Laboratory guide of industrial chemistry

Front matter

'"^S kABORATORY GuiDE

Industrial Chemistry

^LLEN Rogers m liBlsIl

Preface

In the average course of chemistry as taught in our technical schools there is little or no attempt made to bring the student in close touch with manufacturing conditions. This state of affairs is exceedingly difficult to understand, when we consider the large amount of time devoted to practical work in some of our engineering courses.

The factory is surely no less fertile a department of this industrial era than the railroad or the foundry. For in the manufacturing plant there is more need of techno-practical (if such a term may be used) trained men than in any other branch of industry. Unquestionably it is necessary to have organization for the manipulation of power, machinery, and labor, so as to obtain the maximum of production with the minimum of expenditure or depreciation of plant. But in addition, it is highly essential that we understand the chemical principles upon which these industries are based.

The object of this book, therefore, is to acquaint the student of chemistry with a few commercial processes, by introducing practical methods of handling materials on a large scale; the care and use of machinery; the cost of raw material; transportation; wage system; the handling of men and shop discipline.

The subject-matter of this book presupposes a certain knowledge of chemistry; and purposely leaves many of the minor details to be worked out by the student. Great leeway is also given to the instructor in order that he may exerviii PREFACE

cise his own originality. A few suggestions, however, may not be out of place, and may serve as a guide to those engaged in this important branch of teaching.

The first chapter has been introduced in order to insure that the student understands the use and value of the various methods employed for taking the density of liquids, and the tests given should be conducted by each individual.

The work in the second chapter, dealing with inorganic preparations is best conducted on the foremanship system which is carried out at Pratt Institute as follows: One man is assigned as foreman of the chemical works and has as his assistants three or more of his classmates. The work which he is given may be the manufacture of barium chlorid for example. He first has his men make an analysis of witherite to determine the percentage content of barium and also test the strength of the hydrochloric acid. In order that the work may be more commercial he is told to estimate the cost of producing 15,000 lbs., it being understood that all weighings are made in grams. The necessary quantity of mineral is then weighed, crushed and treated with the diluted acid in the kettle as described under that preparation.

During such a preparation as the one cited it will be necessary to remove impurities, this being regulated by analytical tests.

Chapter three is devoted to the dyeing of textile fibers. Here it will be advantageous to have all tests mounted with names of color, method employed, and any other data written under each skein.

In the fourth chapter the preparations given have been selected with the view of manufacturing commercial products rather than following the usual custom of making organic substances to illustrate typical organic groups. Here

PREFACE IX

it has been found advisable to have the student save a 4-dram sample of each compound, which he seals and mounts on cardboard. In the case of the coal-tar colors, the student should make dye-tests with the same, mounting the skeins and color on the same card. In order, also, to illustrate the use of his colors in the manufacture of lakes he should prepare dry and pulp colors, mounting them on cardboard together with rub-outs in glue and Japan.

In the chapters devoted to soap, paint, leather and paper the work outlined comes again under the head of foremanship method and should be conducted along the same line as for inorganic chemicals. The foreman should be held responsible for the quality as well as quantity of the output from his plant; he should see that all machinery is left in perfect condition, and that his factory is clean.

The advantages gained by this foremanship system are self-evident, giving the student more confidence in his own ability than by any other possible means.

As we are only beginning to see the first faint light of dawn in this all-important branch of education, the author will be gratified, indeed, if this book proves to be of any service to those who are attempting to solve the great problem of Industrial Education, and especially the teaching of Industrial Chemistry.

In conclusion, the author desires to express his appreciation of the kindness and courtesy shown to him by his many friends for the many valuable suggestions which have been so helpful to him in the preparation of this volume.

Allen Rogers.

Pratt Institute.

Brooklyn, September, 1908.

Table Of Contents

PAGE

Preface . . vii

I General Processes . . i

Chapter I General Processes

1. Lixiviation. ■ — Weigh out roughly 5000 grams of crude salt, which has been ground to a fairly fine powder in the mill. Agitate with 30 liters of water in a kettle or receptacle provided with an arbor. When all soluble matter has dissolved, run into kettle or tanks and allow to stand until clear. Next draw off the supernatent solution, wash the residue several times with fresh water, or until a test portion shows only minute traces of chlorides in solution. This process demonstrates the method employed in extracting soluble substances from products containing varying amounts of soluble and insoluble matter.

