as if this would ultimately be accomplished through the usc of electricity. AIR. FLOWERS:
Another loss in zinc, which is perhaps not noticed by most chemists, is in the illustrated literature of the country, which is printed from zinc plates. As far as I know, outside of a few cents obtained for the scrap metal, the zinc consumed in etching thcsc plates is never recovered. M K . LANGMUIK : I t seems to me we should not only discuss the waste of zinc, but also the waste of the health and lives of the workmen from the zinc fumes. X I K . B.4SSETT:
I t seems to me that if ive can get some kind of clectrically heated furnace xvith thc electric discharge for condensing zinc fumes and obtain poiver cheap enough, we will be making great strides toward the end sought for. The cffcct of zinc fumes on the health of the casters, in the ordinary casting shops, a t least those connected with the wrought brass industry, are not any more harmful io health than is the use of tobacco. Throughout thc large mills of Connecticut you will find as fine looking men engaged in casting brass as you can find in any tradc where the work is carried on in intense heat. They are mostly big, husky men mho enjoy life to a good old age, and do not seem to mind the effect of the zinc. Occasionally, there are men who do not seem able to stand the \vork, the same as in any trade where work is severc and hot, hut iii almost evcry instance the casters of brass arc healthy and apparently not injured in any way by the zinc fume which, to people who are not accustomed t o it, is quite troublesome. X certain zinc company in starting a new plant found great difficulty in getting help that would work in the bag room, because a considerable amount of zinc oxide was carried into the atmosphere. The laborers, who were unused to zinc, were troubled with the chills, fever and nausea t h a t go with acutc zinc poisoning, and would not stay a t work until they had become accustomed to it. The company offered each man ~ v h o \r-orkcd a month’s pay bonus. This resulted in a numbcr staying to collect the extra pay, and as they soon became accustomed to the zinc the difficulty was overcome. The trouble with zinc is soon over and one becomes immune. II‘ith regard to the recovery of the zinc that is distilled off, Mr. Pricc has answered that question fully. The brass industry has been carried on for more than a century in Connecticut. ‘The industry was imported from England, and considerable study has been given the matter of zinc loss, but up to date i r e have’becn unable to find any way to o\-ercome it. U e hopc t h a t thc work that has been done by the United States Uureau of Mines will help us.
*
So far as protecting the nictal from the currents of air which may s\vcep airay the zinc and produce extra volatilization is concerned, I think that this is now done thoroughly by a good heavy covering of charcoal. Of course, without the covering of charcoal, the zinc would be much more rapidly lost. The temperature a t which the brass is cast, and the loss of zinc on that account, is something that we are unable to control I think there is no industry getting out sheet metal, wire, rods, tubes and other articles of that kind, where the perfection of the product required is as great as it is in the brass industry. Thc brass manufacturer, for instance, is obliged to get out brass for the maker of cartridge shells, which brass must bc absolutely perfect. The practices in use in the brass mills making this material are those which have been found by experience to -give a product that will meet thtsc requirements.
NEED OF SPECIAL ALLOYS FOR SPECIAL
PURPOSES.
I3y \I7. 1%. I ~ A S S E T T .
