated with silver, their surfaces appear to have been whitewashed. The coat of pure silver upon them is composed of a number of fine grains beautifully massed and interlaced together. In this condi- tion they absorb the light, and have a peculiar dead white appearance, named matt in the plat- ing trade. If the solution is contaminated with copper or other base metal, or if the current is too dense, or if the solution is deficient in silver, or if the voltage of the current is too high, the deposit will have a hard and dark appearance, and will be intractable to the burnisher. If the current is too large, the silver will go on loosely in dark gray grains, and the deposit is said to be burnt. This may be prevented by interposing a resistance in the circuit, and thus checking the volume of current passing through the article being plated. It may also be prevented by mov- ing the article at a greater distance from the anode, or by placing more articles in the vat, or by lessening the anode surface exposed to the solution. If the voltage of the current is too high, the bad effects will be intensified, providing the volume of the current is also large, but a thin current with a high voltage will also deposit silver in a hard, dark condition, different from ELECTRO-PLATING WITH SILVER 109 that above noticed. For this there is no other remedy except that of reducing the voltage by running the dynamo at a slower speed, or taking off some of the battery cells and reducing the number in series. If the hard, dark appearance of the deposit is due to a deficiency of silver in the solution, it must be remedied by adding more silver cyanide, or working with a weaker current and placing the articles nearer the anode. If the solution is contaminated with copper or other base metal, it is only fit for the most common work, and can only be remedied by -turning it over to the refiner to be evaporated and reduced to old silver. One other cause of hard, dark sil- ver is due to the addition of brightening liquid to the solution, to get a bright deposit from it. A solution thus treated is spoiled for general work and will rarely recover its former con- dition. If silver-plated articles are exposed for a few minutes to the air and light after taking them from the bath, before rinsing them, the deposit will turn yellow. This is due to the action of light and air on the sub-cyanide of silver left on the surface. To prevent this, gently swill the articles to and fro for a few moments in the plating solution after disconnecting them from the cathode, rinse them at once in hot water and place them in hot, clean box wood sawdust. Extra care should be taken in this finishing oper- ation when the surface has to be left dead white instead of being polished or burnished. 110 THE ELECTRO-PLATERS HAND-BOOK Thickness of Silver Deposits. It is not prac- ticable to gauge the thickness of a silver deposit with a pair of calipers, or even with a micrometer caliper gauge, but the thickness may be ascer- tained if its superficial area and weight are known. The first can be obtained by exact Table Showing the Rate of Silver Deposits. Square Feet Exposed. Rate of Cur- rent in Am- Grains of Silver Deposited in One Grains of Silver Deposited in One Day of peres. Hour. Ten Hours. .10 1 61.344 613.44 .20 2 122.688 1226.88 .30 3 184.032 1840.32 .40 4 245.376 2453 . 76 .50 5 306.720 3067.20 .60 6 368 . 064 3680.64 .70 7 429 . 408 4294 . 08 .80 8 490 . 752 4907.52 .90 9 552.096 5520.96 1.00 10 613.440 6134.40 2.00 20 1226.880 12268.80 3.00 30 1840.320 18403.20 4.00 40 2453 . 760 24537.60 5.00 50 3067 . 200 30672. 00 6.00 60 3680 . 640 36806.40 7.00 70 4294 . 080 42940 . 80 8.00 80 4907 . 520 49075 . 20 9.00 90 5520 . 960 55209.60 10.00 100 6134.400 61344.00 measurement and calculation, and the next by noting the difference between the weight of the article both before and after plating. The weight of silver may also be approximately known by noting the volume of current passing through the solution in a given time. Thus it takes one. ELECTRO-PLATING WITH SILVER 111 ampere of current per second to deposit .017064 grains of silver. If this volume of current passes through the solution for one hour, it should deposit 61.344 grains of silver, and this should be the weight of silver acquired by the article. If the coated surface be measured, the thickness of the silver coat may be accurately obtained. The following calculations may help the plater to determine the thickness of the silver deposit. Upon referring to the table the plater can ascertain at a glance how much current will be required to coat a surface with silver, or how much surface a certain volume of current will coat properly, or how much silver will be de- posited by a known volume of current in a given time. It should be clearly understood, however, that the above figures relate solely to the actual volume of current passing through a solution as measured by an ammeter in circuit, but not to the mere capacity of the generator as ascertained by measurement of the current on short circuit between its poles. When dynamos are advertised as having a capacity of so many amperes or so many ounces of silver per hour, the figures merely give an idea of their maximum output, without reference to the resistance of the circuit. The maximum current obtainable from a dynamo can only be made available in depositing silver when the resistance of the conducting wire Is Low, and the full surfaces of anode and cathode are exposed to the plating solution. 112 THE ELECTRO-PLATERS HAND-BOOK Bright Silver-plating. Silver is deposited from a silver-plating solution in a matt condition with- out luster, and is afterwards made bright by scratch-brushing, polishing and burnishing. It is sometimes desirable to deposit silver in a bright condition upon parts that will not admit of being burnished. This is effected by adding a solution of carbon bisulphide to the plating solution and stirring it in well some hours before the opera- tion of plating. The following is a most con- venient method for preparing a brightening solution. Procure one quart of old silver solu- tion, place it in a bottle capable of holding two quarts and furnished with a glass stopper. Add to this two fluid ounces of carbon bisulphide, place the stopper in the bottle and shake well together, then nearly fill the bottle with a strong solution of potassium cyanide, again shake well together, and then set aside in a cool place for twenty-four hours. The solution for bright plat- ing should either be an old one, or one set aside for the purpose. To this add two fluid ounces of the brightening solution as often as may be re- quired. Too much of this will spoil the plating solution, and the deposit of silver will be brown- ish or spotted with brown spots. The bright deposit spreads from the lower parts of the articles upward until all has been covered. It is darker than ordinary silver, and the somber hue deepens after the article has been removed from the solution unless well rinsed in boiling water. Bisulphide of carbon has a noxious odor and its ELECTRO-PLATING WITH SILVER 113 vapor is inflammable and highly poisonous. It should therefore be used with caution and kept in a closely stoppered bottle in a cool place. Its solution with cyanide of potassium gradually turns black, but the blackness may be lessened by adding plenty of free cyanide. Nitrate of Silver. This is the salt of silver used in making up silver-plating solutions. Other salts, such as the chloride, sulphide, oxide, sulphite, hyposulphite, acetate, iodide, and chromate of silver, may be mentioned, but most of them are made from the nitrate of silver, and all except this one are unsuitable for conversion into cyanide of silver on account of the bad effects of the by-products formed in the process of con- version. In using nitrate of silver there is no waste, since the salt is perfectly soluble in dis- tilled water, from which all the silver can be pre- cipitated as a single cyanide of silver. The nitrate can be cheaply and easily made, and can also be purchased at a reasonably low price in a state of purity. It must be understood that only perfectly pure silver is admissible in a silver-plating solution. Standard silver is useless, because this contains copper, as does also nearly all commercial silver, but alloyed silver may be refined by the plater and then converted into the pure silver nitrate. But. if pure nitrate of silver is desired, pure sil- ver in the form of silver foil or grain silver must be had. This obtained, dissolve the pure metal in a warm mixture of 4 parts of pure nitric acid 114 THE ELECTRO-PLATERS HAND-BOOK and 1 part of distilled water and evaporate off all excess of acid to form the desired silver salt. As this may still contain some free acid, it is advis- able to dissolve the salt in distilled water and again evaporate and re-crystallize the silver nitrate. If now the salt contains