2. Spontaneous Evaporation. — In the warmer climates advantage is taken of the sun's heat to produce evaporation. This may also be accomplished in cooler localities, only less rapidly, by the sun and wind. To demonstrate this process the solution obtained above is placed in shallow pans exposed to the sun and wind in the open air, the rate of evaporation being noted irom day to day. To obtain the best results, the pans should be large, the depth of the liquid not over two inches, and should be arranged in such a manner as to be easily covered in case of rain.

3. Evaporation by Direct Application of Heat. — This method is not used very extensively, but where it is employed there are two general methods in use, i.e. (a) By bringing the flame in contact with the bottom of the pan; {¥) By passing the heated gases or flame over the top of the liquid to be evaporated. The first may be easily illustrated in the laboratory by placing a copper or iron kettle directly over the charcoal fire or gas flame. This vi'iU shortly bring the liquid to a quiet boil, which may then be regulated to suit the required condition. The second form can only be reproduced on a fairly large scale, so that it is not advisable to try to introduce such a process into laboratory work. 4. Evaporation by Indirect Application of Heat. — This

Fig. 1. — Steam Jacket Kettle. The Stuart & Peterson Co., Burlington, N. J.

means of evaporation may be carried out by various methods. The one which is most widely employed is by means of steam, in which case a steam-jacketed kettle, or tank with steam-coils is used, but usually the former. In conducting an evaporation by this means place your solution in the kettle, and open the drip to the outer jacket. The object of this is to drain the kettle, allow the first condensation to escape and to prevent bumping. The exhaust-valve is opened, the inlet valve given a half turn, and then slowly opened until a good supply of dry steam issues from the drip. The drip is then closed and the inlet of steam regulated to secure the proper heat for evaporation. This should not be too strong as it will cause the solution to boil over the sides, and not too weak as this would consume an excessive amount of time. The best condition is a quiet boil, which as the concentra-

STILL

Fig. 2. — Vacuum Pan. Thomas Burkhard, Brooklyn, N. Y.

tion continues may be regulated by slowly cutting down the steam. This is necessary to prevent the formation of a hard cake which would be produced if the heat were continued the same, or increased during the operation.

5. Evaporation in Vacuo. — The dififerent forms of apparatus used for vacuum evaporation vary much in their construction but all depend nevertheless on reduced pressure. The necessary equipment for a plant to demonstrate this process consists of a vacuum-pump (dry system), a pan, condenser and receiver. The pump may be of any form although one taking up a small space and power driven is preferable. The pan consists of a globular copper or iron vessel with steam-jacket, water-gage, manhole, minometer, thermometer, peep glasses, and discharging valve. A "catch-all" is introduced between the pan and condenser to hold back any liquid carried over mechanically by the steam. The condenser is a tin lined copper coil and is surrounded by running water. The receiver should be connected with the bottom of the condenser and also provided with water-gage.

In conducting the process the liquid should be introduced until the pan is about half full. The manhole is then covered, and the pump started. The steam should be slowly introduced into the jacket and so regulated that a quiet boil is obtained. This can be seen through the peepholes. When the operation is complete, the pressure is slowly reduced by means of an exhaust-valve, and the contents removed through the discharge.

6. Crystallization. — The process of crystallization may be demonstrated in connection with evaporation. Thus if a solution is evaporated until small crystals begin to appear on the surface and is then run into tanks and allowed to cool it will be noticed that well-defined crystals shortly begin to collect on the bottom and sides of the vat; the size of which will depend upon the nature of the substance and also upon the rate of evaporation. Thus if evaporation takes place rapidly small crystals are produced, while the slower the evaporation the larger the crystals.

One of the best salts to use for illustrating this process is sodium sulphate, which on slow evaporation yields a large crop of well-defined crystals.

Very good crystallizing vats may be made by having an oak barrel cut in the middle, or small wash-tubs may be used for the purpose. Tanks of porcelain, stoneware, glass or enamel may also be obtained.

Fig. 3. — Settling Tanks.