The development in enginecrinr: c u n s t r u c t i m hzts arrived a t a point \There the u s c ’ o f sllccial ah!-s I‘or specific requirements needs attention. ’l’hcw Ti’quirements may be considered uncler tn-o hcatis : first, the phJ-sical rcquircmcnts ; scwmcl. resistancis to corrosion. The physical prqm-tics ; ~ r cc~+sil>-studied in t h t , laboratory. Xachines have, been t l ing not onl!- the tensile strc’ngtli anti clongntiori, b u t for stud>-inghardness and resistance to :~brasic~ii and the behavior (it’ thcl material uncler rcsl)c’:itc.tl .;trcBss and shock. 1 he mattcr of corrosion has bvcrl ( ~ 1 1 ~ol’ ’ ;I ~ l i o i - c or less mysterious naturc’ : partl!-, 1)erhaI)s. becausc, of a want of knowledge on the 1)at-t of engineers as t o the comliosition o f t h c various clllu~-sTvith Ivhich L they deal. Confusion has arisen i ~ n a c c o u n t I ] ! ’ thi. iiai1ic.s of alloys. Thc nomenclature usecl in the nl in-icvous metals trade is confusing t o t h o s e w h o are not i:ttniliar with the business. This nonienclature has, thruuxh usage, becornk so firmly rooted that it is 1iractically impossible to change it. The tradc names have, [in actual value t o t h e pruduccv-s c ~ fvarious matc4al xncl they would naturally resist changes which would destroy such values. Years ago, Thurston undertoilk t o introduce the name “I“Bronzes ;” the copper-zinc d o ) - s of a red colc~r which are properly red “Brasses ;” anti the classes of alloys (which Thurston called “lialchoids”) which are properly Brasses containing some element or e k ments t o give them strength and I r o t c c t t h e m frorn corrosion. I t would be quite evident t o an!* chemist that accelerated corrosion at the expense of the metal containing the larger proportion uf zinc will take place if two “Bronzes,“ one of an alloy (if cci1)per and tin and the other of the “1ia.lchoid” type, are placed together in a n electrolyte such, for instance. as sea n-ater. \Ce often are asked t o explain why a gun metal pro1)eller is lost from the end of a manganese bronze shaft. I t not infrequently (xcurs t h a t brass strainers are held in position with copper or gun metal bolts, or a brass screen is p u t into position with copper rivets and burrs. Of course, galvanic action is set up in all of these cases to the d ~ struction of the alloy containing thc creater pc:rcentagy of zinc. This destruction is usuall?- brought about b y the dezincification of the alloy containing- the larger proportion of zinc. When this action has taken place, the material left behind is a mass c ~ f spongy copper having very little tenacitJ- but still retaining the shape of the original material. Thc I
.
.
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T H E J O U R N A L OF INDUSTRIAL. A N D E N G I N E E R I N G C H E M I S T R Y .
brass manufacturer has many times, on account of this action, been accused of sending out his material without proper mixing. There is certainly need of more education along the line of prevention of corrosion b y not putting together alloys which will naturally set u p galvanic action under the conditions of exposure t o which they are subjected. With iron and steel there is hardly a parallel case, b u t such a variety of non-ferrous alloys is possible and the composition of alloys produced b y various makers for the same work so different t h a t material of different compositions not infrequently finds its way into the same structure. One of the best examples of the need of alloys for special purposes is t h a t of the condenser tube problem. Condenser tubes have been made of Muntz metal having the composition of approximately 60 parts copper t o 40 parts zinc and of brass having a composition of approximately two ( 2 ) parts copper t o one ( I ) part cinc. Muntz metal is one of the alloys which may be worked hot, and is composed of mixed crystals of the a- and /?-alloys. I n the presence of sea water, galvanic action is started between these alloys with the result t h a t the 8-alloy becomes dezincified, leaving a-crystals in a mass of spongy copper. The action then reverses and the a-crystals are dezincified, finally leaving a tube made u p of spongy and brittle copper which may be snapped off as easily as a rotten stick. Brass tubes have proved but little better, since any substance like carbon or oxide of iron which goes into the condenser starts galvanic action with a result similar to t h a t just described. I n order t o overcome these troubles the Admiralty alloy was devised. This consists of 70 copper, 29 zinc, and I tin. It is much more resistant t o corrosion than the alloys first mentioned as it is richer in copper and the tin exerts a protective influence. Under the conditions of exposure in polluted harbors, even this alloy will be destroyed through dezincification within a few years. Attempts were made t o obtain a n alloy which would be still further resistant to corrosion, and tubes were made from alloys of copper and nickel, b u t these were not enough better than those from the Admiralty alloy t o warrant the extra expense of production. Attempts made t o secure condenser tubes which would last b y lining copper tubes with aluminum failed. Various alloys of copper, zinc and tin were tried but none of these appeared to outlast Admiralty tubes in similar service. Finally a trial has been made with a special grade of aluminum bronze, known t o the trade as "Benedict Bronze," with results which indicate t h a t this bronze is very much superior t o any other alloy which has been used in condenser tubes in the presence of sea water, and especially in the presence of water in polluted harbors. Such bronzes have generally been known t o be particularly resistant t o corrosion, but, on account of the difficulties which were encountered in working the metals,