any copper, it will be shown on the sides of the evaporating dish in greenish or slightly blue streaks and spots. To demonstrate the presence of copper, dissolve a small portion of the nitrate of silver in a test tube with a little distilled water and add to it a few drops of diluted liquor ammonia. If copper is present in the nitrate solution, a blue ring will be formed in the test ' tube where the ammonia meets the nitrate of copper, and the intensity of this blue ring will show at once whether the cop- per is present in a large or in a small quantity. If copper is detected, the whole mass of silver nitrate must be dissolved in distilled water, and common salt (sodium chloride) added as long as a white precipitate of silver chloride is thrown down. The liquid above this will contain all the copper in the form of copper chloride, and as this is soluble in water, while the silver chloride is not, the two may be entirely separated by pouring away the supernatant liquor and washing the sil- ver chloride several times in an abundance of clean hot water. This is done by pouring dis- tilled water into the vessel containing the silver chloride, stirring it up well with a glass rod, allowing the white powder to subside and then pouring off the water. It is not necessary to ELECTRO-PLATING WITH SILVER 115 pour off the last few drops of water each time, and at the last some of it may be left to cover the precipitate, and to this should be added a small quantity of hydrochloric acid. Some clean scraps of zinc or some granulated zinc must now be well stirred into the silver chloride precipitate and frequently moved about in it. The chlorine in the silver chloride, having a stronger affinity for zinc than it has for silver, will now leave the silver in the form of very small gray grains and combine with the zinc to form soluble zinc chloride. When all the silver chloride has been thus decomposed, and not a trace of the white precipitate remains, stir in a little more hydro- chloric acid and pour off the zinc chloride solu- tion. Next add equal parts of hydrochloric acid and water to the gray mass remaining, and stir up well for several minutes to completely dissolve the last trace of zinc remaining entangled in the silver grains and finally well wash the mass in an abundance of water, using distilled water for the last two washings. The gray, wet mass should now be perfectly pure silver, which may be dried and melted in a crucible under a layer of char- coal, or dissolved at once in dilute nitric acid to form silver nitrate. This operation must be performed in a cup- board, or in a fireplace with a very good draught to carry away the highly poisonous fumes of nitrous oxide thrown off from the solution. It is best carried on in a porcelain beaker or an evap- orating dish over a sand bath heated by a small 116 THE ELECTRO-PLATERS HAND-BOOK gas stove. Only enough acid should be employed to dissolve all the silver, as all excess acid will be wasted. The right quantity is about four fluid ounces of acid and one of distilled water to each ounce of silver. The heat applied should be very moderate at first, until all the silver has been dissolved, then increased to evaporate the excess of water and acid, but in no case should the solu- tion be allowed to boil. "When it has become thick it may be taken off the stove and set aside to cool. As the thick liquor cools it will congeal to a mass of crystals, and these may hold some free acid. This may be removed by dissolving the crystals in distilled water and evaporating the solution again. All free acid left in a silver nitrate solution means a corresponding loss of silver and of cyanide when making up the cyanide of silver solution, as the acid decomposes part of the cyanide of potassium, converting it into nitrate of potash and free cyanide gas, while some of the silver is left in the solution. Cyanide of Silver. The single cyanide of silver is N prepared from nitrate of silver by adding a solution of cyanide of potassium to a solution of silver nitrate as long as a precipitate is formed. This precipitate is in the form of small white grains and is composed of one equivalent of sil- ver, 108 parts, added to one equivalent of cyano- gen, 26 parts, making cyanide of silver having a molecular weight of 134. The action which takes places on adding the two solutions is as follows: Potassium cvanide added to silver ELECTRO-PLATING WITH SILVER 117 nitrate exchanges its cyanogen for the nitrogen and oxygen of the silver nitrate and becomes nitrate of potash, whilst the cyanogen unites with an equivalent of silver to form silver cyanide. As nitrate of potash is soluble in water and cyanide of silver is not soluble in water, it is only neces- sary to pour off the supernatant liquor and wash the precipitate in water to obtain pure cyanide of silver. The most practical method of making silver cyanide for electro-plating purposes is as follows: Dissolve the silver nitrate in distilled water or in clean rain water in the proportion of 1^- ounces troy of the salt in half a gallon of water. Next make a solution of cyanide of potassium in dis- tilled water or in clean rain water in the propor- tion of one ounce troy of 90 per cent cyanide to one quart of water. Add this gradually, with frequent stirring, to the silver nitrate solution, pouring in the last few drams carefully and noting the result. If the precipitate settles down and leaves the supernatant liquid clear, enough cyanide has been added, but if the liquid is cloudy, make up some more cyanide solution and add this drop by drop until the cloudy appearance has been removed. If too much cyanide is added it will dissolve some of the precipitate and give a slightly brown tint to the supernatant liquid as it passes through. In this case add a few drops of silver nitrate solution until it ceases to form a white, cloudy precipitate. This operation is best carried on in a glass vessel, such as a bell glass 118 THE ELECTRO-PLATERS HAND-BOOK fixed in a stand of wood, or in the glass cell of an accumulator. When all the precipitate has set- tled down, the supernatant liquor must be poured off into another vessel and treated for recovery of silver, and the silver cyanide well washed with water. It is then ready to be dissolved in a strong cyanide solution to form the plating bath, or may be dried gently on a water bath and be stored away in glass jars for future use. Cyanide of silver is insoluble in water and in cold nitric acid, but is freely soluble in solutions of ammonia, carbonate of ammonia, nitrate of ammonia, sal- ammoniac, hyposulphite of soda, the cyanides of ammonium, sodium, and potassium, ferro-cyanide of potassium, and in solutions of the alkaline chlorides. Hydrochloric acid decomposes it with an evolution of hydrocyanic acid gas. Boiling sulphuric acid and water has a similar effect, and produces a formation of silver sulphate. The gas given off in these reactions is dangerously poisonous and must not be inhaled, as its effects are identical with those of prussic acid. It must be also understood that all the cyanides are equally dangerous poisons and must be used with great care to avoid fatal consequences. Double Cyanide of Silver and Potassium. This salt, dissolved in distilled water, forms the best solution for silver-plating purposes. It is formed by dissolving an equivalent of silver cyanide, 134 parts, in a solution containing an equivalent of pure cyanide of potassium, 65 parts, the resulting salt being composed of one equivalent of silver, ELECTRO-PLATING WITH SILVER 119 108 parts, one equivalent of potassium, 39 parts, and two equivalents of cyanogen, 52 parts, mak- ing together a double salt having the molecular weight 199. In practice, the silver-plating solution of this salt is formed by dissolving the wet cyanide of silver, freshly prepared, in a solution containing as much cyanide of potassium as it takes to throw down the silver cyanide, and then adding about one-fifth more of potassium cyanide to form free cyanide, this excess being necessary to dissolve the silver anode and keep the solution in working order. This solution is then made up with distilled water so as to contain a certain weight of silver per gallon, which may vary from half an ounce up to 5 ounces or more to the gallon. The variation in the strengths of silver-plating solutions adopted by platers is regulated by the special requirements of the trade in which each workman is employed. Attenuated solutions con- taining from one-quarter ounce to one ounce of silver in the gallon, deposit their silver more slowly than rich solutions containing from 4 ounces to 6 ounces of silver in the gallon, but the deposit from each and all may be equally good. As weak solutions are bad conductors of the cur- rent, a higher voltage must be employed to force the current through them than will be found necessary in richer solutions. The amount of silver per gallon may be determined at the outset by reckoning each 170 ounces of silver nitrate to yield 108 ounces of pure silver. 