7. Levigation. — To illustrate this process, the substance is mixed with water and ground in the wet condition. From the mill it passes into a series of settling tanks arranged in battery. The heaviest material is deposited in A and thus becomes finer as it reaches the last tank. Such a plant can be readily obtained by securing several ice-cream packers and arranging them so that A is about two inches higher than A" and so on down the line having an overflow from tank to tank. The coarse particles are then returned to the mill and the process continued until all of the substance is in a very fine state of division.

8. Filtration. — One of the simplest forms of filters consists of a wooden frame of four flat sticks over which is hung either cotton or woolen cloth in such a manner as to form a bag. The filtrate may be turbid at first but soon becomes clear when the first portion may be returned to the filter.

9. Pressure Filtration. — A convenient and rapid form of filtration is by means of pressure. This may be applied by either of two methods.

The first method is one in which a vacuum is employed, the air being thus exhausted from the receiver. This may be demonstrated in the laboratory by means of the laboratory

size of suction filter which is made of stoneware and can be obtained from any dealer in chemical apparatus. The most satisfactory filter is made by spreading a piece of cotton over the perforated plate, pouring over this about one-half inch of asbestos fiber, and then another piece of cloth.

Such a filter wiU retain the finest of precipitates.

A second form of pressure filtration is carried out by means of the filter press which is largely used in the industries, especially where the insoluble portion is the essential product. These presses vary much in construction although all are based upon the same principle. A small press can be secured which will answer for purpose of instruction. The press consists of a strong iron frame in which a number of filter ceUs are supported. Each cell is made up of two flat metal plates, separated by a hollow distance frame. The liquid holding the insoluble matter in suspension enters the frame through openings in the side. The solid matter is retained in the filter cloth while the pressure forces the liquid through

Fig. 4. — \'acuum Filter. A, Filter Bed; B, Exhaust; C, Outlet.

the cloth, where it follows the grooves, and finally escapes through the necessary openings at the lower side of the plate. The sediment retained by the cloth collects in the cells and forms a solid cake, which finally completely fills each cell. The press is then opened, cleaned and is ready to again be put into operation.

Fig. s. — Filter Press. T. Shriver & Co., Harrison, N. J.

10. The Centrifugal Machine. — The centrifugal machine is used more for drying than as a means of filtration, and consists of a cylindrical basket of perforated sheet metal fixed on a vertical shaft, which rotates at a very high speed. The contents of the baskets are driven to the outer wall by the centrifugal force allowing the liquid to be thrown off while the solid is retained by the screen. In working with such a machine much care is necessary to avoid an uneven load, so that it is well in some instances, especially with chemical salts, to pour in the salt after the machine is in motion.

11. Calcination. — This process may be represented by means of a small reverberatory furnace or, if this is not available, the ordinary mufHe furnace may be employed.

By constructing a bridge of fire-clay at the front of the muffle the charge may be introduced and worked as desired. One of the simplest examples of calcination is the preparation of red oxid, which is given under the head of pigments.

12. Sublimation. — In this process the substance passes from a solid to a vapor and then to a solid without passing through the intermediate liquid stage, and may be most readily represented by heating crude naphthalene in an iron kettle over a low flame or, better, on asbestos. The naphthalene vaporizes and may be condensed by placing a cone over the top of the kettle leaving a very small opening in the top for escaping gases. The cone may be made of sheet iron or even of heavy cardboard. A piece of muslin or filter paper may also be stretched over the kettle which serves as a filter and retains any liquid which might be given off.

13. Distillation. — There are many forms of apparatus employed for fractional distillation, but the one which is most available is the French column still; which can be obtained from any copper maker. These stills may be heated by steam-coils, steam-jacket or by open fire according to the nature of the product being distilled.

14. Density. — By density or specific gravity of a liquid is meant its relative weight as compared to the weight of an equal volume of water at a definite temperature. The determination of specific gravity is one of the most frequent operations in chemical work. For all practical purposes the test may be made with the hydrometer, but for very exact results the pyknometer or specific gravity bottle is employed.

Three systems of hydrometer scales are in common use, besides a great many special ones intended for obtaining a particular substance in a liquid; the principle, however, is lo LABORATORY GUIDE OP INDUSTRIAL CHEMISTRY

the same in each. These instruments are usually of glass, having a bulb weighted at the lower end, and drawn but at the upper end to a long slender tube carrying a scale. The graduations on the scale being at the top and read downward, the largest number being at the bottom, except in one instance — that of Baum6's scale for liquids lighter than water, where it is the reverse.