Mar., 1912
i t has not been possible t o handle them with success until recently. Another illustration of the choosing of a proper alloy for a specific purpose is shown in the failures of screens made from brass wire. A number of years ago considerable quantities of wire screens were required for houses in a tropical seaport. Brass wire screen was asked for, and furnished in 2 and I brass. The wire used was of fine size and when exposed t o atmospheric influences would easily give way. The result of the exposure of these screens was t h a t within a few weeks they had simply rotted and fallen t o pieces. It was claimed t h a t inferior brass had been furnished but this was not the case. Fine wire or thin sheets of alloys containing considerable zinc, when exposed t o sea air or t o atmospheres laden with sulphur or t o ammonia fumes which arise from decomposing nitrogenous matter in the presence of dampness, are more or less rapidly disintegrated. Experienced manufacturers of fine wire cloth are aware of this difficulty, and choose only alloys which carry small amounts of zinc, i. e., less than 2 0 per cent., these alloys not being subject t o the disintegrating action of such atmospheres as we have described. Owing t o the fact t h a t alloys have been looked upon as somewhat mysterious, there is a feeling t h a t it is simply necessary t o p u t together some unusual combinations t o make so-called new metals which will resist corrosion or have other valuable properties. This idea, even among intelligent people, is carried t o the extent t h a t statements are accepted t o the effect t h a t fluxes can be added to molten metal which will greatly modify the properties of the castings in their resistance to corrosion or their tensile strength or other physical properties. I t is safe t o assert t h a t one skilled in the a r t of making alloys can duplicate in every particular any alloy of which he can obtain a n adequate sample, provided, of course, that he has a t hand the facilities for its production. There is beginning t o be a well defined literature on the subject of alloys, and from what has already been published one can very closely predict the properties of various combinations of the more commonly known metals. For instance, Roberts-Austen, followed a number of yeais later b y E. S. Shepherd and still later b y Carpenter and Edwards, has very thoroughly covered the field of alloys of copper and zinc. The copper-tin alloys were similarly investigated b y Heycock and Neville, b y Shepherd and Upton, and b y others. The ternary alloys of copper, tin and zinc were pretty thoroughly investigated b y Thurston. An attempt t o give a n account of the work which has been done on the alloys of copper with aluminum, nickel, manganese and other metals would be entirely out of place a t this time. There are, of course, certain particular fields which have not been very thoroughly studied, but the general properties of the alloys in these fields may be known b y consulting a good metallurgical library. I simply desire t o indicate t h a t the microscope and the pyrometer have awakened new interest in the study of alloys and t h a t
Mar., 1912
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y .
this study has now progressed t o the point where one can find, by consulting a reliable authority upon the subject, data which will enable him to predict the nature of almost any alloy of which he can conceive. DISCUSSION.
MR. PARR: Mr. Chairman, I think i t is always dangerous t o talk about anything t h a t has not yet reached the point where you are satisfied with it. However, I do not know t h a t we are ever quite satisfied with anything we are doing, so I will venture a word as to m y work on alloys. It may not interest any one with a laboratory fund so liberal as to make it a n easy matter to keep up their platinum supply to the full extent of their requirerncnts, b u t the case is different with me where I have been obliged to keep actively on the job after sixteen years of almost daily service a piece of apparatus which has in its make-up some three hundred dollars worth of platinum. I refer t o a IIahler bomb of the Atwater type. But more than that, instead of a single bomb to serve the needs of two or three men in investigations, and twenty-five t o thirty students in class work, I want a t lcast a half dozen. I have therefore been attempting t o develop a n alloy with properties as resistant to nitric and sulphuric acids as platinum. We have reached a very satisfactory degree of success with an alloy of the nickel-chrome type having an amount of the latter constituent approximating 2 0 per cent. We have been