120 THE ELECTRO-PLATERS HAND-BOOK The quantity of excess cyanide of potassium in each gallon of solution also varies with the requirements of the work to be done in the solu- tion. This should, however, be lessened if such metals as bare copper, coppered zinc, coppered r iron, or any other metal or alloy on which cyanide of potassium acts quickly, or on which silver is readily deposited from its plating solu- tion, is to be plated in the solution. It is just in such instances as these where quickening the sur- face with mercury comes in useful. It is possible to so arrange the proportion of free cyanide in a solution as to suit exactly one class of work and to deposit an adherent coat of silver in this class without quickening the surface, but it is not always convenient to do so. ELECTRO-PLATING WITH GOLD Gold is easily electro-deposited from all its solu- tions by a small current of electricity, but the deposits of gold are not all equally good from all solutions. Although it is a metal easily de- posited, there is no other capable of such an infi- nite variety in the color and character of the deposit. This varies with the character of the solution from which it was deposited, the tem- perature of the solution at the time of deposition, and the current employed to deposit the metal. As gold is deposited from its solution in potas- sium cyanide in good condition and color, this solution has become the general favorite with electro-gilders. Terchloride of Gold. As this soluble salt of gold can be readily prepared, it is used generally in making up gold solutions. It is easily made by dissolving pure gold in a solution of aqua regia, evaporating the excess of acid and continuing the heat until the salt forms ruby red crystals on the sides of the evaporating dish. The details of this process are as follow : Make up a mixture of 3 parts of pure hydrochloric acid, 1 part of pure nitric acid, and 1 part of distilled water, to dis- solve 1 part of pure gold, that is to say, it will take 6 fluid ounces of this mixture to dissolve 1 Troy ounce of pure gold. The acid mixture must 121 122 THE ELECTRO-PLATERS HAND-BOOK be placed in a large glass beaker or large porcelain evaporating dish, over a sand bath or water bath, in a cupboard or in some place where the highly poisonous and corrosive fumes of the mixture can be carried away by a strong draught. Heat must then be applied to the sand bath until the mix- ture becomes warm, when the gold must be added in small quantities at a time until all the gold is, dissolved or the warm acid ceases to take up any more. During this operation dense brown fumes of a penetrating, pungent and strongly corrosive character will be given off from the mixture. The heat must be continued below boiling point, until all excess of acid and water has been driven off in the form of steam and only a dark, thick liquid remains at the bottom of the evaporating dish. The operator should protect his hands with a pair of thick gloves, and then proceed to turn the dish about, tilting it from side to side until the dark liquid all crystallizes on the sides of the dish in the form of ruby red crystals. The whole contents of the dish should then be dis- solved in hot distilled water and set aside to cool, when it must be filtered through blotting paper to remove any dirt contracted in the previous process. If any brown powder remains at the bottom of the dish, it is in all probability finely divided gold, and this must be dissolved in a little more of the acid mixture and treated like the bulk of the sample. As gold is a very precious metal, great care must be exercised to avoid waste, and all rinsings of the vessels, together ELECTRO-PLATING WITH GOLD 123 with washings of the filter, must be made with distilled water and then added to the filtered solu- tion. The terchloride of gold solution thus made may be again evaporated over a water- bath at a low temperature, and the dried salt stored away in wide-mouthed bottles, or the solution may be diluted with distilled water and treated direct with cyanide of potassium to form gold cyanide. Terchloride of gold is formed of three equiva- lents of chlorine (35.5 x 3) added to one equiva- lent (197) of gold, and has, therefore, the molecular weight 302.15. It is very soluble in water and its solution stains the skin a dark purple tint. Cyanide of Gold. Cyanide of gold is formed as a yellow precipitate when a solution of cyanide of potassium is added to a solution of terchloride of gold in distilled water. The precipitate forms slowly and falls tardily. In making cyanide of gold, the terchloride solution should be largely diluted with distilled water, so as to contain not more than one ounce of gold in half a gallon of water, and the solution of cyanide should also be very dilute to produce good results. If the terchloride solution is too dense, or contains any free acid, or the cyanide solution is too strong, a large proportion of the gold will enter into com- bination with the cyanide of potassium to form a double soluble salt of gold and potassium, and thus be taken up by the supernatant liquid. Even when the greatest care is exercised in mak- ing this salt, some gold is found in the super- 124 THE ELECTRO-PLATERS HAND-BOOK natant liquid and in the wash waters. These should be carefully preserved and treated for the recovery of the gold. The details of the process for making cyanide of gold are precisely the same as those for making cyanide of silver, but, owing to the difficulties experienced in determining the end of the process, and the loss of metal likely to be sustained by the operation, it should only be undertaken by experienced persons. Double Cyanide of Gold and Potassium. When an excess of cyanide of potassium solution is added to the yellow cyanide of gold precipitate, it dissolves and forms a solution containing the double cyanide of gold and potassium. If the gold cyanide has been properly prepared and washed, as directed for the silver cyanide, this solution is undoubtedly the best for electro- gilding. The double cyanide of gold is composed of one equivalent of gold and one equivalent of potas- sium added to two equivalents of cyanogen. But the gilding solutions made by inexperienced operators usually contain a large addition of chloride of potash, formed whilst attempting to throw down the gold cyanide. Owing to the difficulty experienced by many operators in precipitating the cyanide of gold, many makeshifts have been resorted to with a view to avoid having chloride of potash in solu- tion. If an excess of liquid ammonia is added to a solution of terchloride of gold, a brown pre- cipitate is formed. This is an oxide of gold, hav- ELECTRO-PLATING WITH GOLD 125 ing dangerously fulminating properties when dried, as it will then explode violently if heated or subjected to friction. This precipitate must therefore be well washed and dissolved whilst wet in a solution of potassium cyanide to form the gilding bath. It must then be boiled for several minutes to expel the ammonia still held in the solution. This is a fairly good solution, yielding a rich gold deposit when first made up, but liable to deposit a darker gold as it gets older. As it is made from oxide of gold dissolved in cyanide of potassium, it contains an oxide of potash in addi- tion to the double salt of gold and potassium. The same is true of all solutions made from oxide of gold, which may be prepared in another way by adding calcined magnesia to the terchloride of gold solution as long as a brown precipitate falls. This must be removed from the solution by filtra- tion, and then digested in dilute nitric acid to remove the excess magnesia. The gold oxide must then be well washed to remove the last trace of acid, and dissolved in a solution of cyanide of potassium to form the gilding bath in the usual manner. Another solution may be made by first throw- ing down all the gold as a precipitate from its terchloride solution by adding sulphide of ammo- nium. This precipitate is to be well washed and dissolved while wet in a solution of cyanide of potassium to form the gilding bath. It must then be boiled for half an hour to expel the excess ammonia, and the loss due to evaporation made 126 THE ELECTRO-PLATERS HAND-BOOK up with distilled water. With a moderate excess of free cyanide, this solution will yield a fine color when worked at a temperature of 130 de- grees Fahrenheit, and will give good results for a considerable period. Characteristics of Gold Deposits. When gold is deposited from a cold or cool solution it has a paler tint and is less coherent than when de- posited from a hot solution. A rise in tempera- ture causes the gold to be deposited faster and assume a brown tint, which- disappears on scratch- brushing the article. Movement of the article being gilded has a tendency to