When the hydrometer is placed in a liquid it sinks sufficiently to displace a volume equal in weight to the weight of the instrument and floats in an upright position.

15. The Direct Specific Gravity Hydrometer. — This instrument is so constructed that the reading of the scale shows the density of a liquid as compared with water at 15° C. The point to which it sinks in pure water is marked 1. 000.

These hydrometers as usually employed are in a set of four. The first spindle is graduated from .700 to i.ooo and is for liquids hghter than water, the i.ooo being at the bottom; while the remainder of the set are for liquids heavier than water, with the smaller number at the top starting with I.ooo.

Practical use is made of the density of solutions for determining the weight of a given volume.

Measure 1000 c.c. of water and take its specific gravity.

Multiply the specific gravity by 1000.

Now pour the water into a weighted flask and after a second weighing, record the weight of the water. Conclusion ?

Measure 1000 c.c. of a salt solution (10 per cent) and take its specific gravity, multiply the specific gravity by 1000, weigh the salt solution. How does it correspond with the theory ? Conclusion ?

Repeat the experiment with caustic soda solution, sul-

GENERAL PROCESSES ii

furic acid, hydrochloric acid, nitric acid, ammonia, alcohol and benzine or naphtha.

i6. Twaddell's Hydrometer. — This is also a direct reading instrument. The set consists of a series of spindles (usually six) having graduations from o° to 174°. The reading for water at 15.5° is taken as 0° and each rise 0.005 sp. gr. is recorded on the scale as one additional division. Thus 10° Twaddell becomes 1.050 sp. gr. The density by this means is recorded as 10° Tw. for instances.

Twaddell readings are readily converted into specific gravity in the following manner:

Multiply the reading by .005 and add i.ooo to the product. Thus, 15° Tw. = 1.075 sp- gr.

In the reverse order specific gravity may be converted into Twaddell. Thus, 1.150 sp. gr. becomes 30° Tw.

That is, from the specific gravity subtract i.ooo and divide by .005.

This is the most convenient hydrometer for factory or laboratory use. It is, however, not adapted to liquids lighter than water.

Take the density of water with the Twaddell hydrometer.

Take the density of the salt solution used in the former experiment.

Calculate its specific gravity.

How does this agree with the former readings ?

17. Baume's Hydrometer. — This is a very unscientific instrument, but is largely used in technical work. Its readings have no very direct relation to specific gravity. Baume dissolved 15 parts of pure salt in 85 parts of pure water at

12.5° C. The point to which his instrument sank was marked 15; the point to which it sank in pure water was marked o. The distance between these points was divided into fifteen equal parts. This produced an instrument for liquids heavier than water.

For liquids lighter than water, the point to which the instrument sank in a 10 per cent solution of salt was marked o, and that to which it sank in water was marked 10, the distance between these points was divided into ten equal parts, and this graduation continued the entire length of the spindle. The 0° thus being at the bottom of the stem, the lighter the gravity of the liquid tested, the greater numerically is the reading of the scale. For instance, a liquid reading 70 B6 is of less density than one at 50 Be, which in turn is lighter than water at 10 B6.

To further complicate matters, the instrument makers appear to have become confused and produced instruments with erroneous scales. A test made several years ago disclosed thirty-four different scales, none of which were correct.

The conversion of American Standard Baume readings to specific gravity is usually accomplished by reference to tables, but may be worked out as follows:

Sp. ST. = ^^^r— (for liquids heavier than water at

Sp. gr. = -—=r-. (for liquids lighter than water at

There is still another form of Baum6 which is in quite common use, the so-called rational scale Baum6 instrument (Kolb's) which indicates zero in pure water at 15° C. and 66 in sulfuric acid of sp. gr. 1.842 at 15" C.

Take the density of water, salt solution, caustic soda solution, sulfuric acid, hydrochloric acid, nitric acid, ammonia, alcohol, naphtha.

By conversion determine their specific gravity. How does this agree with the first set of experiments in density ?