able to produce quite a number of such pieces showing in 4N.HN0, or +N.H,SO,, or a mixture of the above acids when preferred, a unit of 100sq. cm. of surface and one hour of time, a solubility factor of 0.0 milligram. Other tests have shown dissolved metal to the extent of 0.09 mg., still others 0.17 mg., etc. Our greatest difficulties, however, have been met with in attempting t o cast this material, the shrinkage upon solidifying being very great. With a n alloy of high melting point, above IZOOO C., this feature has made the case a t times almost hopeless. However, we have so far succeeded t h a t a solid cap has been cast of this material and the same has been in use for over six months on our Atwater oxygen bomb with exceedingly gratifying results. MR. BUELL: I should like to ask Mr. Bassett with regard to the amount of ammonia produced from the decomposition of organic material in the various localities and if i t is sufficient t o materially affect brass. We occasionally have cartridges returned from some of the damp warm climates such as occur around Calcutta and in the vicinity of Memphis in this country, which crack in storage from no apparent reason. These cracks are not such as would come from heat cracking or from imperfect annealing or wrong composition. I would like to know if any one has had any such experience with brass. MR. BASSETT: With regard to the question t h a t Mr. Buell asked, I do not believe I know entirely as t o all of the causes for this disintegration of brass. Those mentioned are some t h a t I had had experience with. The exposure of brass articles t o ammonia fumes from a dirty stable, particularly if the brass is in a hard condition, might cause i t to break. An experience which I had a t one time illustrates how rapidly and seriously ammonia will attack brass. A solution,of copper sulphate a r d ammonia was mixed in a brass pail on Saturday afternoon. When the work with this solution was finished a n assistant was directed t o clean out the pail. He failed to do this, and on Monday morning i t was noticed that the solution had begun to leak out, and the pail dropped apart between wind and water, although it wasmade from heavy metal. The brass in the lower d o n was a most
169
perfect example of the so-called “disintegration of brass.” The ammonia solution had simply rotted the alloy. The difficulty in melting aluminum by itself, or in alloys, is its affinity for oxygen, and the failure of the oxide of aluminum t o separate itself from the metal. The aluminum oxide stays in the metal, making a mess and causing all sorts of trouble. It leaves the alloy rotten and full of dirt. MR. PRICE: I think I can supplement these remarks of Mr. Bassett by stating a specific instance which came to my notice. We make brass acetylene generators for automobiles. We had one of these returned t o us t h a t was disintegrated. Upon invcstigation, i t was found t h a t the disintegration was due to ammonia salts formed with the acetylene gas when the calcium carbide was acted upon by water.
-----WASTE AND CONSERVATION OF POTASH AND PHOSPHORIC ACID. B y F. R. CAMERON.
As far as the phosphates are concerned, there is a great deal of waste in the Florida fields. It varies there quite a little, but sometimes amounts t o as much as 2 0 0 or 300 per cent.; t h a t is to say, for every ton of phosphate rock mined there and ground for fertilizer, twice as much phosphate rock in a comminuted condition generally is thrown away, wasted. I n Tennessee, where large deposits of phosphate rock are found, the mining is very much cleaner than in Florida, and there is very little waste. The mining methods in t h a t section have been greatly improved in recent years, and the waste is falling off. In the Charleston, S. C., fields there is still a great deal of waste. The great problems in handling phosphates are t o insist upon clean mining, and to develop methods for segregating phosphoric acid from the rock phosphate and thus make low-grade material available. At the present time there is practically no high-grade rock, that is 7 2 per cent. bone phosphate, used in this country. All of the high-grade rock t h a t we mine, or practically all of it, is shipped abroad and the American market takes only the lower-grade material. I t is improbable, so far as we can judge, that there will be any very great consumption of the high-grade material in this country so long as the foreign demand keeps up, and we have t o utilize the lower-grade material. The estimates which we have been able to make from the survey of the existing fields of this country, indicate t h a t the deposits of the high-grade rock are so large that, a t three times the present rate of consumption in this country, it would last something like 1200 years; t h a t is, excluding any new discoveries. We have not only the Florida fields, the hard rock, the pebble rock, the Charleston field, the Arkansas field, the Kentucky field and the Tennessee field, but the largest deposits of high-grade rock in the world have been discovered in Montana, Utah, Idaho and Wyoming. There are a good many fields in this country t h a t carry some phosphorus in the rock, which makes i t useful locally from the fertilizer point of view; for