prevent this dark brown appearance and cause a lighter colored deposit. If a thick deposit is desired, the article should be taken from the bath every few minutes, scratch- brushed to remove the brown appearance, and returned to the bath for another coat. Gilding Bath, Strength of. Gilding baths will yield good results with only 5 pennyweights of gold in each gallon of solution, if worked under suitable conditions, or they will yield equally good deposits with one ounce or more of gold in each gallon of solution. A very good working strength is insured with from 10 to 15 penny- weights of gold to the gallon. Solutions poor in gold are liable to great fluctuations in the color of the deposit, which will assume a dark, hard appearance, resembling 15 -carat gold, if the bat- tery voltage is too high. A similar appearance will result from the presence of too much free cyanide. A great excess of free cyanide will ELECTRO-PLATING WITH GOLD 127 cause the gold deposit to assume a foxy-red tint, which cannot be altered by subsequent scratch- brushing and polishing. Solutions too rich in gold, deposit the metal too fast, and in a non- coherent condition liable to strip under the bur- nisher. This condition is intensified if the solution contains an excess of free cyanide in addition to an excess of gold. Polishing and Finishing Electro-gilt Articles. After the articles have received the desired coat of gold, they should be rinsed in clean warm water and scratch-brushed whilst wet, then pol- ished and finished. If it is necessary to burnish parts of the work, full directions for this process will be found. Assaying Gold and Silver Solutions. The exact strength of a gold or silver solution may be ascer- tained in the following manner : Take one fluid ounce of the solution and evaporate it to dryness in a porcelain dish, in a sand bath over a small gas stove. To the dried salt add an equal bulk of litharge and mix the whole well together. Calcine the mixture in a small crucible and keep it at a glowing red heat until all the litharge has been decomposed and a small pool of molten lead appears at the bottom of the crucible. This lead will contain all the silver or gold in the sample to be assayed, and must be poured out on a clean iron slab to cool. The button of lead must now be placed on a boneash cupel (a small cup of boneash) and subjected to a strong heat in the presence of air until all the lead has been oxidized 128 THE ELECTRO-PLATERS HAND-BOOK and absorbed into the boneash of the cupel and only a button of pure gold or pure silver remains. This must be allowed to cool on the cupel, from which it can be easily detached, then cleaned from adhering boneash and exactly weighed. The weight of the button thus obtained should be of i J-Tj- that of the silver or gold in a gallon of the solution, therefore if the weight is multiplied by 160 (the number of fluid ounces in a gallon), the exact weight of precious metal in a gallon will be obtained. ELECTRO-PLATING WITH COPPER Copper is deposited from an acid solution of copper sulphate in the various processes of elec- trotyping and copying artistic objects in this metal. The deposits thus obtained are removable from the moulds on which they are deposited, and afterwards have a separate existence of their own. The process of obtaining them, therefore, cannot be deemed a branch of electro-plating proper, but forms a separate art. Copper is em- ployed chiefly as a coating on such metals as iron, steel, zinc, tin, lead, pewter, and white metal when preparing these to receive a deposit of sil- ver, because silver will not adhere perfectly to iron, steel, zinc, tin, or lead when deposited upon these metals direct, but will adhere perfectly to copper when deposited on these metals, and cop- per can be made to adhere firmly to each and all of them. A coat of copper is also preferred by some platers on such alloys of tin and lead as pewter and white metal before these are plated with silver, because a firm and adherent deposit of silver can only be obtained on these alloys by spcial precautions taken in their preparation. It is also deposited on articles made of iron and of zinc, and the coating is subsequently subjected to the action of acids to produce bronzing effects on the copper coating. It is likewise employed as a 129 130 THE ELECTRO-PLATERS HAND-BOOK preparatory coating to a deposit of gold and of nickel on the above-named metals, although this is not always necessary, since gold and nickel can be firmly deposited on iron, steel, zinc, etc., without the intervention of copper. Alkaline Solutions of Copper. As all acid solu- tions of copper, even the saturated solution of copper sulphate, deposit their metal on iron, steel, zinc, lead, and its alloys by simple immer- sion or chemical displacement, they are unsuitable as depositing solutions for electroplating with copper, since such deposits are never firmly adherent to the metal on which they are de- posited. We have therefore to employ an alka- line solution which will not deposit its metal by simple immersion on those we wish to cover. Several various solutions have been employed, among which may be mentioned a solution of cyanide of copper and bisulphite of sodium, a solution of bitartrate of potash and carbonate of copper, a solution of "cyanide of copper and tar- trate of ammonia, a solution of phosphate of cop- per and ammonia, and also a solution of sulphate of copper, tartrate of potash and caustic soda. Cyanide of Copper Solution. The solution in general use for coppering iron and zinc is that of the double cyanide of copper and potassium. This may be readily prepared by the battery process, as directed for preparing gold solutions, using an anode of pure copper in a hot solution of cyanide of potassium. Or it may be prepared by throwing down the copper from any of its acid ELECTRO-PLATING WITH COPPER 131 solutions, as cyanide of copper, and then dissolv- ing this in a solution of potassium cyanide, by the process given for making up the solution of double cyanide of silver and potassium. This solution possesses the disadvantage of having to be used at a temperature of from 160 to 180 de- grees Fahrenheit, and it does not freely dissolve the anode unless a large excess of free cyanide is present in the solution, and this excess is detri- mental to the deposit of copper, since it has a tendency to dissolve the newly deposited coat and make it loose or spongy. Alkaline Copper Solution. The best alkaline copper solution is made as follows: Dissolve eight ounces of copper sulphate in one quart of hot rain or distilled water and set aside to cool. When cool, add liquid ammonia, whilst stirring with a stick or glass rod. At first a green pre- cipitate will fall, and then this will dissolve on adding more ammonia, until the whole solution assumes a blue tint. Dilute this with an equal bulk of cold rain water and add to it enough solution of potassium cyanide, whilst stirring, to destroy the blue color of the ammonia sulphate and give the color of old ale to the solution. Set this aside for a few hours, then pass it through a linen filter and make it up to a gallon of solution with rain or distilled water. This solution may be worked cold, but the rate of deposition is in- creased and the deposited copper of improved quality when the solution is heated to a tempera- ture of from 110 to 130 degrees Fahrenheit. 132 THE ELECTRO-PLATERS HAND-BOOK Working Alkaline Copper Solutions. As the affinity between copper and cyanide is stronger than that between copper and acid, it takes a higher voltage to separate them and deposit the copper in good condition. Copper may be de- posited from an acid solution with a voltage of less than 1 volt, but it takes a voltage of from 6 to 8 volts to deposit copper on iron from an alka- line solution. Gas must be freely given off from the article whilst deposition is proceeding, but the volume of gas must be reduced by reducing the voltage of the current if the deposit shows a tendency to become dark and sandy. An anode of pure copper must always be employed. If the anode coats itself with a green crust soon after deposition commences, add some liquid am- monia, whilst stirring the solution, until the green crust dissolves and the anode works clean. If the anode becomes coated with a blue crust, add cyanide of potassium solution. By thus noting the condition of the anode and adding ammonia or cyanide as required from time to time, the solution may be kept in working order. It is not usual to deposit thick coats of copper from alkaline copper solutions, but to just cover the article with copper and then transfer it at once to the plating solution before the pure cop- per coat can become oxidized by the action of the air. When thick deposits of copper are required, the articles are transferred from the copper plating bath at once to an acid solution of cop- per sulphate, and deposition continued in this