18. The Pyknometer. — This consists of a small bottle, having ground into its neck a capillary tube enlarged at its upper end to form a reservoir which is closed by a stopper. The bottle is filled with the liquid to be tested, and the stopper loosely inserted. When the bottle and contents have reached the normal temperature the excess of liquids in the reservoir is removed by means of filter paper until the lever of the liquid reaches the mark thereon. The stopper is tightly inserted, and after cleaning and drying is then weighed.

The density of the liquid is ascertained by the following:

Weight of bottle and hquid — weight of bottle

Weight of bottle and water — weight of bottle

Or,

Weight of liquid

Sp. gr. = :

Weight of equal volume of water

Determine the specific gravity of salt solution, caustic soda, sulfuric acid, hydrochloric acid, and alcohol.

19. Westphal Balance. — This is a special form of balance for determining the density of liquids. A glass plummet of known weight and volume is suspended from the beam by a fine platinum wire, and is submerged in the liquid to be tested. The weight which the plummet loses is the weight of the liquid displaced. By using a set of riders this loss can be determined, and when recorded gives the specific gravity of the liquid.

Determine the specific gravity of a salt solution, caustic soda solution, sulfuric acid, hydrochloric acid, and alcohol. In all determination of density the question of temperature is an important factor, and all corrections should be made accordingly. When using the Twaddell hydrometer for commercial purposes, however, the addition of i° Tw. for each 20° F. above 60° wiU suffice.

Outlines of Industrial Chemistry. Frank Hall Thorp. New York, 1907.

Hand Book of Industrial Organic Chemistry. S. P. Sadtler. Philadelphia, 1906.

Books on Technical and Analytical Chemistry

Animal Fats and Oils. 6 vols. L. E. Andes. London, 1897-1903-

Oil Analysis. A. H. Gill. Philadelphia, 1503.

Chemical Technology and Analysis of Oils, Fats and Waxes. 2 vols. J. Lewkowitsch. London, 1904.

Commercial Organic Analysis. A. H. Allen. 6 vols. Philadelphia, 1896-1907.

Chemical Analysis of Iron. A. A. Blair. Philadelphia, 1906.

Organic Analysis. A. B. Prescott. New York, 1901.

Quantitative Chemical Analysis. Frank Clowes and J. B. Coleman. London, 1906.

Quantitative Chemical Analysis. C. R. Fresenius. New York, 1903.

Text -book of Quantitative Analysis. J. C. Olsen. New York, 1908.

Chapter II Inorganic Preparations

20. Aluminium Sulfate. — (Al2(S04)3i8H20). Intimately mix looo grams of bauxite with 3000 grams of soda ash, and introduce this mixture in small portions into an iron crucible which is sufficiently heated to cause a fusion of the mass. When the evolution of gas ceases add fresh portions, and so on until all has been introduced, and a quiet fusion results. The temperature is brought to a bright red heat and continued so for about two hours. The whole is then poured while still molten, into a shallow iron pan to cool. The ground mass is then lixiviated, and the dark colored solution boiled with the addition of sodium carbonate to precipitate the iron. After filtering off the iron, the solution is again boiled with sodium bicarbonate or carbon dioxid introduced, to precipitate the aluminium hydroxid. Wash the precipitate with hot water, dissolve in the necessary amount of diluted sulfuric acid, evaporate to a density of 40° Tw. and allowed to crystallize. Evaporating the mother liquor for a further yield.

The filtrate from the aluminium hydroxid precipitate is also evaporated to recover the sodium carbonate.

Reactions. — Al^COH), + 3 Na^COg = Alj(NaO), + 3 COj + 3H,0

Alj(NaO)e + 6 NaHCOs = Al^COH), + 6 Na^CO, k\{OYL), + 3 H^SO, + 12 H^O = Al^CSOJa • 18 H^O

In preparing the above salt an analysis should be made to determine the per cent of AI2O3 in bauxite in order to estil6 LABORATORY GUIDE OF iMbUSTRIAL CHEMiSTkY

mate the necessary quantity of sodium carbonate, sodium bicarbonate and sulfuric acid. The student should also be required to estimate the theoretical yield, and cost per pound of his finished product, taking into account the question of freight, labor, interest on investment, wear and tear of machinery, and containers, besides that of his raw materials.