ELECTRO-PLATING WITH COPPER 133 until the desired thickness of copper has been obtained. Kate and Thickness of Copper Deposits. Cop- per is deposited from its solutions in good condi- tion at the rate of .05045354 grains per second with 1 ampere of current, or at the rate of 18.163 grains per ampere-hour. With 1 ampere of cur- rent depositing copper on one-tenth of a square foot of surface, 181.63 grains are deposited in 10 hours, while with 10 amperes of current 181.63 grains of copper are deposited on 1 square foot of surface in 1 hour, and with 100 amperes 1816.3 grains of copper are deposited per hour. The rate of deposit suitable for a known surface can thus be readily ascertained, together with the volume of current necessary to effect the desired deposit in a given time, bearing in mind always that to force copper rapidly on a small surface it will be necessary to increase the voltage of the current, and this may deposit brittle metal. The thickness of a copper deposit may be ascertained by calculating each 2.2468 grains per square inch to measure one-thousandth of an inch in thick- ness. ELECTRO-PLATING WITH ZINC, TIN, IRON AND PLATINUM Electro-plating with Zinc. Zinc has been elec- tro-deposited from a solution of its sulphate by the use of a feeble current. It has also been deposited from its solutions of chloride, acetate, tartrate, ammonia sulphate, and ammonia chloride. Zinc-plating Solution. Dissolve 200 ounces of best cyanide of potassium in 20 gallons of water and stir into this 80 ounces of strong liquid am- monia. Place several large, clean, porous cells in the solution, and fill these with the bath liquid. In each cell suspend a strip of copper, and con- nect each strip to the negative pole of a strong battery or a plating dynamo. From the other pole suspend a large anode of zinc and pass a cur- rent until 60 ounces of zinc have been dissolved from the anode. Next dissolve 80 ounces of car- bonate of potash in part of the bath solution, stir this into the main bulk and let it rest for 12 hours. Filter the bath before using and work it with a current of from 4 to 5 volts, using anodes of milled zinc. The articles to be zinc-plated should be cleaned and treated as for silver-plat- ing, but not quickened in mercury. Tin-plating. The so-called tin vessels com- monly in use for domestic and other purposes are 134 ZINC, TIN, IRON AND PLATINUM 133 made of thin sheet iron coated with tin. The sheets of iron are dipped in a bath of molten tin, and thus acquire a thin film of this metal. The insides of copper and iron vessels employed for culinary purposes are coated with tin by a similar process. Whenever it is deemed desirable to »oat an article with tin, it may be cheaply and expe- ditiously done by this, the molten process. Small brass articles, such as pins, hooks and eyes, and small copper articles, such as hooks and buttons, may be easily coated with tin by simple immersion in a bath composed of a saturated solution of cream of tartar in which has been dissolved a small quantity of chloride of tin. The quantity of this salt is immaterial, as it is only employed to start the process, the remaining tin being sup- plied from anodes of sheet tin suspended in the bath. The liquid is kept at a boiling tempera- ture and the articles to be tinned are suspended in the bath between the tin anodes until suffi- ciently whitened, when they are rinsed in water and rattled about in hot bran until dry and bright. Iron articles may be similarly whitened in a boiling solution made by dissolving 3 drams of fused protochloride of tin and 6 ounces of ammonia alum in one and a quarter gallons of water. Bronze may be coated with tin in a hot solution of caustic soda in contact with anodes of pure tin. Electro-plating with Tin. Tin may be readily deposited by the single cell process from its solu- tion in caustic soda or in caustic potash. Make 136 THE ELECTRO-PLATERS HAND-BOOK up a strong solution of either of those caustic alkalies, and add to it a small quantity of per- chloride of tin, also put some plates of pure tin in the cell. Place some of the caustic alkali solu- tion in porous cells with strips or bars of zinc, and connect the articles to be tinned to copper wires attached to the zinc and immerse the whole in the tinning solution. Solutions for the electro- deposition of tin with current from a separate battery are here given. Solution No. 1 is made in the following manner : Dissolve 30 pounds of caustic potash in 20 gallons of water, 30 pounds of cyanide of potassium in 20 gallons of water, and 30 pounds of pyrophosphate of soda in 60 gallons of water. Into the caustic potash solu- tion pour gently, whilst stirring all the time with a glass rod, 200 fluid ounces of the chloride of tin solution, then all the cyanide solution, and lastly all the soda solution. This solution is used for tinning zinc articles and is worked at a tempera- ture of 70 degrees Fahrenheit, with a current having an electromotive force of from 3 to 4 volts. Solution No. 2 is made up of 20 pounds pyrophos- phate of soda dissolved in 40 gallons of water into which is poured 100 fluid ounces of the chloride of tin solution, and, finally, there is added to this 56 pounds of sal-ammoniac dissolved in 60 gallons of water. This solution may be worked with a weaker current than that employed for No 1 solution, but must be used at a temperature of from 100 to 110 degrees Fahrenheit. ZINC, TIN, IRON AND PLATINUM 137 Electro-plating with Iron. Iron may be de- posited from suitable solutions, in a condition resembling hard steel, and in this state has been found useful for facing printers' type, engraved copper plates, and electrotypes of copper. The process has been named acierage, or steel-facing. Various solutions have been tried for the purpose. One solution is made as follows: Dissolve a quantity of iron sulphate in water and add a solu- tion of ammonia carbonate until all the iron has been thrown down. Wash the precipitate several times, and dissolve it in sulphuric acid, taking care to only add as much acid as will dissolve the precipitate. Use this solution in a concentrated state, with iron anodes having a combined surface some seven or eight times larger than the copper surface to be coated. The bath must not be allowed to get acid, so it must be kept well sup- plied with iron, and it is advisable to add car- bonate of ammonia occasionally. The copper plate to be steel-faced must be well cleaned with benzine, then with caustic potash, and well rinsed in water. It should be placed at once in the iron solution and well scrubbed every five minutes, until a sufficient thickness of iron has been secured. When the face is deemed thick enough, wash it thoroughly in warm water, dry it quickly whilst rubbing with a soft brush, then coat it with a thin film of wax to preserve it from rust. Good results have been obtained from a solu- tion of the double salt of ammonio-sulphate of iron. Also from a solution of sulphate of iron 138 THE ELECTRO-PLATERS HAND-BOOK and sulphate of ammonia, one part of iron sul- phate to five parts of water. A solution of iron sulphate gives good results when sal-ammoniac is added to the bath. It is advisable to cover the surface of the bath with glycerine while at work, and to keep it under cover when not in use, to prevent decomposition by action of the air. Electro-plating with Platinum. The peculiar character of platinum, as shown in its non-liability to corrosion in acid fumes and in all the simple acids, points to its usefulness as a protective coat- ing to articles of brass, copper, German silver, etc., used in chemists' laboratories. With reasonable care in conducting the process, plati- num can be deposited in good condition from a solution of the double cyanide of platinum and potassium in distilled water. The solution is to be made up as directed for making the double cyanide of gold and potassium, by precipitation from a dilute solution of chloride of platinum (made as directed for obtaining terchloride of gold) , and dissolving the precipitate in a solution of cyanide of potassium. As platinum solutions are easily decomposed by the introduction of other metals, and thus always liable to deposit the metal by simple immersion, success is achieved in its electro-deposition only by employ- ing dilute solutions and a low voltage. If a high voltage is used the deposit will be loose and spongy, presenting the appearance of black grains, instead of a reguline deposit. ZINC, TIN, IRON AND PLATINUM 139 The solution of double cyanide of platinum and potassium must therefore be very dilute, and care must be taken to add some chloride of platinum at frequent intervals to neutralize the free cyanide, and also to replenish the solution with metal, since platinum anodes are not soluble in solutions of potassium cyanide. The following solution gives less trouble than that previously mentioned, but requires more bat- tery power. Take 5 fluid ounces of platinic chloride containing one-quarter ounce of platinum in 5 ounces of water, and stir it into 10 pints of distilled water. Take 20 drams of crystallized phosphate of ammonia and dissolve it in distilled water, then add the solution to the platinic chloride solution whilst stirring it with a glass rod. Take 100 drams of crystallized phosphate of soda, dissolve in distilled water and stir this into the mixed solution before prepared, to dis- solve the precipitate caused by adding the phos- phate of ammonia. Boil the whole in an enameled iron vessel until it ceases to give out the odor of ammonia and will slightly redden blue litmus paper, it is then ready for use. Work the solu- tion at a temperature of from 190 to 200 degrees Fahrenheit, using a large platinum anode and a current having a voltage of from 5 to 6 volts. As the anode does not dissolve in the solution, it is necessary to add some chloride of platinum occa- sionally to maintain the bath at its proper metal strength. This is best done at the close of an operation, adding just as much chloride as will 140 THE ELECTRO-PLATERS HAND-BOOK contain enough platinum to represent that drawn from the bath, and stirring all well together. It is also advisable to add occasionally a small quantity of phosphate of soda to dissolve any platinum precipitate which may form at the bot- tom of the bath and to prevent it from becoming too acid. This solution will deposit reguline platinum of the usual steel-gray appearance on copper and brass and alloys of copper. If it is wished to coat with platinum such metals as iron, zinc, lead, tin, or alloys of these metals, they must first be electro-coppered, since they decom- pose the platinum bath and deposit the metal on themselves by simple immersion. ELECTRO-PLATING WITH ALLOYS Alloyed metals may be successfully deposited by using two or more of the metals together which compose the alloy to be imitated. Thus, various proportions of copper and zinc may be deposited together to form varieties of brass and of bronze, or copper and tin may be deposited together to form bronze. Copper, zinc and nickel may be deposited together to form German silver. Some interesting effects may be produced by depositing gold and copper, gold and silver, gold, silver and copper, and copper and silver together, from mixtures of the double cyanide solutions of these metals. Greater skill and care must be exercised to successfully deposit an alloy than would be employed in depositing either of the metals composing the alloy. Special conditions must be adhered to respecting the regulation of the current strength, strength and condition of the bath, and surface of the anode employed. Any variation from these conditions will result in a variation in the composition and appearance of the deposited alloy. The color of alloys, made by melting two or more metals together, depends very largely on the proportionate parts of the composition. If equal bulks of copper and of zinc solutions containing equal weights of the two metals are mixed together a mixed deposit con- 141 142 THE ELECTRO-PLATERS HAND-BOOK sisting of equal parts of the two metals copper and zinc will result. In practice, from such a solution a great variety in shades of brass may be obtained, depending on the temperature of the solution and the strength of the current. As the quantity of metal deposited from a solution de- pends greatly on its electric valency, and this varies with each metal, it becomes a matter of difficulty to always adjust the current to the com- position of the solution so as to deposit each metal in the proportion desired to obtain a given effect of color in the deposited alloy. Electro-deposition of Brass. Brass has been deposited from a great variety of brass solutions, as will be seen by reference to the annexed table. Among the first attempts to deposit brass may be mentioned that of M. de Ruolz in 1841, who employed a mixed solution of the double cyanides of copper, zinc and potassium. Cyanide of potassium forms an important ingredient in the majority of alloy solutions, but ammonia in some form is also necessary to keep the solutions in working order. The following conditions are to be observed in making up the solutions according to the propor- tions given in the accompanying table. Fluid ounces are given for liquids and avoirdupois ounces for the solids. When potassium car- bonate, carbonate of potash, is to be used, the copper and zinc salts are first dissolved in water and then precipitated as carbonates from this solution by adding a portion of the potassium ELECTRO-PLATING WITH ALLOYS 143 d o o •iO •O ; oo lis : tH o • CO 01 • i— i oo CO •o co O CO 00 T-H *""* • CO : cr o Is to o iO *C fc id o i—i CO O U3 Eh P o s^ to hH o iO 00 o o ■* o OQ ■^ CO i" 1 ' CO CQ to C5 fc o o ; O o < o co (N o CO CO tH CO e Handy Vest-Pocket ELECTRICAL DICTIONARY BY WM. L. WEBER, M.E. ILLUSTRATED CONTAINS upwards of 4.800 words, terms and phrases employed in the electrical profession, with their definitions given in the most concise, lucid and comprehensive manner. The practical business advantage and the educational benefit derived from the ability to at once understand the meaning of some term involving the description, action or functions of a machine or apparatus, or the physi- cal nature and cause of certain phe- nomena, cannot be overestimated, and will not be, by the thoughtful assidu- ous and ambitious electrician, because he knows that a thorough understand- ing, on the spot, a.nd in the presence of any phenomena, effected by the aid of his little vest-pocket book of refer- ence, is far more valuable and lasting in its impression upon the mind, than any memorandum which he might make at the time, with a view to the future consultation of some volumin- ous standard textbook, and which is more frequently neglected or.f orgotten than done. The Dook is of convenient size for carrying in the vest pocket, being only 2% inches by bV 2 nches, and hi inch thick; 224 pages illustrated, and bound in two different styles: Cloth, Red Edges, Indexed . . 25c Fuii Leather, Gold Edges, Indexed, 50c by Dookseilers generally or sent postpaid to any address upon receipt of price. FREDERICK J. DRAKE & CO. Sold PUBLISHERS CHICAGO. ILLINOIS ^^m THE AUTOMOBILE HAND-BOOK OVER 200,000 SOLD By ELLIOTT BROOKES. Assissted by Other Weil-Known Expert* Revised and Enlarged New Edition— The largest and most practical work published. Used by all up-to-date automobile schools as their everyday text-book. over 720 pages and over 329 illustrations. Full Leather Limp, Round Corners, Red Edges. Price. $2.00. At the present time nearly all automobile troubles or breakdowns may, in almost every case, be traced to the lack of knowl- edge or carelessness of the owner or opera- tor of the car, rather than to the car itself. The automobile hand book is a work of p-actical information for the use of owners, operators and automobile mechanics, giv- ing full and concise information on all questions relating to the construction, care and operat'.on of gasoline and electric auto- mobiles, including road troubles, motor troubles, -rbureter troubles, ignition troubles, battery troubles, clutch troubles, starting troubles. With numerous tables, useful rules and formulae, wiring diagrams and over329illustrations. Special efforts have been put forth to treat the subjects of ignition, and igni- tion devices, in a manner befitting their importance. A large section has been devoted to t ese subjects, including bat- teries, primary and secondary, magnetos, carburators, spark plugs, and in fact all devices used in connection with the production of the spark. Power transmissio is thoroughly discussed, and the various systems of transmitting the power from the motor to the driving axle are analyzed and compared. The perusal of this work for a few minutes when troubles occur, will often not only save time, money, and worry, but give greater confidence in the car, with regard to its going qualities on the road, when properly and intelligently cared for. A WORD TO THE WISE The time is at hand when any person caring for and operating any kind of self-propelling vehicle in a public or private capacity, will have to undergo a rigid examination before a state board of examiners and secure a license before they can collect their salary or get employment. . Already New York State has enacted such a law and before long, with a positive certainty every state in the Union will pass such an ordinance for the protection of life and property. Remember this is a brand new book from cover to cover, just from the press— New Edition— and must not be confounded with any former editions of this popular work. Sent prepaid to any address upon receipt of price FREDERICK J. DRAKE & CO., Publishers 1325 Michigan Avenue. CHICAGO, U.S. A. JUST THE BOOK FOR BEGINNERS AND ELECTRICAL WORKERS WHOSE OPPORTUNITIES FOR GAINING INFORMATION ON THE BRANCHES