Example:

1000 lbs. of Bauxite at ^ c. per lb $5.00

3000 lbs. of Soda-ash at i| c 37-5°

3230 lbs. of Sodium bicarbonate at 2 c 64.60

1884 lbs. of Sulfuric acid at 2 c 37-68

91 14 lbs. of Incoming freight at 6 c. per 100 lbs.

4269 lbs. of Outgoing freight at 6 c. per 100 f. o. b.,

Containers at 15 c. per 100 lbs 6.30

$159.07 Addition of 20 per cent for labor, interest, wear

and tear, etc 31-80

Total cost $190.88

190.88

21. Antimony-Potassium Tartrate. — KSbO(C4H405) ^ H,0.

Dissolve 1000 grams of cream of tartar in 15 liters of boiling water and slowly add 800 grams antimony oxid. When all has dissolved filter the hot solution and evaporate to point of crystallization. Allow to cool, separate the crystals and again evaporate the mother liquor for further yield.

This salt is known commercially as Tartar Emetic.

Estimate cost per pound.

INORGANIC PREPARATIONS

22. Ammonium Sulfate. — (NHJ2SO4.

Determine the amount of ammonium hydroxid and sulfuric acid necessary to produce 2000 grams of (NHJj SO4 as follows:

Take the specific gravity of your ammonia and refer to the table to find the per cent of NH3

= amt. of ammonium hydroxid to use.

y = amt. of HjSO,.

Take specific gravity and refer to table as for ammonia. Now mix the sulfuric acid with about ten times its volume of water and slowly add the ammonia. Evaporate to obtain crystals.

Estimate cost per pound.

23. Barium Chlorid. — (BaClj, 2 HjO).

To estimate the necessary quantity of material for the production of 5000 grams of barium chlorid the following method should be employed.

Calculation. — BaClz 2 HjO : Ba :: 5000 : x. X = amt. of Ba necessary.

As the barium is derived from the mineral witherite the percentage content should be determined by analysis and from this the quantity of mineral determined thus:

amt. of witherite.

per cent of Ba BaCl22 H2O : 2 HCl :: 5000 : y y = amt. HCl

By taking the specific gravity of the acid and referring to table the percentage strength is obtained when

= amt of acid required.

per cent of HCl

The mineral is ground, placed in a suitable vessel, and lo liters of water added. The hydrochloric acid is then slowly introduced, and the solution brought to boiling; about 200 grams of powerded witherite is added to precipitate the iron and aluminium, and the solution evaporated to 55° Tw. filtered, and allowed to crystallize. The mother liquor being concentrated for a further yield.

Estimate cost per pound.

24. Ferrous Ammonium Sulfate. — (FeS04(NH4)2S04- 6 H,0).

Dissolve 1400 grams of ferrous sulfate and 664 grams of ammonium sulfate in 2000 c.c. of water separately, heating to 60° C. Filter if necessary and mix the two solutions, concentrate, add 36 grams of sulfuric acid and allow to crystallize. Remove the crystals from the mother liquor, dry in the centrifugal machine, and evaporate the mother liquor for more crystals.

Test for purity and estimate the cost per pound.

In order to manufacture 2000 grams of lead acetate it will first be necessary to make an analysis of the litharge and acetic acid and from the percentage composition determine the quantity of each to be employed.

Reaction. — PbO -1- 2 C^H^O^ = PbCCjHjOj)^ + H^O

26. Lead Nitrate. — Pb(N03)2.

This compound may be prepared in the same manner as recommended for the acetate.

INORGANIC PREPARATIONS 19

27. Magnesium Chlorid. — (MgCl^- 6 HjO).

Having determined the per cent of magnesium in magnesite, and the strength of hydrochloric acid, estimate the quantity of each necessary to produce 4000 grams of the salt.

Mix the magnesite with an equal quantity, by weight, of water, slowly add the acid and heat on the steam bath until the action ceases. If acid in reaction make neutral with magnesite. Digest for an hour and filter while still hot. Evaporate the filtrate on the steam bath to a density of 60° Tw. and allow to cool. The crystals are removed and separated from the mother liquor in the centrifugal machine. The liquor being evaporated for further yield.

Estimate the cost per pound.

Magnesium chlorid is very deliquescent, and should be placed in a bottle as soon as removed from the centrifugal machine.