OF ELECTRICITY HAVE BEEN LIMITED ELECTRICITY Made Simple By CLARK CARYL HASKINS A BOOK DEVOID OF TECHNICALITIES SIMPLE, PLAIN AND UNDERSTANDABLE There are many elementary books about electricity upon the market but this is the first one presenting the matter In such shape that the layman may under- stand it, and at the same time, not writ* ten in a childish manner. FOR ENGINEERS, DYNAMO MEN, FIREMEN, LINEMEN, WIREMEN AND LEARNERS. FOP STUTY OR REFERENCE. This little work is not intended for the instruction of experts, nor as a guide for professors. The author has endeavored throughout the book to bring the matter down to the level of those whose opportunities for gaining information on the branches treated have been limited. Four chapters are devoted to Static Electricity ; three each to Chemi- cal Batteries and Light and Power; two each to Terrestrial Magnetism and Electro-Magnetism; one each to Atmospheric Electricity; Lightning Rods; Electro -Chemistry; Applied Electro -Magnetism; Force, Work and Energy; Practical Application of Ohm's Law; also a chapter upon Methods of Developing Electricity, other than Chemical. The large number of examples that are given to illustrate the practi- cal application of elementary principles is gaining for it a reputation 9M ft text book for schools and colleges. In reviewing this book an eminent electrician says of it : "All that 999 men out of 1000 want to know can be imparted in plats iguage and arithmetic. I therefore think that such a book as your* the kind that does the greatest good to the greatest number." I2mo, Cloth, 233 Pages, 108 Illustrations Ctfv aa ppir.r. j»^rf Jpl.VKJ For Sale by booksellers generally or sent postpaid to .any address upon receipt of price, FREDERICK J. DRAKE & CO., Publishes CHICAGO, ILL. The Practical Gas & Oil Engine hand -boo k 111 PRACTICAL GAS i l ANDOIL ENGINE ill HANDBOOK A MANUAL of useful in- formation on the care, maintenance and repair of Gqs and Oil Engines. This work gives full and clear instructions on all points relating to the care, mainte- nance and repair of Stationary, Portable and Marine, Gas and Oil Engines, including How to Start, How to Stop, How to Ad- just, How to Repair, How to Test. Pocket size, 4x6tf. 232 pages. With numerous rules and formulas and dia- grams, and over 70 illustrations by L. Elliott Brookes, au- thor of the "Construction of a Gasoline Motor," and the "Au- tomobile Hand-Book." This book has been written with the intention of furnishing practical information regarding gas, gasoline and kerosene engines, for the use of owners, operators and others who may be interested in their construction, operation and man- agement. In treating the various subjects it has been the endeavor to avoid all technical matter as far as possible, and to present the information given in a clear and practical manner. f 6mo. Popular Edition— Cloth. Price $1.00 Edition de Luxe— Full Leather Limp. Price 1.56 Sent Postpaid to any Address in the World upon Receipt of Price FREDERICK J. DRAKE & CO. PUBLISHERS DYNAMO TENDING for ENGINEERS Or, ELECTRICITY FOR STEAM ENGINEERS By HENRY C. HORSTMANN and VICTOR H. TOUSLEY, Authors of "Modern Wiring Diagrams and Descriptions for El ectrical Workers." This excellent treatise is written by engineers for engineers, and is a clear and comprehensive treatise on the prin- ciples, construction and operation of Dynamos, Motors, Lamps, Storage Bat- teries, Indicators and Measuring Instru- ments, as well as full explanations of the principles governing the generation of alternating currents and a descrip- tion of alternating current instruments x and machinery. There are perhaps but few engineers who have not in the course of their labors come in contact with the electrical ap paratus sue! as pertains to light and power distribution and generation. It the present rate of increase In the use of Electricity it is but a question of time when every steam Installation will have in connecton with it an electrical generator, even in such buildings where light and power are supplied by some central station, it is essential that the man in charge of Engines, Boilers, Elevators, etc., be familiar with electrical matters, ana it cannot well be other than an advantage to him and his employers. It is with a view to assisting engineers and others to obtain such knowledge as will enable them to intelligently manage such electrical apparatus as will ordinarily come under their control that this book has been written. The authors have had the co-operation of the best authorities, each in his chosen field, and the information given is just such as a steam engineer should know, To further this information, and to more carefully explain the text, nearly 100 illustrations are used, which, with perko ps a very few excep- tions, have been especially made for this book. There are many tables covering all sorts of electrical matters, so that immediate reference can be made without resorting to figuring. It covers the subject thoroughly, but so simply that any one can understand it fully A ny one making a Sretense to electrical engineering needs this book. Nothing keeps a man own like the lack of training; nothing lifts him up as quickly or as surely as a thorough, practical knowledge of the work he has to do. This book was written for the man without an opportunity. No matter what he is, or what work he has to do, it gives him just such information and training as are required to attain success. It teaches just what the steam engineer should know in his engine room about electricity. 13mo, Cloth, 100 Illustrations. Size 5^x7%. PRICE NET (M (?A Sold by booksellers generally, or sent, all charges paid, upo n yitUU receipt of price .' FREDERICK J. DRAKE & CO., Publishers CHICAGO. ILL. PRACTICAL BUNGALOWS AND COTTAGES FOR TOWN AND COUNTRY THIS BOOK CONTAINS PERSPECTIVE DRAWINGS AND FLOOR PLANS Of one hundred and fifty low and medium priced houses ranging from four hundred to four thou- sand dollars each. Also thirty selected designs of bungalows for summer and country homes, furnishing the prospective builder withmany new and up-to-date ideas and suggestions in modern architecture The houses advertised in this book are entirely different in style from those shown in Hodgson's Low Cost Homes 12 MO. CLOTH, 420 PAGES, 400 ILLUSTRATIONS PRICE, POSTPAID $1.00 FREDERICK J. DRAKE & CO, CHTCAGO ELEMENTARY ELECTRICITY UP TO DATE By SIDNEY AYLMER-SMALL, M. A. I. E. E. THIS book opens up the way for anyone who desires an accurate fo^/^tfJ^J^TSfC^ : and complete knowledge of elec- — r ^^ ^5?uw ^^ * tricity as a useful agent, in the hands ELECTRICITY of man ' for the transmission ° f me * * '"' chanical energy, and the creation of light. In addition to opening up the way as referred to above, the book also serves as a guide and instructor to the seeker after knowledge along these lines. Beginning in the form of a simple catechism on the primary aspects of the subject it conducts the student by easy stages through the various as- pects of static electricity, the different types of apparatus for producing it, all of which are plainly described and illustrated and their action made plain and easy of comprehension. Quite a large space is devoted to this important topic, although no more than is actually necessary, as the subjects of condensers and simple electrical machines are also thoroughly handled, and the principles governing their action clearly explained and illustrated. The subject of atmospheric electricity is next dealt with, and lightning arresters treated upon, especially in their relation to electric power stations, sub-stations and line wires. The wonderful and mysterious subject of magnetism is next treated upon at length and clearly explained— the explanations being accompanied by illustrations. Primary batteries of all types, storage batteries and the effects of elec- trolysis each and all receive a large share of attention. Electric circuits and the laws governing the flow of current, including Ohm's law, are all clearly explained. The student has now arrived at the point where electrical work, power and efficiency is the topic, and where the genera- tion and transmission of electrical currents of high potential and large volume are explained. Sold by booksellers generally or sent postpaid to any address upon receipt of price. 12mo. Cloth, 500 Pages, Fully Illustrated : Price, $1.25 FREDERICK J. DRAKE & CO. PUBLISHERS CHICAGO, ILLINOIS HODGSON'S Low Cost American Homes Arranged and Edited by FRED T. HODGSON Architect This book contains perspective vlewt and floor plans of one hundred houses, churches, school houses and barns, and la » \fl i >VV w •'• i\| without a doubt the most practical work *»£ Ml *-V iaU ^ Ij: ever issued. The plans shown have been built from, and many of them duplicated many times over. All are practical, the creation of the well-known author, including many other architects through- • out the United States and Canada, and are alike valuable to builders and any on« who has in view the erection of a house, etc. The plans are susceptible of slight changes that will adapt them to any taste. The carpenter, remote from the city, .needs just such a book to refer to, or to exhibit to his customer so that the latter can give his orders in an intelligible manner. The much desired economy on these structures is not, however, obtained at the expense of beauty— every one of thf designs, even the very cheapest, is pleas« ing to the eye. Following the ideas laMI down , the builder is sure to obtain a pretty result. Another result aimed at by Mr. Hodgson is the convenience of internal arrangements. Many a good house has been spoiled by having the much needed closet room omitted. All this has been carefully studied by the practical and experienced architects who have compiled this book, so the owner 01 working builder who selects a design from this work will be sure to secure all the elegance, convenience and economy possible in the erection of the house. The publishers furnish perfect blue prints, including a book of specifications at the printed prices shown in the book. The average price of blue prints and specifications is $5.00 per set, and thejf are just the same as plans which, if prepared especially by an architect, would cost from $50.00 to $75.00. The book contains over 350 pages, nearly 325 illustration* printed on a superior quality of machine finished paper, durably bound in English cloth with ""* unique design Price $1,00 FREDERICK J. DRAKE & CO., Publisher* CHICAGO, ILL. NOTICE To the many workmen who are purchasing the publications under tha authorship of Fred T. Hodgson, and who we feel sure have been benefited by his excellent treatises on many Carpentry and Building subjects, we desire to inform them that the following list of books have been puolished PRACTICAL USES OF THE STEEL SQUARE, two volumes, over 500 pages, including 100 perspective views and Joor plans of medium- priced houses. Cloth, two volumes, price $2.00. MODERN CARPENTRY AND JOINERY, 300 pages, including 50 house plans, perspective views and floor plans of medium and low-cost houses. Cloth, price $1.00. BUILDERS' ARCHITECTURAL DRAWING SELF-TAUGHT, over 350 pages, including 50 house plans. Cloth, price $2.00. MODERN ESTIMATOR AND CONTRACTORS' GUIDE, for pricing build- ers' work, 350 pages, including 50 house plans. Cloth, price $1.50. MODERN LOW-COST AMERICAN HOMES, over 200 pages. Cloth, pri« $1.00. PRACTICAL UP-TO-DATE HARDWOOD FINISHER, over 300 pages. Cloth, price $1.00. COMMON SENSE STAIR BUILDING AND HANDRAILING, over 250 pages, including perspective views and floor plans of 50 medium-priced houses. Cloth, price $1.00. STONEMASONS' AND BRICKLAYERS' GUIDE, over 200 pages. Cloth, price $1.50. PRACTICAL WOOD CARVING, over 200 pages. Cloth, price $1.50. Sold by booksellers generally, or sent, all charges paid, upon receipt oi price, to any address in the world. FREDERICK J. DRAKE & CO. Publishers CHICAGO, : : : : U. S. A. FREDERICK J. DRAKE & CO.'S PRACTICAL MECHANICAL BOOKS FOR HOME STUDY Price. Titles. Cloth. Lea. Air Brake Practice, Modern — Dukesmith. Illustrated 1.50 ... Air Brake, Complete Examinations, West- inghouse and New York 2.00 Air Brake, Westinghouse System 2.00 . . . Air Brake, New York System 2.00 ... American Homes, Low Cost — Hodgson. Il- lustrated 1.00 . . . Architectural Drawing, Self - Taught — Hodgson. Illustrated 2.00 ... Architecture, Easy Steps to — Hodgson. Il- lustrated 1.50 . . . Architecture, Five Orders — Hodgson. Il- lustrated 1.00 ... Armature and Magnet Winding — Horst- mann & Tousley 1.50 Artist, The Amateur — Delamotte 1.00 ... Automobile Hand Book — Brookes. Illus- trated 2.00 Automobile, The Mechanician's Catechism. — Swingle 1.25 Blacksmithing, Modern — Holmstrom. Il- lustrated 1.00 ... Boat Building, for Amateurs — Neison. Il- lustrated 1.00 ... Bricklayers' and Masons' Assistant, The 20th Century — Hodgson. Illustrated.. 1.50 ... Bricklaying, Practical, Self - Taught — > Hodgson. Illustrated 1.00 .., Bungalows and Low Priced Cottages — Hodgson 1.00 ... Calculation of Horse Power Made Easy — Brookes. Illustrated 75 . . • Carpentry, Modern. Vol. I — Hodgson. Il- lustrated 1.00 ..., Carpentry, Modern. Vol. II — Hodgson. Illustrated 1.00 ..* Chemistry, Elementary, Self - Taught— Roscoe. Illustrated 1.00 ... Concretes, Cements, Plasters, etc. — Hodg- son. Illustrated 1.50 ... Correct Measurements, Builders' and Con- tractors' Guide to — Hodgson 1.50 ... Catechism, Swingle's Steam, Gas and Electrical Engineering 1.50 Cabinet Maker, The Practical, and Fur- niture Designer — Hodgson. Illustrated 2.00 ... Dynamo Tending for Engineers — Horst- mann & Tousley. Illustrated 1.50 ... Dynamo — Electric Machines — Swingle. Il- lustrated 1.50 ... Electric Railway Troubles and How To Find Them — Lowe 1.50 ... Electric Power Stations — Swingle 2.50 ... Electrical Construction, Modern. Illus- trated 1-59 Electrical Dictionary, Handy, Weber 25 .50 Electrical Wiring and Construction Ta- bles — Horstmann & Tousley 1.50 Electricity, Easy Experiments in — Dick* inson. Illustrated 1«U* • •.« Price. Titles. Cloth. Lea. Electricity Made Simple — Hasklns. Illus- trated 1.00 ... Electric Railroading — Aylmer-Small. Il- lustrated 3.Bt Electro - Plating Hand Book — "Weston. Illustrated 1.00 l.Bt Elementary Electricity, Up To Date — Aylmer-Small 1.25 . . . Estimator, Modern, for Builders and Architects — Hodgson 1.60 ... Examination Questions and Answers for Locomotive Firemen — Wallace. Illus- trated 1.5* Examination Questions and Answers for Marine and Stationary Engineers — Swingle. Illustrated 1.50 Elevators, Hydraulic and Electric — Swin- gle. Illustrated 1.00 . . . Electrician's Operating and Testing Manual — Horstmann & Tousley. Illus- trated l.Bt Farm Engines and How to Run Them — Stephenson. Illustrated 1.00 ... Furniture Making, Home — Raeth. Illus- trated 6t ... Gas and Oil Engine Hand Book — Brookes. Illustrated 1.00 1.50 Hand Book for Engineers and Electri- cians — Swingle. Illustrated. Pocket Book Style 3.0t Hardwood Finishing, Up-to-date — Hodg- son. Illustrated 1.00 ... Horse Shoeing, Correct — Holmstrom. Il- lustrated 1.00 ... Hot Water Heating, Steam and Gas Fit- ting — Donaldson. Illustrated 1.50 ... Heating and Lighting Railway Passen- ger Cars — Prior 1.25 . . . Locomotive Breakdowns, with Questions and Answers — Wallace. Illustrated l.Bt Locomotive Fireman's Boiler Instructor — Swingle l.Bt Locomotive Engineering — Swingle. Illus- trated. Pocket Book Style 3.0t Machine Shop Practice — Brookes. Illus- trated 2.00 . . . Mechanical Drawing and Machine Design — Westinghouse. Illustrated 2.00 ... Motorman, How to Become a Successful. Aylmer-Small. Illustrated l.Bt Motorman's Practical Air Brake Instruc- tor — Denehie l.Bt Modern Electric Illumination, Theory and Practice — Horstmann & Tousley. Illustrated 2.0t Millwright's Practical Hand Book — Swin- gle. Illustrated i.00 ... Modern American Telephony In All Its Branches — Smith. Illustrated - *t« Price. Titles. Cloth. Lea. Operation of Trains and Station Work — Prior. Illustrated 1.60 Painting, Cyclopedia of — Maire. Illus- trated 1.60 ... Pattern Making and Foundry Practice — Hand. Illustrated 1.69 Picture Making for Pleasure and Profit — Baldwin. Illustrated 1.25 ... Plumbing, Practical, Up-to-Date — Clow. Illustrated 1.60 . . . Railway Roadbed and Track, Construc- tion and Maintenance of — Prior. Illus- trated 2.00 Railway Shop Up-to-Date — Haig. Illus- trated 2.00 S'heet Metal Workers' Instructor — Rose. Illustrated 2.00 Signist's Book of Modern Alphabets — Del- amotte 1.50 Sign Painting, The Art of — Atkinson... 3.00 Stair Building and Hand Railing — Hodg- son. Illustrated . . . 1.00 Steam Boilers — Swingle. Illustrated Steel Square, A Key to — Woods.. 1.50 Steel Square, Vol. I — Hodgson. Illus- trated 1.00 Steel Square, Vol. II — Hodgson. Illus- trated 1.00 Steel Square, A B C — Hodgson 60 Steel Construction, Practical — Hodgson. Illustrated 50 Storage Batteries — Niblett 50 Sho* Cards, A Show At — Atkinson and Atkinson 3.00 Stonemasonry, Practical, Self-Taught — Hodgson. Illustrated 1.00 Telegraphy Salf-Taught — Edison. Illus- trated 1.00 Telephone Hand-Book— Illus- trated 1.00 Timber Framing, Light and Heavy — Hodgson 2.00 Toolsmith and Steel Worker — Holford. Illustrated 1.50 Turbine, The Steam — Swingle. Illustrated 1.00 Walschaert Valve Gear Breakdowns and How to Adjust Them — Swingle. Illus- trated 1.00 Wiring Diagrams, Modern — Horstmann & Tousley. Illustrated 1.60 Wireless Telegraphy and Telephony — V. H. Laughter 1.00 Wood Carving, Practical — Hodgson. Illus- trated 1.50 THE BED BOOK SERIES OF TRADE SCHOOL MANUALS By F. Maire 16 mo., Cloth, Illustrated. Price, each, $0.60 Exterior Painting, Wood, Iron and Brick. Interior Painting, Water and Oil Colors. Colors, What They Are and What to Expect from Them. Graining and Marbling. Carriage Painting. The Wood Finisher.